Surveillance of Invasive Bacterial Disease in Alaska, 2011 

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, 2011 2 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 3 

Alaska Statewide Invasive Bacterial Disease 

Table of Contents 

 Page 

Summary 4 

Introduction 5 

Invasive Pneumococcal Disease 6 

Invasive Haemophilus influenzae 16 

 

Invasive Neisseria meningitidis 22 

Invasive Group A Streptococcus 23 

Invasive Group B Streptococcus 30 

References 34 

Appendix 36 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 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, 2011 

In 2011, the total numbers of cases of invasive disease caused by these organisms reported to AIP were

141 S. pneumoniae, 24 H. influenzae, 2 N. meningitidis, 74 group A streptococci (GAS) and 40 group B 

streptococci (GBS). Alaska Native people had higher rates of disease overall than non-Native people for 

Arctic Slope

Interior

Kotzebue

Norton Sound

YK Delta

Bristol Bay

Anchorage

Southeast
Surveillance of Invasive Bacterial Disease in Alaska, 2011 5 

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, 2011 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

GAS 

n (rate*) 

GBS 

n (rate*) 

Anchorage 97 (20.3) 12 (2.5) 1 (0.2) 54 (11.3) 29 (6.1) 

Arctic Slope 1 (11.6) 0 (0) 0 (0) 4 (46.5) 0 (0) 

Bristol Bay 1 (13.7) 1 (13.7) 0 (0) 0 (0) 2 (27.4) 

Interior 17 (15.2) 1 (0.9) 0 (0) 5 (4.5) 4 (3.6) 

Kotzebue 4 (48.2) 0 (0) 0 (0) 0 (0) 0 (0) 

Norton Sound 0 (0) 0 (0) 0 (0) 1 (10.3) 0 (0) 

Southeast 10 (13.6) 2 (2.7) 1 (1.4) 3 (4.1) 5 (6.8)

YK Delta 11 (43.3) 8 (31.5) 0 (0) 7 (27.6) 0 (0) 

Total 141 (19.5) 24 (3.3) 2 (0.3) 74 (10.2) 40 (5.5) 

*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 723,424 persons in 2011 [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 2011, 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, 2011 6 

Invasive Pneumococcal Disease 

Overall Incidence

A total of 130 pneumococcal isolates were received at AIP in 2011. An additional 3 cases were detected 

through year-end follow up with participating laboratories and 8 cases through shared surveillance with 

the State DPH for a total of 141 cases of invasive pneumococcal disease. The overall rate for invasive 

pneumococcal disease in 2011 was 19.5 cases per 100,000 persons per year. Alaska rates for 2011 were 

higher than the Active Bacterial Core surveillance (ABCs) 2011 national projected rate of 11.8/100,000

[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 2011. The largest number of 

cases (n=21) was reported in February. 

Race 

In 2011, the state population was comprised of 19.7% Alaska Native people (Alaska Natives 142,162, 

non-Natives 582,262) [1]. Of all reported S. pneumoniae cases in 2011, 40% occurred among Alaska 

Native people for a total of 56 cases; the age-adjusted rate was 45.1/100,000 persons per year. Eightyfive cases occurred among the non-Native population for an age-adjusted rate of 14/100,000 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 2011 was 3.2. 

0

5

10

15

20

25

Number of Cases

Figure 2: Invasive Pneumococcal Disease, by 

Month of Culture - Alaska, 2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 7 

Table 2: Invasive Streptococcus pneumoniae Cases by Race – Alaska, 2011 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 56 (40) 45.1 63% 9 (16.1) 

Non-Native† 85 (60)† 14 58% 12 (14.1) 

Total 141 60% 21 (14.9) 

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

†Includes 17 cases for which race was unknown 

Region 

The highest percentage (69%) of invasive pneumococcal disease cases occurred in the Anchorage area 

in 2011. Rates of disease, however, were highest in the Kotzebue region (48.2/100,000 persons per 

year) and the YK Delta (43.3/100,000 persons per year). 

Age

Cases occurred in all age groups in 2011 ranging from 2 months to 88 years with a median age of 52 

years. Overall, the highest rates of disease occurred in adults 55-64 years old. 

 

When stratified by age and race, the highest rates of disease in 2011 occurred in Alaska Native 55-64 

years old (106.8/100,000 persons per year). 

0

20

40

60

0

20

40

60

80

100

120

Cases per 100,000

Number of Cases

Figure 3: Invasive Pneumococcal Disease, Cases 

& Rates by Region - Alaska, 2011

Cases

Rate
Surveillance of Invasive Bacterial Disease in Alaska, 2011 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 2002, overall yearly 

rates of pneumococcal disease in children less than 2 years dropped to a low of 67.9/100,000 and then 

increased to 142.2/100,000 in 2006. 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. 

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, the rate was 116.9/100,000; this reflects 

0

20

40

60

80

100

120

0

5

10

15

20

25

30

35

40

<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, 2011

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

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, 2002-2011

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 9 

only an additional two cases from 2009 and is not statistically significant (p=0.6). 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 13.3/100,000 in 2010 following introduction of the 13-valent vaccine. In 

2011, disease rates in both Alaska Native and non-Native children less than 2 years decreased to 

30.7/100,000 and 12.8/100,000, respectively. 

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 2011 (66%) followed by bacteremia (19%). Fifteen cases had a secondary 

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, 2002-2011

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

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 

Non-Natives, by Age Group - Alaska, 2002-2011

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 10 

pneumococcal-related diagnosis in 2011 - 10 pneumonia, 1 cellulitis, 1 endocarditis, 1 septic arthritis, 1 

osteomyelitis and 1 pericarditis. 

In 2011, blood was the most common source of a positive culture which was used to identify 132 (94%) 

of 141 cases. Cerebrospinal fluid was the positive site for 5 (4%) of cases; one case each was identified 

from pleural fluid, peritoneal fluid and a surgical specimen. One case was identified using PCR on CSF 

from a person pre-treated with antibiotics.

Mortality 

In 2010, the overall case fatality ratio for S. pneumoniae in Alaska was 14.9% (21 deaths out of 141 

cases). The case fatality ratio for AK Natives was slightly higher (16.1%, 9 deaths) than non-Natives

(14.1%, 12 deaths). The largest number of deaths and the highest case fatality ratio occurred in the 65+ 

age category (8 deaths) 26.7%. 

93

27

8 3 3 1 1 1 1 1 1

0

20

40

60

80

100

Number of Cases

Figure 8: Primary Clinical Presentations of 

Invasive Pneumococcal Disease - Alaska, 2011

*with bacteremia

0

5

10

15

20

25

30

0

1

2

3

4

5

6

7

8

9

<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, 2011

Deaths

CFR
Surveillance of Invasive Bacterial Disease in Alaska, 2011 11 

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 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, 2011 

 Alaska Native Non-Native 

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

01 1 (1) - - - - - - 1 - 

03 12 (9) - - 2 1 - - 6 3 

06C 6 (5) - 1 1 2 - - - 2 

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

07F 28 (22) - 2 7 - 1 4 11 3 

08 11 (9) - 1 6 1 - - 2 1 

09N 4 (3) - - - - - - 4 - 

10A 2 (2) - - 2 - - - - - 

11A 3 (2) - - 1 1 - - - 1 

12F 1 (1) - - - - - - 1 - 

15A 6 (5) - 1 1 - - - 1 3 

15B 2 (2) - - - - 1 1 - - 

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

16F 6 (5) - - 2 - - - 2 2 

17F 1 (1) - - - - - - 1 - 

19A 8 (6) 1 - 2 - - 1 3 1 

19F 2 (2) - - - - - - 2 - 

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

22F 10 (8) - - 3 1 - - 3 3 

23A 4 (3) - - 1 - - - 2 1 

23B 2 (2) - - - - - 1 1 - 

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

31 6 (5) - - 4 - - - 1 1 

33A 1 (1) - - 1 - - - - - 

33F 1 (1) - - - - - - - 1 

34 1 (1) - - - - - - 1 - 

35B 1 (1) - - - - - - 1 - 

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

42 1 (1) - - 1 - - - - - 

Total 129 2 5 39 6 2 8 45 22 

In 2011, the most common pneumococcal serotypes were 7F (28 isolates, 22%), 8 (11 isolates, 9%), and 

22F (10 isolates, 8%). 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 the last case was in 2009. 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 7F cases continue to cause the most cases of invasive pneumococcal disease, the proportion of

cases caused by serotype 19A has dropped from 20% in 2010 to 6% in 2011. It is anticipated that the 

number of cases of invasive pneumococcal disease caused by serotypes 7F and 19A will continue to 

decline. The majority (75%) of serotype 7F cases occurred in the Anchorage area in 2011. 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 12 

Table 4: Invasive Pneumococcal Serotype Distribution by Region – Alaska, 2011 

Serotype 

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

01 1 - - - - - - - 

03 7 - - 3 - - 2 - 

06C 4 - - 1 - - - 1 

07C 1 - - - - - - - 

07F 21 - - 2 - - 3 2 

08 6 - - 1 - - - 4 

09N 3 - - 1 - - - - 

10A 1 - - - - - - 1 

11A 2 - - 1 - - - - 

12F - - - 1 - - - - 

15A 4 - - - - - 1 1 

15B 2 - - - - - - - 

15C 1 - - - - - - - 

16F 4 - - 1 - - - 1 

17F 1 - - - - - - - 

19A 6 - - - - - 2 - 

19F 2 - - - - - - - 

20 1 - - - - - 1 1 

22F 7 - - 3 - - - - 

23A 4 - - - - - - - 

23B 2 - - - - - - - 

29 - - - 1 - - - - 

31 5 - - 1 - - - - 

33A - 1 - - - - - - 

33F 1 - - - - - - - 

34 1 - - - - - - - 

35B 1 - - - - - - - 

38 1 - 1 1 - - - - 

42 1 - - - - - - - 

Unknown 7 - - - 4 - 1 - 

Total 97 1 1 17 4 0 10 11 

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 2011 that were due to serotypes found in the PCV13 vaccine. There were three cases of 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 13 

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 as coverage by this vaccine increases over time. 

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

– Alaska, 2011 

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

<2 1 (50%) of 2 1 (50%) of 2 2 (50%) of 4 

2-4 1 (100%) of 1 0 (0%) of 2 1 (33%) of 3 

5+ 13 (27%) of 49 35 (48%) of 73 48 (39%) of 122 

Total 15 (29%) of 52 36 (48%) of 77 51 (40%) of 129

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 2011, for persons 65 years and older, 17 (61%) of 28 cases serotyped 

were potentially vaccine preventable invasive pneumococcal illnesses. 

Vaccine Failures 

In 2011, pneumococcal vaccine status was known for 95 (67%) of the 141 cases; 55 cases (58%) of 

cases with known vaccine status did receive a pneumococcal vaccine prior to illness and 40 cases (42%)

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 2011; the child was 2 years old, was a premature infant and had multiple 

underlying conditions including chronic lung disease. Serotype of the case was 19A. 

Preventable Deaths

Overall, 67% of all pneumococcal-related mortality in 2011 was preventable with the use of the 23-

valent polysaccharide vaccine in persons over 2 years old; 28.5% of deaths were due to disease caused 

by serotypes not contained in the 23-valent vaccine. 

Table 6: Vaccine Preventable Invasive Pneumococcal Deaths – Alaska, 2011 

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

PCV13 0 0 0 0 0 0 0 

Ps23V 0 0 0 5 (71%) 3 (60%) 6 (75%) 14 (67%) 

Non-Vaccine 0 0 0 2 (29%) 1 (20%) 2 (25%) 6 (28.5%)

Unknown 0 0 0 0 1 (20%) 0 1 (4.5%) 

Total 0 0 0 7 5 8 21 

Fourteen of the 21 deaths in 2011 from invasive S. pneumoniae occurred from serotypes contained 

within the Ps23V vaccine; 6 of the deaths were in individuals eligible for the vaccine. Of those six 

deaths, five occurred in vaccinated individuals; time since vaccination ranged from 10 months to nine 

years. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 14 

Table 7: Invasive Pneumococcal Disease, Serotypes of Fatal Cases – Alaska, 2011 

Serotype 

Deaths 

n (%) 

Serotype 

Frequency (n) 

03†* 2 (17%) 12 

07C 1 (100%) 1 

07F†* 1 (4%) 28 

08* 3 (27%) 11 

09N* 1 (25%) 4 

10A* 2 (100%) 2 

11A* 2 (67%) 3 

15A 2 (33%) 6 

16F 1 (17%) 6 

19A†* 1 (13%) 8 

22F* 2 (20%) 10 

23B 1 (50%) 2 

34 1 (100%) 1 

† 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 89% of invasive pneumococcal 

cases in 2011. Cigarette smoking was the most prevalent risk factor observed in adults followed by 

alcohol abuse and chronic lung disease. 

Table 8: Associated Risk Factors Identified in Invasive Pneumococcal Cases – Alaska, 2011* 

Medical Condition/Risk 

Factor 

Adult Cases (≥ 18 years) 

n=121, Cases (%) 

Cigarette smoking 59 (49%) 

Alcohol abuse 39 (32%) 

Chronic lung disease 32 (26%) 

Diabetes 28 (23%) 

Immunosuppressive treatment 6 (5%) 

Injection drug use 2 (2%) 

Asplenia 0 (0%) 

*More than one risk factor was identified in several cases 

Antibiotic Resistance

Susceptibility testing was performed on 129 isolates received in 2011. Results of the testing are 

presented in the following table. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 15 

Table 9: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2011 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 106 (84%) 0 (0%) 21 (16%) 21 (16%) 129

TMP-sulfa 116 (90%) 5 (4%) 8 (6%) 13 (10%) 129 

Erythromycin 111 (86%) 0 (0%) 18 (14%) 18 (14%) 129

Ceftriaxone 124 (96%) 2 (2%) 3 (2%) 5 (4%) 129 

Tetracycline 121 (94%) 0 (0%) 8 (6%) 8 (6%) 129 

Chloramphenicol 128 (99%) 0 (0%) 1 (1%) 1 (1%) 129 

Vancomycin 129 (100%) 0 (0%) 0 (0%) 0 (0%) 129 

Levofloxacin 128 (99%) 1 (1%) 0 (0%) 1 (1%) 129 

Clindamycin 125 (97%) 0 (0%) 4 (3%) 4 (3%) 129 

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 resistant 

isolates tested in 2011 may be due to the introduction of the vaccine last year. 

0

5

10

15

20

25

30

35

Percent Resistant

Year

Figure 10: Trends in Antibiotic Resistance Among 

Invasive Pneumococcal Isolates - Alaska, 1990 - 2011

Penicillin

Erythro

TMP-Sulfa

Tet
Surveillance of Invasive Bacterial Disease in Alaska, 2011 16 

Invasive Haemophilus influenzae

Overall Incidence 

In 2011, there were 24 cases of invasive Haemophilus influenzae in Alaska, for a statewide rate of 

3.3/100,000 persons per year. This rate is higher than the national projected rate of 1.66/100,000 

persons per year [8]. There were two deaths caused by H. influenzae in 2011 for a case fatality ratio of 

9%. 

Seasonality 

Cases of invasive H. influenzae occurred throughout 2011; however, due to the small number of cases, 

trends in seasonality cannot be determined. 

Region 

The highest rates of disease caused by invasive H. influenzae cases in 2011 were in YK Delta, 

31.5/100,000 (8 cases), and Bristol Bay, 13.7/100,000 (1 case). Although a large number of cases 

occurred in the Anchorage area (12 cases), the rate was much lower (2.5/100,000). 

0

1

2

3

4

5

Number of Cases

Month of Culture

Figure 11: Haemophilus influenzae Disease by 

Month of Culture - Alaska, 2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 17 

Race 

Table 10: Invasive Haemophilus influenzae Cases by Race – Alaska, 2011 

Race 

Cases 

 n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 15 (62.5%) 8.8 60% 1 (7%) 

Non-Native 9 (37.5%) 1.4 33% 1 (11%) 

Total 24 50% 2 (8%) 

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

In 2011, 62.5% 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 2011 was 6.3. 

Age 

H. influenzae cases ranged in age from newborn to 101 years of age in 2011 (median 18.2 years). 

Overall, the highest rates of disease occurred in children less than 2 years old. 

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, 168.8/100,000 persons per year 

and Alaska Native adults 65 years and older, 23/100,000 persons per year. 

0

10

20

30

40

0

2

4

6

8

10

12

14

Cases per 100,000

Number of Cases

Figure 12: Invasive Haemophilus influenzae, 

Cases & Rates by Region - Alaska, 2011

Cases

Rate
Surveillance of Invasive Bacterial Disease in Alaska, 2011 18 

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 2011, pneumonia with bacteremia was the most common presentation (29% of cases). 

Nineteen (79%) of H. influenzae isolates were from blood samples in 2011, two from cerebral spinal 

fluid, one from joint fluid and two cases were from surgical sites, one of those identified H. influenzae

by PCR only. 

0

10

20

30

40

50

60

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

Cases per 100,000

Age (yrs)

Figure 13: Invasive Haemophilus influenzae by 

Age Group - Alaska, 2011

0

20

40

60

80

100

120

140

160

180

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, 2011

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2011 19 

Table 11: Primary Clinical Presentation of Invasive Haemophilus influenzae - Alaska, 2011 

Primary Presentation n (%) 

Pneumonia* 7 (29%) 

Bacteremia 4 (17%) 

Meningitis 4 (17%) 

Empyema 3 (13%) 

Cellulitis 2 (8%) 

Septic arthritis 1 (4%) 

Epiglottitis 1 (4%) 

Endocarditis 1 (4%) 

Other 1 (4%) 

Total 24 

*with bacteremia 

Serotypes 

All isolates received at AIP are serotyped; 22 of the 24 cases in 2011 had isolates and were serotyped. 

One case was also identified and serotyped using PCR technology (one serotype a case). 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 12: Serotypes of Invasive Haemophilus influenzae Cases by Race – Alaska, 2011 

 Alaska Native Non-Native 

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

a 7 (30%) 7 0 0 0 0 0 0 0 

b 2 (9%) 2 0 0 0 0 0 0 0 

e 1 (4%) 0 0 1 0 0 0 0 0 

f 3 (13%) 0 0 0 0 0 0 2 1 

NT* 10 (44%) 2 0 0 2 1 0 2 3 

Total 23 11 0 1 2 1 0 4 4 

*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. Two cases of Hib occurred in 2011 in vaccinated children. Both children 

were under the age of 2 years; one child had received one dose and the second two doses of the PRPOMP vaccine. 

Hia 

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

2003 [9], cases have occurred sporadically until 2010 when an outbreak began in the YK Delta and 

continued through 2011 [10]. Seven cases of Hia were detected in 2011; 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 2011 was 107.4/100,000. 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 20 

Antibiotic Resistance 

Twenty-two Haemophilus influenzae isolates received at AIP were tested for susceptibility to 

chloramphenicol, ceftriaxone and TMP/sulfa. All 22 isolates were susceptible to chloramphenicol and 

ceftriaxone; 5 isolates were fully resistant to TMP/sulfa, 2 had intermediate resistance and 15 were 

susceptible. 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 21 

Table 13: Summary of Invasive Haemophilus influenzae Case Characteristics, Alaska, 2011 

Sex Age (Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype* 

Associated Medical 

Conditions Survived 

M Newborn Non-Native Anchorage Blood Bacteremia NT None Yes 

M 0.2 AK Native Other Blood Cellulitis b None Yes 

M 0.3 AK Native Other CSF Meningitis a None Yes 

F 0.4 AK Native Other CSF Meningitis a None No 

M 0.6 AK Native Other Blood Meningitis a None Yes 

F 0.6 AK Native Other PCR+ Cellulitis a None Yes 

F 0.8 AK Native Other Blood Meningitis b None Yes 

M 1.0 AK Native Other Blood Empyema, 

pneumonia NT None Yes 

M 1.1 AK Native Anchorage Surgical 

aspirate Other NT None Yes 

M 1.3 AK Native Anchorage Joint fluid Septic arthritis a None Yes 

F 1.3 AK Native Other Blood Pneumonia a None Yes 

M 1.5 AK Native Other Blood Pneumonia a None Yes 

F 34.8 Non-Native Anchorage Blood Pneumonia NT Diabetes No 

F 47.3 AK Native Anchorage Blood Bacteremia Unknown Diabetes Yes 

F 58.4 Non-Native Anchorage Blood Bacteremia NT Diabetes Yes 

F 62.5 Non-Native Anchorage Blood Empyema, 

pneumonia f Smoking Yes 

F 62.9 Non-Native Anchorage Blood Bacteremia f Diabetes Yes 

M 64.6 AK Native Other Blood Pneumonia e Smoking, alcohol 

abuse Yes 

F 66 AK Native Anchorage Blood Endocarditis NT Immune suppressive 

treatment Yes 

F 66.2 Non-Native Anchorage Blood Pneumonia NT Unknown Yes 

M 66.4 Non-Native Anchorage Blood Epiglottitis, 

pneumonia f Diabetes Yes 

M 73.8 Non-Native Other Blood Pneumonia NT Smoking, chronic lung 

disease, alcohol abuse Yes 

M 80.6 AK Native Other Blood Pneumonia NT Diabetes Yes 

F 101.1 Non-Native Anchorage Blood Empyema, 

pneumonia NT None Yes 

*NT = non-typeable 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 22 

Invasive Neisseria meningitidis

Overall Incidence

Two cases of invasive Neisseria meningitidis were reported to AIP in 2011 for an overall rate of 

0.3/100,000. The Alaska rate is similar to the ABCs 2011 national projected rate of 0.2/100,000 

[11]. There were no invasive N. meningitidis-related deaths in Alaska in 2011. 

Race 

Table 14: Invasive Neisseria meningitidis Cases by Race – Alaska, 2011 

Race 

Cases 

 n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 1 (50%) 0.8 0% 0 (0%) 

Non-Native 1 (50%) 0.2 100% 0 (0%) 

Total 2 50% 0 (0%) 

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

In 2011, 50% 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 2011 was 4. 

Table 15: Summary of Invasive Neisseria meningitidis Case Characteristics, Alaska, 2011 

Sex Age (Yrs) Race Residence 

Site of 

Isolation 

Clinical 

Presentation(s) Serogroup 

Associated Medical 

Conditions Survived 

M 13.8 Non-Native Other Blood Bacteremia C None Yes

F 41.5 AK Native Anchorage Blood Bacteremia B 

Smoking, chronic 

lung disease, 

alcohol abuse 

Yes 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 23 

Invasive group A Streptococcus

Overall Incidence

A total of 74 cases of invasive group A Streptococcus (GAS) were reported to AIP in 2011. The 

overall rate of invasive GAS disease in the state of Alaska was 10.2/100,000 persons per year. 

The Alaska rate is higher than the ABCs 2011 national projected rate of 4.3/100,000 [12]. In 

2011, there were 7 GAS-related deaths for a case fatality ratio of 9.5%. 

Seasonality 

Cases of group A Streptococcus occurred throughout the year in 2011 with no apparent trends in 

seasonality. The largest number of cases (n=10) occurred in December. 

Race

In 2011, 50% of invasive GAS cases in Alaska occurred in the Alaska Native population. The 

age-adjusted rate ratio of invasive GAS disease for the Alaska Native population compared with 

the non-Native population in 2011 was 4.7. 

Table 16: Invasive group A Streptococcus Cases by Race – Alaska, 2011 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 37 (50%) 28.8 51% 2 (5%) 

Non-Native 37† (50%) 6.1 65% 5 (13.5%) 

Total 74 58% 7 (9.5%) 

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

†Includes seven cases for which race is unknown 

 

0

2

4

6

8

10

12

Number of Cases

Month of Culture

Figure 15: Invasive group A Streptococcus, by 

Month of Culture - Alaska, 2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 24 

Region 

Fifty-four (73%) of the 74 invasive group A Streptococcus cases in 2011 were reported in the 

Anchorage area, 7 cases in the YK Delta, 5 cases in the Interior, 4 cases in the Arctic Slope, 3 

cases in the Interior and one case in Norton Sound. The highest rates of disease occurred in the 

Arctic Slope region (46.5/100,000) and the YK Delta (27.6/100,000). 

Age

Invasive group A Streptococcus cases reported in 2011 ranged in age from 8 months to 90 years 

old; the median age was 49.3 years. Highest rates of disease occurred in adults 65 years and 

older (27.2/100,000). 

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

Alaska Native adults 65 years and older (68.9/100,000 persons per year). The highest GAS 

0

10

20

30

40

50

0

10

20

30

40

50

60

Number of Cases

Cases per 100,00

Figure 16: Invasive GAS Disease, Cases & Rates 

by Region - Alaska, 2011

Cases

Rate

0

5

10

15

20

25

30

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

Cases per 100,000

Age (yrs)

Figure 17: Invasive group A Streptococcus by Age 

Group - Alaska, 2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 25 

disease rate in the non-Native population also occurred in adults 65 and older (19.9/100,000 

persons per year). 

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 17 shows the primary clinical presentations 

of invasive group A Streptococcus in Alaska for 2011. Twenty-five cases also presented with 

secondary diagnoses including pneumonia, septic arthritis and cellulitis. 

Group A Streptococcus was isolated from blood samples in 67 (91%) of 74 cases, three from 

joint fluid and four from other sterile sites. 

 

Table 17: Primary Clinical Presentations of Invasive group A Streptococcus – Alaska, 2011 

Primary Presentation n (%) 

Bacteremia 20 (27%) 

Cellulitis* 18 (24%) 

Pneumonia* 12 (16%) 

Endocarditis 6 (8%) 

Septic arthritis 5 (7%) 

Necrotizing fasciitis 4 (5%) 

Empyema 3 (4%) 

Meningitis 1 (1%) 

Appendicitis 1 (1%) 

Epiglottitis 1 (1%) 

Other 3 (4%) 

Total 74 

*with bacteremia

0

10

20

30

40

50

60

70

80

0

5

10

15

20

25

<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, 2011

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2011 26 

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 mid1990s, many reference labs started using a molecular approach based on sequencing of the Nterminal 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 2011, 62 invasive GAS isolates were emm typed at AIP. The most common emm types were 

emm 49 (28.5%), followed by emm 1 (14%) and emm 108 (9.5%). The following graph shows 

emm typing trends over time. Strains that totaled ≤ 5 over the time period were not included. 

Associated Risk Factors

The presence of one or more associated risk factors was reported in 96% of invasive GAS cases 

in 2011. Cigarette smoking was the most prevalent risk factor observed in adults followed by 

alcohol abuse and diabetes. 

Table 18: Associated Risk Factors Identified in Invasive GAS Cases – Alaska, 2011* 

Medical Condition/Risk 

Factor 

Adult Cases (≥ 18 years) 

n=66, Cases (%) 

Cigarette smoking 23 (35%) 

Alcohol abuse 18 (27%) 

Diabetes 14 (21%) 

Chronic lung disease 6 (9%) 

Injection drug use 2 (3%) 

Immunosuppressive treatment 1 (2%) 

Asplenia 0 (0%) 

*More than one risk factor was identified in several cases 

0

10

20

30

40

50

60

70

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Number of Cases

Figure 19: Invasive group A Streptococcus emm 

Typing Trends - Alaska, 2001-2011

1 3 5 12 28 41 49 58 73 82 87 89 92 108 114 Unknown
Surveillance of Invasive Bacterial Disease in Alaska, 2011 27 

Antibiotic Resistance 

Sixty-one 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 

erythromycin, and one of those was also resistant to clindamycin. The multi-drug resistant 

isolate was emm type 94.
Surveillance of Invasive Bacterial Disease in Alaska, 2011 28 

Table 19: Summary of Invasive group A Streptococcus Case Characteristics, Alaska, 2011 

Sex 

Age 

(yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) 

emm

Type 

Associated Medical 

Conditions Survived 

F 0.7 AK Native Other Blood Endocarditis, cellulitis 12 None Yes 

M 1.4 AK Native Anchorage Blood Pneumonia 28 None Yes 

M 1.5 Unknown Anchorage Blood Bacteremia 12 None Yes 

F 2.9 AK Native Other Pleural fluid Empyema, pneumonia 1 Chronic lung disease No 

M 7.9 Non-Native Anchorage Blood Septic arthritis, 

osteomyelitis 12 None Yes 

M 8.9 AK Native Other Blood Other 49 None Yes 

M 12.1 AK Native Anchorage Blood Bacteremia ND None Yes 

F 15 AK Native Anchorage Blood Bacteremia 58 Injection drug use No 

F 19.2 AK Native Other Blood Pneumonia 1 None Yes 

F 25.9 Non-Native Anchorage Blood Other 22 Injection drug use Yes 

F 27.2 AK Native Anchorage Blood Cellulitis 33 Diabetes Yes 

F 28.6 AK Native Anchorage Blood Pneumonia, cellulitis 49 Smoking, alcohol abuse Yes 

F 31.9 AK Native Anchorage Blood Cellulitis 49 Smoking, alcohol abuse Yes 

F 33.5 Non-Native Other Blood Bacteremia ND None Yes 

M 34.2 AK Native Other Joint fluid Cellulitis 49 None Yes 

F 35.3 AK Native Anchorage Blood Appendicitis 94 Smoking Yes 

M 35.4 Non-Native Anchorage Blood Endocarditis, septic 

arthritis, cellulitis 3 None Yes 

M 35.7 Non-Native Anchorage Blood Pneumonia 49 Smoking, injection drug use Yes 

F 36.9 Unknown Anchorage Blood Endocarditis, 

osteomyelitis, cellulitis 28 Diabetes Yes 

F 37.3 AK Native Anchorage Joint fluid Pneumonia, bursitis 49 Smoking, alcohol abuse Yes 

F 38 Unknown Anchorage Blood Bacteremia 49 Smoking, alcohol abuse No 

M 38.6 Non-Native Other Joint fluid Cellulitis, bursitis ND Smoking Yes 

M 41.1 Non-Native Anchorage Blood Bacteremia 108 Smoking Yes 

M 41.4 AK Native Anchorage Blood Bacteremia 11 Smoking, chronic lung disease Yes 

M 42.2 Non-Native Other Blood Bacteremia 108 Alcohol abuse No 

M 42.4 Non-Native Other Blood Cellulitis 91 Diabetes Yes 

M 44.3 Non-Native Anchorage Blood Pneumonia 3 None Yes 

M 44.5 AK Native Anchorage Blood Pneumonia, cellulitis 82 Smoking, alcohol abuse Yes 

F 45.4 Non-Native Anchorage Blood Necrotizing fasciitis, 

STSS 1 None Yes 

F 45.9 Non-Native Anchorage Blood Necrotizing fasciitis 12 None No 

M 46.1 AK Native Anchorage Blood Septic arthritis 89 Smoking, alcohol abuse Yes 

F 46.1 AK Native Anchorage Blood Cellulitis 49 Smoking, alcohol abuse Yes 

M 47.4 AK Native Other Wound Necrotizing fasciitis, 

cellulitis ND Alcohol abuse Yes 

F 47.5 AK Native Anchorage Blood Cellulitis 108 None Yes 

F 49 AK Native Anchorage Blood Other 44 None Yes 

M 49.2 Unknown Anchorage Blood Cellulitis 49 None Yes 

M 49.3 AK Native Anchorage Blood Pneumonia, cellulitis 49 Alcohol abuse Yes 

M 49.3 AK Native Anchorage Blood Bacteremia ND Alcohol abuse Yes 

M 50 Non-Native Other Blood Cellulitis 12 None Yes 

F 50.9 Non-Native Anchorage Blood Cellulitis ND None Yes 

M 52.6 AK Native Anchorage Blood Cellulitis 49 Smoking, alcohol abuse, 

diabetes Yes 

M 52.7 AK Native Other Blood Septic arthritis ND Smoking Yes 

M 52.8 Non-Native Anchorage Blood Cellulitis 49 Smoking, diabetes Yes 

M 53.2 AK Native Anchorage Blood Bacteremia 49 Smoking, alcohol abuse, 

diabetes Yes 

F 54.8 AK Native Anchorage Blood Pneumonia 89 Smoking, chronic lung 

disease, alcohol abuse Yes 

M 55.1 Non-Native Anchorage Blood Epiglottitis 3 Chronic lung disease Yes 

M 55.1 Non-Native Anchorage Blood Pneumonia 1 Smoking Yes 

M 55.3 AK Native Other Blood Pneumonia, cellulitis 91 Smoking Yes 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 29 

Sex 

Age 

(yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) 

emm

Type 

Associated Medical 

Conditions Survived 

F 55.4 AK Native Anchorage Blood Bacteremia ND None Yes 

F 56 Non-Native Anchorage Blood Septic arthritis 1 Diabetes Yes 

M 56.7 Non-Native Anchorage Blood Endocarditis, septic 

arthritis 49 Smoking No 

M 56.7 Non-Native Anchorage Blood Empyema, pneumonia ND Immune suppressive 

treatment, diabetes Yes 

M 57.3 Non-Native Anchorage Blood Bacteremia 82 Diabetes Yes 

M 57.9 Non-Native Anchorage Blood Endocarditis 49 Diabetes Yes 

M 58.4 Non-Native Anchorage Blood Cellulitis 82 None Yes 

M 59.2 AK Native Other Blood Cellulitis 108 Alcohol abuse Yes 

M 60.9 AK Native Other Blood Endocarditis 108 Smoking, alcohol abuse Yes 

F 63.3 AK Native Other Blood Bacteremia 18 Smoking Yes 

M 66.5 AK Native Anchorage Blood Bacteremia 1 Chronic lung disease Yes 

F 68.6 Non-Native Anchorage Surgical 

specimen 

Necrotizing fasciitis, 

STSS, cellulitis 1 None Yes 

M 69.1 AK Native Anchorage Blood Bacteremia 49 Chronic lung disease, diabetes Yes 

M 69.4 Non-Native Other Blood Cellulitis stG6.0 Alcohol abuse, diabetes Yes 

F 70.3 Non-Native Anchorage Blood Bacteremia 22 None Yes 

M 70.5 Non-Native Anchorage Blood Bacteremia ND Alcohol abuse Yes 

F 70.9 Unknown Anchorage Blood Cellulitis 108 Diabetes Yes 

F 73.5 AK Native Other Blood Bacteremia 82 None Yes

F 73.8 AK Native Anchorage Blood Septic arthritis, cellulitis 28 Smoking Yes 

F 76.4 AK Native Other Blood Meningitis 1 None Yes 

M 76.8 Non-Native Anchorage Blood Pneumonia 3 None Yes 

M 82.4 AK Native Other Pleural fluid Empyema, pneumonia ND None Yes 

F 84.3 Non-Native Anchorage Blood Bacteremia 49 None Yes 

M 85 Unknown Anchorage Blood Bacteremia 28 Chronic lung disease, diabetes Yes 

M 87.7 Non-Native Anchorage Blood Cellulitis 49 None No 

F 90 Unknown Anchorage Blood Cellulitis 1 None Yes 

STSS = Streptococcal toxic shock syndrome 

ND = typing not done
Surveillance of Invasive Bacterial Disease in Alaska, 2011 30 

Invasive group B Streptococcus

Overall Incidence

A total of 40 cases of invasive group B Streptococcus (GBS) were reported to AIP in 2011. The 

overall rate of invasive GBS disease in the state of Alaska was 5.5/100,000 persons per year. 

The Alaska rate is lower than the ABCs 2011 national projected rate of 8.7/100,000 [13]. In 

2011, there were four GBS-related deaths for a case fatality ratio of 10%. 

Seasonality

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

seasonality. 

 

Race

In 2011, 28% of invasive group B Streptococcus cases in Alaska occurred in the Alaska Native 

population; the age-adjusted rate was 9.2/100,000 persons per year which is nearly twice the 

non-Native rate of 4.7/100,000 persons per year. 

Table 20: Invasive group B Streptococcus Cases by Race – Alaska, 2011 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native 11 (28) 9.2 18 2 (18) 

Non-Native 29 (72)‡ 4.7 52 2 (7) 

Total 40 43 4 (10) 

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

‡Includes six cases 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, 2011
Surveillance of Invasive Bacterial Disease in Alaska, 2011 31 

Region 

In 2011, 29 (72%) of the 40 reported GBS cases occurred in Anchorage; five cases were reported 

in Southeast Alaska, four cases in the Interior, and two cases in Bristol Bay. The highest rates of 

disease occurred in the Bristol Bay region (27.4/100,000). 

Age

Invasive group B Streptococcus cases reported in 2011 ranged in age from newborn to 93.8 years 

old; the median age was 60.3 years. Highest rates of disease overall occurred in adults 65 years 

and older (28.9/100,000 persons per year). 

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

(45.9/100,000 persons per year). There was one case of early-onset disease (less than 7 days old) 

for a rate of 0.1/1,000 live births. 

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, 2011

0

5

10

15

20

25

30

35

40

45

50

0

2

4

6

8

10

12

14

<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, 2011

AK Native (#

cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2011 32 

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 2011, the most common clinical presentation 

was cellulitis with bacteremia which occurred in 14 cases (35%). 

Group B Streptococcus was isolated from blood in 37 (92.5%) of 40 cases in 2011; one each was 

isolated from joint fluid, a surgical aspirate and other sterile site. 

Table 21: Primary Clinical Presentations of Invasive group B Streptococcus – Alaska, 2011 

*with bacteremia

Antibiotic Resistance

Susceptibility testing was performed on 35 GBS isolates received in 2011. Results of the testing 

are presented in the following table. 

Table 22: Antibiotic Resistance in Invasive group B Streptococcus Isolates – Alaska, 2011 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 35 (100%) 0 (0%) 0 (0%) 0 (0%) 35 

Ceftriaxone 35 (100%) 0 (0%) 0 (0%) 0 (0%) 35 

Erythromycin 19 (54%) 0 (0%) 16 (46%) 16 (46%) 35 

Tetracycline 8 (23%) 0 (0%) 27 (77%) 27 (77%) 35 

Levofloxacin 35 (100%) 0 (0%) 0 (0%) 0 (0%) 35 

Clindamycin 24 (69%) 0 (0%) 11 (31%) 11 (31%) 35 

Vancomycin 35 (100%) 0 (0%) 0 (0%) 0 (0%) 35 

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

Resistance to tetracycline, erythromycin and clindamycin was seen in 86%, 50% and 26%, 

respectively, of isolates tested. The isolate from the one early onset case was resistant to 

tetracycline and erythromycin.

Primary Presentation n (%) 

Cellulitis* 14 (35%) 

Bacteremia 10 (25%) 

Pneumonia* 4 (10%) 

Peritonitis 3 (7.5%) 

Meningitis 2 (5%) 

Endocarditis 2 (5%) 

Osteomyelitis 2 (5%) 

Bursitis 1 (2.5%) 

Septic abortion 1 (2.5%) 

Other 1 (2.5%) 

Total 40 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 33 

Table 23: Summary of Invasive group B Streptococcus Case Characteristics, Alaska, 2011 

Sex Age (yrs) Race Residence 

Site of 

Isolation Clinical Presentation(s) Associated Medical Conditions Survived 

M Newborn Non-Native Anchorage Blood Bacteremia None Yes 

F 0.2 Non-Native Anchorage CSF Meningitis None Yes 

M 25.1 Unknown Anchorage Blood Endocarditis, pneumonia None Yes 

F 25.5 AK Native Anchorage Other Septic abortion None Yes 

M 43.6 Unknown Anchorage Blood Cellulitis None Yes 

F 46.2 Non-Native Anchorage Blood Cellulitis Smoking, alcohol abuse Yes 

F 46.3 Non-Native Anchorage Joint fluid Bursitis None Yes 

F 46.5 AK Native Anchorage Blood Pneumonia Smoking, alcohol abuse No 

F 46.8 Unknown Anchorage CSF Meningitis Smoking Yes

F 48.3 Non-Native Anchorage Blood Pneumonia Diabetes Yes 

F 48.5 Non-Native Anchorage Blood Pneumonia, other Chronic lung disease, diabetes Yes 

F 49.9 AK Native Other Blood Bacteremia None No 

F 50 AK Native Other Blood Peritonitis, pneumonia Alcohol abuse No 

M 50.3 AK Native Other Surgical 

aspirate Osteomyelitis Smoking Yes 

M 51.8 Non-Native Anchorage Peritoneal 

fluid Peritonitis Alcohol abuse Yes 

F 52.7 AK Native Anchorage Blood Peritonitis Smoking, chronic lung disease, 

alcohol abuse No 

F 53.4 Non-Native Anchorage Blood Pneumonia None Yes 

F 57.2 AK Native Anchorage Blood Cellulitis Chronic lung disease, alcohol abuse Yes 

M 57.8 Non-Native Anchorage Blood Endocarditis, septic 

arthritis Chronic lung disease Yes 

F 59.2 Non-Native Anchorage Blood Cellulitis Diabetes Yes 

M 61.4 Non-Native Other Blood Other Smoking, chronic lung disease Yes 

F 63.5 Unknown Anchorage Blood Cellulitis Unknown Yes 

F 65 Non-Native Anchorage Blood Cellulitis None Yes

M 65.1 Non-Native Anchorage Blood Cellulitis Diabetes Yes 

F 67.1 Unknown Anchorage Blood Cellulitis Chronic lung disease, diabetes Yes 

F 68.3 AK Native Anchorage Blood Bacteremia Chronic lung disease, diabetes Yes 

M 68.5 Non-Native Anchorage Blood Cellulitis None Yes 

M 71.8 Unknown Anchorage Blood Cellulitis None Yes 

F 72.6 AK Native Anchorage Blood Bacteremia Diabetes Yes 

M 73.4 Non-Native Anchorage Blood Cellulitis Chronic lung disease Yes 

M 74.8 Non-Native Other Blood Bacteremia Diabetes Yes 

F 76.1 Non-Native Other Blood Cellulitis None Yes 

M 76.8 AK Native Other Blood Bacteremia None Yes 

M 78.4 Non-Native Anchorage Blood Bacteremia None Yes 

M 79.8 Non-Native Anchorage Blood Osteomyelitis Diabetes Yes 

M 80 Non-Native Other Blood Bacteremia None Yes 

F 82.4 AK Native Other Blood Bacteremia None Yes 

M 83.5 Non-Native Anchorage Blood Cellulitis Chronic lung disease, diabetes Yes 

F 87.3 Non-Native Other Blood Bacteremia None Yes 

F 93.8 Non-Native Other Blood Cellulitis None Yes 
Surveillance of Invasive Bacterial Disease in Alaska, 2011 34 

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[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 3/17/11 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] Centers for Disease Control and Prevention. 2012. Active Bacterial Core Surveillance 

Report, Emerging Infections Program Network, Haemophilus influenzae, 2011. 

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Surveillance of Invasive Bacterial Disease in Alaska, 2011 35 

[13]Centers for Disease Control and Prevention. 2012. Active Bacterial Core Surveillance 

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Surveillance of Invasive Bacterial Disease in Alaska, 2011 36 

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 β-lactams in urine) 

or when a higher dosage of a drug can be used (e.g., β-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., β-lactamases) are likely, and 

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