Surveillance of Invasive Bacterial Disease in Alaska, 2014 

Arctic Investigations Program 

National Center for Emerging & Zoonotic Infectious Diseases 

Centers for Disease Control and Prevention 

4055 Tudor Centre Dr. 

Anchorage, AK 99508 

(907) 729-3400 

ncidaip@cdc.gov
Surveillance of Invasive Bacterial Disease in Alaska, 2014 2
Surveillance of Invasive Bacterial Disease in Alaska, 2014 3

Alaska Statewide Invasive Bacterial Disease 

Table of Contents 

 Page 

Summary 4 

Introduction 5 

Invasive Pneumococcal Disease 6 

Invasive Haemophilus influenzae 19 

 

Invasive Neisseria meningitidis 24 

Invasive Group A Streptococcus 25 

Invasive Group B Streptococcus 31 

References 37 

Appendix 39 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 4

Summary 

The Centers for Disease Control and Prevention's Arctic Investigations Program (AIP) in 

Anchorage, Alaska, maintains a statewide surveillance system for invasive diseases caused by 

Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, and groups A and B 

streptococci. Laboratories throughout the state are requested to send to AIP any isolates of these

organisms recovered from a blood culture, CSF, or other normally sterile site in an Alaska 

resident. Isolate identification is confirmed and, when appropriate, serotyped and tested for 

antimicrobial susceptibility. The objectives of this system are to provide information on disease 

rates within the state, monitor the emergence of antimicrobial resistance, and to monitor the 

effectiveness of implemented vaccine programs, such as the 23-valent pneumococcal 

polysaccharide vaccine, the pneumococcal conjugate vaccine and Haemophilus influenzae type b 

vaccines. 

Figure 1: Invasive Bacterial Disease Surveillance Regions – Alaska, 2014 

In 2014, the total numbers of cases of invasive disease caused by these organisms reported to 

AIP were 85 S. pneumoniae, 23 H. influenzae, 3 N. meningitidis, 57 group A Streptococci (GAS) 

Arctic Slope 

Interior 

Kotzebue 

Norton Sound 

YK Delta 

Bristol Bay 

Anchorage 

Southeast 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 5

and 65 group B Streptococci (GBS). Alaska Native people had higher rates of disease overall 

than non-Native people for all surveillance organisms. Rates of invasive pneumococcal disease 

were highest in the YK Delta and Kotzebue regions. Rates for each organism by region are 

presented in the following table. 

Table 1: Surveillance Organisms Reported by Region – Alaska, 2014 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

GAS 

n (rate*) 

GBS 

n (rate*) 

Anchorage 53 (10.8) 11 (2.2) 1 (0.2) 37 (7.6) 45 (9.2) 

Arctic Slope 2 (22.8) 1 (11.4) 0 (0) 0 (0) 0 (0) 

Bristol Bay 2 (27.3) 0 (0) 0 (0) 2 (27.3) 0 (0) 

Interior 12 (10.7) 4 (3.6) 0 (0) 4 (3.6) 6 (5.4) 

Kotzebue 3 (35.5) 0 (0) 1 (11.8) 1 (11.8) 0 (0) 

Norton Sound 0 (0) 0 (0) 1 (10) 2 (20) 0 (0) 

Southeast 6 (8) 2 (2.7) 0 (0) 2 (2.7) 10 (13.4) 

YK Delta 7 (26.6) 5 (19) 0 (0) 9 (34.2) 3 (11.4) 

Total 85 (11.5) 23 (3.1) 3 (0.4) 57 (7.7) 64 (8.7) 

*Cases per 100,000 population 

Introduction 

AIP conducts statewide surveillance of invasive Streptococcus pneumoniae, Haemophilus 

influenzae, Neisseria meningitidis, and groups A and B Streptococcus. This program is part of a 

passive, laboratory-based surveillance system in which laboratories from all hospitals throughout 

the state are encouraged to participate. The population included in the AIP surveillance is the 

State of Alaska, which totaled 737,354 persons in 2014 [1]. Case detection occurs year-round as 

participating laboratories send isolates recovered from sterile sites to the AIP laboratory in 

Anchorage; materials and forms for isolate shipment and data collection are provided to each 

laboratory by AIP. Demographic and clinical information on the cases are collected from a 

review of medical records. At year-end, AIP asks that each laboratory review their records and 

provide information on any cases that may have been overlooked. In 2014, 23 laboratories in 

Alaska participated in the invasive disease surveillance system, either by sending isolates to the 

AIP laboratory throughout the year, conducting year-end record reviews, or both. Beginning in 

January, 2007, invasive S. pneumoniae, GAS and GBS became reportable conditions to the State 

of Alaska Division of Public Health (DPH). Reports of cases of disease caused by these 

organisms, along with cases of invasive H. influenzae and N. meningitidis which were previously 

reportable, are shared between AIP and DPH. 

AIP defines a case of invasive S. pneumoniae, H. influenzae, N. meningitidis, GAS or GBS as an 

isolate of the bacteria from a normally sterile site, including blood, cerebrospinal fluid, pleural 

fluid, peritoneal fluid or joint fluid that has been taken from a resident of Alaska. In addition, for 

GAS, isolates are requested from deep tissue infections such as might be collected from surgical 

debridement of cases of necrotizing fasciitis.
Surveillance of Invasive Bacterial Disease in Alaska, 2014 6

Invasive Pneumococcal Disease 

Overall Incidence

A total of 75 pneumococcal isolates were received at AIP in 2014. An additional 10 cases were 

detected through shared surveillance with the State DPH for a total of 85 cases of invasive 

pneumococcal disease. The overall rate for invasive pneumococcal disease in 2014 was 11.5 

cases per 100,000 persons per year. Alaska rates for 2014 were higher than the Active Bacterial 

Core Surveillance (ABCs) 2014 national projected rate of 8.8/100,000 [2]. ABCs is a 

surveillance system operated in 10 states which covers a population of up to 42 million persons. 

Seasonality

Invasive Streptococcus pneumoniae cases were identified in each month of 2014. The largest 

number of cases (n=14) was reported in April. 

Race 

In 2014, the state population was comprised of 19% Alaska Native people (Alaska Natives 

143,367 non-Natives 593,987) [1]. Of all reported S. pneumoniae cases in 2014, 42% occurred 

among Alaska Native people for a total of 36 cases; the age-adjusted rate was 27.8/100,000 

persons per year. Forty-nine cases occurred among the non-Native population for an ageadjusted rate of 7.4/100,000 persons per year. The rate ratio of age-adjusted rates of S. 

pneumoniae disease for the Alaska Native population compared with the non-Native population 

in 2014 was 3.8. 

Table 2: Invasive Streptococcus pneumoniae Cases by Race – Alaska, 2014 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 36 (42) 27.8 67% 5 (14) 

Non-Native† 49 (58)† 7.4 61% 6 (12) 

Total 85 64% 11 (13) 

*Cases per 100,000 per percent distribution of Alaska 2010 population 

†Includes 3 cases for which race was unknown 

0

5

10

15 Number of Cases

Figure 2: Invasive Pneumococcal Disease, by 

Month of Culture - Alaska, 2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 7

Region 

The highest percentage (62%) of invasive pneumococcal disease cases occurred in the 

Anchorage area in 2014. Rates of disease, however, were highest in the Kotzebue region 

(35.5/100,000 persons per year), Bristol Bay (27.3/100,000 persons per year) and the YK Delta 

(26.6/100,000 persons per year). 

Age

Cases occurred in all age groups in 2014 ranging from 3 months to 91 years with a median age of 

58 years. Overall, the highest rates of disease occurred in children less than two years old and 

adults 65 years and older. 

 

When stratified by age and race, the highest rates of disease in 2014 occurred in Alaska Native 

adults 65 years and older (100.6/100,000 persons per year). 

0

20

40

0

20

40

60 Cases per 100,000 Number of Cases

Figure 3: Invasive Pneumococcal Disease, Cases 

& Rates by Region - Alaska, 2014

Cases

Rate

0

20

40

60

80

100

120

0

2

4

6

8

10

12

14

16

18

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000 Number of Cases

Age (yrs)

Figure 4: Invasive Pneumococcal Disease, Cases 

& Rates by Age Group & Race - Alaska, 2014

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2014 8

Since the initiation of a pneumococcal 7-valent conjugate vaccine program in 2001, overall rates 

of invasive disease declined dramatically in children less than 2 years of age [3]. In 2008, the 

rate of invasive pneumococcal disease in children less than 2 years declined to 65.6/100,000 

which was the lowest rate observed in this age group since introduction of the 7-valent vaccine. 

Following introduction of a 13-valent conjugate vaccine in 2010, rates of disease observed in 

children less than 2 years old declined to 18/100,000 in 2011. In 2012, however, disease rates in 

this age group increased to 60.3/100,000 due to disease caused by serotypes not included in the 

current vaccine. In 2014, rates have declined to 47.5/100,000. 

