Surveillance of Invasive Bacterial Disease in Alaska, 2001 - 2002 

Arctic Investigations Program 

National Center for Infectious Diseases 

Centers for Disease Control 

4055 Tudor Centre Dr. 

Anchorage, AK 99508 

(907) 729-3400 

ncidaip@cdc.gov
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 2 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 3 

Alaska Statewide Invasive Bacterial Disease 

Table of Contents 

 Page 

Summary 4 

Introduction 5 

Streptococcus pneumoniae 6 

Haemophilus influenzae 17 

 

Neisseria meningitidis 23 

Group A Streptococcus 27 

Group B Streptococcus 33 

Appendix 39 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 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. 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 7-valent pneumococcal conjugate vaccine and Haemophilus influenzae type b 

vaccines. 

Figure 1: Invasive Bacterial Disease Surveillance Regions – Alaska, 2001 - 2002 

In 2001 - 2002, the total number of cases of invasive disease caused by these organisms reported to AIP 

were 192 S. pneumoniae, 21 H. influenzae, 12 N. meningitidis, 70 Group A Strep and 43 Group B Strep. 

Alaska Native populations had higher rates of disease than non-Native populations in all invasive disease 

except those caused by Group B Strep. Rates of invasive pneumococcal disease were highest in Norton 

Sound; H. influenzae rates were highest in YK Delta. Rates for each organism by region are presented in 

the following tables. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 5 

Table 1: Surveillance Organisms Reported by Region – Alaska, 2001 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

Group A Strep 

n (rate*) 

Group B Strep 

n (rate*) 

Anchorage 61 (14.9) 7 (1.7) 4 (1.0) 19 (4.6) 19 (4.6) 

Arctic Slope 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 

Bristol Bay 0 (0) 0 (0) 0 (0) 1 (13.3) 0 (0) 

Interior 14 (14.5) 0 (0) 1 (1.0) 7 (7.2) 0 (0) 

Kotzebue 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 

Norton Sound 6 (60.0) 0 (0) 1 (10.0) 0 (0) 0 (0) 

Southeast 17 (23.5) 2 (2.8) 0 (0) 1 (1.4) 1 (1.4) 

YK Delta 5 (20.9) 1 (4.2) 0 (0) 1 (4.2) 0 (0) 

Total 103 (16.3) 10 (1.6) 6 (0.9) 29 (4.6) 20 (3.2)

*Cases per 100,000 

Table 2: Surveillance Organisms Reported by Region – Alaska, 2002 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

Group A Strep 

n (rate*) 

Group B Strep 

n (rate*) 

Anchorage 59 (14.1) 9 (2.2) 4 (1.0) 28 (6.7) 17 (4.1) 

Arctic Slope 1 (16.0) 0 (0) 0 (0) 0 (0) 0 (0) 

Bristol Bay 1 (13.6) 0 (0) 0 (0) 1 (13.6) 0 (0) 

Interior 11 (11.2) 1 (1.0) 2 (2.0) 5 (5.1) 4 (4.1) 

Kotzebue 1 (12.5) 0 (0) 0 (0) 1 (12.5) 0 (0) 

Norton Sound 5 (49.9) 0 (0) 0 (0) 0 (0) 0 (0) 

Southeast 5 (6.9) 0 (0) 0 (0) 2 (2.8) 2 (2.8) 

YK Delta 6 (24.8) 1 (4.1) 0 (0) 4 (16.5) 0 (0) 

Total 89 (13.8) 11 (1.7) 6 (0.9) 41 (6.4) 23 (3.6) 

*Cases per 100,000 

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, laboratorybased 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 633,630 

persons in 2001 and 643,786 persons in 2002 (Alaska Department of Labor & Workforce Development, 

http://almis.labor.state.ak.us). Case detection occurs year-round as participating laboratories send 

isolates recovered from sterile sites to the AIP lab in Anchorage, accompanied by basic demographic and 

clinical information on the cases. Materials and forms for isolate shipment and data collection are 

provided to each lab by AIP. At year-end, AIP asks that each laboratory review their records and provide 

information on any cases that may have been overlooked. In 2001 and 2002, 24 labs in Alaska 

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

throughout the year, conducting year-end record reviews, or both. 

AIP defines a case of invasive Streptococcus pneumoniae, Haemophilus influenzae, Neisseria 

meningitidis, or Groups A and B Streptococcus 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 Group A Streptococcus, 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, 2001-2002 6 

Invasive Pneumococcal Disease 

Overall Incidence

A total of 92 pneumococcal isolates were received at AIP in 2001 and 76 pneumococcal isolates 

were received in 2002. An additional 11 cases in 2001 and 13 cases in 2002 were detected 

through year-end follow up with participating labs throughout the state for a total of 103 cases of 

invasive pneumococcal disease in 2001 and 89 cases in 2002. Overall invasive pneumococcal 

cases rates for 2001 and 2002 were 16.3 and 13.8 per 100,000 persons per year respectively. 

Alaska rates for 2001 and 2002 were slightly less than the Active Bacterial Core Surveillance 

(ABCs) 2001 national projected rate of 17.1/100,000 (Active Bacterial Core Surveillance (ABCs) 

Report Emerging Infections Program Network Streptococcus pneumoniae, 2001). ABCs is a 

surveillance system operated in 9 states which covers a population of over 36 million persons. 

Seasonality

Invasive Streptococcus pneumoniae cases were identified in each month of 2001 and 2002. The 

smallest number of cases was reported in April during both years. 

Figure 2: Invasive Pneumococcal Disease, by 

Month of Culture - Alaska, 2001-2002

0

2

4

6

8

10

12

14

January

February

March

AprilMay

June

July

August

September

October

November

December

Month of Culture

Number of Cases

2001

2002

Race 

In 2001 and 2002, the state population was comprised of 19% Alaska Natives (Alaska 

Department of Labor & Workforce Development: http://almis.labor.state.ak.us 11/30/2003; 

2001, Alaska Natives 121,857, non-Natives 511,773; 2002, Alaska Natives 124,803, non-Natives 

518,983). The percentages of all reported S. pneumoniae cases that occurred in 2001 and 2002 

among Alaska Natives were 30% and 48%, respectively. In 2001, a total of 31 cases occurred 

among Alaska Natives, resulting in an age-adjusted rate of 26.2/100,000 persons per year. 

Seventy-two cases occurred among the non-Native population for an age-adjusted rate of 

14/100,000 persons per year. The age-adjusted rate ratio of S. pneumoniae disease for the 

Alaska Native population compared with the non-Native population in 2001 is 1.9. In 2002, a 

total of 43 cases occurred among Alaska Natives, resulting in an age-adjusted rate of 36/100,000 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 7 

persons per year. Forty-six cases occurred among the non-Native population for an age-adjusted 

rate of 8.6/100,000 persons per year. The age-adjusted rate ratio of pneumococcal disease for the 

Alaska Native population compared with the non-Native population in 2002 is 4.2. 

Table 3: Invasive Streptococcus pneumoniae Cases by Race – Alaska, 2001-2002 

Year Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

2001 Alaska Native 31 (30) 26.2 42 4 (13) 

 Non-Native† 72 (70) 14 52 8 (11) 

 Total 103 49 12 (12) 

2002 Alaska Native 43 (48) 36 47 5 (12) 

 Non-Native† 46 (52) 8.6 46 6‡ (13) 

 Total 89 66 11 (12) 

*Cases per 100,000 per percent distribution of Alaska 2000 population 

†Includes 14 cases in 2001 and 8 cases in 2002 for which race was unknown 

‡Includes 1 death in 2002 for which race was unknown

Region 

The highest percentage of invasive pneumococcal disease cases occurred in the Anchorage area 

in 2001 and 2002, 59% (61 cases) and 66% (59 cases) respectively. Rates of disease, however, 

were highest in Norton Sound both years; 64.4/100,000 persons per year in 2001 and 

53.5/100,000 persons per year in 2002. 

Figure 3: Invasive Pneumococcal Disease, Cases 

& Rates by Region - Alaska, 2001 - 2002

0

10

20

30

40

50

60

70

Anchorage

Arctic Slope

Bristol Bay

Interior

Kotzebue

Norton Sound

Southeast

YK Delta

Number of Cases

0

10

20

30

40

50

60

70

Rate per 100,000

2001 Cases

2002 Cases

2001 Rate

2002 Rate

Age

Cases occurred in all age groups in 2001 and 2002. In 2001, the age of cases ranged from 0.2 

years to 100.6 years with a median of 40.5 years. In 2002, cases ranged in age from 0.2 years to 

94.3 years with a median of 45.4 years. Overall, the highest rates of disease occurred in children 

less than 2 years old and in adults greater than 65 years old during both 2001 and 2002. 

 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 8 

Figure 4: Invasive Pneumococcal Disease by Age 

Group - Alaska, 2001-2002

0

20

40

60

80

100

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

Age (yrs)

Rate per 100,000

2001

2002

Figure 5: Invasive Pneumococcal Disease, Cases 

& Rates by Age Group & Race - Alaska, 2001

0

5

10

15

20

25

30

35

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

Age (yrs)

Number of Cases

0

20

40

60

80

100

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Figure 6: Invasive Pneumococcal Disease, Cases 

& Rates by Age Group & Race - Alaska, 2002

0

5

10

15

20

25

30

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

Age (yrs)

Number of Cases

0

20

40

60

80

100

120

140

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 9 

When stratified by age and race, the highest rates of disease in 2001 and 2002 occurred in Alaska 

Native children less than 2 years old; 93.6/100,000 persons per year in 2001 and 130.7/100,000 

persons per year in 2002. High rates of invasive pneumococcal disease also occurred in Alaska 

Natives greater than 65 years old in 2001, 74.9/100,000 persons per year, however, rates of 

disease in this age category declined to 42.8/100,000 persons per year in 2002. Overall during 

2001 and 2002, rates of disease were higher in the Alaska Native population in all age categories 

with the exception of the 2-4 year old and 55-64 year old categories in 2001. 

Clinical Presentation

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

indicated in each patient’s individual medical record associated with the illness resulting in the 

culture. In cases with multiple discharge diagnoses, the most serious diagnosis related to the 

pneumococcal infection was recorded as the primary clinical presentation. Pneumonia was the 

most common primary clinical presentation in 2001 (63%) and 2002 (62%) followed by 

septicemia (15.5% in 2001 and 20% in 2002). Six cases had a secondary pneumococcal-related 

diagnosis in 2001: 2 pneumonia and 1 each endocarditis, septic arthritis, cellulitis and 

unspecified other. In 2002, nine cases had a secondary pneumococcal-related diagnosis; eight of 

these were pneumonia and one was septic arthritis. 

Figure 7: Primary Clinical Presentations of 

Invasive Pneumococcal Disease - Alaska, 2001-

2002

0

10

20

30

40

50

60

70

Bacteremia

Meningitis

Peritonitis

Pneumonia

Septic arthritis

Cellulitis

Septicemia

Osteomyelitis

Nec fasciitis

Other

Number of Cases

2001

2002

In 2001 and 2002, blood was the most common source of a positive culture which was used to 

identify 93% of the 103 cases in 2001 and 91% of the 89 cases in 2002. Cerebrospinal fluid was 

the positive site for 4% of cases in 2001 and 6% of cases in 2002. The remaining cases in 2001 

were identified through joint fluid, peritoneal fluid and other unidentified sterile site (1 case 

each). In 2002, the remaining cases were identified through pleural fluid (4 cases) and one case 

through an unidentified sterile site. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 10 

Mortality 

In 2001, the overall case fatality ratio for S. pneumoniae in Alaska was 11.7% (12 deaths out of 

103 cases) and in 2002, it was 12.4% (11 deaths out of 89 cases). In both years, the case fatality 

ratio for non-Natives was higher than Natives; 13.8% (8 deaths) in non-Natives compared to 

12.9% (4 deaths) in Natives in 2001 and 13% (6 deaths) in non-Natives compared to 11.6% (5 

deaths) in Natives in 2002. Although the majority of deaths occurred in the 19-54 year old age 

category in both 2001 (7 deaths) and 2002 (5 deaths), the highest case fatality ratios occurred in 

the 65+ age category; 18.8% (3 deaths) in 2001 and 26.7% (4 deaths) in 2002. 

Figure 8: Invasive Pneumococcal Deaths & Case 

Fatality Ratios by Age Group - Alaska, 2001-2002

0

1

2

3

4

5

6

7

8

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

Age (yrs)

Number of 

Deaths

0

5

10

15

20

25

30

Case Fatality 

Ratio

Deaths '01

Deaths '02

CFR '01

CFR '02

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 principle virulence factor for pneumococci. This information provides a way to 

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

use of one of the two available pneumococcal vaccine types. Serotyping was performed on 91 of 

the 103 S. pneumoniae cases that occurred in Alaska in 2001 and on 76 of the 89 cases in 2002. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 11 

Table 4: Invasive Pneumococcal Serotype Distribution by Race and Age Group – Alaska, 2001 

 Alaska Native Non-Native Unknown 

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

01 5 (5.4) - 3 2 - - - - - - 

03 4 (4.3) - - - - - 1 3 - - 

04 10 (10.9) - - 1 - - 2 3 2 2 

06A 3 (3.3) - - - - - - 1 1 1 

06B 7 (7.6) - - 1 - 3 - 2 1 - 

07F 1 (1.1) - - - - - - 1 - - 

08 3 (3.3) 1 - 1 - - - 1 - - 

09N 3 (3.3) - - 2 - - - 1 - - 

09V 7 (7.6) - - 2 1 - - 2 1 1 

11A 4 (4.3) - - 1 - - - 2 1 - 

12F 6 (6.5) - - 1 - - - 5 - - 

14 16 (17.4) 1 - 1 - 1 3 4 1 5 

15A 1 (1.1) - - 1 - - - - - - 

17F 1 (1.1) - - - 1 - - - - - 

18C 2 (2.2) - - - - - - - 1 1 

19A 2 (2.2) - - - - 1 1 - - - 

19F 2 (2.2) 1 - - - 1 - - - - 

20 1 (1.1) - - - - 1 - - - - 

22F 2 (2.2) - - - 1 - - 1 - - 

23F 4 (4.3) - - - 1 - - - 1 2 

31 1 (1.1) - - - - - - 1 - - 

33F 3 (3.3) 1 - 1 - 1 - - - - 

34 1 (1.1) - - - - - - 1 - - 

NT* 2 (2.2) - - 1 - - - 1 - - 

Total 91 4 3 15 4 8 7 29 9 12 

*Non-typable 

Table 5: Invasive Pneumococcal Serotype Distribution by Race and Age Group – Alaska, 2002 

 Alaska Native Non-Native Unknown 

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

03 4 (5.3) - 1 1 1 - - 1 - - 

04 12 (15.8) - - 4 1 - - 5 1 1 

05/10F 1 (1.3) - - 1 - - - - - - 

06A 3 (3.9) 1 - 1 - - - - - 1 

06B 3 (3.9) - 1 - - - - - 2 - 

07F 6 (7.9) - - 5 - - - 1 - - 

08 5 (6.6) - - 2 - - - 1 - 2 

09N 7 (9.2) - - 2 - - - 1 3 1 

10A 2 (2.6) - - - - - 1 1 - - 

12F 3 (3.9) - - 1 - 1 - - - 1 

14 5 (6.6) 1 - 2 - - - 1 1 - 

15B 1 (1.3) - - - - - 1 - - - 

15C 2 (2.6) 1 - - - - 1 - - - 

16F 4 (5.3) - - 2 - - 1 - 1 - 

19A 3 (3.9) - 1 1 - 1 - - - - 

19F 2 (2.6) - - 2 - - - - - - 

22A 3 (3.9) 1 - 1 - - - 1 - - 

22F 4 (5.3) 1 - 1 - 1 1 - - - 

23F 1 (1.3) - - - - - - 1 - - 

33F 2 (2.6) - - - 1 - - - 1 - 

38 3 (3.9) 2 - - - 1 - - - - 

Total 76 7 3 26 3 4 5 13 9 6 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 12 

Table 6: Invasive Pneumococcal Serotype Distribution by Region – Alaska, 2001-2002 Anchorage Arctic Slope YK Delta Bristol Bay Kotzebue Southeast Interior Norton Sound 

Serotype

2001200220012002200120022001200220012002200120022001200220012002

01 - - - - - - - - - - - - - - 5 - 

03 2 1 - - - 1 - 1 - 1 - - 2 - - - 

04 7 7 - - - - - - - - 2 - 1 5 - - 

05/10F - 1 - - - - - - - - - - - - - - 

06A 3 2 - - - 1 - - - - - - - - - - 

06B 4 3 - - - - - - - - 1 - 2 - - - 

07F 1 2 - - - - - - - - - - - 1 - 3 

08 3 4 - 1 - - - - - - - - - - - - 

09N 3 6 - - - - - - - - - - - 1 - - 

09V 4 - - - - - - - - - 2 - 1 - - - 

10A - 2 - - - - - - - - - - - - - - 

11A 3 - - - - - - - - - - - 1 - - - 

12F 1 2 - - - - - - - - 5 1 - - - - 

14 9 4 - - 1 - - - - - 3 1 3 - - - 

15A - - - - - - - - - - 1 - - - - - 

15B - 1 - - - - - - - - - - - - - - 

15C - 1 - - - - - - - - - - - - - 1 

16F - 3 - - - - - - - - - - - 1 - - 

17F - - - - - - - - - - - - - - 1 - 

18C 1 - - - - - - - - - - - 1 - - - 

19A 2 1 - - - - - - - - - - - 1 - 1 

19F 1 1 - - - - - - - - 1 - - 1 - - 

20 - - - - - - - - - - - - 1 - - - 

22A - 1 - - - 2 - - - - - - - - - - 

22F - 3 - - 1 1 - - - - 1 - - - - - 

23F 2 1 - - - - - - - - 1 - 1 - - - 

31 1 - - - - - - - - - - - - - - - 

33F 2 2 - - 1 - - - - - - - - - - - 

34 1 - - - - - - - - - - - - - - - 

38 - 1 - - - 1 - - - - - - - 1 - - 

NT* 1 - - - - - - - - - - - 1 - - - 

*Non-typable 

In 2001, the most common serotypes were 14 (16 isolates, 17.4%) and 4 (10 isolates, 10.9%). 

The serotype 14 cases were distributed throughout the state, 9 in Anchorage, 3 each in the 

Southeast and Interior and one in the YK Delta. Serotype 4 cases occurred in Anchorage (7 

cases), the Interior (5 cases) and Southeast (2 cases). In 2002, the most common serotypes were 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 13 

4 (12 isolates, 15.8%) and 9N (7 cases, 9.2%). Both serotype 4 and serotype 9N cases occurred 

in Anchorage (7 cases serotype 4, 6 cases serotype 9N) and the Interior (5 cases serotype 4, 1 

case serotype 9N). 

Vaccine Serotypes

Two vaccine types are licensed for prevention of pneumococcal disease. In 2001, the 

pneumococcal conjugate vaccine (PCV7) was included in the Alaska childhood vaccination 

schedule. This vaccine provides protection against the 7 most common pneumococcal serotypes 

causing invasive disease among children (types 4, 6B, 9V, 14, 18C, 19F, 23F). The table below 

shows the proportion of invasive infections from 2001 and 2002 that were due to serotypes found 

in the PCV7 vaccine. 

Table 7: Proportion of Invasive Isolates Contained in the PCV7 Vaccine by Age Group 

and Race – Alaska, 2001-2002 

Age 

(yrs) 

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

2001 2002 2001 2002 2001 2002 

<2 2 (40%) of 5 1 (14%) of 7 5 (63%) of 8 0 (0%) of 4 10 (59%) of 17 1 (8%) of 

13 

2-4 0 (0%) of 0 0 (0%) of 2 1 (33%) of 3 0 (%) of 2 4 (67%) of 6 0 (0%) of 4 

5+ 6 (27%) of 

22 

10 (33%) of 

30 

19 (45%) of 

42 

11 (44%) 

of 25 30 (43%) of 69 22 (37%) of 59 

Total 8 (31%) of 

27 

11 (28%) of 

39 

25 (47%) of 

53 

11 (35%) 

of 31 44 (48%) of 92 27 (36%) of 76 

The 23-valent polysaccharide vaccine (Ps23V) is recommended in Alaska for all persons 55 

years and older, and for persons over age 2 who are at higher risk for pneumococcal disease. 

Revaccination is recommended after 6 years. In 2001 and 2002, for persons 55 years and older, 

18 (86%) of 21 and 22 (88%) of 25 cases serotyped, respectively, were potentially vaccine 

preventable invasive pneumococcal illnesses. 

Vaccination Status

In 2001, pneumococcal vaccine status was known for 59 (57%) of the 103 cases; 21 cases (20%) 

did receive a pneumococcal vaccine prior to illness and 38 cases (37%) had no record of a 

pneumococcal vaccine. Pneumococcal vaccine status in 2002 was known for 57 (64%) of the 89 

cases; 31 cases (35%) did receive a pneumococcal vaccine prior to illness. Twenty-six (29%) had 

no record of a pneumococcal vaccine. 

A PCV7 vaccine failure is defined as invasive pneumococcal disease caused by a serotype 

contained in the PCV7 vaccine in an individual who has had at least two doses of vaccine. There 

were no vaccine failures in 2001 or 2002. 

Two of the 12 deaths in 2001 and 5 of the 11 deaths in 2002 from invasive S. pneumoniae were 

due to serotypes found in the PCV7 vaccine. None of these deaths, however, occurred in persons 

in the age group for which vaccine is recommended (< 2 years). Six of the 12 fatal cases in 2001 

(50%) and 8 of 11 in 2002 (73%) were due to serotypes contained within the 23-valent 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 14 

polysaccharide vaccine. Three cases in each year occurred in persons 55 years or older which is 

the age group eligible for this vaccine. Vaccine status was known for 8 of the 12 deaths in 2001 

and 5 of the 11 deaths in 2002. It is unknown if these individuals received the 7-valent or 23-

valent vaccine. 

Table 8: Invasive Pneumococcal Disease, Serotypes of Fatal Cases – Alaska, 2001-2002 

2001 2002 

Serotype Deaths (%) Serotype Frequency Deaths (%) Serotype Frequency

03† 1 (25%) 4 0 (0%) 0 

04*† 1 (10%) 10 4 (33%) 12 

6A 1 (33%) 3 0 (0%) 0 

07F† 0 (0%) 0 1 (17%) 6 

09N† 1 (33%) 3 0 (0%) 0 

09V*† 1 (14%) 7 0 (0%) 0 

10A† 0 (0%) 0 1 (50%) 2 

16F 0 (0%) 0 1 (25%) 4 

17F† 1 (100%) 1 0 (0%) 0 

19F*† 0 (0%) 0 1 (50%) 2 

22F† 1 (50%) 2 0 (0%) 0 

31 1 (100%) 1 0 (0%) 0 

33F† 0 (0%) 0 1 (50%) 2 

NT 2 (100%) 2 0 (0%) 0 

*Serotypes contained in the PCV7 vaccine 

†Serotypes contained in the 23-valent polysaccharide vaccine

Overall, 50% of all pneumococcal-related mortality in 2001 and 73% in 2002 was potentially 

preventable with the use of the 23-valent polysaccharide vaccine in persons over 2 years old. 

Table 9: Potentially Vaccine Preventable Invasive Pneumococcal Deaths – Alaska, 2001 

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

PCV7 0 0 0 1 (14%) 1 (100%) 0 2 (17%) 

Ps23V 0 1 (100%) 0 2 (29%) 1 (100%) 2 (67%) 6 (50%) 

Total 0 1 0 7 1 3 12 

Table 10: Potentially Vaccine Preventable Invasive Pneumococcal Deaths – Alaska, 2002 

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

PCV7 0 0 0 3 (60%) 1 (100%) 1 (25%) 5 (45%) 

Ps23V 0 0 1 (100%) 4 (80%) 1 (100%) 2 (50%) 8 (73%) 

Total 0 0 1 5 1 4 11 

Associated Medical Conditions

The presence of one or more associated medical conditions was reported in 67% of invasive 

pneumococcal cases in 2001 and 74% in 2002. Data on associated medical conditions was 

unavailable for 7% (7 cases) in 2001 and 3% (3 cases) in 2002. Cigarette smoking was the most 

prevalent risk factor observed in adults in both years followed closely by alcohol abuse. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 15 

Table 11: Associated Medical Conditions Identified in Invasive Pneumococcal Cases – 

Alaska, 2001-2002* 

Medical Condition 

Adult Cases (≥ 18 years) 

2001, n=70 

Cases (%) 

2002, n=62 

Cases (%) 

Diabetes 6 (9) 6 (10) 

Cigarette smoking 26 (37) 30 (48) 

Chronic lung disease 18 (26) 19 (31) 

Alcohol abuse 24 (34) 29 (47) 

Immunosuppressive treatment 4 (6) 3 (5) 

Injection drug use 5 (7) 0 (0) 

Asplenia 0 (0) 2 (3) 

*More than one risk factor was identified in several cases 

Antibiotic Resistance

Susceptibility testing was performed on 91 isolates in 2001 and 76 isolates in 2002. Results of 

the testing are presented in the following two tables. 

