Surveillance of Invasive Bacterial Disease in Alaska, 2003 

Arctic Investigations Program 

National Center for 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, 2003 2 
Alaska Statewide Invasive Bacterial Disease 

Table of Contents 

 Page

Summary 4

Introduction 5

Streptococcus pneumoniae 6 

Haemophilus influenzae 16

 

Neisseria meningitidis 22

Group A streptococcus 24

Group B streptococcus 28

Appendix 32

Surveillance of Invasive Bacterial Disease in Alaska, 2003 3 
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, 2003 

In 2003, the total number of cases of invasive disease caused by these organisms reported to AIP were 98 S. 

pneumoniae, 18 H. influenzae, 4 N. meningitidis, 23 group A strep and 20 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 streptococcus. 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, 2003 4 
Table 1: Surveillance Organisms Reported by Region – Alaska, 2003 

Region 

S. pneumoniae 

n (rate*) 

H. influenzae 

n (rate*) 

N. meningitidis 

n (rate*) 

Group A Strep 

n (rate*) 

Group B Strep 

n (rate*) 

Anchorage 52 (12.2) 8 (1.9) 3 (0.7) 16 (3.8) 15 (3.5) 

Arctic Slope 1 (16.2) 0 (0) 0 (0) 1 (16.2) 0 (0) 

Bristol Bay 1 (13.7) 0 (0) 0 (0) 1 (13.7) 0 (0) 

Interior 13 (13.7) 0 (0) 0 (0) 1 (1.1) 2 (2.1) 

Kotzebue 4 (49.8) 0 (0) 0 (0) 0 (0) 0 (0) 

Norton Sound 12 (128.1) 0 (0) 0 (0) 0 (0) 0 (0) 

Southeast 9 (12.5) 2 (2.8) 1 (1.4) 2 (2.8) 3 (4.2) 

YK Delta 6 (24.4) 8 (32.6) 0 (0) 2 (8.1) 0 (0) 

Total 98 (15.1) 18 (2.8) 4 (0.6) 23 (3.5) 20 (3.1) 

*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, 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 648,818 persons in 2003 (Alaska 

Department of Labor & Workforce Development, http://almis.labor.state.ak.us; 8/6/2004). 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 2003, 23 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, 2003 5 
Invasive Pneumococcal Disease 

Overall Incidence

A total of 89 pneumococcal isolates were received at AIP in 2003. An additional 9 cases were detected 

through year-end follow up with participating labs throughout the state for a total of 98 cases of invasive 

pneumococcal disease. The overall invasive pneumococcal case rate for 2003 was 15.1 per 100,000 

persons per year. Alaska rates for 2003 were slightly higher than the Active Bacterial Core Surveillance 

(ABCs) 2003 national projected rate of 13.8/100,000 (Active Bacterial Core Surveillance (ABCs) Report 

Emerging Infections Program Network Streptococcus pneumoniae, 2003 - preliminary). 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 2003. The largest number of 

cases was reported in April. 

Figure 2: Invasive Pneumococcal Disease, by

Month of Culture - Alaska, 2003

0

2

4

6

8

10

12

14

16

18

January

February

March

April

May

June

July

August

September

October

November

December

Nu

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b

er of Ca

s

e

s

Race

In 2003, the state population was comprised of 19% Alaska Natives (Alaska Department of Labor & 

Workforce Development: http://almis.labor.state.ak.us 2/1/2005; Alaska Natives 124,122, non-Natives 

524,696). The percentage of all reported S. pneumoniae cases that occurred in 2003 among Alaska 

Natives was 58%; for a total of 57 cases resulting in an age-adjusted rate of 47.6/100,000 persons per 

year. Forty-one cases occurred among the non-Native population for an age-adjusted rate of 

7.4/100,000 persons per year. The rate ratio of age-adjusted rates of S. pneumoniae disease for the 

Alaska Native population compared with the non-Native population in 2003 is 6.4. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 6 
Table 2: Invasive Streptococcus pneumoniae Cases by Race – Alaska, 2003 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male

Deaths 

n (%) 

Alaska Native 57 (58) 47.6 51 6 (11) 

Non-Native† 41 (42) 7.4 66 4 (10)‡ 

Total 98 57 10 (10)

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

†Includes 3 cases for which race was unknown 

‡Outcome unknown for 1 case

Region

The highest percentage (53%) of invasive pneumococcal disease cases occurred in the Anchorage area 

in 2003. Rates of disease, however, were highest in Norton Sound, 128.1/100,000 persons per year. 

Figure 3: Invasive Pneumococcal Disease, Cases 

& Rates by Region - Alaska, 2003

0

10

20

30

40

50

60

Anchorage

Arctic Slope

Bristol Bay

Interior

Kotzebue

Norton Sound

Southeast

YK Delta

Nu

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s

0

20

40

60

80

100

120

140

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ate p

er 100,

0

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Cases

Rate

Age

Cases occurred in all age groups in 2003 ranging from 0.3 years to 88.4 years with a median of 48.1 

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

 

When stratified by age and race, the highest rates of disease in 2003 occurred in Alaska Native children 

less than 2 years old (193.4/100,000 persons per year). However, there were no cases of invasive 

pneumococcal disease in AK Native children 2-4 years of age.

Surveillance of Invasive Bacterial Disease in Alaska, 2003 7 
Figure 4: Invasive Pneumococcal Disease, Cases 

& Rates by Age Group & Race - Alaska, 2003

0

5

10

15

20

25

30

35

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

Age (yrs)

Nu

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0

50

100

150

200

250

Rate p

er 1

0

0,0

0

0

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Since the initiation of a pneumococcal conjugate vaccine program in 2001, overall rates of invasive

disease have declined dramatically in children less than 5 years of age. In 2000, overall yearly rates of 

pneumococcal disease in children less than 2 years were 191.2/100,000, dropping to 67.9/100,000 in 

2002 and 73/100,000 in 2003. 

Figure 5: Invasive Pneumococcal Disease by Age 

Group - Alaska, 2000-2003

0

50

100

150

200

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

Age (yrs)

R

ate p

er 100,00

0

2000

2001

2002

2003

Although pneumococcal disease rates dropped in AK Native and non-Native children less than 2 years 

after 2000, the rates of disease in AK Native children less than 2 years have been trending upward from

a low of 93.6/100,000 in 2000 to 130.7/100,000 in 2001 and 193.4/100,000 in 2003. Rates of invasive 

disease in non-Native children less than 2 years have continued to decline during the same time period. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 8 
Figure 6: Invasive Pneumococcal Disease in

Alaska Natives, by Age Group - Alaska, 2000-2003

0

100

200

300

400

500

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

Age (yrs)

R

ate p

er 100,00

0

2000

2001

2002

2003

Figure 7: Invasive Pneumococcal Disease in NonNatives, by Age Group - Alaska, 2000-2003

0

100

200

300

400

500

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

Age (yrs)

Rate p

er 100,

0

0

0

2000

2001

2002

2003

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 was the most common primary clinical presentation in 

2003 (66%) followed by septicemia (15%). Nine cases had a secondary pneumococcal-related diagnosis 

in 2003; 7 pneumonia and 1 each endocarditis and septic arthritis. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 9 
Figure 8: Primary Clinical Presentations of

Invasive Pneumococcal Disease - Alaska, 2003

65

15

6 5 2 2 111

0

10

20

30

40

50

60

70

Pneumonia

Septicemia

Empyema

Meningitis

Cellulitis

Peritonitis

Endocarditis

Septic arthritis

Osteomyelitis

Nu

m

b

er of Ca

s

e

s

In 2003, blood was the most common source of a positive culture which was used to identify 89 (91%) 

of 98 cases. Pleural fluid was the positive site for 4% of cases and cerebrospinal fluid for 3%. The 

remaining cases were identified through joint fluid and another unidentified sterile site (1 case each).

Mortality

In 2003, the overall case fatality ratio for S. pneumoniae in Alaska was 10% (10 deaths out of 98 cases). 

The case fatality ratio for non-Natives was similar to Natives; 10% (4 deaths) and 11% (6 deaths), 

respectively. Although the majority of deaths occurred in the 19-54 year old age category (7 deaths), the 

highest case fatality ratio occurred in the 65+ age category; 18.8% (3 deaths). 

Figure 9: Invasive Pneumococcal Deaths & Case 

Fatality Ratios by Age Group - Alaska, 2003

0

1

2

3

4

5

6

7

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

Age (yrs)

Nu

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ath

s

0

5

10

15

20

Ca

s

e F

atality Ratio

Deaths

CFR

Surveillance of Invasive Bacterial Disease in Alaska, 2003 10 
Serotype

Serotyping of invasive pneumococcal isolates is performed at AIP using internationally standardized 

methods. Serotype identification is based on the organism’s polysaccharide capsule which is a principal 

virulence factor for pneumococci. This information provides a way to 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 all of the S. pneumoniae cases for which an 

isolate was available. 

Table 3: Invasive Pneumococcal Serotype Distribution by Race and Age Group – Alaska, 2003 

Alaska Native Non-Native Unknown 

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

03 8 (9) - - 4 - - - - 3 1

04 6 (6.7) - - - - - - 2 2 2

06A 2 (2.2) - 1 - 1 - - - - -

06B 1 (1.1) - - - - - - 1 - -

07C 1 (1.1) - - - - - - 1 - -

07F 2 (2.2) - - 1 - - - 1 - -

08 8 (9) - - 7 - - - - 1 -

09V 1 (1.1) - - - - - - 1 - -

10A 3 (3.4) 1 - 1 1 - - - - -

11A 1 (1.1) - - 1 - - - - - -

12F 11 (12.4) - 1 9 - - 1 - - -

13 1 (1.1) 1 - - - - - - - -

14 2 (2.2) - - 1 - 1 - - - -

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

15B 1 (1.1) - - - - - - - 1 -

15C 2 (2.2) 1 - - - - - 1 - -

16F 4 (4.5) - - 2 - - - 2 - -

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

18C 3 (3.4) 1 - 1 - - - 1 - -

19A 15 (16.9) 5 1 3 2 1 1 2 - -

19F 3 (3.4) - - 1 - - - 2 - -

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

22F 3 (3.4) - - 1 - - 1 1 - -

23A 1 (1.1) - - 1 - - - - - -

23F 1 (1.1) - - - - - 1 - - -

33F 1 (1.1) - - - - 1 - - - -

37 1 (1.1) - - 1 - - - - - -

38 4 (4.5) 1 - - - 1 - 2 - -

Total 89 10 3 36 4 4 4 17 8 3

In 2003, the most common serotypes were 19A (15 isolates, 16.9%) and 12F (11 isolates, 12.4%). From