Although pneumococcal disease rates dropped initially in AK Native and non-Native children 

less than 2 years of age after introduction of the 7-valent vaccine, the rates of disease in AK 

Native children less than 2 years trended upward from a low of 93.6/100,000 in 2001 to 

335.9/100,000 in 2006. This increase in rates was due primarily to disease caused by serotypes 

not contained in the pneumococcal conjugate vaccine [4,5]. In 2009, rates of disease in AK 

Native children less than 2 years declined to 87.1/100,000 which was the lowest rate since the 

introduction of the seven-valent pneumococcal vaccine. After introduction of the 13-valent 

vaccine in 2010, rates declined to 30.7/100,000 in 2011, however, increased to 177.5/100,000 in 

2012 and declined to 70.1/100,000 in 2014. All four of the cases in AK Native children less than 

2 years old during 2014 were caused by serotypes not contained in the 13-valent vaccine. Rates 

of invasive disease in non-Native children less than 2 years declined during the same time period 

reaching 26.8/100,000 in 2005, and following an increase to 64.4/100,000 in 2007, declined in 

2008 to 6.2/100,000. In 2009, the rate of disease in non-Native children less than 2 years 

increased to 60.3/100,000, but declined to 13/100,000 in 2012 with use of the 13-valent vaccine. 

Following an increase in 2013 (26.3/100,000), rates in non-Native children less than 2 years 

were similar in 2014 (25.9/100,000); three of four cases were caused by non-vaccine serotypes 

and the serotype for the fourth case was unknown. 

0

20

40

60

80

100

120

140

160

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000

Age (yrs)

Figure 5: Invasive Pneumococcal Disease by Age 

Group - Alaska, 2005-2014

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 9

Clinical Presentation

The primary clinical presentation was determined by a review of the discharge diagnoses in each 

patient’s individual medical record associated with the invasive bacterial illness. In cases with 

multiple discharge diagnoses, the most serious diagnosis related to the pneumococcal infection 

was recorded as the primary clinical presentation. Pneumonia with bacteremia was the most 

common primary clinical presentation in 2014 (66%) followed by bacteremia (24%). Three 

cases had a secondary pneumococcal-related diagnosis in 2014; all were pneumonia with 

bacteremia. 

0

100

200

300

400

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000

Age (yrs)

Figure 6: Invasive Pneumococcal Disease in 

Alaska Natives, by Age Group - Alaska, 2005-2014

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

0

100

200

300

400

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000

Age (yrs)

Figure 7: Invasive Pneumococcal Disease in NonNatives, by Age Group - Alaska, 2005-2014

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 10

In 2014, blood was the most common source of a positive culture which was used to identify 82 

(97%) of 85 cases. Three cases were identified from a surgical specimen. 

Mortality 

In 2014, the overall case fatality ratio for S. pneumoniae in Alaska was 13% (11 deaths out of 85 

cases). The case fatality ratio for AK Natives was similar (14%, 5 deaths) to non-Natives (12%, 

6 deaths). The largest number of deaths occurred in the 65 and older age category (6 deaths), 

however, the highest case fatality ratio occurred in the 2-4 age category (1 death) 33%. 

Serotype 

Serotyping of invasive pneumococcal isolates is performed at AIP using internationally 

standardized methods. Serotype identification is based on the organism’s polysaccharide capsule 

which is a principal virulence factor for pneumococci. This information provides a way to 

categorize organisms and to determine if the infection was due to a type that could be prevented 

56

20

2 1 1 1 1 1 1 1 1

0

20

40

60 Number of Cases

Figure 8: Primary Clinical Presentations of 

Invasive Pneumococcal Disease - Alaska, 2014

*with bacteremia

0

5

10

15

20

25

30

35

0

1

2

3

4

5

6

7

<2 2-4 5-18 19-54 55-64 65+ Case Fatality Ratio (%) Number of Deaths

Age (yrs)

Figure 9: Invasive Pneumococcal Deaths & Case 

Fatality Ratios by Age Group - Alaska, 2014

Deaths

CFR
Surveillance of Invasive Bacterial Disease in Alaska, 2014 11

by use of one of the available pneumococcal vaccines. Serotyping was performed on all of the S. 

pneumoniae cases for which an isolate was available. 

Table 3: Invasive Pneumococcal Serotype Distribution by Race and Age Group – Alaska, 2014 

 Alaska Native Non-Native 

Serotype Total n (%) <2 2-4 5-18 19-64 65+ <2 2-4 5-18 19-64 65+ 

03 7 (10) - - - 2 - - - - 3 2 

06C 3 (4) - - - - 2 - - - - 1 

07C 1 (1) - - - - - - - - - 1 

07F 2 (3) - 1 - - - - - - 1 - 

08 3 (4) - - - - - - - - 3 - 

09N 9 (12) - - - 3 - - - - 5 1 

10A 2 (3) 1 - - - - - - - - 1 

12F 3 (4) - - - - 1 - - - 2 - 

15A 2 (3) - - - 2 - - - - - - 

15C 1 (1) - - - - 1 - - - - - 

16F 7 (10) - - - 4 1 - - - 2 - 

19A 2 (3) - - - - 1 - 1 - - - 

19F 1 (1) - - - - - - - - - 1 

20 2 (3) - - - 1 - - - - 1 - 

22F 11 (15) 1 1 - - 1 2 - - 3 3 

23A 2 (3) - - - 1 - - - - - 1 

23B 1 (1) - - - 1 - - - - - - 

28A 2 (3) - - - 1 - - - - - 1 

29 1 (1) 1 - - - - - - - - - 

31 2 (3) - - - 1 - - - - 1 - 

33F 4 (5) 1 - - 2 - - - - 1 - 

35B 3 (4) - - - - - - - - 2 1 

35F 1 (1) - - - - - - - - - 1 

38 2 (3) - - - - 1 1 - - - - 

Total 74 4 2 0 18 8 3 1 0 24 14 

In 2014, the most common pneumococcal serotypes were 22F, (11 isolates, 15%), 9N (9 isolates, 

12%), 3 (7 isolates, 10%) and 16F (7 isolates, 10%). From 1986 through 2001, serotype 14 was 

the most common invasive pneumococcal serotype ranging from 7.4% to 23.5% of isolates. 

Following introduction in 2001 of the pneumococcal conjugate vaccine which includes serotype 

14, the proportion of serotype 14 isolates dropped to 1.5% of serotyped isolates in 2006 and there 

were no serotype 14 cases in 2014. Disease caused by serotypes 7F and 19A, which are not 

included in the 7-valent conjugate vaccine, continually increased until the introduction of the 13-

valent vaccine in 2010 which does include these two serotypes. Although cases caused by 7F 

and 19A continue to occur, they are no longer the most common serotypes and it is anticipated 

that the number of cases will continue to decline with the use of the vaccine. The majority (50%) 

of serotype 22F cases and serotype 9N cases (78%) occurred in the Anchorage area in 2014. 

 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 12

Table 4: Invasive Pneumococcal Serotype Distribution by Region – Alaska, 2014 

Serotype Anchorage Arctic Slope Bristol Bay Interior Kotzebue Norton Sound Southeast YK Delta 

03 4 - - 3 - - - - 

06C 2 - - 1 - - - - 

07C 1 - - - - - - - 

07F - - - - - - 1 1 

08 2 - - 1 - - - - 

09N 7 - - - 1 - 1 - 

10A 2 - - - - - - - 

12F 2 - - - - - - 1 

15A 1 - - - - - - 1 

15C 1 - - - - - - - 

16F 7 - - - - - - - 

19A - - - 1 - - - 1 

19F 1 - - - - - - - 

20 1 1 - - - - - - 

22F 6 - - 3 1 - - 1 

23A 2 - - - - - - - 

23B 1 - - - - - - - 

28A 2 - - - - - - - 

29 - - - - - - - 1 

31 2 - - - - - - - 

33F 1 1 - 1 1 - - - 

35B 2 - - - - - - 1 

35F 1 - - - - - - - 

38 1 - - - - - 1 - 

Unknown 8 - 2 2 - - 3 - 

Total 53 2 2 12 3 0 6 7 

Vaccine Serotypes

In 2001, the pneumococcal conjugate vaccine (PCV7) was included in the Alaska childhood 

vaccination schedule. This vaccine provided protection against the 7 most common 

pneumococcal serotypes causing invasive disease among children (types 4, 6B, 9V, 14, 18C, 

19F, 23F). In early 2010, a new pneumococcal conjugate vaccine (PCV13) was introduced into 

the Alaska childhood vaccination schedule. This vaccine provided protection against the 7 

pneumococcal serotypes contained in the PCV7 vaccine plus six additional serotypes (1, 3, 5, 

6A, 7F, 19A) that have caused invasive disease since the introduction of the PCV7 vaccine. The 

table below shows the proportion of invasive infections from 2014 that were due to serotypes 

found in the PCV13 vaccine. There were two cases of pneumococcal disease caused by 

serotypes contained in the PCV13 vaccine in children less than 5 years of age, the age group for 

which the vaccine is recommended. It is anticipated that the number of cases caused by these 

serotypes will decrease over time. 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 13

Table 5: Proportion of Invasive Isolates Contained in the PCV13 Vaccine by Age Group 

and Race – Alaska, 2014 

Age (yrs) Alaska Native (%) Non-Native (%) Total (%) 

<2 0 (0%) of 4 0 (0%) of 4 0 (0%) of 8 

2-4 1 (50%) of 2 1 (100%) of 1 2 (67%) of 3 

5+ 3 (10%) of 30 7 (16%) of 44 10 (16%) of 74 

Total 4 (12%) of 36 8 (16%) of 49 12 (14%) of 85 

For the year covered by this report, the 23-valent polysaccharide vaccine (Ps23V) was 

recommended in Alaska for all persons 65 years and older, and for persons over age 2 who are at 

higher risk for pneumococcal disease [5]. In 2014, for persons 65 years and older, 11 (50%) of 

22 cases serotyped were potentially vaccine preventable invasive pneumococcal illnesses. 

Vaccine Failures 

In 2014, pneumococcal vaccine status was known for 72 (85%) of the 85 cases; 53% (n=38) of 

cases with known vaccine status did receive a pneumococcal vaccine prior to illness and 34 cases 

(47%) had no record of a pneumococcal vaccine. 

A PCV13 vaccine failure is defined as invasive pneumococcal disease caused by a serotype 

contained in the PCV13 vaccine in a child less than five years old who has had at least two doses 

of vaccine. There was one vaccine failure in 2014. The child had received 4 doses of PCV13 

and had anemia and vitamin D deficiency; serotype of the case was 7F. 

Potentially Preventable Deaths

Overall, 46% of all pneumococcal-related mortality in 2014 was potentially preventable with the 

use of the 23-valent polysaccharide vaccine in persons over 5 years old; 46% of deaths were due 

to disease caused by serotypes not contained in the 23-valent vaccine. 

Table 6: Potentially Vaccine Preventable Invasive Pneumococcal Deaths – Alaska, 2014 

Serotypes < 2 years 2-4 5-18 19-54 55-64 65+ Total 

PCV13 0 1 (100%) 0 0 0 0 1 (9%) 

Ps23V 0 0 0 1 (50%) 0 3 (50%) 4 (36%) 

Non-Vaccine 1 (100%) 0 0 1 (50%) 1 (100%) 2 (33%) 5 (46%) 

Unknown 0 0 0 0 0 1 (17%) 1 (9%) 

Total 1 1 0 2 1 6 11 

Four of the 11 deaths in 2014 from invasive S. pneumoniae occurred from serotypes contained 

within the Ps23V vaccine; three of the deaths were in individuals eligible for the vaccine. One 

death occurred in a vaccinated individual; time since vaccination was 5 years. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 14

Table 7: Invasive Pneumococcal Disease, Serotypes of Fatal Cases – Alaska, 2014 

Serotype 

Deaths 

n (%) 

Serotype 

Frequency (n) 

03†* 2 (29%) 7 

06C 1 (33%) 3 

09N* 1 (11%) 9 

15A 1 (50%) 2 

19A†* 2 (100%) 2 

35B 1 (33%) 3 

35F 1 (100%) 1 

38 1 (50%) 2 

† Serotypes contained in the 13-valent conjugate vaccine 

*Serotypes contained in the 23-valent polysaccharide vaccine 

Associated Risk Factors

The presence of one or more associated risk factors was reported in 78% of invasive 

pneumococcal cases in 2014. Cigarette smoking was the most prevalent risk factor observed in 

adults followed by chronic lung disease and alcohol abuse. 

Table 8: Associated Risk Factors Identified in Invasive Pneumococcal Cases – Alaska, 

2014* 

Risk Factor 

Adult Cases (≥ 18 years) 

n=74, Cases (%) 

Cigarette smoking 29 (39%) 

Chronic lung disease 27 (37%) 

Alcohol abuse 19 (26%) 

Diabetes 15 (20%) 

Immunosuppressive treatment 3 (4%) 

Injection drug use 0 (0%) 

Asplenia 0 (0%) 

*More than one risk factor was identified in several cases 

Antibiotic Resistance

Susceptibility testing was performed on 74 isolates received in 2014. Results of the testing are 

presented in the following table. 

Table 9: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2014 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 65 (88%) 3 (4%) 6 (8%) 9 (12%) 74 

TMP-sulfa 65 (88%) 7 (9%) 2 (3%) 9 (12%) 74 

Erythromycin 56 (76%) 0 (0%) 18 (24%) 18 (24%) 74 

Ceftriaxone 69 (93%) 3 (4%) 2 (3%) 5 (7%) 74 

Tetracycline 68 (92%) 0 (0%) 6 (8%) 6 (8%) 74 

Chloramphenicol 71 (96%) 0 (0%) 3 (4%) 3 (4%) 74 

Vancomycin 74 (100%) 0 (0%) 0 (0%) 0 (0%) 74 

Levofloxacin 74 (100%) 0 (0%) 0 (0%) 0 (0%) 74 

Clindamycin 68 (92%) 0 (0%) 6 (8%) 6 (8%) 74 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 15

Cut points from the Minimum Inhibitory Concentration (MIC) Interpretive Standards were used 

to determine if an isolate was ‘susceptible’, ‘intermediate’, or ‘resistant’ to the antibiotic being 

tested [7]. The MIC Interpretive Standards definitions of ‘susceptible’, ‘intermediate’, and 

‘resistant’ can be found in the Appendix. 

Serotypes found in the PCV7 and PCV13 vaccines are more likely to be non-susceptible to 

penicillin and erythromycin than non-vaccine serotypes. One potential benefit of the use of these 

vaccines was an anticipated decline in antibiotic resistance among circulating pneumococci. 

Following the initiation of the PCV7 vaccine in 2001, antibiotic resistance among invasive 

pneumococci dropped. During 2003, TMP-sulfa and penicillin resistance increased, however, 

following an increase in disease caused by serotype 19A. This serotype is included in the 

PCV13 vaccine; decreasing proportions of isolates resistant to most antibiotics tested may be due 

to the introduction of the vaccine. However, the proportion of isolates resistant to erythromycin 

has increased which is a trend that was also seen after the introduction of PCV7 [8]. 

 0

5

10

15

20

25

30

35 Percent Resistant

Year

Figure 10: Trends in Antibiotic Non-Susceptibility Among 

Invasive Pneumococcal Isolates - Alaska, 1994 - 2014

Penicillin

Erythro

TMP-Sulfa

Tet
Surveillance of Invasive Bacterial Disease in Alaska, 2014 16

Table 10: Summary of Invasive Streptococcus pneumoniae Case Characteristics, Alaska, 2014 

Sex 

Age 

(Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype Associated Risk Factors Survived 