Table 12: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2001 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 79 (87%) 7 (8%) 5 (5%) 12 (13%) 91 

TMP-sulfa 72 (79%) 2 (2%) 17 (19%) 19 (21%) 91 

Erythromycin 79 (87%) 0 12 (13%) 12 (13%) 91 

Ceftriaxone 85 (93%) 6 (7%) 0 6 (7%) 91 

Tetracycline 89 (98%) 0 2 (2%) 2 (2%) 91 

Chloramphenicol 91 (100%) 0 0 0 91 

Rifampin 91 (100%) 0 0 0 91 

Vancomycin 91 (100%) 0 0 0 91 

Levoflox 91 (100%) 0 0 0 91 

Clindamycin 83 (100%) 0 0 0 83 

Table 13: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2002

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 67 (88%) 7 (9%) 2 (3%) 9 (12%) 76 

TMP-sulfa 61 (80%) 2 (3%) 13 (17%) 15 (20%) 76 

Erythromycin 69 (91%) 0 7 (9%) 7 (9%) 76 

Ceftriaxone 73 (96%) 3 (4%) 0 3 (4%) 76 

Tetracycline 72 (95%) 0 4 (5%) 4 (5%) 76 

Chloramphenicol 74 (97%) 0 2 (3%) 2 (3%) 76 

Rifampin 76 (100%) 0 0 0 76 

Vancomycin 76 (100%) 0 0 0 76 

Levoflox 48 (100%) 0 0 0 48 

Clindamycin 74 (97%) 0 2 (3%) 2 (3%) 76 

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 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 16 

tested (National Committee for Clinical Laboratory Standards (NCCLS) MIC Testing, 

Supplemental Tables, M100-S10 (M7), January, 2000). The MIC Interpretive Standards 

definitions of ‘susceptible’, ‘intermediate’, and ‘resistant’ can be found in the Appendix. 

Serotypes found in the PCV7 vaccine are more likely to be non-susceptible to penicillin and 

erythromycin than non-vaccine serotypes. One potential benefit of the vaccine is an anticipated 

decline in antibiotic resistance among circulating pneumococci. The data in the following graph 

supports this assumption; since the initiation of the PCV7 vaccine in 2001, antibiotic resistance 

has dropped. TMP-sulfa resistance has declined from 32.1% of isolates tested in 2000 to 20% in 

2002, erythromycin resistance from 20.8% in 2000 to 9% in 2002, and penicillin fully resistant 

isolates from 13.2% in 2000 to 3% in 2002. 

Figure 9: Trends in Antibiotic Resistance Among 

Invasive Pneumococcal Isolates - Alaska, 1986 - 2002

0

5

10

15

20

25

30

35

86 88 90 92 94 96 98 00 02

Year

Percent Resistant

Pen-FR*

Pen-NS*

Erythro

TMP-Sulfa

Tet

 *Pen-FR = fully resistant, Pen-NS = non-susceptible 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 17 

Invasive Haemophilus influenzae

Overall Incidence 

In 2001, there were 10 cases of invasive Haemophilus influenzae in Alaska, giving a statewide 

rate of 1.6/100,000 persons per year. This rate was slightly higher than the national projected 

rate of 1.3/100,000 persons per year, as stated in the Active Bacterial Core Surveillance (ABCs) 

Report Emerging Infections Program Network, 2001. In 2001, two Haemophilus influenzae 

cases resulted in death, giving a case-fatality ratio of 20%. 

In 2002, there were 11 cases of invasive Haemophilus influenzae in Alaska, for a statewide rate 

of 1.7/100,000 persons per year. This rate was higher than the national projected rate of 

1.3/100,000 persons per year, according to the Active Bacterial Core Surveillance (ABCs) Report 

Emerging Infections Program Network, 2002. One of these cases resulted in death, giving a 

case-fatality ratio of 9.1%.

Seasonality 

Figure 10: Haemophilus influenzae Disease by Month 

of Culture - Alaska, 2001-2002

0

1

2

3

4

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Number of Cases

2001

2002

No true trends in seasonality are evident. 

Region 

The Anchorage area had the highest numbers of reported cases and percentages of reported cases 

both years. The Anchorage area had 70% (7 cases) and 82% (9 cases) in 2001 and 2002, 

respectively. The Yukon-Kuskokwim Delta area presented only one case both years and had the 

highest disease rate of just over 4.1/100,000 persons per year in both years. The Southeast 

region had two cases in 2001 and the Interior had one case in 2002. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 18 

Figure 11: Invasive Haemophilus Influenzae , 

Cases & Rates by Region - Alaska, 2001 - 2002

0

2

4

6

8

10

Anchorage

Arctic Slope

Bristol Bay

Interior

Kotzebue

Norton Sound

Southeast

YK Delta

Number of Cases

0

1

2

3

4

5

Rate per 100,000

2001 Cases

2002 Cases

2001 Rate

2002 Rate

Race 

Table 14: Invasive Haemophilus influenzae Cases by Race – Alaska, 2001-2002 

 Race 

Cases 

n (%) 

Age Adjusted 

Rate * % Male 

Deaths 

n (%) 

2001 Alaska Native 3 (30) 2.4 66.7 0 (0) 

 Non-Native† 7 (70) 1.4 83.3 2 (29) 

 Total 10 70 2 (20) 

2002 Alaska Native 6 (55) 4.6 33.3 0 (0) 

 Non-Native 5 (45) 1.0 60 1 (20) 

 Total 11 45.5 1 (9) 

*Cases per 100,000 per percent distribution of Alaska 2000 population 

†Includes 1 case for which race was unknown 

In 2001, 60% of the cases occurred in non-Natives and 46% in 2002. 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 2001 was 

1.7 and 4.6 in 2002. 

Age 

Haemophilus influenzae cases ranged in age from infancy to 78 years of age in 2001 (median 

41.5 years) and from infancy to 73 years of age in 2002 (median 39.2 years). Overall, the 

highest rates of disease occurred in children less than 2 years old and in adults greater than 65 

years old during both 2001 and 2002.
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 19 

Figure 12: Invasive Haemophilus Influenzae by 

Age Group - Alaska, 2001 - 2002

0

5

10

15

20

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

Age (yrs)

Rate per 100,000

2001

2002

Figure 13: Invasive Haemophilus influenzae, Cases & 

Rates by Age Group & Race - Alaska, 2001-2002

0

1

2

3

4

5

6

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

Age (yrs)

Number of Cases

0

5

10

15

20

25

30

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

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

between the years 2001 and 2002; overall numbers of cases and rates by race and age group for 

the two year reporting period are presented in Figure 13. In 2001, the highest rates of disease 

occurred in Alaska Natives 2 to 4 years of age (12.8/100,000 persons per year) and those greater 

than 65 years old (15/100,000 persons per year). There were no cases of Haemophilus 

influenzae in the 2-4 year old age group in non-Natives and the rate of disease in those greater 

than 65 was less than half that of the Alaska Native population in that category. No H. 

influenzae cases were reported in Alaska Natives less than two years old in 2001, however, in 

2002, the rate of disease in this age category increased to 56/100,000 persons per year compared 

to a rate of 0 in non-Native children less than two years old. 

Clinical Presentation 

Primary clinical presentations were determined by a review of the discharge diagnoses from each 

patient’s individual medical record associated with the illness resulting in the culture. For cases 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 20 

with more than one diagnosis, the most serious Haemophilus influenzae-related diagnosis was 

recorded as the primary clinical presentation. 

In 2001, all isolates of Haemophilus influenzae were from blood samples. In 2002, eight isolates 

were from blood samples, two were from CSF, and one from peritoneal fluid. 

Table 15: Primary Clinical Presentation of Invasive Haemophilus influenzae - Alaska, 

2001-2002 

Primary Presentation 

2001 Cases 2002 Cases

n (%) n (%) 

Pneumonia 5 (50) 4 (36.4) 

Septicemia 4 (40) 3 (27.3) 

Meningitis 0 (0) 2 (18.2) 

Empyema 1 (10) 0 (0) 

Peritonitis 0 (0) 1 (9.1) 

Pericarditis 0 (0) 1 (9.1) 

Total 10 11 

Serotypes 

All isolates received at AIP are serotyped. The bacterial capsule is the basis for serotyping and is 

the primary virulence factor. Serotype B has been 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. 

Table 16: Serotypes of Invasive Haemophilus influenzae Cases by Race – Alaska, 2001-

2002 

Serotype 

2001 2002

AK Native Non-Native Unknown Total AK Native Non-Native Total 

A - - - 0 (0) 2 2 4 (36.4) 

B - 1 - 1 (10) 1 - 1 (9.1) 

D - 2 - 2 (20) - - 0 

F 1 1 1 3 (30) - - 0 

NT 2 2 - 4 (40) 3 3 6 (54.5) 

Total 3 6 1 10 6 5 11 

In 2001, the most common serotype was F. In 2002, serotype A was the most prevalent, 

accounting for 4 (36.4%) of the 11 cases. Four cases were non-typable in 2001 and 6 were nontypable in 2002. 

Hib

In recent years, the prevalence of Haemophilus influenzae type B has declined due to increased 

use of a childhood vaccine against this serotype. In 2001, only one case was reported in a 36-

year old non-Native male. In 2002, only one case occurred in an Alaska Native infant female 

who had received two doses of PedVaxHib, but also had low birth weight and chronic lung 

problems. The statewide rate for both 2001 and 2002 was 0.16/100,000 persons per year.
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 21 

Antibiotic Resistance 

Table 17: Antibiotic Susceptibilities of Haemophilus influenzae isolates – Alaska, 2001-

2002 

Antibiotic 

2001 2002 

Susceptible Intermediate Resistant Susceptible Intermediate Resistant 

Chloramphenicol 9 (90%) 1 (10%) - 11 (100%) - - 

Ceftriaxone 10 (100%) - - 11 (100%) - - 

TMP/sulfa 9 (90%) - 1 (10%) 9 (81.8%) 1 (9.1%) 1 (9.1%) 

Susceptibility to ceftriaxone was 100% for both 2001 and 2002. One isolate demonstrated 

intermediate susceptibility for chloramphenicol and one isolate was resistant to TMP/sulfa in 

2001. In 2002, all isolates were susceptible for chloramphenicol. Intermediate susceptibility for 

TMP/sulfa was demonstrated by one isolate; one isolate showed resistance to TMP/sulfa also. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 22 

Table 18: Summary of Invasive Haemophilus influenzae Case Characteristics, Alaska, 2001

Sex 

Age 

(Yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype* 

Associated Medical 

Conditions Outcome 

F 0.9 Non-Native Anchorage Blood Septicemia F None 

F 2 AK Native Anchorage Blood Empyema, 

pneumonia F Chronic lung disease, Immunosuppressed 

F 5 Unknown Anchorage Blood Septicemia F None 

M 31 AK Native Other Blood Pneumonia NT Cigarette smoking, 

alcohol abuse 

M 36 Non-Native Other Blood Pneumonia B None 

M 46 Non-Native Other Blood Septicemia NT Alcohol abuse Death 

M 46 Non-Native Anchorage Blood Pneumonia NT Cigarette smoking, 

alcohol abuse 

M 70 Non-Native Anchorage Blood Septicemia D None Death 

M 73 AK Native Other Blood Pneumonia NT None 

M 78 Non-Native Other Blood Pneumonia D None 

*NT = non-typeable 

Table 19: Summary of Invasive Haemophilus influenzae Case Characteristics, Alaska, 2002 

Sex 

Age 

(Yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype* 

Associated Medical 

Conditions Outcome 

M 2 days AK Native Anchorage Blood Septicemia NT None 

M 0.4 AK Native Other CSF Meningitis A None 

F 0.7 AK Native Other Blood Pneumonia B Chronic lung disease 

M 2 Non-Native Anchorage Blood Pericarditis, 

pneumonia NT None 

F 24 AK Native Anchorage Peritoneal 

Fluid Peritonitis NT None 

F 39 AK Native Anchorage CSF Meningitis NT Cigarette smoking, 

alcohol abuse 

F 40 AK Native Other Blood Septicemia A Cigarette smoking, 

chronic lung disease 

M 59 Non-Native Anchorage Blood Pneumonia A Chronic lung disease, 

diabetes 

Death 

M 72 Non-Native Other Blood Pneumonia NT Cigarette smoking, 

chronic lung disease 

F 72 Non-Native Other Blood Septicemia, 

cellulitis NT Immunosuppressed 

F 73 Non-Native Anchorage Blood Pneumonia A Chronic lung disease, 

diabetes 

*NT = non-typeable
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 23 

Invasive Neisseria meningitidis

Overall Incidence

A total of 6 cases of invasive Neisseria meningitidis were reported to AIP in each year of 2001 

and 2002 for an overall rate of invasive N. meningitidis disease in the state of Alaska of 0.9. The 

Alaska rates are similar to the ABCs 2001 and 2002 national projected rates of 0.7/100,000 and 

0.5/100,000, respectively (Active Bacterial Core Surveillance (ABCs) Report Emerging 

Infections Program Network Neisseria meningitidis, 2001 & 2002). There were no invasive N. 

meningitidis-related deaths in Alaska in 2001. In 2002, there was one death which resulted in a 

case fatality ratio of 17%. 

Seasonality

N. meningitidis cases occurred throughout the year; no clusters of related cases were reported. 

Figure 14: Invasive Neisseria meningitidis , by 

Month of Culture - Alaska, 2001-2002

0

1

2

3

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Number of Cases

2001

2002

Race

In 2001, 83% of invasive N. meningitidis cases in Alaska occurred in the non-Native population 

for an age-adjusted rate of 1.0/100,000 persons per year compared to the Alaska Native rate of 

0.6/100,000 persons per year. Cases of N. meningitidis were split between the Alaska Native and 

non-Native populations in 2002; there were three in each group. The age-adjusted rate of disease 

in Alaska Natives was 1.8/100,000 persons per year and the non-Native rate was 0.6/100,000 

persons per year. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 24 

Table 20: Invasive Neisseria meningitidis Cases by Race – Alaska, 2001 - 2002 

Year Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

2001 Alaska Native 1 (17) 0.6 0 0 (0) 

 Non-Native 5 (83) 1.0 40 0 (0) 

 Total 6 33 0 (0) 

2002 Alaska Native 3 (50) 1.8 0 0 (0) 

 Non-Native 3 (50) 0.6 33 1 (33) 

 Total 6 17 1 (17) 

*Cases per 100,000 per percent distribution of Alaska 2000 population 

Region

Four of the six invasive N. meningitidis cases in 2001 occurred in Anchorage; the remaining two 

cases were in the Interior and Norton Sound. In 2002, four of the six cases occurred in 

Anchorage and the remaining two in the Interior. 

Age

Invasive N. meningitidis cases reported in 2001 ranged in age from 0.5 to 90 years old; the 

median age was 36.9 years. Highest rates of disease occurred in children less than two years old 

(5/100,000 persons per year) and children 2-4 years old (3.4/100,000 person per year). In 2002, 

cases ranged in age from 2.9 years to 52.6 years with a median age of 12.1 years. Children 2-4 

years old had the highest rates of disease, 6.5/100,000 persons per year. 

Figure 15: Invasive Neisseria meningitidis by Age 

Group - Alaska, 2001 - 2002

0

1

2

3

4

5

6

7

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

Age (yrs)

Rate per 100,000

2001

2002

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

between the years 2001 and 2002. In 2001, the highest rates of disease occurred in Alaska 

Native children less than 2 years of age (18.7/100,000 persons per year). There were no cases of 

invasive Neisseria meningitidis in children less than 2 years old in non-Natives. No N. 

meningitidis cases were reported in Alaska Natives 2 - 4 years old in 2001, however, in 2002, the 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 25 

rate of disease in this age category increased to 12.5/100,000 persons per year compared to a rate 

of 4.4/100,000 persons per in non-Native children 2 – 4 years old. 