1986 through 2001, serotype 14 was the most common invasive pneumococcal serotype ranging from

7.4% to 23.5% of isolates. Following introduction of the pneumococcal conjugate vaccine in 2001 

which includes serotype 14, the proportion of serotype 14 isolates has dropped to 2.2% in 2003. 

However, disease caused by serotype 19A, which is not included in the conjugate vaccine, increased. 

Prior to 2003, yearly numbers of cases of serotype 19A disease and the proportion of total isolates have 

ranged from 2 to 7 and 1.6% to 6.1%, respectively. The majority (73%) of serotype 19A disease 

occurred in AK Natives; cases occurred in all age groups and in various regions across the state. An 

outbreak of serotype 12F disease was identified through surveillance and was reported (Centers for 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 11 
Disease Control and Prevention. Outbreak of Invasive Pneumococcal Disease – Alaska. MWR 

2005;54:72-75.). 

Table 4: Invasive Pneumococcal Serotype Distribution by Region – Alaska, 2003 

Serotype 

Anchorage 

Arctic Slope 

Bristol Bay

Interior 

Kotzebue 

Norton Sound 

Southeast 

YK Delta 

03 5 - - 1 - - - 2

04 6 - - - - - - -

06A - - - 1 - - - 1

06B 1 - - - - - - -

07C - - - - - 1 - -

07F - - - 1 - 1 - -

08 7 - 1 - - - - -

09V 1 - - - - - - -

10A - - - 2 - - - 1

11A 1 - - - - - - -

12F 3 - - - - 7 1 -

13 1 - - - - - - -

14 1 - - - - - 1 -

15A 1 - - - - - - -

15B 1 - - - - - - -

15C - - - - 1 - 1 -

16F 2 - - 2 - - - -

17F - - - 1 - - - -

18C 1 - - - - - 2 -

19A 7 1 - 1 3 - 1 2

19F 1 - - 1 - - 1 -

20 1 - - - - - - -

22F 1 - - 1 - 1 - -

23A - - - 1 - - - -

23F 1 - - - - - - -

33F - - - - - - 1 -

37 1 - - - - - - -

38 3 - - - - 1 - -

Total 46 1 1 12 4 11 8 6

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 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 12 
among children (types 4, 6B, 9V, 14, 18C, 19F, 23F). The table below shows the proportion of invasive 

infections from 2003 that were due to serotypes found in the PCV7 vaccine. 

Table 5: Proportion of Invasive Isolates Contained in the PCV7 Vaccine by Age Group and Race 

– Alaska, 2003 

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

<2 1 (10%) of 10 1 (25%) of 4 2 (14%) of 14 

2-4 0 (0%) of 0 1 (50%) of 2 1 (50%) of 2 

5+ 3 (7%) of 43 9 (30%) of 30 12 (16%) of 73 

Total 4 (8%) of 53 11 (31%) of 36 15 (17%) of 89 

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 2003, for persons 55 years and older, 25 (93%) of 27 cases serotyped 

were potentially vaccine preventable invasive pneumococcal illnesses. 

Vaccination Failures

In 2003, pneumococcal vaccine status was known for 64 (65%) of the 98 cases; 38 cases (39%) did

receive a pneumococcal vaccine prior to illness and 26 cases (27%) 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 a child less than five years old who has had at least two doses of vaccine. There 

were two vaccine failures in 2003; one was in a 17-month old and one in a 2-year old. Both children 

received three doses of vaccine. The 17-month old presented with pneumonia and had no underlying 

illnesses or risk factors; the isolate from the case was serotype 18C. The 2-year old, who had diabetes 

and asthma, presented with pharyngitis; the isolate from the case was serotype 23F. 

One of the 10 deaths in 2003 from invasive S. pneumoniae was due to a serotype (03) found in the 

Ps23V vaccine. This death did not occur in a person in the age group for which vaccine is 

recommended, however, the individual had received vaccine. Time since vaccination was 9 years.

Table 6: Invasive Pneumococcal Disease, Serotypes of Fatal Cases – Alaska, 2003 

Serotype Deaths (%) Serotype Frequency 

03† 2 (33) 6

04*† 1 (16.7) 6

12F† 1 (9) 11

15B† 1 (100) 1

16F 2 (50) 4

23A 1 (100) 1

38 1 (25) 4

*Serotypes contained in the PCV7 vaccine 

†Serotypes contained in the 23-valent polysaccharide vaccine

Surveillance of Invasive Bacterial Disease in Alaska, 2003 13 
Overall, 56% of all pneumococcal-related mortality in 2003 was potentially preventable with the use of 

the 23-valent polysaccharide vaccine in persons over 2 years old. 

