Surveillance of Invasive Bacterial Disease in Alaska, 2017 

Arctic Investigations Program 

Division of Preparedness and Emerging Infections 

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, 2017 2
Surveillance of Invasive Bacterial Disease in Alaska, 2017 3

Alaska Statewide Invasive Bacterial Disease 

Table of Contents 

 Page 

Summary 4 

Introduction 5 

Invasive Pneumococcal Disease 6 

Invasive Haemophilus influenzae 15 

 

Invasive Neisseria meningitidis 19 

Invasive Group A Streptococcus 20 

Invasive Group B Streptococcus 25 

References 28 

Appendix 29 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 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, cerebrospinal 

fluid (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, 2017 

In 2017, the total numbers of cases of invasive disease caused by these organisms reported to AIP were 125 S. 

pneumoniae, 23 H. influenzae, 2 N. meningitidis, 127 group A Streptococci (GAS) and 61 group B Streptococci

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

organisms except N. meningitidis. Rates of disease were highest in the Anchorage region for N. meningitidis, 

Bristol Bay for S. pneumoniae, Kotzebue for groups A and B Streptococci and the YK Delta for H. influenzae. 

Rates for each organism by region are presented in the following table. 

Arctic Slope

Interior

Kotzebue

Norton Sound

YK Delta

Bristol Bay 

Anchorage

Southeast
Surveillance of Invasive Bacterial Disease in Alaska, 2017 5

Table 1: Surveillance Organisms Reported by Region – Alaska, 2017 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

GAS 

n (rate*) 

GBS 

n (rate*) 

Anchorage 64 (13) 10 (2) 2 (0.4) 93 (18.9) 45 (9.1)

Arctic Slope 2 (22.6) 0 (0) 0 (0) 2 (22.6) 0 (0)

Bristol Bay 5 (70.3) 0 (0) 0 (0) 0 (0) 0 (0)

Interior 19 (17.1) 1 (0.9) 0 (0) 5 (4.5) 3 (2.7)

Kotzebue 4 (46.9) 2 (23.4) 0 (0) 5 (58.6) 2 (23.4)

Norton Sound 1 (10) 1 (10) 0 (0) 4 (40) 2 (20)

Southeast 12 (16.5) 2 (2.7) 0 (0) 5 (6.9) 6 (8.2)

YK Delta 18 (67.8) 7 (26.4) 0 (0) 13 (49) 3 (11.3)

Total 125 (16.9) 23 (3.1) 2 (0.3) 127 (17.2) 61 (8.3)

*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 737,847 persons in 2017 

[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 2017, 22 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 isolation of the 

bacteria from a normally sterile site, including blood, cerebrospinal fluid, pleural fluid, peritoneal fluid or joint 

fluid collected from a resident of Alaska. In addition, for GAS, isolates are requested from deep tissue infection 

specimens, such as might be collected from surgical debridement of cases of necrotizing fasciitis.
Surveillance of Invasive Bacterial Disease in Alaska, 2017 6

Invasive Pneumococcal Disease (IPD) 

Overall Incidence

A total of 118 pneumococcal isolates were received at AIP in 2017. An additional 7 cases were detected 

through shared surveillance with the State DPH for a total of 125 cases of invasive pneumococcal disease. The 

overall rate for invasive pneumococcal disease in 2017 was 16.9 cases per 100,000 persons per year. Alaska 

rates for 2017 were higher than the Active Bacterial Core Surveillance (ABCs) 2017 national projected rate of 

9.5/100,000 [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 2017. The largest number of cases 

(n=15) was reported in September, October and November. 

Race 

In 2017, the state population was comprised of 20% Alaska Native (AN) people (Alaska Native persons alone 

or in combination 147,752 non-Native persons 590,095) [1]. Of all reported S. pneumoniae cases in 2017, 51% 

occurred among Alaska Native people for a total of 64 cases; the age-adjusted rate was 44.5/100,000 persons 

per year. Sixty-one cases occurred among the non-Native (NN) population for an age-adjusted rate of 

9.2/100,000 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 2017 was 4.8. 