Figure 16: Invasive Neisseria meningitidis , Cases 

& Rates by Age Group & Race - Alaska, 2001-2002

0

1

2

3

4

5

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

Age (yrs)

Number of Cases

0

2

4

6

8

10

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Clinical Presentation

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

indicated in each patient’s individual medical record associated with the illness resulting in the 

culture. In cases with multiple discharge diagnoses, the most serious diagnosis related to the N. 

meningitidis infection was recorded as the primary clinical presentation. See Table 21 for the 

primary clinical presentations of invasive N. meningitidis in Alaska in 2001 and 2002. 

N. meningitidis was isolated from blood samples in 4 of 6 (67%) cases in 2001. The remaining 2 

cases in 2001 were isolated from cerebrospinal fluid and another unspecified sterile site. In 

2002, 3 cases (50%) had N. meningitidis isolated from blood and three from cerebrospinal fluid. 

Table 21: Primary Clinical Presentations of Invasive Neisseria Meningitidis – Alaska, 2001 

- 2002 

Primary Presentation 

2001 Cases 

n (%) 

2002 Cases 

n (%) 

Meningitis 2 (33) 5 (83) 

Septicemia 3 (50) 1 (17) 

Pneumonia 1 (17) 0 (0) 

Total 6 6 

Mortality

There were no N. meningitidis-related deaths reported in Alaska in 2001. In 2002, one patient 

died due to infection with Neisseria meningitidis resulting in a case-fatality ratio of 17% for the 

year (1 death out of 6 cases). 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 26 

Table 22: Summary of Invasive Neisseria Meningitidis Case Characteristics, Alaska, 2001 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) 

Associated Medical 

Conditions 

F 0.6 AK Native Other Blood Septicemia None 

F 4.0 Non-Native Anchorage CSF Meningitis None 

M 24.4 Non-Native Anchorage Other Meningitis Unknown 

F 49.3 Non-Native Anchorage Blood Septicemia None 

M 60.9 Non-Native Other Blood Septicemia Asplenia 

F 90.0 Non-Native Anchorage Blood Pneumonia None 

Table 23: Summary of Invasive Neisseria Meningitidis Cases Characteristics, Alaska, 2002 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) 

Associated 

Medical 

Conditions Outcome 

F 2.9 Native Anchorage Blood Meningitis None - 

M 4.3 Non-Native Anchorage CSF Meningitis None - 

F 7.0 Native Other Blood Septicemia None - 

F 17.3 Native Other CSF Meningitis None - 

F 46.8 Non-Native Anchorage CSF Meningitis 

Cigarette 

smoking, 

alcohol abuse 

Death 

F 52.6 Non-Native Anchorage Blood Meningitis, 

pneumonia 

Chronic lung 

disease - 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 27 

Invasive Group A Streptococcus

Overall Incidence

A total of 29 cases of invasive Group A Streptococcus (GAS) were reported to AIP in 2001 and a 

total of 41 cases were reported in 2002. Overall rates of invasive GAS disease in the state of 

Alaska were 4.6/100,000 persons per year in 2001 and 6.4/100,000 persons per year in 2002. 

The Alaska rates are higher than the ABCs 2001 and 2002 national projected rates of 

3.7/100,000 and 3.2/100,000, respectively (Active Bacterial Core Surveillance (ABCs) Report 

Emerging Infections Program Network group A streptococcus, 2001 & 2002). In 2001, there 

were 3 GAS-related deaths and 5 GAS-related deaths in 2002 for case fatality ratios of 10% and 

12%, respectively. 

Seasonality 

Cases of Group A Streptococcus occurred throughout the year in 2001 and 2002. No apparent 

trends in seasonality appear in either year. 

Figure 17: Invasive Group A Streptococcus , by 

Month of Culture - Alaska, 2001 - 2002

0

2

4

6

8

10

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Number of Cases

2001

2002

Race

In 2001, 41% of invasive GAS cases in Alaska occurred in the Alaska Native population for an 

age-adjusted rate of 10.5/100,000 persons per year which was higher than the non-Native rate of 

3.2/100,000 persons per year. Age-adjusted rates of invasive GAS increased in both the Alaska 

Native and non-Native populations in 2002 to 14.3/100,000 persons per year and 4/100,000 

persons per year, respectively. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 28 

Table 24: Invasive Group A Streptococcus Cases by Race – Alaska, 2001 - 2002 

Year Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

2001 Alaska Native 12 (41) 10.5 58 2 (17) 

 Non-Native 17† (59) 3.2 63 1 (6) 

 Total 29 62 3 (10) 

2002 Alaska Native 19 (46) 14.3 58 2 (11) 

 Non-Native 22† (54) 4 33 3 (14) 

 Total 41 46 5 (12) 

*Cases per 100,000 per percent distribution of Alaska 2000 population 

†Includes one case for which race was unknown 

Region

Nineteen (66%) of the 29 invasive Group A Streptococcus cases in 2001 were reported in 

Anchorage, 7 cases in the Interior and one case each in Bristol Bay, the Southeast and YK Delta. 

In 2002, 68% (28 cases) occurred in Anchorage, 5 in the Interior, 4 in YK Delta, 2 in the 

Southeast and one each in Kotzebue and Bristol Bay. 

Age

Invasive Group A Streptococcus cases reported in 2001 ranged in age from 0.1 to 83.4 years old; 

the median age was 46.5 years. Highest rates of disease occurred in children less than two years 

old (14.9/100,000 persons per year) and in the 55 - 64 year old age category (12.6/100,000 

person per year). In 2002, cases ranged in age from 0.1 years to 82.3 years with a median age of 

41 years. The highest rates of disease occurred in the 65 and older age category, 18.1/100,000 

persons per year. 

Figure 18: Invasive Group A Streptococcus by 

Age Group - Alaska, 2001 - 2002

0

5

10

15

20

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

Age (yrs)

Rate per 100,000

2001

2002

Rates of invasive Group A Streptococcus disease in Alaska Natives were higher in the majority 

of age categories in 2001 and 2002 versus non-Native populations. In 2001, the highest rates of 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 29 

disease occurred in Alaska Natives 55 – 64 years old (43.1/100,000 persons per year) and Alaska 

Native children less than 2 years of age (37.5/100,000 persons per year). The highest Group A 

Strep disease rate in the non-Native population occurred in the 65 and older age category 

(9.9/100,000 persons per year). In 2002, the highest rates of disease occurred in Alaska Native 

children 2 – 4 years old (50/100,000 persons per year) and less than two years old (37.3/100,000 

persons per year). No cases were reported in the non-Native population in either of these age 

categories. 

Figure 17: Invasive Group A Streptococcus, Cases & 

Rates by Age Group & Race - Alaska, 2001-2002

0

5

10

15

20

25

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

Age (yrs)

Number of Cases

0

5

10

15

20

25

30

35

40

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Clinical Presentation

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

indicated in each patient’s individual medical record associated with the illness resulting in the 

culture. In cases with multiple discharge diagnoses, the most serious diagnosis related to the 

GAS infection was recorded as the primary clinical presentation. Table 25 shows the primary 

clinical presentations of invasive Group A Streptococcus in Alaska for 2001 and 2002. 

