[Resistance surveillance of major pathogens for adult community-acquired respiratory tract infections in China: a multicenter study 2012].

Objective: To investigate antimicrobial resistance among pathogens responsible for adult community-acquired respiratory tract infections from 11 hospitals of China.

Methods: From January to December 2012, a total of 599 strains causing adult community-acquired respiratory tract infection were collected from 11 hospitals, including 381 Streptococcus pneumonia, 137 Haemophilus influenza, and 81 Moraxella catarrhalis. The minimal inhibitory concentration (MIC) of antibacterial agents was determined by agar dilution method.

Results: Of all the strains, 50% (300/599 strains) were from adults more than 60 years old and only 16.2% (97/599 strains) were from patients aged less than 40 years. According to oral penicillin breakpoints, 56.7% (216/381 strains) of Streptococcus pneumoniae were penicillin non-susceptible strains (PNSSP). More than 90% (345/381 strains) and 39.9% (152/381 strains)-50.7% (193/381 strains) of Streptococcus pneumoniae were resistant to macrolides and oral cephalosporins respectively, but over 97.8% (372/381 strains) and 99% (377/381 strains) were susceptible to levofloxacin and moxifloxacin. PNSSP strains exhibited significant higher resistance to ceftriaxone, amoxicillin/clavulanate, cefaclor and cefuroxime compared with penicillin susceptible Streptococcus pneumoniae (PSSP). The susceptibility rates of Haemophilus influenza to the antimicrobial agents were over 90% except for ampicillin (71.5%, 272/381 strains) and cefaclor (75.2%, 286/381 strains). The prevalence of β-lactamase positive Haemophilus influenza were 21.9% (30/137 strains), and β-lactamase positive Haemophilus influenza strains were more resistant to ampicillin, cefaclor, chloramphenicol and tetracycline compared with β-lactamase-negative strains. Moraxella catarrhalis strains were extremely susceptible to all the antimicrobial agents tested except for clindamycin, azithromycin and clarithromycin.

Conclusions: The activities of macrolides and oral cephalosporins against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were limited. Levofloxacin and moxifloxacin exhibited good activities against Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis.