High prevalence of beta-lactam-resistant Haemophilus influenzae type b isolates derived from respiratory tract specimens in Japanese patients.
OBJECTIVE
Serotypeable strains of Haemophilus influenzae, which can cause invasive infections, are found in the respiratory tract at low frequencies. We compared the antibiotic resistance of the typeable and nontypeable strains of H. influenzae in respiratory tract specimens obtained in Japan.


METHODS
We determined the serotypes and the antibiotic susceptibilities of 440 clinical H. influenzae strains isolated from respiratory tract specimens. We also examined the prevalence of genotypes that are associated with beta-lactam resistance.


RESULTS
The majority of the strains were nontypeable (421 strains, 95.7%). The remainder belonged to serotypes b (10 strains, 2.3%), e (three strains, 0.7%), or f (six strains, 1.4%). The type b strains exhibited the expression of beta-lactamase and resistance mutations in penicillin-binding protein 3 with significantly higher frequencies than other strains.


CONCLUSIONS
H. influenzae type b strains, which are associated with meningitis and bacteremia, derived from respiratory tract specimens, shared more beta-lactam-resistant mechanisms than nontypeable and other serotype strains.
Yokota
Shin-ichi
S
Department of Microbiology, Sapporo Medical University School of Medicine, South-1, West-17, Chuo-ku, Sapporo 060-8556, Japan.
Ohkoshi
Yasuo
Y
Sato
Kiyoshi
K
Fujii
Nobuhiro
N
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000382:microbiology; D019741:Haemophilus influenzae type b / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D007564:Japan / Q000453:epidemiology; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D046915:Penicillin-Binding Proteins / Q000235:genetics; D015995:Prevalence; D012137:Respiratory System / Q000382:microbiology*; D012703:Serotyping; D055815:Young Adult; D018440:beta-Lactam Resistance; D047090:beta-Lactams / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D046915:Penicillin-Binding Proteins; D047090:beta-Lactams