M 0.3 Non-Native Anchorage Blood Bacteremia 38 None No 

M 0.5 AK Native Anchorage Blood Bacteremia 22F Immune suppressive 

therapy, diabetes Yes 

M 0.6 AK Native Other Surgical 

specimen Empyema 33F None Yes 

M 0.9 AK Native Other Blood Pneumonia 29 None Yes 

M 1.4 Non-Native Anchorage Blood Bacteremia 22F None Yes 

M 1.5 Non-Native Anchorage Blood Bacteremia 22F None Yes 

M 1.6 AK Native Anchorage Blood Pneumonia 10A None Yes 

F 1.9 Unknown Other Blood Bacteremia ND None Yes 

F 2.1 AK Native Other Blood Pneumonia 22F None Yes 

M 2.9 Unknown Other Blood Pneumonia 19A None No 

F 3.5 AK Native Other Blood Pneumonia 07F None Yes 

M 26.1 Non-Native Other Surgical 

specimen Bacteremia ND Smoking Yes 

F 32 Non-Native Anchorage Blood Endometritis 12F Chronic lung disease Yes 

M 33.4 AK Native Anchorage Blood Pneumonia 09N Alcohol abuse Yes 

M 35.4 AK Native Other Blood Pneumonia 09N Alcohol abuse Yes 

M 36.8 Non-Native Anchorage Blood Pneumonia 16F Smoking Yes 

M 40.3 Non-Native Other Blood Pneumonia ND None Yes 

M 41.8 Non-Native Anchorage Blood Bacteremia 09N Smoking Yes 

M 44 AK Native Other Blood Pneumonia 20 None Yes 

M 44.1 AK Native Anchorage Blood Pneumonia 31 Alcohol abuse Yes 

M 44.7 AK Native Anchorage Blood Bacteremia 15A Chronic lung disease, 

alcohol abuse, diabetes No 

M 45.8 Non-Native Anchorage Blood Bacteremia 09N None Yes 

F 48.1 AK Native Other Blood Pneumonia 03 Alcohol abuse No 

F 49.1 AK Native Anchorage Blood Pneumonia 16F Smoking, chronic lung 

disease, alcohol abuse Yes 

M 50.3 Non-Native Anchorage Blood Pneumonia 16F Smoking, alcohol abuse Yes 

M 50.6 AK Native Other Blood Pneumonia ND Smoking, alcohol abuse Yes 

M 52 AK Native Anchorage Blood Cellulitis 16F Smoking, chronic lung 

disease Yes 

F 52.2 Unknown Other Blood Bacteremia ND None Yes 

M 52.5 Non-Native Other Blood Pneumonia 07F Smoking, alcohol abuse Yes 

M 52.9 Non-Native Other Blood Pneumonia 33F Smoking Yes 

F 53.1 Non-Native Anchorage Blood Pneumonia 09N None Yes 

M 53.1 Non-Native Anchorage Blood Pneumonia 12F None Yes 

M 53.2 Non-Native Other Blood Pneumonia 09N None Yes 

M 53.4 Non-Native Anchorage Blood Pneumonia ND Smoking, diabetes Yes 

M 53.8 AK Native Anchorage Blood Pneumonia 28A Smoking Yes 

M 55.1 AK Native Anchorage Blood Pneumonia ND None Yes 

F 55.4 Non-Native Anchorage Blood Pneumonia 31 Smoking, chronic lung 

disease Yes 

M 56.2 AK Native Anchorage Blood Pneumonia 16F Alcohol abuse Yes 

F 56.4 AK Native Anchorage Blood Bacteremia 16F Smoking, alcohol abuse Yes 

F 56.5 Non-Native Other Blood Bacteremia 22F Diabetes Yes 

M 56.9 Non-Native Anchorage Blood Pneumonia 35B 

Smoking, chronic lung 

disease, immune 

suppressive therapy 

No 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 17

Sex 

Age 

(Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype Associated Risk Factors Survived 

M 57.1 Non-Native Other Blood Pneumonia 03 Chronic lung disease, 

diabetes Yes 

M 57.6 Non-Native Anchorage Blood Pneumonia 09N Smoking, chronic lung 

disease Yes 

M 57.8 Non-Native Other Blood Pneumonia 22F Smoking, diabetes Yes 

M 58.4 Non-Native Other Blood Pneumonia 03 None Yes 

F 58.9 AK Native Anchorage Blood Empyema, 

pneumonia 23A Smoking, immune suppressive therapy Yes 

F 59.2 Non-Native Anchorage Blood Pneumonia 03 Chronic lung disease, 

alcohol abuse, diabetes Yes 

M 59.2 Non-Native Anchorage Blood Pneumonia 08 None Yes 

F 59.8 Non-Native Anchorage Blood Meningitis 08 None Yes 

M 60.2 Non-Native Other Blood Pneumonia 08 Smoking, chronic lung 

disease, diabetes Yes 

M 60.8 AK Native Anchorage Blood Pneumonia 03 Smoking, chronic lung 

disease Yes 

F 60.8 Non-Native Anchorage Blood Pneumonia 20 Smoking, chronic lung 

disease Yes 

M 60.9 AK Native Anchorage Blood Pneumonia 09N Smoking, chronic lung 

disease Yes 

F 61.9 AK Native Other Blood Pneumonia 33F Smoking Yes 

M 62 AK Native Other Blood Other 15A Chronic lung disease, 

alcohol abuse Yes 

F 62.1 Non-Native Anchorage Blood Pneumonia 22F 

Chronic lung disease, 

immune suppressive 

therapy, diabetes 

Yes 

F 63.3 AK Native Anchorage Blood Bacteremia 23B Smoking, alcohol abuse Yes 

M 64.3 Non-Native Other Blood Peritonitis, 

pneumonia 35B None Yes 

M 64.7 AK Native Anchorage Blood Pneumonia 33F Smoking, chronic lung 

disease, alcohol abuse Yes 

M 65.5 AK Native Other Blood Pneumonia 19A Smoking, chronic lung 

disease No 

F 66.4 Non-Native Anchorage Blood Pneumonia 07C None Yes 

F 68.5 AK Native Anchorage Blood Pneumonia 16F None Yes 

M 69 Non-Native Anchorage Blood Pneumonia 22F Chronic lung disease Yes 

M 70.2 Non-Native Anchorage Blood Bacteremia 35F None No 

M 70.6 AK Native Other Blood Osteomyelitis 22F Smoking, chronic lung 

disease Yes 

F 71.3 Non-Native Anchorage Blood Pneumonia 03 None Yes 

F 73 Non-Native Anchorage Blood Bacteremia 19F Chronic lung disease Yes 

M 73.3 Non-Native Anchorage Blood Pneumonia ND Diabetes Yes 

F 74.4 Non-Native Anchorage Blood Bacteremia 10A None Yes 

M 75.2 Non-Native Anchorage Blood Pneumonia 03 Alcohol abuse No 

M 75.9 AK Native Anchorage Blood Pneumonia 15C Chronic lung disease, 

alcohol abuse Yes 

F 77.6 Non-Native Other Blood Pneumonia 22F Chronic lung disease, 

diabetes Yes 

M 77.7 AK Native Other Blood Pneumonia ND Smoking, diabetes No 

M 78.1 Non-Native Anchorage Blood Pneumonia 06C None Yes 

M 78.5 Non-Native Anchorage Blood Pneumonia 23A Smoking, chronic lung 

disease, diabetes Yes 

M 79 AK Native Other Surgical 

specimen Bacteremia ND None Yes 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 18

Sex 

Age 

(Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype Associated Risk Factors Survived 

F 80.1 AK Native Other Blood Pneumonia 06C Chronic lung disease Yes 

M 80.5 Non-Native Anchorage Blood Pneumonia 28A None Yes 

F 81.3 AK Native Other Blood Pneumonia 12F Diabetes Yes 

F 82 Non-Native Anchorage Blood Bacteremia 35B Chronic lung disease, 

diabetes Yes 

F 82 Non-Native Anchorage Blood Septic arthritis ND Chronic lung disease Yes 

M 82.8 AK Native Anchorage Blood Bacteremia 06C Smoking No 

F 83.7 AK Native Other Blood Pneumonia 38 Diabetes Yes 

F 84.9 Non-Native Anchorage Blood Pneumonia 09N Chronic lung disease No 

F 90.7 Non-Native Anchorage Blood Pneumonia 22F None Yes 

ND = typing not done 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 19 

Invasive Haemophilus influenzae

Overall Incidence 

In 2014, there were 23 cases of invasive Haemophilus influenzae in Alaska, for a statewide rate of 

3.1/100,000 persons per year. This rate is higher than the national projected rate of 1.63/100,000 

persons per year [9]. There were five deaths associated with H. influenzae in 2014 for a case fatality 

ratio of 22%. 

Seasonality 

Cases of invasive H. influenzae occurred throughout 2014; however, due to the small number of cases, 

trends in seasonality cannot be determined. The largest number of cases (n=4) occurred in February and 

October. 

Region 

The highest rates of disease caused by invasive H. influenzae cases in 2014 were in the regions of the 

YK Delta, 19/100,000 (5 cases), and the Arctic Slope, 11.4/100,000 (1 case). Although a large number 

of cases occurred in the Anchorage area (11 cases), the rate was much lower (2.2/100,000). 

0

1

2

3

4

5 Number of Cases

Month of Culture

Figure 11: Haemophilus influenzae Disease by 

Month of Culture - Alaska, 2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 20 

Race 

Table 11: Invasive Haemophilus influenzae Cases by Race – Alaska, 2014 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 12 (52%) 7.9 58% 3 (25%) 

Non-Native 11 (48%) 1.7 64% 2 (18%) 

Total 23 61% 5 (22%) 

*Cases per 100,000 per percent distribution of Alaska 2010 population 

In 2014, 52% of the cases occurred in Alaska Natives. Age-adjusted rates were calculated for Alaska 

Natives and non-Natives. The age-adjusted rate ratio of H. influenzae disease for the Alaska Native 

population compared with the non-Native population in 2014 was 4.6. 

Age 

H. influenzae cases ranged in age from newborn to 95 years of age in 2014 (median 39.2 years). 

Overall, the highest rates of disease occurred in children less than 2 years old (33.1/100,000). 

Rates of disease in Alaska Native versus non-Native populations by age group were variable; overall 

numbers of cases and rates by race and age group are presented in Figure 14. The highest rates of 

disease occurred in Alaska Native children less than two years of age, 87.7/100,000 persons per year and 

Alaska Native adults 65 years and older, 20.1/100,000 persons per year. 

0

10

20

0

2

4

6

8

10

12 Cases per 100,000 Number of Cases

Figure 12: Invasive Haemophilus influenzae, Cases & Rates by Region - Alaska, 2014

Cases

Rate
Surveillance of Invasive Bacterial Disease in Alaska, 2014 21 

Clinical Presentation 

The primary clinical presentation was determined by a review of the discharge diagnoses in each 

patient’s individual medical record associated with the invasive bacterial illness. For cases with more 

than one diagnosis, the most serious H. influenzae-related diagnosis was recorded as the primary clinical 

presentation. In 2014, pneumonia with bacteremia and bacteremia alone were the most common 

presentation (52% and 39% of cases, respectively). 

Twenty-two (96%) H. influenzae isolates were from blood samples in 2014, and one was from 

cerebrospinal fluid. 

0

10

20

30

40

50

<2 2-4 5-18 19-54 55-64 65+ Rate per 100,000

Age (yrs)

Figure 13: Invasive Haemophilus influenzae by 

Age Group - Alaska, 2014

0

20

40

60

80

100

0

1

2

3

4

5

6

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000 Number of Cases

Age (yrs)

Figure 14: Invasive Haemophilus influenzae, Cases & 

Rates by Age Group & Race - Alaska, 2014

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2014 22 

Table 12: Primary Clinical Presentation of Invasive Haemophilus influenzae - Alaska, 2014 

Primary Presentation n (%) 

Pneumonia* 12 (52%) 

Bacteremia 9 (39%) 

Meningitis 1 (4%) 

Cellulitis* 1 (4%) 

Total 23 

*with bacteremia 

Serotypes 

All isolates received at AIP are serotyped; all 23 cases in 2014 had isolates and were serotyped. The 

bacterial capsule is the basis for serotyping and is the primary virulence factor. Serotype b was the most 

common serotype in the past, but its prevalence has decreased with use of the childhood Hib vaccine. 

Surveillance of serotypes is important for monitoring vaccine effectiveness and emergence of nonvaccine serotypes. 

Table 13: Serotypes of Invasive Haemophilus influenzae Cases by Race – Alaska, 2014 

 Alaska Native Non-Native 

Serotype Total n (%) <2 2-18 19-64 65+ <2 2-18 19-64 65+ 

a 2 (9%) 2 - - - - - - - 

b 1 (4%) - 1 - - - - - - 

e 1 ((4%) - - 1 - - - - - 

f 2 (9%) - - - - 1 - - 1 

NT* 17 (74%) 3 - 3 2 1 - 4 4 

Total 23 5 1 4 2 2 0 4 5 

*Non-typeable 

Hib

In recent years, the prevalence of H. influenzae type b has declined due to increased use of a childhood 

vaccine against this serotype. There were no cases of Hib in children less than 5 years old in 2014. 

Hia 

Prior to 2002, H. influenzae type a (Hia) had not been detected in Alaska. Following an outbreak in 

2003 [10], cases have occurred sporadically until 2010 when an outbreak began in the YK Delta and 

continued through 2011 [11]. Two cases of Hia were detected in 2014; all occurred in AK Native 

children less than 2 years old. The rate of invasive disease caused by Hia in AK Native children less 

than 2 years old for 2014 was 35.1/100,000. 

Antibiotic Resistance 

Twenty-three H. influenzae isolates received at AIP were tested for susceptibility to ampicillin, 

chloramphenicol, ceftriaxone and TMP/sulfa. All isolates tested were susceptible to ceftriaxone and 

chloramphenicol, 13 isolates were resistant to ampicillin (5 intermediate, 8 fully resistant) and 15 

isolates were resistant to TMP/sulfa (8 intermediate and 8 fully resistant). 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 23 

Table 14: Summary of Invasive Haemophilus influenzae Case Characteristics, Alaska, 2014 

Sex Age (Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype* Associated Risk Factors Survived 

F Newborn AK Native Anchorage Blood Bacteremia NT None Yes 

F 0.1 Non-Native Other Blood Pneumonia NT None Yes 

M 0.3 Non-Native Anchorage Blood Bacteremia f None Yes 

F 0.5 AK Native Anchorage CSF Meningitis, 

empyema 

NT None Yes 

F 0.5 AK Native Other Blood Cellulitis a None Yes 

M 1 AK Native Other Blood Pneumonia a None Yes 

M 1.1 AK Native Other Blood Pneumonia NT None Yes 

M 5.5 AK Native Other Blood Pneumonia b None Yes 

F 23.3 Non-Native Anchorage Blood Bacteremia NT None Yes 

F 30.5 AK Native Other Blood Pneumonia e Alcohol abuse No 

M 33.9 Non-Native Other Blood Bacteremia NT None Yes 

F 39.2 AK Native Other Blood Pneumonia NT 

Smoking, alcohol 

abuse, injection drug 

use 

No 

M 48.8 AK Native Other Blood Pneumonia NT 

Smoking, alcohol 

abuse, injection drug 

use 

Yes 

M 49.8 AK Native Anchorage Blood Pneumonia NT Smoking, alcohol 

abuse Yes 

F 57.9 Non-Native Anchorage Blood Bacteremia NT Chronic lung disease, 

diabetes Yes 

M 61.6 Non-Native Other Blood Bacteremia NT 

Chronic lung disease, 

immune suppressive 

therapy, diabetes 

No 

M 67.7 Non-Native Anchorage Blood Pneumonia f Chronic lung disease, 

diabetes Yes 

M 73.6 AK Native Other Blood Bacteremia NT None No 

M 76.1 AK Native Other Blood Bacteremia NT 

Chronic lung disease, 

immune suppressive 

therapy 

Yes 

M 80.7 Non-Native Anchorage Blood Pneumonia NT Smoking, chronic lung 

disease, alcohol abuse Yes 

M 90.7 Non-Native Anchorage Blood Pneumonia NT Chronic lung disease Yes 

F 94.4 Non-Native Anchorage Blood Bacteremia NT None Yes 

M 95 Non-Native Anchorage Blood Pneumonia NT Diabetes No 

*NT = non-typeable 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 24 

Invasive Neisseria meningitidis

Overall Incidence

Three cases of invasive Neisseria meningitidis were reported to AIP in 2014 for an overall rate of 

0.4/100,000. The Alaska rate is slightly higher than the ABCs 2014 national projected rate of 

0.14/100,000 [12]. There were no invasive N. meningitidis-related deaths in Alaska in 2014. 

 

Race 

Table 15: Invasive Neisseria meningitidis Cases by Race – Alaska, 2014 

Race 

Cases 

 n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 2 (67%) 1.3 100% 0 (0%) 

Non-Native 1 (33%) 0.3 0% 0 (0%) 

Total 3 67% 0 (0%) 

*Cases per 100,000 per percent distribution of Alaska 2010 population 

In 2014, 67% of the cases occurred in Alaska Natives. Age-adjusted rates were calculated for Alaska 

Natives and non-Natives. The age-adjusted rate ratio of N. meningitidis disease for the Alaska Native 

population compared with the non-Native population in 2014 was 4.3. 

Table 16: Summary of Invasive Neisseria meningitidis Case Characteristics, Alaska, 2014 

Sex Age (Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serogroup 

Associated Risk 

Factors Survived 

M 7.1 AK Native Other Blood Meningitis C None Yes 

M 25.4 AK Native Other Blood Bacteremia C Smoking, alcohol 

abuse Yes 

F 73.1 Non-Native Anchorage Blood Meningitis, 

cellulitis C 

Smoking, chronic 

lung disease, 

diabetes 

Yes 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 25 

Invasive group A Streptococcus

Overall Incidence

A total of 57 cases of invasive group A Streptococcus (GAS) were reported to AIP in 2014. The overall 

rate of invasive GAS disease in the state of Alaska was 7.7/100,000 persons per year. The Alaska rate is 

higher than the ABCs 2014 national projected rate of 4.4/100,000 [13]. In 2014, there were 4 GASrelated deaths for a case fatality ratio of 7%. 

Seasonality 

Cases of group A Streptococcus occurred throughout the year in 2014 with no apparent trends in 

seasonality. The largest number of cases (n=8) occurred in October. 

Race

In 2014, 47% of invasive GAS cases in Alaska occurred in the Alaska Native population. The ageadjusted rate ratio of invasive GAS disease for the Alaska Native population compared with the nonNative population in 2014 was 4.3. 

Table 17: Invasive group A Streptococcus Cases by Race – Alaska, 2014 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 27 (47%) 21.9 67% 1 (4%) 

Non-Native 30† (53%) 5.1 63% 3 (10%) 

Total 57 65% 4 (7%) 

*Cases per 100,000 per percent distribution of Alaska 2010 population 

†Includes one case for which race is unknown 

 

0

1

2

3

4

5

6

7

8

9 Number of Cases

Month of Culture

Figure 15: Invasive group A Streptococcus, by 

Month of Culture - Alaska, 2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 26 

Region 

Thirty-seven (65%) of the 57 invasive group A Streptococcus cases in 2014 were reported in the 

Anchorage area, 9 cases in the YK Delta, 4 cases in the Interior, 2 cases each in Bristol Bay, Norton 

Sound and Southeast, and 1 case in Kotzebue. The highest rates of disease occurred in the YK Delta 

(34.2/100,000) and Bristol Bay (27.4/100,000). 

Age

Invasive group A Streptococcus cases reported in 2014 ranged in age from 3 months to 93.5 years old; 

the median age was 44.6 years. Highest rates of disease occurred in adults 65 years and older 

(15.4/100,000). 

When stratified by race, the highest rates of invasive group A streptococcal disease occurred in Alaska 

Native adults 55-64 years old (44.74/100,000 persons per year). The highest GAS disease rate in the 

non-Native population occurred in children less than two years old (13/100,000 persons per year). 

0

10

20

30

40

0

10

20

30

40 Number of Cases Cases per 100,00

Figure 16: Invasive GAS Disease, Cases & Rates 

by Region - Alaska, 2014

Cases

Rate

0

2

4

6

8

10

12

14

16

18

<2 2-4 5-18 19-54 55-64 65+ Rate per 100,000

Age (yrs)

Figure 17: Invasive group A Streptococcus by Age 

Group - Alaska, 2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 27 

Clinical Presentation

The primary clinical presentation was determined by a review of the discharge diagnoses in each 

patient’s individual medical record associated with the invasive bacterial illness. In cases with multiple 

discharge diagnoses, the most serious diagnosis related to the GAS infection was recorded as the 

primary clinical presentation. Table 15 shows the primary clinical presentations of invasive group A 

Streptococcus in Alaska for 2014. Nine cases also presented with secondary diagnoses including 

pneumonia, septic abortion and cellulitis. 

Group A Streptococcus was isolated from blood samples in 34 (60%) of 57 cases, 12 from surgical 

specimens, 8 from joint fluid, one from synovial fluid and two from other sterile sites. 

 

Table 18: Primary Clinical Presentations of Invasive group A Streptococcus – Alaska, 2014 

Primary Presentation n (%) 

Cellulitis* 26 (46%) 

Septic arthritis 9 (16%) 

Bacteremia 8 (14%) 

Necrotizing fasciitis 4 (7%) 

Pneumonia* 2 (3%) 

Osteomyelitis 2 (3%) 

Endometritis 2 (3%) 

Epiglottitis 1 (2%) 

Empyema 1 (2%) 

Bursitis 1 (2%) 

Other 1 (2%) 

Total 57 

*with bacteremia

Associated Risk Factors

The presence of one or more associated risk factors was reported in 86% of invasive GAS cases in 2014. 

Cigarette smoking was the most prevalent risk factor observed in adults followed by diabetes and 

alcohol abuse. 

0

10

20

30

40

50

0

2

4

6

8

10

12

14

16

18

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000 Number of Cases

Age (yrs)

Figure 18: Invasive group A Streptococcus, Cases 

& Rates by Age Group & Race - Alaska, 2014

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2014 28 

Table 19: Associated Risk Factors Identified in Invasive GAS Cases – Alaska, 2014* 

Medical Condition/Risk 

Factor 

Adult Cases (≥ 18 years) 

n=54, Cases (%) 

Cigarette smoking 19 (35%) 

Alcohol abuse 17 (31%) 

Diabetes 9 (17%) 

Injection drug use 9 (17%) 

Chronic lung disease 6 (11%) 

Immunosuppressive treatment 4 (7%) 

Asplenia 0 (0%) 

*More than one risk factor was identified in several cases 

Molecular Typing 

Strain characterization of GAS has traditionally been based on serological identification of the M protein 

which is a major surface protein and an important GAS virulence factor. In the mid-1990s, many 

reference labs started using a molecular approach based on sequencing of the N-terminal region of the M 

protein gene (emm gene). To date, more than 200 different emm types have been reported. While there 

are currently no vaccines available to protect against invasive GAS disease, baseline data on the burden 

of GAS disease to include emm typing are critical to evaluate the potential utility of any candidate 

vaccines.

In 2014, 54 invasive GAS isolates were emm typed at AIP. The most common emm types were emm 91 

(33%) and emm 89 (13%). The following graph shows emm typing trends over time. Strains that totaled 

≤ 10 over the time period were not included. 

Antibiotic Resistance 

Fifty-three GAS isolates received at AIP were tested for susceptibility to penicillin, ceftriaxone, 

erythromycin, vancomycin, levofloxacin and clindamycin. All isolates tested were susceptible to 

penicillin, ceftriaxone, vancomycin and levofloxacin. Two isolates were resistant to both erythromycin 

and clindamycin; one isolate was emm type 91 and one was emm type 11. A third isolate was resistant 

to erythromycin only; the isolate was emm type 91. 

0

10

20

30

40

50

60

70

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Number of Cases

Figure 19: Invasive group A Streptococcus emm 

Typing Trends - Alaska, 2001-2014

1 3 5 12 28 41 49 73 82 87 89 91 92 101 108 Unknown
Surveillance of Invasive Bacterial Disease in Alaska, 2014 29 

Table 20: Summary of Invasive group A Streptococcus Case Characteristics, Alaska, 2014 

Sex 

Age 

(yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) 

emm

Type Associated Risk Factors Survived 

M 0.3 Non-Native Anchorage Blood Bacteremia 1 None No 

M 0.4 Non-Native Anchorage Blood Bacteremia 28 Immune suppressive therapy Yes 

M 6.6 Non-Native Anchorage Blood Osteomyelitis 11 None Yes 

F 18.9 Non-Native Anchorage Other Cellulitis 4 None Yes 

M 19 Unknown Anchorage Blood Bacteremia 87 Alcohol abuse Yes 

F 21.4 Non-Native Other Blood Endometritis, septic 

abortion 89 None Yes 

M 23.4 AK Native Anchorage Surgical 

specimen Cellulitis 28 None Yes 

F 23.6 AK Native Other Blood Cellulitis 12 Injection drug use Yes 

M 24.4 Non-Native Anchorage Surgical 

specimen Cellulitis 89 Smoking, injection drug use Yes 

M 26.1 Non-Native Anchorage Blood Cellulitis 53 Diabetes Yes 

M 26.6 Non-Native Anchorage Blood Cellulitis 101 Chronic lung disease, immune 

suppressive therapy, diabetes Yes 

M 27.6 Non-Native Anchorage Surgical 

specimen Septic arthritis, cellulitis 4 Smoking, injection drug use Yes 

F 28.5 AK Native Other Joint fluid Septic arthritis, cellulitis 91 None Yes 

M 28.5 AK Native Other Blood Cellulitis 87 Injection drug use Yes 

M 29.1 AK Native Anchorage Joint fluid Septic arthritis, cellulitis 91 Alcohol abuse Yes 

M 29.5 AK Native Other Surgical 

specimen Septic arthritis 91 Smoking, alcohol abuse Yes 

F 30.5 AK Native Other Surgical 

specimen Cellulitis 238 Smoking Yes 

M 31.5 Non-Native Anchorage Blood Cellulitis 89 Smoking, alcohol abuse Yes 

F 32 Non-Native Anchorage Blood Bacteremia 91 Injection drug use Yes 

F 32.9 Non-Native Anchorage Blood Pneumonia 91 Smoking, injection drug use Yes 

M 36.9 AK Native Other Surgical 

specimen Septic arthritis, cellulitis 87 Smoking Yes 

F 38.3 Non-Native Anchorage Blood Endometritis 4 None Yes 

M 38.7 AK Native Other Surgical 

specimen Necrotizing fasciitis 89 Alcohol abuse Yes 

M 39.4 AK Native Anchorage Blood Necrotizing fasciitis 91 Smoking, alcohol abuse Yes 

F 41.1 Non-Native Anchorage Blood Cellulitis 11 Smoking, injection drug use Yes 

M 43.2 Non-Native Other Joint fluid Bursitis ND None Yes 

F 43.6 AK Native Other Blood Cellulitis 87 

Smoking, chronic lung 

disease, alcohol abuse, 

diabetes 

Yes 

F 44.2 Non-Native Other Blood Cellulitis 77 Injection drug use Yes 

M 44.6 Non-Native Anchorage Blood Cellulitis 91 Alcohol abuse, injection drug 

use 

Yes 

M 45.3 AK Native Anchorage Blood Septic arthritis 101 Immune suppressive therapy Yes 

M 45.3 AK Native Other Surgical 

specimen Cellulitis 91 None Yes 

M 46.4 Non-Native Anchorage Joint fluid Septic arthritis 91 Smoking Yes 

M 50.5 AK Native Anchorage Blood Bacteremia 89 Alcohol abuse No 

F 53.4 AK Native Other Surgical 

specimen Necrotizing fasciitis 28 Smoking, chronic lung disease, alcohol abuse Yes 

M 53.7 AK Native Anchorage Blood Cellulitis 91 Smoking, immune 

suppressive therapy Yes 

M 54 Non-Native Anchorage Blood Pneumonia 1 None Yes 

M 54.9 AK Native Other Joint fluid Bacteremia 101 Smoking, alcohol abuse Yes 

F 56.5 AK Native Other Other Cellulitis 91 Diabetes Yes 

M 56.8 Non-Native Anchorage Surgical 

specimen Cellulitis 91 Smoking, chronic lung disease, alcohol abuse Yes 

F 57.2 Non-Native Anchorage Blood Bacteremia 82 None Yes 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 30 