Table 7: Potentially Vaccine Preventable Invasive Pneumococcal Deaths – Alaska, 2003 

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

PCV7 0 0 0 0 1 (100%) 0 1 (11%)

Ps23V 0 0 0 2 (33%) 1 (100%) 2 (100%) 5 (56%) 

Total 0 0 0 6 1 2 9

Associated Medical Conditions

The presence of one or more associated medical conditions was reported in 84% of invasive 

pneumococcal cases in 2003. Alcohol use was the most prevalent risk factor observed in adults 

followed closely by cigarette smoking. 

Table 8: Associated Medical Conditions Identified in Invasive Pneumococcal Cases – Alaska, 

2003* 

Medical Condition 

Adult Cases (≥ 18 years) 

n=73, Cases (%) 

Alcohol abuse 36 (49) 

Cigarette smoking 32 (44) 

Chronic lung disease 22 (30) 

Diabetes 11 (15)

Immunosuppressive treatment 4 (5) 

Injection drug use 2 (3) 

Asplenia 2 (3)

*More than one risk factor was identified in several cases 

Antibiotic Resistance

Susceptibility testing was performed on all isolates in 2003. Results of the testing are presented in the 

following table. 

Table 9: Antibiotic Resistance in Invasive Streptococcus pneumoniae Isolates – Alaska, 2003 

Antibiotic Susceptible Intermediate Resistant I + R Total Tested 

Penicillin 72 (81%) 14 (16%) 3 (3%) 17 (19%) 89 

TMP-sulfa 65 (73%) 10 (11%) 16 (19%) 26 (30%) 89 

Erythromycin 83 (94%) 0 5 (6%) 5 (6%) 88 

Ceftriaxone 86 (97%) 3 (3%) 0 3 (3%) 89 

Tetracycline 84 (94%) 0 5 (6%) 5 (6%) 89 

Chloramphenicol 87 (98%) 0 2 (2%) 2 (2%) 89 

Rifampin 88 (100%) 0 0 0 88

Vancomycin 89 (100%) 0 0 0 89

Levoflox 89 (100%) 0 0 0 89

Clindamycin 77 (97%) 0 2 (3%) 2 (3%) 79 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 14 
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

(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. 

However, during 2003, TMP-sulfa resistance has increased from 20% of isolates tested in 2002 to 30% 

and penicillin non-susceptible isolates from 13% in 2002 to 19%. 

Figure 10: Trends in Antibiotic Resistance Among

Invasive Pneumococcal Isolates - Alaska, 1986 - 2003

0

5

10

15

20

25

30

35

198

6

198

8

199

0

199

2

199

4

199

6

199

8

200

0

200

2

Year

P

ercent Resi

stant

Pen-FR*

Pen-NS*

Erythro

TMP-Sulfa

Tet

 *Pen-FR = fully resistant, Pen-NS = non-susceptible 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 15 
Invasive Haemophilus influenzae

Overall Incidence

In 2003, there were 18 cases of invasive Haemophilus influenzae in Alaska, for a statewide rate of 

2.8/100,000 persons per year. This rate is 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 Haemophilus influenzae, 2003 - preliminary. In 2003, four Haemophilus influenzae 

cases resulted in death, giving a case-fatality ratio of 22%. 

Seasonality

Figure 11: Haemophilus influenzae Disease by

Month of Culture - Alaska, 2003

0

1

2

3

4

5

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Nu

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s

Due to the small number of cases, trends in seasonality cannot be determined. 

Region

The Anchorage (8 cases, 44%) and Yukon-Kuskokwim Delta (8 cases, 44%) areas had the highest 

numbers of reported cases and percentages of reported cases. The Yukon-Kuskokwim Delta area, 

however, had the highest disease rate of 32.6/100,000 persons per year and is eight times the 2002 rate 

of 4.1/100,000. The Southeast region had two cases. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 16 
Figure 12: Invasive Haemophilus influenzae , 

Cases & Rates by Region - Alaska, 2003

0

1

2

3

4

5

6

7

8

9

Anchorage

Arctic Slope

Bristol Bay

Interior

Kotzebue

Norton Sound

Southeast

YK Delta

Nu

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0

5

10

15

20

25

30

35

Rate p

er 1

0

0,0

0

0

Cases

Rate

Race

Table 10: Invasive Haemophilus influenzae Cases by Race – Alaska, 2003 

Race 

Cases 

n (%) 

Age Adjusted 

Rate * % Male 

Deaths 

n (%) 

Alaska Native 11 (61) 7.3 54.6 1 (9) 

Non-Native 7 (39) 1.3 57.1 3 (43) 

Total 18 55.6 4 (22)

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

In 2003, 61% of the cases occurred in Alaska Natives. Age-adjusted rates were calculated for Alaska 

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

population compared with the non-Native population in 2003 was 5.6. 

