Nasopharyngeal carriage for Heamophilus influenzae among healthy residents in Dongyang,Zhejiang

Objective To investigate nasopharyngeal carriage for Haemophilus influenzae(Hi) among healthy residents in Dongyang City,Zhejiang,and explore the type distribution and antibiotic resistance of isolated strains.Methods A total of 238 throat swabs were collected from healthy residents in Dongyang,Zhejiang.The isolated strains of Hi were analyzed by bio-typing,serotyping and pulsed-field gel electrophoresis(PFGE) typing.Drug susceptibility tests were conducted for the isolated strains of Hi by Kirby-Bauer method.Results The carriage rate of Hi was 9.13%(21/238) for healthy residents.The positive rates of Hi were higher among residents aged over 19 years old(22.86%) or between 4 and 6 years old(22.22%).One strain of Hib was confirmed and the others were non-determinable strains.Biotype Ⅲ(38.10%) was predominant by the assay of bio-typing.There were 15 patterns of PFGE typing with a similarity rate of 48.8%.The variety of PFGE patterns showed a wide diversity of genotypes.Isolated strains were sensitive to most antibiotics except for sulphamethoxazole/trimethoprim(resistance rate:28.57%).Conclusion Hib carriage rate was low in healthy residents in Dongyang,Zhejiang.The variety of PFGE patterns suggested heterogeneous source of origin for isolated strains.