Distribution and antimicrobial resistance of clinical isolates of Haemophilus influenzae from Hubei province from 2008 to 2010

Objective To investigate the distribution and antimicrobial resistance of clinical isolates of Haemophilus influenzae(H.influenzae) from Hubei province.Methods Clinical isolates of H.influenzae were collected from 15 tertiary hospitals in Hubei province from 2008 to 2010.Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion method and results were analyzed according to CLSI 2009 guideline;β-lactamase was detected with nitrocefin disk testing.Results A total of 855 H.influenzae isolates were collected,673(78.71%) of which were from inpatients;87.37%(747 isolates) were from respiratory samples;575 isolates(67.25%) were from adults,and 280(32.75%) from children,56.07%(157 isolates) of which were from children under 2 years old.The resistant rate to trimethoprim-sulfamethoxazole,ampicillin,chloramphenicol and ampicillin/sulbactam was 58.0%,42.9%,16.9% and 16.2%,respectively,the resistant rate to cefuroxime,cefotaxime,ciprofloxacin,levofloxacin and azithromycin were all 10%.232 isolates(27.13%) produced beta-lactamase;22.26% of adult isolates and 37.14% of child isolates were beta-lactamase positive.A total of 32 isolates were beta-lactamase negative ampicillin-resistant(BLNAR) H.influenzae.Conclusion Most isolated H.influenzae from Hubei province were from respiratory samples of inpatients,the resistance to trimethoprim/sulfamethoxazole and ampicillin are high,the prevalence of beta-lactamase isolates from children is higher than that from adults.The primary mechanism of ampicillin resistance in H.influenzae is production of beta-lactamase.