Group A Streptococcus was isolated from blood samples in all 2001 cases. In 2002, GAS was 

isolated from blood in 35 (85%) of 41 cases; the remaining cases were isolated from abscesses (3 

cases), wound samples (2 cases) and one unspecified sterile site. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 30 

Table 25: Primary Clinical Presentations of Invasive Group A Streptococcus – Alaska, 

2001 - 2002 

Primary Presentation 

2001 Cases 

n (%) 

2002 Cases 

n (%) 

Septicemia 11 (38) 6 (15) 

Cellulitis 8 (28) 18 (44) 

Pneumonia 4 (14) 4 (10) 

Empyema 2 (7) 1 (2) 

Bacteremia 0 (0) 2 (5) 

Meningitis 1 (3) 1 (2) 

Epiglottitis 1 (3) 0 (0) 

Peritonitis 0 (0) 1 (2) 

Septic arthritis 0 (0) 1 (2) 

Osteomyelitis 0 (0) 1 (2) 

Necrotizing fasciitis 1 (3) 6 (15) 

Other 1 (3) 0 (0) 

Total 29 41 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 31 

Table 26: Summary of Invasive Group A Streptococcus Case Characteristics, Alaska, 2001 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) 

Associated Medical 

Conditions Outcome 

M 0.1 AK Native Other Blood Pneumonia Chronic lung disease 

M 0.7 Non-Native Other Blood Septicemia None 

F 1.6 AK Native Anchorage Blood Septicemia None 

F 5.5 AK Native Anchorage Blood Empyema, 

pneumonia None 

M 22.8 Non-Native Anchorage Blood Empyema, 

pneumonia None 

M 25.6 Non-Native Other Blood 

Meningitis, 

pericarditis, septic 

arthritis 

None 

F 29.4 Non-Native Anchorage Blood Septicemia Cigarette smoking, alcohol 

abuse, injection drug use 

M 32.1 Non-Native Anchorage Blood Septicemia Unknown 

F 35.5 AK Native Anchorage Blood Cellulitis None 

M 37.8 AK Native Anchorage Blood Cellulitis Alcohol abuse 

M 37.8 AK Native Other Blood Septicemia Cigarette smoking, alcohol 

abuse 

M 38.6 Non-Native Anchorage Blood Septicemia Cigarette smoking, alcohol 

abuse 

M 42.4 AK Native Anchorage Blood Cellulitis Cigarette smoking, chronic 

lung disease, alcohol abuse 

M 43 Non-Native Anchorage Blood Pneumonia Cigarette smoking, chronic 

lung disease, alcohol abuse 

M 46.5 AK Native Anchorage Blood Cellulitis Cigarette smoking, alcohol 

abuse 

M 51.5 Non-Native Other Blood Necrotizing 

fasciitis, cellulitis Cigarette smoking 

F 52 Non-Native Other Blood Cellulitis Diabetes 

F 53.9 Non-Native Anchorage Blood Septicemia Cigarette smoking, chronic 

lung disease, diabetes Death 

F 54.5 Non-Native Anchorage Blood Septicemia None 

F 55.6 AK Native Other Blood Cellulitis Alcohol abuse 

M 56.5 Non-Native Other Blood Cellulitis Cigarette smoking, alcohol 

abuse 

M 58.8 AK Native Other Blood Other Alcohol abuse Death 

M 60.5 Unknown Other Blood Septicemia Diabetes 

F 62.5 Non-Native Anchorage Blood 

Pneumonia, 

necrotizing 

fasciitis, cellulitis 

Chronic lung disease, 

diabetes 

M 63.2 AK Native Anchorage Blood Septicemia Diabetes Death 

F 65.9 AK Native Anchorage Blood Septicemia None 

M 66.6 Non-Native Anchorage Blood Cellulitis Diabetes 

F 80 Non-Native Anchorage Blood Pneumonia Chronic lung disease 

M 83.4 Non-Native Anchorage Blood Epiglottitis Cigarette smoking, chronic 

lung disease, diabetes 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 32 

Table 27: Summary of Invasive Group A Streptococcus Case Characteristics, Alaska, 2002 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) Associated Medical Conditions Outcome 

M 0.1 AK Native Anchorage Blood Septicemia None 

F 0.6 AK Native Other Abscess Cellulitis None 

F 2.3 AK Native Other Blood Cellulitis Chronic lung disease 

M 2.5 AK Native Other Blood Meningitis None 

M 3.3 AK Native Other Abscess Cellulitis None 

M 4 AK Native Other Blood Septicemia Chronic lung disease 

F 5.7 Non-Native Anchorage Blood Osteomyelitis None 

F 12.4 AK Native Anchorage Blood Cellulitis None 

M 15.9 AK Native Other Abscess Cellulitis None 

M 17.7 AK Native Anchorage Blood Septicemia None Death 

F 18.9 AK Native Anchorage Blood Cellulitis Chronic lung disease 

F 21.5 Non-Native Anchorage Blood Necrotizing fasciitis Cigarette smoking 

F 21.5 Non-Native Anchorage Blood Cellulitis, other Cigarette smoking 

M 24.3 AK Native Other Blood Cellulitis None 

F 25.2 Non-Native Anchorage Blood Septicemia None 

M 25.2 AK Native Anchorage Blood Bacteremia None 

F 25.5 Non-Native Anchorage Wound Necrotizing fasciitis, 

cellulitis Cigarette smoking 

F 32.1 AK Native Other Blood Septicemia Alcohol abuse 

F 33.8 Non-Native Anchorage Blood Septic arthritis, 

cellulitis None 

F 40.7 Non-Native Anchorage Blood Peritonitis, cellulitis Alcohol abuse 

M 41 Non-Native Anchorage Wound Necrotizing fasciitis, 

cellulitis None 

M 43.2 Non-Native Anchorage Other Empyema, 

pneumonia, cellulitis 

Cigarette smoking, injection 

drug use 

F 44.8 Non-Native Anchorage Blood Cellulitis None 

M 45 Non-Native Anchorage Blood Cellulitis Cigarette smoking 

M 50.1 AK Native Anchorage Blood Cellulitis Alcohol abuse 

M 53 AK Native Anchorage Blood Bacteremia Alcohol abuse, diabetes 

M 53.7 AK Native Anchorage Blood Cellulitis Alcohol abuse, diabetes 

F 56.1 AK Native Anchorage Blood Pneumonia, cellulitis Cigarette smoking, chronic lung 

disease, alcohol abuse 

F 56.5 Non-Native Anchorage Blood Cellulitis Cigarette smoking, chronic lung 

disease 

Death 

F 57.1 Non-Native Other Blood Cellulitis None 

M 60.3 Non-Native Anchorage Blood Pneumonia, cellulitis, 

other Alcohol abuse 

F 61.6 AK Native Anchorage Blood Pneumonia 

Cigarette smoking, chronic lung 

disease, immuno-suppressive 

treatment 

F 61.7 Non-Native Anchorage Blood Necrotizing fasciitis None 

M 64.5 Non-Native Other Blood Cellulitis Chronic lung disease, diabetes 

F 69.6 Non-Native Other Blood Cellulitis None 

F 69.7 AK Native Anchorage Blood Cellulitis None Death 

M 70.1 Non-Native Anchorage Blood Necrotizing fasciitis Diabetes Death 

F 72.9 Non-Native Other Blood Cellulitis None 

M 75.6 Non-Native Anchorage Blood Necrotizing fasciitis None 

F 77.9 Non-Native Anchorage Blood Septicemia None Death 

M 82.3 Unknown Other Blood Pneumonia, cellulitis None 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 33 

Invasive Group B Streptococcus

Overall Incidence

A total of 20 cases of invasive Group B Streptococcus (GBS) were reported to AIP in 2001 and a 

total of 23 cases were reported in 2002. Overall rates of invasive GBS disease in the state of 

Alaska were 3.6/100,000 persons per year in 2001 and 2002. The Alaska rate is lower than the 

ABCs 2001 and 2002 national projected rates of 6.9/100,000 and 7.0/100,000, respectively 

(Active Bacterial Core Surveillance (ABCs) Report Emerging Infections Program Network group 

B streptococcus, 2001 & 2002). In 2001, there was one GBS-related death and 5 GBS-related 

deaths in 2002 for case fatality ratios of 5% and 22%, respectively. 

Seasonality

Cases of Group B Streptococcus occurred throughout the year in 2001 and 2002. No apparent 

seasonal trends appear in either year. 

Figure 20: Invasive Group B Streptococcus , by 

Month of Culture - Alaska, 2001 - 2002

0

1

2

3

4

5

6

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Number of Cases

2001

2002

Race

In 2001, 25% of invasive Group B Streptococcus cases in Alaska occurred in the Alaska Native 

population for an age-adjusted rate of 4.4/100,000 persons per year compared with the nonNative rate of 2.9/100,000 persons per year. Age-adjusted rates of invasive GBS decreased 

slightly in the Alaska Native population in 2002 (4.2/100,000 persons per year) and increased in 

the non-Native population to 3.4/100,000 persons per year. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 34 

Table 28: Invasive Group B Streptococcus Cases by Race – Alaska, 2001 - 2002 

Year Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male 

Deaths 

n (%) 

2001 Alaska Native 5 (25) 4.4 80 0 (0) 

 Non-Native 15 (75) 2.9 60 1 (7) 

 Total 20 65 1 (5) 

2002 Alaska Native 5 (22) 4.2 60 0 (0) 

 Non-Native 18 (78) 3.4 50 5 (28) 

 Total 23 52 5 (22) 

*Cases per 100,000 per percent distribution of Alaska 2000 population 

Region 

In 2001, 19 of the 20 reported GBS cases occurred in Anchorage; one case was reported in 

Southeast Alaska. Seventy four percent (17 cases) of invasive GBS reported in 2002 occurred in 

Anchorage; four cases occurred in the Interior and two cases occurred in Southeast. 

Age

Invasive Group B Streptococcus cases reported in 2001 ranged in age from newborn to 85.6 

years old; the median age was 45 years. Highest rates of disease occurred in children less than 

two years old (14.9/100,000 persons per year) and in the 65 and older age category (5.4/100,000 

person per year). In 2002, cases ranged in age from newborn to 75.4 years with a median age of 

46.3 years. As in 2001, the highest rates of disease occurred in children less than two years old 

and person 65 and older, however, the rates more than doubled in each category to 38.8/100,000 

in the less than two year olds and to 13/100,000 in the 65 and older age group. 

Figure 21: Invasive Group B Streptococcus by 

Age Group - Alaska, 2001 - 2002

0

10

20

30

40

50

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

Age (yrs)

Rate per 100,000

2001

2002

Rates of GBS disease in Alaska Native versus non-Native populations by age group were 

variable between the years 2001 and 2002. In 2001, the highest rates of disease occurred in nonNative children less than 2 years of age (20.2/100,000 persons per year). There were no cases of 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 35 

invasive GBS in children less than 2 years old in Alaska Natives, however, in 2002, the rate of 

disease in this age category increased to 18.7/100,000 persons per year. Rates of disease in nonNative children less than two years of age more than doubled in 2002 to 45.8/100,000 persons 

per year. 

Figure 22: Invasive Group B Streptococcus, Cases & 

Rates by Age Group & Race - Alaska, 2001-2002

0

2

4

6

8

10

12

14

16

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

Age (yrs)

Number of Cases

0

5

10

15

20

25

30

35

Rate per 100,000

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Clinical Presentation

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

indicated in each patient’s individual medical record associated with the illness resulting in the 

culture. In cases with multiple discharge diagnoses, the most serious diagnosis related to the 

GBS infection was recorded as the primary clinical presentation. In 2001, the most common 

clinical presentation was septicemia which occurred in 8 cases (40%). Two cases of 

osteomyelitis had additional presentations, one with septic arthritis and one with cellulitis. The 

most common clinical presentation in 2002 was cellulitis (6 cases, 26%); there were no 

additional presentations reported. 

Group B Streptococcus was isolated from blood in 18 (90%) of 20 cases in 2001; one case was 

isolated from cerebrospinal fluid and one from joint fluid. In 2002, 74% (17 of 23 cases) were 

isolated from blood, 3 cases from cerebrospinal fluid, 2 cases from autopsy samples and one case 

from an unspecified sterile site. 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 36 

Table 29: Primary Clinical Presentations of Invasive Group B Streptococcus – Alaska, 

2001 - 2002 

Primary Presentation 

2001 Cases 

n (%) 

2002 Cases 

n (%) 

Septicemia 8 (40) 5 (22) 

Cellulitis 3 (15) 6 (26) 

Pneumonia 4 (20) 3 (13) 

Meningitis 1 (5) 5 (22) 

Amnionitis 1 (5) 0 (0) 

Peritonitis 1 (5) 2 (9) 

Endocarditis 0 (0) 1 (4) 

Osteomyelitis 2 (10) 0 (0) 

Other 0 (0) 1 (4) 

Total 20 23 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 37 

Table 30: Summary of Invasive Group B Streptococcus Case Characteristics, Alaska, 2001 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s)

Associated Medical 

Conditions Outcome 

M 1 day Non-Native Anchorage Blood Septicemia None Death 

M 1 day Non-Native Anchorage Blood Septicemia None 

F 0.03 Non-Native Anchorage CSF Meningitis None 

M 18.8 AK Native Anchorage Joint fluid Cellulitis Alcohol abuse 

F 23.9 Non-Native Anchorage Blood Pneumonia None 

F 29.4 AK Native Anchorage Blood Osteomyelitis, 

cellulitis Diabetes 

F 36.9 Non-Native Anchorage Blood Amnionitis None 

M 42.3 Non-Native Anchorage Blood Cellulitis Alcohol abuse 

M 44.1 Non-Native Anchorage Blood Septicemia 

Cigarette smoking, 

chronic lung disease, 

alcohol abuse 

F 44.6 Non-Native Anchorage Blood Cellulitis None 

M 45.4 AK Native Anchorage Blood Septicemia Cigarette smoking, 

alcohol abuse 

M 47 Non-Native Anchorage Blood Septicemia Cigarette smoking, 

alcohol abuse 

M 47 Non-Native Anchorage Blood Pneumonia Cigarette smoking, 

alcohol abuse 

M 49.5 Non-Native Anchorage Blood Peritonitis Cigarette smoking, 

alcohol abuse 

F 51 Non-Native Anchorage Blood Septicemia Diabetes 

F 53.6 Non-Native Anchorage Blood Septicemia Cigarette smoking 

M 56.1 AK Native Anchorage Blood Pneumonia Cigarette smoking, 

alcohol abuse, diabetes 

M 56.2 Non-Native Anchorage Blood Osteomyelitis, 

septic arthritis Diabetes 

M 76.8 AK Native Other Blood Septicemia Diabetes 

M 85.6 Non-Native Anchorage Blood Pneumonia Cigarette smoking 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 38 

Table 31: Summary of Invasive Group B Streptococcus Case Characteristics, Alaska, 2002 

Sex 

Age 

(yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s)

Associated Medical 

Conditions Outcome 

F 1 day Non-Native Anchorage Blood Septicemia None 

F 1 day Non-Native Anchorage Blood Pneumonia None 

F 0.01 Non-Native Anchorage CSF Meningitis None 

F 0.01 Non-Native Anchorage CSF Meningitis None 

M 0.1 Non-Native Anchorage CSF Meningitis None 

F 0.2 Non-Native Anchorage Autopsy Other Unknown Death 

F 0.2 AK Native Other Blood Meningitis None 

F 0.3 Non-Native Other Autopsy Pneumonia None Death

F 28 Non-Native Anchorage Blood Cellulitis Diabetes 

M 39.8 Non-Native Other Blood Peritonitis Cigarette smoking, 

alcohol abuse, diabetes 

M 42.9 Non-Native Anchorage Blood Septicemia Cigarette smoking, 

alcohol abuse, diabetes 

M 46.3 AK Native Other Blood Endocarditis Diabetes 

M 46.7 AK Native Anchorage Peritoneal 

fluid Peritonitis Alcohol abuse 

M 49 Non-Native Anchorage Blood Septicemia Cigarette smoking Death 

F 49.8 AK Native Anchorage Blood Cellulitis Diabetes 

M 51.5 Non-Native Other Blood Cellulitis Diabetes 

M 55.8 Non-Native Anchorage Blood Meningitis Alcohol abuse Death 

F 63.1 Non-Native Other Blood Cellulitis Diabetes 

M 65.9 AK Native Anchorage Blood Cellulitis Diabetes 

F 70.1 Non-Native Anchorage Blood Cellulitis None 

M 72.9 Non-Native Anchorage Blood Pneumonia Chronic lung disease, 

diabetes Death 

M 74 Non-Native Anchorage Blood Septicemia Diabetes 

M 75.4 Non-Native Anchorage Blood Septicemia Chronic lung disease 
Surveillance of Invasive Bacterial Disease in Alaska, 2001-2002 39 

Appendix 

MIC Interpretive Standards Definitions: 

 NCCLS provides recommended interpretive categories for various Minimum Inhibitory Concentration 

values (cut points) for each organism which are defined as follows:* 

1. Susceptible (S): 

The “susceptible” category implies that an infection due to the strain may be appropriately treated 

with the dosage of antimicrobial agent recommended for that type of infection and infecting 

species, unless otherwise contraindicated. 

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 applicability in body sites 

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

when a high 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 a narrow pharmacotoxicity 

margins. 

3. Resistant (R): 

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

with normal dosage schedules and/or fall in the range where specific microbial resistance 

mechanisms are likely (e.g., β-lactamases) and clinical efficacy has not been reliable in treatment 

studies. 

* NCCLS, MIC Testing, Supplemental Tables, M100-S10 (M&), January 2000, p.9.