Age

Haemophilus influenzae cases ranged in age from less than 1 year to 82 years of age in 2003 (median 

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

greater than 65 years old.

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

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

disease occurred in Alaska Natives children less than two years of age (105.5/100,000 persons per year) 

and adults greater than 65 years old (28.6/100,000 persons per year). There were no cases of 

Haemophilus influenzae in non-Native children less than 18 years old and none reported in the 5-18 year 

old age groups in AK Natives. In adult age categories, there were no H. influenzae cases reported in 

non-Natives 55-64 years old. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 17 
Figure 13: Invasive Haemophilus influenzae by

Age Group - Alaska, 2003

0

5

10

15

20

25

30

35

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

Age (yrs)

R

ate p

er 100,

0

0

0

Figure 14: Invasive Haemophilus influenzae, Cases &

Rates by Age Group & Race - Alaska, 2003

0

1

2

3

4

5

6

7

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

Age (yrs)

Nu

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0

20

40

60

80

100

120

Rate p

er 100,

0

0

0

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 in each 

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

than one diagnosis, the most serious Haemophilus influenzae-related diagnosis was recorded as the 

primary clinical presentation. In 2003, four cases had a secondary Haemophilus influenzae-related

diagnosis; 2 each pneumonia and cellulitis with bacteremia. 

Haemophilus influenzae was isolated from 17 (94%) blood samples and 1 (6%) joint fluid sample. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 18 
Table 11: Primary Clinical Presentation of Invasive Haemophilus influenzae - Alaska, 2003 

Primary Presentation n (%) 

Pneumonia* 7 (39)

Septicemia 6 (33)

Meningitis 2 (11)

Septic arthritis 2 (11) 

Empyema 1 (6)

Total 18

*with bacteremia 

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 12: Serotypes of Invasive Haemophilus influenzae Cases by Race – Alaska, 2003 

Alaska Native Non-Native 

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

a 6 (33) 5 - - - - - 1 -

b 2 (11) 1 - 1 - - - - -

c 1 (6) - - - - - - - 1

d 1 (6) - 1 - - - - - -

f 1 (6) - - - - - - - 1

NT* 7 (39) - - 1 2 - - 1 3

Total 18 6 1 2 2 0 0 2 5

*Non-typable 

In 2003, the most common serotype was a; 83% occurred in AK Native children less than 2 years. 

Seven cases were non-typable. An outbreak of serotype a disease in infants was detected through 

surveillance and will be reported in The Pediatric Infectious Disease Journal in spring, 2005. 

Hib

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

childhood vaccine against this serotype. Two cases of Hib occurred in 2003; one in a 13 month old male 

AK Native and one in a 47 year old AK Native female. The 13 month old male had received two doses 

of PedVaxHib (2 and 6 months), presented with meningitis and cellulitis, and resulted in death. The 

overall Hib rate for 2003 was 0.3/100,000 persons per year; for children less than 2 years, the rate was 

4.9/100,000.

Surveillance of Invasive Bacterial Disease in Alaska, 2003 19 
Antibiotic Resistance

The 18 Haemophilus influenzae isolates received at AIP were tested for susceptibility to 

chloramphenicol, ceftriaxone and TMP/sulfa. All 18 isolates were susceptible to chloramphenicol and 

ceftriaxone; 4 isolates showed intermediate resistance to TMP/sulfa, the remaining 14 were susceptible. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 20 
Table 13: Summary of Invasive Haemophilus influenzae Case Characteristics, Alaska, 2003 

Sex 

Age 

(Yrs) Race 

Anchorage 

/Other 

Site of 

Isolation 

Clinical 

Presentation(s) Serotype* 

Associated Medical

Conditions Outcome 

M 0.4 AK Native Other Blood Septicemia a None

F 0.5 AK Native Other Blood Pneumonia a Chronic lung disease 

M 0.7 AK Native Other Joint fluid Septic arthritis, 

cellulitis a None

F 0.9 AK Native Other Blood Meningitis, 

pneumonia 

a Chronic lung disease

M 1 AK Native Other Blood Septic arthritis a Chronic lung disease 

M 1.1 AK Native Other Blood Meningitis, 

cellulitis b Chronic lung disease Death

M 3 AK Native Other Blood Pneumonia d None

M 31.7 Non-Native Anchorage Blood Pneumonia a Chronic lung disease

F 47.8 Non-Native Anchorage Blood Pneumonia NT Cigarette smoking,

injection drug use 

F 47.8 AK Native Anchorage Blood Empyema, 

pneumonia 

b Cigarette smoking,

alcohol abuse, diabetes 

F 58.8 AK Native Other Blood Pneumonia NT Immune suppressive 

treatment 

M 66.7 Non-Native Anchorage Blood Pneumonia f

Chronic lung disease, 

immune suppressive 

treatment 

Death 

M 66.9 Non-Native Anchorage Blood Septicemia NT Cigarette smoking,

diabetes Death 

F 68.5 AK Native Other Blood Septicemia NT None

F 69.5 Non-Native Anchorage Blood Septicemia NT Diabetes

M 76.5 AK Native Anchorage Blood Septicemia NT None

F 79.9 Non-Native Other Blood Pneumonia NT Chronic lung disease Death

M 82.6 Non-Native Anchorage Blood Septicemia c None

*NT = non-typeable

Surveillance of Invasive Bacterial Disease in Alaska, 2003 21 
Invasive Neisseria meningitidis

