Low rate of nasopharyngeal carriage and high rate of ampicillin resistance for Haemophilus influenzae among healthy children younger than 5 years old in northern Taiwan.
OBJECTIVE
Surveillance data of colonization by Haemophilus influenzae in Taiwan are lacking. This study aimed to define the nasopharyngeal carriage rate of H. influenzae among children younger than 5 years in northern Taiwan, and to determine the antibiotic susceptibility, serotype and the clonal relationship of these isolates.


METHODS
Nasopharyngeal specimens were obtained from 511 healthy children younger than 5 years. All H. influenzae isolates were serotyped. The minimal inhibitory concentrations for various antibiotics were determined. Pulsed-field gel electrophoresis (PFGE) was used for clonal analysis.


RESULTS
Among 511 children, 269 (52.6%) had been vaccinated with at least one dose of H. influenzae type b (Hib) conjugate vaccine, 236 (46.2%) were unvaccinated and 6 (1.2%) had no vaccination records available. Twenty six H. influenzae strains were isolated. There were three Hib isolates and the others were nontypeable H. influenzae (NTHi). The carriage rate for Hib was 0.6% (3/511) and of NTHi was 5% (23/511). Three (1.27%) of the 236 unvaccinated children were carriers of Hib, whereas none of the 269 vaccinated children carried Hib. Two out of the three Hib isolates and 14 (60.9%) of 23 NTHi isolates were ampicillin-resistant. Multidrug resistance was found in 7 (26.9%) of the isolates. Among the isolates, 61.5% were beta-lactamase producers; there were no beta-lactamase-negative ampicillin-resistant isolates. The PFGE restriction patterns showed a wide diversity of genotypes.


CONCLUSIONS
There is very low nasopharyngeal carriage of Hib among children younger than 5 years in northern Taiwan. This may explain why the incidence of invasive Hib disease is also low in Taiwan. In addition, we found a high prevalence of beta-lactamase-positive ampicillin-resistant nasopharyngeal H. influenzae isolates.
Wang
Sheng-Ru
SR
Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Lo
Wen-Tsung
WT
Chou
Chen-Ying
CY
Chen
Ying-Yan
YY
Tsai
Shu-Ying
SY
Chu
Mong-Ling
ML
Wang
Chih-Chien
CC
D017677:Age Distribution; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001428:Bacterial Vaccines / Q000008:administration & dosage; D002353:Carrier State / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology*; D002675:Child, Preschool; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects* / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D009305:Nasopharynx / Q000382:microbiology*; D012703:Serotyping; D013624:Taiwan / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data
D000900:Anti-Bacterial Agents; D001428:Bacterial Vaccines