Biotypes and antimicrobial resistance of Haemophilus parainfluenzae isolated from adults with respiratory tract infection

Abstract:

ObjectiveTo investigate the biotypes of Haemophilus parainfluenzae(H.parainfluenzae) isolated from adults with respiratory tract infection in a hospital and relationship of H.parainfluenzae with producing of βlactamase and antimicrobial resistance.Methods1 994 sputum specimens from adult patients with respiratory tract infection from October 2011 to July 2012 were taken for Haemophilus isolation and culture, the isolated H.parainfluenzae were identified, performed biotyping, βlactamase detection and antimicrobial susceptibility testing.ResultsA total of 102 isolates （5.12%） of Haemophilus were isolated, 68(66.67%) of which were H.parainfluenzae, 20（19.61%） were Haemophilus influenzae，and 14（13.72%）were other types of Haemophilus.Six biotypes(ⅠⅥ)were detected among H.parainfluenzae, type Ⅰ, Ⅱ, Ⅲ, Ⅳ，Ⅴ,Ⅵ were 42,4,2,2, 14, and 4 isolates,respectively. There were 54(79.41%) βlactamaseproducing isolates. H.parainfluenzae had higher resistance to ampicillin(83.82%), levofloxacin(60.29%), tetracycline(57.35%), and sulfamethoxazole /trimethoprim (70.59%). The resistant rates to cefotaxime，ampicillin/sulbactam, cefaclor,clarithromycin, and rifampicin was 8.82%,13.24%,5.89%,20.58% and 25.00%,respectively; There were no strains resistant to imipenem and chloramphenicol. There were some differences in antimicrobial resistance among various biotypes.ConclusionH.parainfluenzae is a common pathogen in adults with respiratory tract infection in this hospital,the major epidemic biotypes are type Ⅰand V,most isolates produce βlactamase, detection of biotypes and antimicrobial resistance of H.parainfluenzae should be paid attention.