Table 2: IPD Cases by Race – Alaska, 2017 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native Persons 64 (51) 44.5 63% 5 (8)

Non-Native Persons† 61 (49)† 9.2 64% 7 (11.5)

Total 125 63% 12 (10)

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

†Includes 6 cases for which race was unknown 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 7

Region 

The highest percentage (73%) of IPD cases occurred in the Anchorage area in 2017. Rates of disease, however, 

were highest in Bristol Bay (70.3/100,000 persons per year) and the YK Delta (46.9/100,000 persons per year). 

Age

Cases occurred in all age groups in 2017, with patient ages ranging from 2 months to 83 years, with a median 

age of 53.6 years. Overall, the highest rates of disease occurred in children < 2 years old and adults 65 years 

and older. 

 

When stratified by age and race, the highest rates of disease in 2017 occurred in Alaska Native children < 2 

years old (174.4/100,000 persons per year) and adults 65 years and older (149.8/100,000 persons per year). 

Trends over Time 

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 IPD in children less 

than 2 years declined to 65.6/100,000; following introduction of a 13-valent conjugate vaccine in 2010, rates 

declined further to 18/100,000 in 2011. The annualized rate from 2012 to 2017 in this age group is 40.9/100,000 

and ranged from 18.8/100,000 to 60.3/100,000. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 8

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 (data not shown, historical trend). 

This rate increase 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 aged less than 2 years declined to 

87.1/100,000 and, after introduction of the 13-valent vaccine in 2010, rates declined to 30.7/100,000 in 2011. 

The annualized rate from 2012 to 2017 in this age group was 105.3/100,000 and ranged from 35.1/100,000 to 

177.5/100,000. Rates of invasive disease in non-Native children aged 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 aged less than 2 years increased to 

60.3/100,000 but declined to 13/100,000 in 2012 following introduction of the 13-valent vaccine. The 

annualized rate from 2012 to 2017 in this age group was 16.2/100,000 and ranged from 6.7/100,000 to 

26.3/100,000. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 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 2017 (65%) 

followed by bacteremia (17%). Ten cases had a secondary pneumococcal-related diagnosis in 2017; seven were 

pneumonia with bacteremia, two were cellulitis, and one was septic arthritis. 

In 2017, blood was the most common source of a positive culture which was used to identify 113 (92%) of 125 

cases. Five cases were identified from pleural fluid, two cases each were identified from CSF or peritoneal 

fluid, and one case each was identified from joint fluid or a surgical specimen. 

Mortality 

In 2017, the overall case fatality ratio for S. pneumoniae in Alaska was 10% (12 deaths out of 125 cases). The 

case fatality ratio for non-Natives was higher (11.5%, 7 deaths) than that for AK Natives (8%, 5 deaths). The 

highest case fatality ratio occurred in the 55-64 years of age category: 3 deaths, CFR 13.6%. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 10

Serotype

Serotyping of IPD 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. AIP received and serotyped 117 

isolates in 2017. 

Table 3: IPD Serotype Distribution by Race and Age Group – Alaska, 2017 

Alaska Native Non-Native 

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

03 9 (8) - - 1 2 2 - - - 2 2

06C 5 (4) - - 1 2 - - - - 2 -

07C 2 (2) - - - 1 - - - 1 1 -

07F 9 (8) - - - 1 1 - - - 6 -

08 5 (4) - - - 2 1 - - - 2 -

09N 11 (9) 2 1 - 1 4 1 - - 1 1

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

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

12F 5 (4) - - - 1 - - - - 3 1

15A 5 (4) 1 - - 1 2 - - - - 1

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

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

16F 4 (3) - - - 2 1 - - - - 1

17F 2 (2) - - - - - - - - 1 1

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

19F 6 (5) - 1 - 2 - - - - 2 1

20 10 (9) 2 - - 6 - - - - 2 -

22F 8 (7) - - - 1 1 - - 1 2 3

23A 5 (4) - 1 - 1 1 - - - 1 1

23B 5 (4) - - - 1 - - - - 2 2

24 1 (<1) - - - 1 - - - - - -

28A 1 (<1) - - - - - - - - 1 -

31 1 (<1) - - - - - - - - 1 -

33F 6 (5) 3 - - - - - - 1 2 -

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

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

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

38 2 (2) 1 - 1 - - - - - - -
Surveillance of Invasive Bacterial Disease in Alaska, 2017 11

Alaska Native Non-Native 

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

Total 117 9 3 3 28 15 1 1 4 34 19

In 2017, the most common pneumococcal serotypes were 9N, (11 isolates, 9%), 20 (10 isolates, 9%), 3 (9

isolates 8%) and 7F (9 isolates, 8%). The majority (50%) of serotype 9N cases, serotype 20 cases (70%), and 

serotype 7F cases (56%) occurred in the Anchorage area in 2017. 

 

Table 4: IPD Serotype Distribution by Region – Alaska, 2017 

Serotype

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

03 2 1 - 3 - - 1 2

06C 1 - - 2 - - - 2

07C 1 - - 1 - - - -

07F 5 - - 1 1 - 2 -

08 3 - - - - - - 2

09N 5 - - 1 - - 2 3

10A 2 - - 1 - - - -

11A 3 - - - - - - -

12F 4 - - - - - 1 -

15A 4 - - - - - - 1

15B - 1 - 1 - - - -

15C - - - 1 - - - -

16F 3 - - 1 - - - -

17F 1 - - 1 - - - -

19A 3 - - - - - - -

19F 4 - - 1 - - 1 -

20 7 - - 1 1 - - 1

22F 3 - - 2 - - 2 1

23A 1 - - 1 1 - 1 1

23B 4 - - - - - - 1

24 - - 1 - - - - -

28A 1 - - - - - - -

31 1 - - - - - - -

33F 2 - - - - - 1 3

34 1 - - - - - - -

35B 1 - - - - - - -

35F 1 - - - - - - -

38 - - 1 - 1 - - -

Unknown 1 - 3 1 - 1 1 1

Total 64 2 5 19 4 1 12 18

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 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 12

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 caused most invasive disease since the introduction of the PCV7 vaccine. 

The table below shows the proportion of invasive infections from 2017 that were due to serotypes found in the 

PCV13 vaccine. There were two cases (1 each 19A, 19F) of pneumococcal disease caused by serotypes 

contained in the PCV13 vaccine in children less than 5 years of age. 

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

and Race – Alaska, 2017 

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

<2 0 (0%) of 10 0 (0%) of 1 0 (0%) of 11

2-4 1 (33%) of 3 1 (100%) of 1 2 (50%) of 4

5+ 9 (18%) of 51 16 (27%) of 59 25 (23%) of 110

Total 10 (16%) of 64 17 (28%) of 61 27 (22%) of 125

For the year covered by this report, the 23-valent polysaccharide vaccine (PPSV23) 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 addition, one dose of PCV13 was also recommended for persons 65 years and older. In 2017, 

for persons 65 years and older, 22 (65%) of 34 cases serotyped were potentially vaccine preventable invasive 

pneumococcal illnesses. 

Vaccine Failures 

In 2017, pneumococcal vaccine status was known for 125 (100%) of the 125 cases; 54% (n=68) of cases with 

known vaccine status did receive a pneumococcal vaccine prior to illness; for 57 (46%) cases, there was no 

record of the patient having previously been vaccinated with a pneumococcal vaccine. 

A PCV13 vaccine failure is defined as IPD caused by a serotype contained in PCV13 in a child less than five 

years old who has had at least two doses of vaccine. There were two PCV13 vaccine failures in 2017. 

Potentially Preventable Deaths

Overall, 25% of all pneumococcal-related mortality in 2017 was potentially preventable with the use of the 23-

valent polysaccharide vaccine in persons over 5 years old; 50% of deaths were due to disease caused by

serotypes not contained in pneumococcal vaccines. 

Table 6: IPD Deaths by Vaccine Serotype – Alaska, 2017 

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

PCV13 0 0 0 0 1 (33%) 1 (25%) 2 (17%)

PPSV23 0 0 0 1 (20%) 0 2 (50%) 3 (25%)

Non-Vaccine 0 0 0 4 (80%) 1 (33%) 1 (25%) 6 (50%)

Unknown 0 0 0 0 1 (33%) 0 1 (8%)

Total 0 0 0 5 3 4 12

Three of the 12 IPD deaths in 2017 were caused by serotypes contained in the PPSV23 vaccine; three of the 

deaths were in individuals eligible for the vaccine. All deaths occurred in unvaccinated individuals. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 13

Table 7: IPD, Serotypes of Fatal Cases – Alaska, 2017 

Serotype

Deaths 

n (%) 

Serotype 

Frequency (n) 

07C 1 (50) 2

11A* 1 (33) 3

16F 2 (50) 4

19F†* 2 (33) 6

22F* 2 (25) 8

23A 1 (20) 5

23B 1 (20) 5

24 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 75% of IPD cases in 2017. 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 IPD Cases – Alaska, 2017 

Risk Factor 

Adult Cases (≥ 18 years) 

n=102, Cases (%) 

Cigarette smoking 42 (41)

Chronic lung disease 35 (34)

Alcohol abuse 23 (23)

Diabetes 17 (17)

Immunosuppressive treatment 10 (10)

Injection drug use 7 (7)

Asplenia 0 (0)

*Multiple risk factors may be reported for a given case 

Antibiotic Resistance

Number of isolates tested for antibiotic resistance varied by the antibiotic tested, ranging from 64 to 117 

isolates. 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. Results of the testing are presented in the following table. 

Table 9: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2017 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 102 (87%) 13 (11%) 2 (2%) 15 (13%) 117

TMP-sulfa 105 (90%) 8 (7%) 4 (3%) 12 (10%) 117

Erythromycin 101 (86%) 0 (0%) 16 (14%) 16 (14%) 117

Ceftriaxone 115 (98%) 0 (0%) 2 (2%) 2 (2%) 117

Tetracycline 58 (91%) 0 (0%) 6 (9%) 6 (9%) 64

Chloramphenicol 117 (100%) 0 (0%) 0 (0%) 0 (0%) 117

Vancomycin 116 (99%) 0 (0%) 1 (1%) 1 (1%) 117

Levofloxacin 117 (100%) 0 (0%) 0 (0%) 0 (0%) 117

Clindamycin 107 (95%) 0 (0%) 6 (5%) 6 (5%) 113
Surveillance of Invasive Bacterial Disease in Alaska, 2017 14

Isolates with serotypes found in PCV7 and PCV13 are more likely to be non-susceptible to penicillin and 

erythromycin than non-vaccine serotype isolates. One potential benefit of the use of these vaccines was an 

anticipated decline in antibiotic resistance among circulating pneumococci. Following introduction of PCV7 in 

2001, antibiotic resistance among invasive pneumococci dropped. However, during 2003, TMP-sulfa and 

penicillin resistance increased, associated with an increase in disease caused by serotype 19A. This serotype is 

included in PCV13; decreasing proportions of isolates resistant to most antibiotics tested are most likely due to 

the introduction of PCV13 [8]. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 15

Invasive Haemophilus influenzae

Overall Incidence 

In 2017, 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 ABCs 2017 national projected rate of 2.32/100,000 persons per 

year [9]. There were 5 deaths associated with H. influenzae in 2017 for a case fatality ratio of 22%. 

Seasonality 

Cases of invasive H. influenzae occurred throughout 2017; however, the small number of cases precludes 

describing seasonality. The majority of cases (n=16) occurred during the 3rd and 4th quarters of the year. 

Region 

The highest rates of disease caused by invasive H. influenzae cases in 2017 were in the YK Delta region, 

26.4/100,000 (7 cases), and the Kotzebue region, 23.4/100,000 (2 cases). Although a large number of cases 

occurred in the Anchorage area (10 cases), the rate was much lower (2/100,000). 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 16

Race 

Table 10: Invasive Haemophilus influenzae Cases by Race – Alaska, 2017 

Race Cases n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native Persons 14 (61%) 8.2 43% 2 (14%)

Non-Native Persons 9 (39%) 1.4 56% 3 (33%)

Total 23 48% 5 (22%)

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

In 2017, 61% of the cases occurred in Alaska Native persons. Age-adjusted rates were calculated for Alaska 

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

population compared with the non-Native population in 2017 was 5.9. 

Age 

H. influenzae cases ranged in age from 1.5 months to 78.7 years in 2017 (median 2.9 years). Overall, the 

highest rates of disease occurred in children less than 2 years old (48.2/100,000). 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 and 65+ years of age, 139.5/100,000 persons per year and 26.4/100,000 persons per year, 

respectively. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 17

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 2017, 

pneumonia with bacteremia was the most common presentation (43% of cases). 

Fifteen (65%) H. influenzae isolates were from blood samples in 2017, six were from CSF and one each was 

from pleural fluid and joint fluid. 

Table 11: Primary Clinical Presentation of Invasive Haemophilus influenzae - Alaska, 2017 

Primary Presentation n (%)

Pneumonia* 10 (43%)

Meningitis 6 (26%)

Bacteremia 3 (13%)

Empyema 2 (9%)

Osteomyelitis 1 (4%)

Septic arthritis 1 (4%)

Total 23

*with bacteremia 

Serotypes 

All isolates received at AIP are serotyped; 22 cases in 2017 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 non-vaccine serotypes. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 18

Table 12: Serotypes of Invasive Haemophilus influenzae Cases by Race – Alaska, 2017 

Alaska Native Persons Non-Native Persons 

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

a 7 (30) 7 - - - - - - -

b 2 (9) - 1 - - 1 - - -

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

NT* 11 (47) 1 - 1 3 - 1 3 2

Unknown 1 (4) - - - - - - - 1

Total 23 8 2 1 3 2 1 3 3

*Non-typeable 

Hib

In recent decades, the prevalence of H. influenzae type b has declined following introduction of universal infant 

vaccination in 1991. There were two cases of Hib in a child less than 5 years old in 2017; one child was fully 

vaccinated, and one child was less than 2 months old and had not yet received any vaccine. 

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]. Seven cases of Hia were detected in 2017; 100% 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 2017 was 

122.1/100,000. 

Antibiotic Resistance 

Nineteen 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, 5 isolates 

were resistant to ampicillin (1 intermediate, 4 fully resistant), and 14 isolates were resistant to TMP/sulfa (1 

intermediate and 13 fully resistant). 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 19

Invasive Neisseria meningitidis

Overall Incidence

Two cases of invasive Neisseria meningitidis were reported to AIP in 2017 for an overall rate of 0.3/100,000. 

The Alaska rate is higher than the Enhanced Meningococcal Disease Surveillance 2017 national rate of 

0.11/100,000 [12]. There were no invasive N. meningitidis-related deaths in Alaska in 2017. 

Table 13: Invasive Neisseria meningitidis Cases by Race – Alaska, 2017 

Race 

Cases 

 n (%) 

Age 

Adjusted 

Rate* 

% 

Male 

Deaths 

n (%) 

Alaska Native Persons 0 (0) 0.0 0 0 (0)

Non-Native Persons 2 (100) 0.3 50 0 (0)

Total 2 50 0 (0)

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

Both invasive N. meningitidis cases reported in 2017 occurred in non-Native persons aged ≥50 years, one 

patient presented with meningitis and the other with pneumonia. Isolates from both patients were obtained from 

blood, and both were serogroup C. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 20

Invasive group A Streptococcus

Overall Incidence

A total of 127 cases of invasive group A Streptococcus (GAS) were reported to AIP in 2017. The overall rate 

of invasive GAS disease in the state of Alaska was 17.2/100,000 persons per year. The Alaska rate is higher 

than the ABCs 2017 national projected rate of 7.26/100,000 [13]. In 2017, there were 8 GAS-related deaths for 

a case fatality ratio of 6%. 

Seasonality 

Cases of group A Streptococcus occurred throughout the year in 2017 with no apparent trends in seasonality. 

The largest number of cases (n=17) occurred in January. 

Race

In 2017, 55% 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 

2017 was 6.0. 

Table 14: Invasive group A Streptococcus Cases by Race – Alaska, 2017 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native Persons 70 (55%) 52.5 60% 4 (6%)

Non-Native Persons 57† (45%) 8.7 56% 4 (7%)

Total 127 58% 8 (6%)

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

†Includes 4 cases for which race is unknown 

Region 

Ninety-three (73%) of the 127 invasive group A Streptococcus cases in 2017 were reported in the Anchorage 

area, 13 cases in the YK Delta, 5 cases each in the Interior, Southeast, and Kotzebue regions, 4 cases in Norton 

0

2

4

6

8

10

12

14

16

18

Number of Cases

Month of Culture

Figure 15: Invasive group A Streptococcus, by 

Month of Culture - Alaska, 2017
Surveillance of Invasive Bacterial Disease in Alaska, 2017 21

Sound, and 2 cases in the Arctic Slope. The highest rates of disease occurred in the Kotzebue region 

(58.6/100,000) and the YK Delta (49/100,000). 

Age

Invasive group A Streptococcus cases reported in 2017 ranged in age from 1 month to 93 years old; the median 

age was 53 years. Highest rates of disease occurred in adults 65 years and older (38.6/100,000). 

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

adults 65+ years old (132.2/100,000 persons per year). The highest GAS disease rate in the non-Native

population also occurred in adults 65 years and older (23.8/100,000 persons per year). 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 22

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 18 shows the primary clinical presentations of invasive group A Streptococcus in Alaska 

for 2017. 

Group A Streptococcus was isolated from blood samples in 77 (61%) of 127 cases, 36 (28%) from surgical 

specimens, 6 from wounds, 4 from joint fluid, 3 from pleural fluid, and one from CSF. 

 

Table 15: Primary Clinical Presentations of Invasive group A Streptococcus – Alaska, 2017 

Primary Presentation n (%) 

Cellulitis* 34 (27%)

Bacteremia 32 (25%)

Necrotizing fasciitis 20 (16%)

Pneumonia* 12 (9%)

Septic arthritis 8 (6%)

Osteomyelitis 4 (3%)

Strep toxic shock 3 (2%)

Empyema 3 (2%)

Meningitis 2 (2%)

Endocarditis 2 (2%)

Bursitis 2 (2%)

Peritonitis 1 (1%)

Amnionitis 1 (1%)

Other 3 (2%)

Total 127

*with bacteremia
Surveillance of Invasive Bacterial Disease in Alaska, 2017 23

Associated Risk Factors

The presence of one or more associated risk factors was reported in 83% of invasive GAS cases in 2017. 

Cigarette smoking was the most prevalent risk factor reported in adults, followed by alcohol abuse and chronic 

lung disease. 

Table 16: Associated Risk Factors Identified in Invasive GAS Cases – Alaska, 2017* 

Medical Condition/Risk 

Factor 

Adult Cases (≥ 18 years) 

n=118, Cases (%) 

Cigarette smoking 47 (39%)

Alcohol abuse 37 (31%)

Chronic lung disease 27 (23%)

Diabetes 20 (17%)

Injection drug use 11 (9%)

Immunosuppressive treatment 8 (7%)

Asplenia 0 (0%)

*Multiple risk factors may be reported for a given case 

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 2017, 122 invasive GAS isolates were emm typed at AIP. The most common emm types were emm 26 (29%) 

and emm 11 (28%). The following graph shows emm typing trends over time. Strains that totaled ≤ 10 over the 

time period were not included. 

0

20

40

60

80

100

120

140

160

2002200320042005200620072008200920102011201220132014201520162017

Number of Cases

Figure 19: Invasive group A Streptococcus emm 

Typing Trends - Alaska, 2002-2017 Unknown

238

108

101

92

91

89

87

82

73

49

41

28

26

12

11

5

4

3

1
Surveillance of Invasive Bacterial Disease in Alaska, 2017 24

Antibiotic Resistance 

One hundred twenty-two 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, and vancomycin and levofloxacin. Thirty-eight isolates were resistant to erythromycin; 35 of those 

were emm type 11, two were emm type 26.3 and one was emm type 4. One erythromycin-resistant emm type 11 

isolate was also resistant to clindamycin. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 25

Invasive group B Streptococcus

Overall Incidence

A total of 61 cases of invasive group B Streptococcus (GBS) were reported to AIP in 2017. The overall rate of 

invasive GBS disease in the state of Alaska was 8.3/100,000 persons per year. The Alaska rate is less than the 

ABCs 2017 national projected rate of 9.8/100,000 [14]. In 2017, there were four GBS-related deaths for a case 

fatality ratio of 6.6%. 

Seasonality

Cases of GBS occurred throughout the year with no apparent trends in seasonality. 

 

Race

In 2017, 21% of invasive GBS cases in Alaska occurred in the Alaska Native population. The age-adjusted rate 

ratio of invasive GBS disease for the Alaska Native population compared with the non-Native population in 

2017 was 1.4. 

Table 17: Invasive group B Streptococcus Cases by Race – Alaska, 2017 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

Alaska Native Persons 13 (21) 9.9 77 1 (8)

Non-Native Persons 48 (79)† 7.0 67 3 (6)

Total 61 69 4 (7)

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

†Includes 6 cases for which race was unknown 

Region 

In 2017, 45 (74%) of the 61 reported GBS cases occurred in Anchorage; 6 cases were reported in the Southeast, 

three cases each in the Interior and the YK Delta and two cases each in the Kotzebue and Norton Sound regions. 

The highest rates of disease occurred in the Kotzebue region (23.4/100,000) and Norton Sound (20/100,000). 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 26

Age

Invasive GBS cases reported in 2017 ranged in age from newborn to 93 years old; the median age was 53 years. 

Highest rates of disease overall occurred in persons 65 years and older (32.6/100,000 persons per year). 

 

When stratified by race, the highest rates of disease occurred in AK Native persons 55-64 years old and 65 

years and older, 35.2/100,000 persons per year and 52.9/100,000 persons per year, respectively. There were 

two cases of early-onset disease (disease in infants 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 2017, the most common clinical presentations were cellulitis and osteomyelitis, which occurred 

in 19 (31%) and 12 (20%) cases, respectively. 

Group B Streptococcus was isolated from blood in 46 (75%) of 61 cases in 2017; 10 isolates were obtained 

from surgical specimens, two each from joint fluid and bone and one from cerebrospinal fluid. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 27

Table 18: Primary Clinical Presentations of Invasive group B Streptococcus – Alaska, 2017 

*with bacteremia

Associated Risk Factors

The presence of one or more associated risk factors was reported in 87% of invasive GBS cases in 2017. 

Diabetes was the most prevalent risk factor observed in adults, followed by chronic lung disease and cigarette 

smoking. 

Table 19: Associated Risk Factors Identified in Adult Invasive GBS Cases – Alaska, 2017* 

Medical Condition/Risk 

Factor 

Adult Cases (≥ 18 years) 

n=57, Cases (%) 

Diabetes 28 (49%)

Chronic lung disease 14 (25%)

Cigarette smoking 13 (23%)

Alcohol abuse 5 (9%)

Injection drug use 4 (7%)

Immunosuppressive treatment 2 (4%)

Asplenia 0 (0%)

*Multiple risk factors may be reported for a given case 

Antibiotic Resistance

Number of isolates tested for antibiotic resistance varied by the antibiotic tested, ranging from 20 to 57 isolates. 

Results of the testing are presented in the following table. 

Table 20: Antibiotic Resistance in Invasive group B Streptococcus Isolates – Alaska, 2017 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 56 (100%) 0 (0%) 0 (0%) 0 (0%) 56

Ceftriaxone 56 (100%) 0 (0%) 0 (0%) 0 (0%) 56

Erythromycin 26 (46%) 0 (0%) 31 (54%) 31 (54%) 57

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

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

Clindamycin 16 (80%) 0 (0%) 4 (20%) 4 (20%) 20

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

erythromycin and clindamycin was seen in 54% and 20%, respectively, of isolates tested. The isolate for one 

early onset case was resistant to erythromycin. 

Primary Presentation n (%) 

Cellulitis* 19 (31)

Osteomyelitis 12 (20)

Bacteremia 11 (18)

Pneumonia* 9 (15)

Septic arthritis 5 (8)

Meningitis 2 (3)

Endocarditis 2 (3)

Other 1 (2)

Total 61
Surveillance of Invasive Bacterial Disease in Alaska, 2017 28

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. 2017. Active Bacterial Core Surveillance Report, Emerging 

Infections Program Network, Streptococcus pneumoniae, 2017.

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. 2017. Active Bacterial Core Surveillance Report, Emerging 

Infections Program Network, Haemophilus influenzae, 2017. 

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. 

12. Centers for Disease Control and Prevention. Enhanced Meningococcal Disease Surveillance Report, 2017. 

From https://www.cdc.gov/meningococcal/downloads/NCIRD-EMS-Report-2017.pdf

13. Centers for Disease Control and Prevention. 2017. Active Bacterial Core Surveillance Report, Emerging 

Infections Program Network, Group A Streptococcus, 2017. 

14. Centers for Disease Control and Prevention. 2017. Active Bacterial Core Surveillance Report, Emerging 

Infections Program Network, Group B Streptococcus, 2017. 
Surveillance of Invasive Bacterial Disease in Alaska, 2017 29

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., βlactams). 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.