Overall Incidence

A total of 4 cases of invasive Neisseria meningitidis were reported to AIP in 2003 for an overall 

rate of 0.6/100,000. The Alaska rates are similar to the ABCs 2003 national projected rate of 

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

Network Neisseria meningitidis, 2003 - preliminary). There was one invasive N. meningitidisrelated death in Alaska in 2003 which resulted in a case fatality ratio of 25%. 

Seasonality

N. meningitidis cases occurred one each in February, April, September and October; no clusters 

of related cases were reported. 

Race

In 2001, 75% of invasive N. meningitidis cases in Alaska occurred in the non-Native population 

for an age-adjusted rate of 0.6/100,000 persons per year compared to the Alaska Native rate of 

0.5/100,000 persons per year. 

Table 14: Invasive Neisseria meningitidis Cases by Race – Alaska, 2003 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male

Deaths 

n (%) 

Alaska Native 1 (25) 0.5 100 1 (100) 

Non-Native 3 (75) 0.6 100 0 (0) 

Total 4 100 1 (25)

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

Region

Three of the four invasive N. meningitidis cases in 2003 occurred in Anchorage; the remaining 

case was in Southeast. 

Age

Invasive N. meningitidis cases reported in 2003 ranged in age from 1.6 to 19 years old; the 

median age was 12.2 years. There were no cases of invasive Neisseria meningitidis in persons 

greater than 19 years old. 

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 N. meningitidis infection 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 22 
was recorded as the primary clinical presentation. Two cases presented with septicemia and two 

cases presented with meningitis. 

N. meningitidis was isolated from blood samples in 3 of 4 (75%) cases in 2003. The remaining 

case was isolated from cerebrospinal fluid. 

Mortality

There was one N. meningitidis-related death reported in Alaska in 2003. The case occurred in a 

1.6 year old AK Native male who presented with meningitis. No risk factors were reported 

associated with this case.

Table 15: Summary of Invasive Neisseria Meningitidis Cases Characteristics, Alaska, 2003 

Sex 

Age

(yrs) Race 

Anchorage

/Other 

Site of 

Isolation 

Clinical

Presentation(s) 

Associated 

Medical 

Conditions Outcome 

M 1.6 AK Native Other Blood Meningitis None Death

M 6.3 Non-Native Anchorage Blood Septicemia None -

M 18 Non-Native Anchorage Blood Septicemia Cigarette 

smoking - 

M 19.3 Non-Native Anchorage CSF Meningitis

Chronic lung

disease - 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 23 
Invasive group A streptococcus 

Overall Incidence

A total of 23 cases of invasive group A streptococcus (GAS) were reported to AIP in 2003. 

Overall rates of invasive GAS disease in the state of Alaska were 3.5/100,000 persons per year. 

The Alaska rate is similar to the ABCs 2003 national projected rate of 3.8/100,000 (Active 

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

streptococcus, 2003 - preliminary). In 2003, there were 4 GAS-related deaths for a case fatality 

ratio of 17%. 

Seasonality

Cases of group A streptococcus occurred throughout the year in 2003 with no apparent trends in 

seasonality.

Figure 15: Invasive group A streptococcus, by 

Month of Culture - Alaska, 2003

0

1

2

3

4

5

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

Nu

m

b

er of Ca

s

e

s

Race

In 2003, 30% of invasive GAS cases in Alaska occurred in the Alaska Native population for an 

age-adjusted rate of 5/100,000 persons per year which was higher than the non-Native rate of 

2.8/100,000 persons per year. 

Table 16: Invasive group A streptococcus Cases by Race – Alaska, 2003 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male

Deaths 

n (%) 

Alaska Native 7 (30) 5 43 1 (14) 

Non-Native 16 (70) 2.8 81 3 (19) 

Total 23 70 4 (17)

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

Surveillance of Invasive Bacterial Disease in Alaska, 2003 24 
Region

Sixteen (69.7%) of the 23 invasive group A streptococcus cases in 2003 were reported in 

Anchorage, 2 cases each in the YK Delta and Southeast and one case each in Bristol Bay, the 

Interior and the Arctic Slope regions. 

Age

Invasive group A streptococcus cases reported in 2003 ranged in age from 0.9 to 73.8 years old; 

the median age was 46.3 years. Highest rates of disease occurred in children less than two years 

old (9.7/100,000 persons per year) and in the 55 - 64 year old age category (7.5/100,000 persons 

per year). 

Figure 16: Invasive group A streptococcus by Age

Group - Alaska, 2003

0

2

4

6

8

10

12

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

Age (yrs)

R

ate p

er 100,

0

0

0

Figure 17: Invasive group A streptococcus, Cases

& Rates by Age Group & Race - Alaska, 2003

0

1

2

3

4

5

6

7

8

9

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

Age (yrs)

Nu

m

b

er of Ca

s

e

s

0

5

10

15

20

25

30

35

40

R

ate p

er 100,

0

0

0

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

Surveillance of Invasive Bacterial Disease in Alaska, 2003 25 
In 2003, the highest rates of invasive group A streptococcal disease occurred in Alaska Natives 

less than 2 years old (35.2/100,000 persons per year) and Alaska Native adults 65 years of age 

and older (14.3/100,000 persons per year). The highest GAS disease rate in the non-Native 

population occurred in the 55-64 years age category (10.4/100,000 persons per year). No cases 

were reported in the AK Native population in the 2-4 and 55-64 age categories and no cases were 

reported in the non-Native population in the less than 2 and 5-18 age categories. 

Clinical Presentation

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

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

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

recorded as the primary clinical presentation. Table 17 shows the primary clinical presentations 

of invasive group A streptococcus in Alaska for 2003. 

Group A streptococcus was isolated from blood samples in 20 (87%) of 23 cases and one each 

from tissue, pleural fluid and a tracheal aspirate. 

 

Table 17: Primary Clinical Presentations of Invasive group A streptococcus – Alaska, 2003 

Primary Presentation n (%) 

Cellulitis* 10 (44)

Septicemia 5 (22)

Pneumonia* 5 (22)

Empyema 1 (4)

Septic arthritis 1 (4) 

Other 1 (4)

Total 23

*with bacteremia

Surveillance of Invasive Bacterial Disease in Alaska, 2003 26 
Table 18: Summary of Invasive group A streptococcus Case Characteristics, Alaska, 2003 

Sex 

Age

(yrs) Race

Anchorage

/Other 

Site of 

Isolation 

Clinical

Presentation(s) Associated Medical Conditions Outcome

F 0.9 AK Native Other Blood Pneumonia Chronic lung disease 

M 1.7 AK Native Anchorage

Pleural 

fluid 

Empyema, 

pneumonia 

Chronic lung disease 

M 4.6 Non-Native Anchorage Blood Septicemia None

F 6.6 AK Native Other

Tracheal

aspirate Pneumonia None

M 15.7 AK Native Anchorage Blood Cellulitis None

M 22.3 AK Native Anchorage Tissue

Cellulitis, necrotizing

fasciitis 

Cigarette smoking, alcohol

abuse 

F 24.4 AK Native Other Blood

Septic arthritis, 

cellulitis, necrotizing

fasciitis 

Cigarette smoking 

F 36.1 Non-Native Anchorage Blood Cellulitis

Cigarette smoking, chronic lung

disease 

M 39.8 Non-Native Other Blood Cellulitis, necrotizing

fasciitis Cigarette smoking Death 

M 40.6 Non-Native Anchorage Blood Septicemia Immune suppressive treatment

M 42.8 Non-Native Other Blood Other Alcohol abuse

M 46.3 Non-Native Anchorage Blood Cellulitis Cigarette smoking

F 48.6 Non-Native Anchorage Blood Septicemia

Cigarette smoking, chronic lung

disease, alcohol abuse 

F 53.2 Non-Native Anchorage Blood Cellulitis

Cigarette smoking, injection 

drug use 

M 53.9 Non-Native Anchorage Blood Cellulitis Diabetes

M 55.6 Non-Native Anchorage Blood Cellulitis Alcohol abuse, diabetes 

M 62.1 Non-Native Anchorage Blood Septicemia

Cigarette smoking, alcohol

abuse 

M 62.6 Non-Native Anchorage Blood Pneumonia Diabetes

M 64.2 Non-Native Anchorage Blood Cellulitis Diabetes

M 64.9 Non-Native Other Blood Cellulitis, septicemia None Death

F 66 AK Native Anchorage Blood Pneumonia Chronic lung disease Death 

M 72.6 Non-Native Other Blood Septicemia

Chronic lung disease, immune 

suppressive treatment 

M 73.8 Non-Native Anchorage Blood Pneumonia None Death

Surveillance of Invasive Bacterial Disease in Alaska, 2003 27 
Invasive group B streptococcus 

Overall Incidence

A total of 20 cases of invasive group B streptococcus (GBS) were reported to AIP in 2003. 

Overall rates of invasive GBS disease in the state of Alaska were 3.1/100,000 persons per year. 

The Alaska rate is lower than the ABCs 2003 national projected rate of 7.0/100,000 (Active 

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

streptococcus, 2003 - preliminary). In 2003, there were two GBS-related deaths for a case 

fatality ratio of 12% (outcome was unknown in 3 cases). 

Seasonality

Cases of group B streptococcus occurred throughout the year. The highest proportion (20%) of 

GBS cases occurred in the month of June. 

Figure 18: Invasive group B streptococcus, by

Month of Culture - Alaska, 2003

0

1

2

3

4

5

January

February

March

April

May

June

July

August

September

October

November

December

Month of Culture

N

u

mbuer of Ca

s

e

s

Race

In 2003, 15% of invasive group B streptococcus cases in Alaska occurred in the Alaska Native 

population for an age-adjusted rate of 2.4/100,000 persons per year compared with the nonNative rate of 3.2/100,000 persons per year. 

Table 19: Invasive group B streptococcus Cases by Race – Alaska, 2003 

Race 

Cases 

n (%) 

Age Adjusted 

Rate* % Male

Deaths 

n (%)†

Alaska Native 3 (15) 2.4 0 0 (0) 

Non-Native 17 (85) 3.2 41 2 (13) 

Total 20 35 2 (12)

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

†Outcome unknown in 1 AK Native case, 2 non-Native cases 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 28 
Region

In 2003, 15 of the 20 reported GBS cases occurred in Anchorage; three cases were reported in 

Southeast Alaska and two in the Interior. 

Age

Invasive group B streptococcus cases reported in 2003 ranged in age from newborn to 90.2 years 

old; the median age was 49.7 years. Highest rates of disease occurred in children less than two 

years old (19.5/100,000 persons per year) and in the 65 and older age category (10/100,000 

person per year). 

Figure 19: Invasive group B streptococcus by

Age Group - Alaska, 2003

0

5

10

15

20

25

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

Age (yrs)

R

ate p

er 100,

0

0

0

Figure 20: Invasive group B streptococcus, Cases

& Rates by Age Group & Race - Alaska, 2003

0

1

2

3

4

5

6

7

8

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

Age (yrs)

Nu

m

b

er of Ca

s

e

s

0

5

10

15

20

25

30

R

ate p

er 100,

0

0

0

AK Native

(# cases)

Non-Native

(# cases)

AK Native

(rate)

Non-Native

(rate)

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

variable. The highest rates of disease occurred in non-Native children less than 2 years of age 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 29 
(26.9/100,000 persons per year). The four cases that occurred in this age category were earlyonset disease (cases were less than 7 days old); and comprised a rate of 56.7/100,000 persons per 

year. There were no cases of invasive GBS in children less than 2 years old in Alaska Natives. 

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 2003, the most common clinical presentation 

was septicemia which occurred in 8 cases (40%). Two cases of septic arthritis had additional 

presentations of osteomyelitis, one case had a third presentation of cellulitis. 

Group B streptococcus was isolated from blood in 19 (95%) of 20 cases in 2003; one case was 

isolated from an unspecified sterile site. 

Table 20: Primary Clinical Presentations of Invasive group B streptococcus – Alaska, 2003 

*with bacteremia

Primary Presentation n (%) 

Septicemia 8 (40)

Cellulitis* 3 (15)

Pneumonia* 3 (15)

Bacteremia 2 (10)

Septic arthritis 2 (10) 

Meningitis 1 (5)

Total 20

Surveillance of Invasive Bacterial Disease in Alaska, 2003 30 
Table 21: Summary of Invasive group B streptococcus Case Characteristics, Alaska, 2003 

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 

M < 1 day Non-Native Anchorage Blood Pneumonia None 

M < 1 day Non-Native Other Blood Septicemia None Death 

F < 1 day Non-Native Anchorage Blood Meningitis None 

F 2.9 AK Native Other Blood Pneumonia Chronic lung disease Unknown 

M 12.5 Non-Native Anchorage Blood Pneumonia None

F 20.2 Non-Native Anchorage Blood Cellulitis, 

osteomyelitis Diabetes

F 33.6 Non-Native Anchorage Blood Septicemia None

M 47.5 Non-Native Anchorage Blood Septic arthritis, 

osteomyelitis 

Cigarette smoking, 

diabetes, injection 

drug use 

F 49.1 Non-Native Anchorage Blood Septicemia Chronic lung 

disease, diabetes 

F 50.2 Non-Native Anchorage Blood Bacteremia Chronic lung 

disease, diabetes Unknown 

F 50.5 Non-Native Other Blood Peritonitis

Chronic lung 

disease, alcohol 

abuse 

Unknown 

M 54 Non-Native Other Other Cellulitis Immune suppressive 

treatment, diabetes 

F 56.4 AK Native Other Blood Septicemia Diabetes

M 61.9 Non-Native Anchorage Blood Septicemia

Cigarette smoking, 

chronic lung disease, 

diabetes 

F 63.5 Non-Native Anchorage Blood

Septic arthritis, 

cellulitis, 

osteomyelitis 

None

M 66.9 Non-Native Anchorage Blood Septicemia Cigarette smoking, 

diabetes Death 

F 79.5 Non-Native Anchorage Blood Septicemia None

F 81.1 AK Native Anchorage Blood Bacteremia Alcohol abuse 

F 90.2 Non-Native Anchorage Blood Cellulitis None

Surveillance of Invasive Bacterial Disease in Alaska, 2003 31 
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. 

Surveillance of Invasive Bacterial Disease in Alaska, 2003 32