CHINET 2007 surveillance of antimicrobial resistance in Haemophilus influenzae in China

Objective To investigate the antibiotic resistance in clinical isolates of Haemophilus influenzae (HI) in China during 2007.Methods Clinical isolates of HI were collected from 9 hospitals in China. Antimicrobial susceptibility was tested by Kirby-Bauer method. Results were analyzed according to CLSI 2007. Beta-lactamases were detected by nitrocefin disk test.Results A total of 755 clinical isolates of HI were collected. About 59.4%, 30.1% and 16.9% of the 755 strains were resistant to trimethoprim-sulfamethoxazole, ampicillin, and chloramphenicol, respectively. No more than 10% of these strains were resistant to ampicillin-sulbactam, ciprofloxacin, ceftazidime, amoxicillin-clavulanic acid, azithromycin, or cefuroxime. About 37.4% of the strains were resistant to ampicillin. Beta-lactamase was produced in 34.9% of the isolates from children. Beta-lactamase-positive strains were more resistant than the isolates from adults (13.7% and 10.6%). Only 1.6% of the isolates from children were resistant to ciprofloxacin, apparently lower than the isolates from adults (19.1%). The overall prevalence of β-lactamase was 27.4%. The prevalence of multidrug-resistant strains was 25.3% (159/609).Conclusions The resistance of HI to ampicillin and trimethoprim-sulfamethoxazole is increasing. Trimethoprim-sulfamethoxazole should not be used as empirical treatment of HI infection. The resistance rate to ampicillin and prevalence of β-lactamase are higher in children′s isolates than in the isolates from adults(P0.05). The primary mechanism of antibiotic resistance in HI is production of beta-lactamases. More attention should be paid to the multidrug-resistant HI isolated from children.