Sex 

Age 

(yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) 

emm

Type Associated Risk Factors Survived 

M 57.8 AK Native Other Synovial 

fluid Septic arthritis, cellulitis 87 Smoking, chronic lung disease, alcohol abuse Yes 

M 57.9 AK Native Anchorage Blood Cellulitis 91 Alcohol abuse, diabetes Yes 

M 57.9 AK Native Other Joint fluid Empyema, pneumonia, 

cellulitis 101 None Yes 

M 59.2 AK Native Anchorage Blood Cellulitis 91 Smoking, alcohol abuse Yes 

M 62/2 AK Native Other Blood Septic arthritis, cellulitis 91 Smoking, alcohol abuse, 

immune suppressive therapy Yes 

F 64.8 Non-Native Anchorage Joint fluid Necrotizing fasciitis ND Smoking Yes 

F 71.6 Non-Native Anchorage Blood Cellulitis 89 Diabetes Yes 

F 77.1 Non-Native Other Blood Cellulitis 11 None Yes 

M 79.4 Non-Native Anchorage Blood Cellulitis 1 Alcohol abuse Yes 

M 79.8 Non-Native Anchorage Blood Celluliits 4 Diabetes Yes 

M 79.9 AK Native Anchorage Surgical 

specimen Other 91 Diabetes Yes 

F 80.1 AK Native Anchorage Joint fluid Osteomyelitis 89 None Yes 

M 80.2 Non-Native Anchorage Blood Epiglottitis 12 Chronic lung disease No 

F 81.4 AK Native Other Surgical 

specimen Cellulitis ND None Yes 

M 81.5 Non-Native Anchorage Blood Cellulitis 91 Diabetes Yes 

F 91.1 AK Native Anchorage Blood Bacteremia 91 None Yes 

M 93.5 Non-Native Anchorage Blood Cellulitis 87 None No 

ND = typing not done
Surveillance of Invasive Bacterial Disease in Alaska, 2014 31 

Invasive group B Streptococcus

Overall Incidence

A total of 64 cases of invasive group B Streptococcus (GBS) were reported to AIP in 2014. The 

overall rate of invasive GBS disease in the state of Alaska was 8.7/100,000 persons per year. 

The Alaska rate is similar to the ABCs 2014 national projected rate of 8.3/100,000 [14]. In 

2014, there were four GBS-related deaths for a case fatality ratio of 6.3%. 

Seasonality

Cases of group B Streptococcus occurred throughout the year with no apparent trends in 

seasonality. 

 

Race

In 2014, 23% of invasive group B Streptococcus cases in Alaska occurred in the Alaska Native 

population; the age-adjusted rate was 11.6/100,000 persons per year which is higher than the 

non-Native rate of 7.3/100,000 persons per year. 

Table 21: Invasive group B Streptococcus Cases by Race – Alaska, 2014 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 15 (23) 11.6 53 0 (0) 

Non-Native 49 (77)‡ 7.3 49 4 (8.2) 

Total 64 50 4 (6.3) 

*Cases per 100,000 per percent distribution of Alaska 2010 population 

‡Includes one case for which race was unknown 

 

0

1

2

3

4

5

6

7

8 Number of Cases

Month of Culture

Figure 20: Invasive group B Streptococcus, by 

Month of Culture - Alaska, 2014
Surveillance of Invasive Bacterial Disease in Alaska, 2014 32 

Region 

In 2014, 45 (70%) of the 64 reported GBS cases occurred in Anchorage; 10 cases were reported 

in Southeast Alaska, six cases in the Interior, and three cases in the YK Delta. The highest rates 

of disease occurred in Southeast Alaska (13.4/100,000) and the YK Delta (11.4/100,000). 

Age

Invasive group B Streptococcus cases reported in 2014 ranged in age from newborn to 102.6 

years old; the median age was 57.5 years. Highest rates of disease overall occurred in adults 65 

years and older (30.9/100,000 persons per year). 

 

 

0

5

10

15

20

25

30

35

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000

Age (yrs)

Figure 21: Invasive group B Streptococcus by Age 

Group - Alaska, 2014

0

10

20

30

40

50

60

0

2

4

6

8

10

12

14

16

18

<2 2-4 5-18 19-54 55-64 65+ Cases per 100,000 Number of Cases

Age (yrs)

Figure 22: Invasive group B Streptococcus, Cases & 

Rates by Age Group & Race - Alaska, 2014

AK Native (#

cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2014 33 

When stratified by race, the highest rates of disease occurred in AK Native adults 65 years and 

older (50.3/100,000 persons per year). There were two cases of early-onset disease (less than 7 

days old) for a rate of 0.2 cases per 1,000 live births. 

Clinical Presentation

The primary clinical presentation was determined by a review of the discharge diagnoses in each 

patient’s individual medical record associated with the invasive bacterial illness. In cases with 

multiple discharge diagnoses, the most serious diagnosis related to the GBS infection was 

recorded as the primary clinical presentation. In 2014, the most common clinical presentation 

was bacteremia which occurred in 21 cases (33%). 

Group B Streptococcus was isolated from blood in 50 (78%) of 64 cases in 2014; six cases were 

isolated from surgical specimens, three cases from bone, two cases from cerebrospinal fluid, one 

case from amniotic fluid, one from a wound and one case from another sterile site. 

Table 22: Primary Clinical Presentations of Invasive group B Streptococcus – Alaska, 2014 

*with bacteremia

Antibiotic Resistance

Susceptibility testing was performed on 57 GBS isolates received in 2014. Results of the testing 

are presented in the following table. 

Table 23: Antibiotic Resistance in Invasive group B Streptococcus Isolates – Alaska, 2014 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 57 (100%) 0 (0%) 0 (0%) 0 (0%) 57 

Ceftriaxone 57 (100%) 0 (0%) 0 (0%) 0 (0%) 57 

Erythromycin 26 (45%) 1 (2%) 30 (53%) 31 (55%) 57 

Tetracycline 11 (19%) 0 (0%) 46 (81%) 46 (81%) 57 

Levofloxacin 57 (100%) 0 (0%) 0 (0%) 0 (0%) 57 

Clindamycin 40 (70%) 1 (2%) 16 (28%) 17 (30%) 57 

Vancomycin 57 (100%) 0 (0%) 0 (0%) 0 (0%) 57 

Primary Presentation n (%) 

Bacteremia 21 (33) 

Cellulitis* 17 (27) 

Pneumonia* 9 (14) 

Osteomyelitis 4 (6) 

Septic arthritis 4 (6) 

Amnionitis 3 (5) 

Endocarditis 2 (3) 

Meningitis 1 (1.5) 

Necrotizing fasciitis 1 (1.5) 

Peritonitis 1 (1.5) 

Other 1 (1.5) 

Total 64 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 34 

All isolates tested were susceptible to penicillin, ceftriaxone, levofloxacin and vancomycin. 

Resistance to tetracycline, erythromycin, and clindamycin was seen in 81%, 55%, and 30%, 

respectively, of isolates tested. Of the two early onset cases, all isolates were available for 

susceptibility testing; both were resistant to tetracycline.
Surveillance of Invasive Bacterial Disease in Alaska, 2014 35 

Table 24: Summary of Invasive group B Streptococcus Case Characteristics, Alaska, 2014 

Sex Age (yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) Associated Risk Factors Survived 

M Newborn Non-Native Anchorage Blood Amnionitis None Yes 

F Newborn Non-Native Other Blood Bacteremia None Yes 

M 18 days Non-Native Anchorage Blood Bacteremia None Yes 

F 1 month AK Native Anchorage CSF Bacteremia Diabetes Yes 

F 17.6 AK Native Other Amniotic 

fluid Septic abortion None Yes 

F 21.7 Non-Native Other CSF Bacteremia None Yes 

F 30.2 Non-Native Anchorage Blood Bacteremia None Yes 

M 33.2 Unknown Other Blood Bacteremia Alcohol abuse Yes 

F 33.7 Non-Native Anchorage Other Amnionitis None Yes 

F 34.2 Non-Native Other Surgical 

specimen Cellulitis Diabetes Yes 

M 34.7 AK Native Anchorage Bone Osteomyelitis Smoking Yes 

F 34.9 AK Native Other Blood Bacteremia Diabetes Yes 

M 35.5 Non-Native Anchorage Blood Endocarditis, empyema Smoking, injection drug use Yes 

M 38.9 AK Native Anchorage Bone Osteomyelitis None Yes 

F 39.3 Non-Native Anchorage Blood Osteomyelitis Diabetes Yes 

F 39.9 Non-Native Anchorage Blood Septic arthritis None Yes 

M 43 Non-Native Anchorage Blood Cellulitis Diabetes Yes 

F 43.8 Non-Native Anchorage Blood Bacteremia None Yes 

M 45.1 Non-Native Anchorage Blood Bacteremia Smoking, alcohol abuse No 

M 47.9 AK Native Anchorage Blood Cellulitis Alcohol abuse Yes 

F 47.9 Non-Native Other Blood Cellulitis None Yes 

F 48.3 Non-Native Anchorage Blood Pneumonia Diabetes Yes 

F 51.1 Non-Native Anchorage Blood Pneumonia Chronic lung disease No 

F 52.1 Non-Native Other Blood Bacteremia None Yes 

M 52.6 AK Native Other Blood Cellulitis Diabetes Yes 

M 55.2 Non-Native Anchorage Blood Bacteremia Diabetes Yes 

M 55.2 Non-Native Anchorage Blood Bacteremia None Yes 

F 55.8 Non-Native Anchorage Surgical 

specimen Other None Yes 

M 56.7 Non-Native Anchorage Blood Cellulitis, osteomyelitis Chronic lung disease, alcohol abuse, 

diabetes Yes 

M 57.1 Non-Native Anchorage Blood Cellulitis, osteomyelitis Diabetes Yes 

M 57.1 AK Native Anchorage Surgical 

specimen Cellulitis Diabetes Yes 

F 57.1 Non-Native Anchorage Blood Cellulitis None Yes 

M 57.9 Non-Native Anchorage Blood Pneumonia None Yes 

F 58.1 Non-Native Other Wound Necrotizing fasciitis Smoking, diabetes Yes 

M 58.4 AK Native Anchorage Surgical 

specimen Cellulitis, osteomyelitis Smoking, diabetes Yes 

M 59 Non-Native Anchorage Blood Pneumonia None Yes 

M 59.3 Non-Native Anchorage Blood Pneumonia Smoking, chronic lung disease, 

diabetes Yes 

M 59.3 Non-Native Other Blood Bacteremia Chronic lung disease, diabetes Yes 

M 59.4 AK Native Other Blood Septic arthritis, 

osteomyelitis 

Smoking, alcohol abuse, injection 

drug use Yes 

M 62 Non-Native Anchorage Blood Bacteremia Diabetes Yes 

F 63.1 Non-Native Anchorage Blood Bacteremia None Yes 

F 63.2 Non-Native Anchorage Blood Peritonitis None Yes 

M 67.9 AK Native Anchorage Bone Osteomyelitis Alcohol abuse, diabetes Yes 

M 68 Non-Native Anchorage Blood Pneumonia None Yes 

M 70.6 Non-Native Anchorage Blood Bacteremia Immune suppressive therapy Yes 

M 71.2 Non-Native Anchorage Blood Cellulitis Chronic lung disease, diabetes Yes 

F 71.6 Non-Native Anchorage Surgical 

specimen Septic arthritis Diabetes Yes 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 36 

Sex Age (yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) Associated Risk Factors Survived 

F 71.7 AK Native Other Surgical 

specimen Septic arthritis None Yes 

F 71.8 AK Native Anchorage Blood Cellulitis None Yes 

F 72 Non-Native Other Blood Pneumonia Chronic lung disease Yes 

F 73.4 Non-Native Anchorage Blood Bacteremia None Yes 

F 74.1 Non-Native Other Blood Cellulitis Smoking Yes 

M 74.1 Non-Native Anchorage Blood Bacteremia None Yes 

M 74.1 Non-Native Anchorage Blood Bacteremia Immune suppressive therapy, diabetes No 

M 78.1 Non-Native Other Blood Cellulitis Chronic lung disease, diabetes Yes 

F 78.2 AK Native Anchorage Blood Pneumonia, cellulitis Chronic lung disease Yes 

F 81.2 AK Native Other Blood Bacteremia Diabetes Yes 

F 82.2 Non-Native Anchorage Blood Cellulitis None Yes 

F 82.6 Non-Native Anchorage Blood Cellulitis Chronic lung disease, diabetes Yes 

F 82.8 Non-Native Other Blood Endocarditis Diabetes Yes 

F 85.9 Non-Native Anchorage Blood Bacteremia Diabetes Yes 

M 87.6 Non-Native Anchorage Blood Cellulitis Chronic lung disease, diabetes Yes 

M 89.6 Non-Native Anchorage Blood Pneumonia Chronic lung disease, diabetes Yes 

M 102.6 Non-Native Other Blood Meningitis Chronic lung disease No 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 37 

References 

1. State of Alaska, Department of Labor & Workforce Development. From 

http://laborstats.alaska.gov/pop/popest.htm

2. Centers for Disease Control and Prevention. 2014. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Streptococcus pneumoniae, 2014.

3. Hennessy TW, Singleton RJ, Bulkow LR, Bruden DL, Hurlburt DA, Parks, D, Moore M, 

Parkinson AJ, Schuchat A, Butler JC. Impact of heptavalent pneumococcal conjugate 

vaccine on invasive disease; antimicrobial resistance and colonization in Alaska Natives: 

progress towards elimination of a health disparity. Vaccine 2005;23:5464-73. 

4. Singleton RJ, Hennessy TW, Bulkow LR, Hammitt LL, Zulz T, Hurlburt DA, Butler JC, 

Rudolph K, Parkinson A. Invasive pneumococcal disease caused by nonvaccine serotypes 

among Alaska Native children with high levels of 7-valent pneumococcal conjugate vaccine 

coverage. JAMA 2007;297(16):1784-92. 

5. Wenger JD, Zulz T, Bruden D, Singleton R, Bruce MG, Bulkow L, Parks D, Rudolph K, 

Hurlburt D, Ritter T, Klejka J, Hennessy T. Invasive pneumococcal disease in Alaskan 

children: impact of the seven-valent pneumococcal conjugate vaccine and the role of water 

supply. Pediatr Infect Dis J 2010;29: 251-256. 

6. State of Alaska, Department of Health & Human Services. Retrieved 5/2/16 from 

http://www.epi.hss.state.ak.us/bulletins/docs/b2009_24.pdf

7. Clinical and Laboratory Standards Institute (CLSI). Performance Standards for 

Antimicrobial Susceptibility Testing; Nineteenth Informational Supplement. 2009; 29(3): 

M100-S19. p.21. 

8. Rudolph K, Bulkow L, Bruce M, Zulz T, Reasonover A, Harker-Jones M, Hurlburt D, 

Hennessy T. Molecular resistance mechanisms of macrolide-resistant invasive Streptococcus 

pneumoniae isolates from Alaska, 1986 to 2010. Antimicrobial Agents and Chemotherapy

2013;57 (11): 5415-22. 

9. Centers for Disease Control and Prevention. 2014. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Haemophilus influenzae, 2014. 

10. Hammitt LL, Block S, Hennessy TW, DeByle C, Peters H, Parkinson A, Singleton R, Butler 

JC. Outbreak of invasive Haemophilus influenzae serotype a disease. Pediatr Infect Dis J

2005;24(5): 453-6. 

11. Bruce MG, Zulz T, DeByle C, Singleton R, Hurlburt D, Bruden D, Rudolph K, Hennessy T, 

Klejka J, Wenger JD. Haemophilus influenzae serotype a invasive disease, Alaska, USA, 

1983-2011. Emerg Infect Dis 2013;19(6): 932-7. 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 38 

12. Centers for Disease Control and Prevention. 2014. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Neisseria meningitidis, 2014. 

13. Centers for Disease Control and Prevention. 2014. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Group A Streptococcus, 2014. 

14. Centers for Disease Control and Prevention. 2014. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Group B Streptococcus, 2014. 
Surveillance of Invasive Bacterial Disease in Alaska, 2014 39 

Appendix 

MIC Interpretive Standards Definitions: 

CLSI [7] provides recommended interpretive categories for various Minimum Inhibitory 

Concentration values (cut points) for each organism/antibiotic combination which are defined as 

follows: 

1. Susceptible (S): 

The “susceptible” category implies that isolates are inhibited by the usually achievable 

concentrations of antimicrobial agent when the recommended dosage is used for the site of 

infection. 

2. Intermediate (I): 

The “intermediate” category includes isolates with antimicrobial agent MICs that approach 

usually attainable blood and tissue levels and for which response rates may be lower than for 

susceptible isolates. The “intermediate” category implies clinical efficacy applicability in body 

sites where the drugs are physiologically concentrated (e.g., quinolones and -lactams in urine) 

or when a higher dosage of a drug can be used (e.g., -lactams). The “intermediate” category 

also includes a buffer zone which should prevent small, uncontrolled technical factors from 

causing major discrepancies in interpretations, especially for drugs with narrow 

pharmacotoxicity margins. 

3. Resistant (R): 

Resistant strains are not inhibited by the usually achievable concentrations of the agent with 

normal dosage schedules, and/or that demonstrate MICs or zone diameters that fall in the range 

where specific microbial resistance mechanisms are likely (e.g., -lactamases) are likely, and 

clinical efficacy of the agent against the isolate has not been reliably shown in treatment studies.