Objective: To investigate the drug-resistance rates of community-acquired respiratory tract pathogens isolated from adults in China during 2009 and 2010.
Methods: A total of 1793 strains (S. aureus 421, S. pneumoniae 420, K. pneumoniae 404, H. influenzae 313, other Streptococcus. spp 149, and M. catarrhalis 86) of non-duplicated community-acquired respiratory tract pathogens were isolated from 11 hospitals in 6 cities. The MIC values were determined by the broth microdilution method, and the production of β-lactamase was tested using a nitrocefin-based test.
Results: All of the S.aureus isolates were methicillin-sensitive (MSSA). Of the MSSA isolates, less than 1% (4/421) was resistant to β-lactamase inhibitor combinations, about 13.1% (55/421) and 9% (38/421) resistant to levofloxacin and moxifloxacin, and 57% (240/421), 53.2% (224/421), and 88.7% (373/421) resistant to azithromycin, clarithromycin, and penicillin, respectively. No S. aureus isolates resistant to vancomycin were detected in this study. Based on different criteria, the percentages of penicillin-sensitive S. pneumoniae (PSSP), penicillin-intermediate S. pneumoniae (PISP), and penicillin-resistant S. pneumoniae (PRSP) were 24.4% (102/420), 27.3% (115/420), 48.3% (203/420) (Oral) and 1.9% (8/420), 9% (38/420), 89.1% (374/420) (parenteral), respectively. The resistance rates of S. pneumonia to azithromycin, clarithromycin, cefaclor, cefuroxime, ceftriaxone and amoxicillin with clavulanic acid were 88.2% (370/420), 87.4% (367/420), 45.3% (190/420), 41.9% (176/420), 10.2% (43/420), and 5.2% (22/420), respectively. About 2.6% (11/420) and 0.2% (1/420) of S. pneumonia isolates were resistant to levofloxacin and moxifloxacin. More than 70% (104/149) of β-hemolytic streptococci isolates were resistant to azithromycin and clarithromycin, and about 10.1% (15/149) of isolates were resistant to levofloxacin. The resistance rates of K.pneumonia to most antibiotics were > 20% (81/404), and that of ceftazidime was lower than cefuroxime, cefaclor, and ceftriaxone. The mean prevalence value of ESBL producing K. pneumonia was 38.8% (157/404), with significantly regional variations. More than 90% of H. influenza and M. catarrhalis were susceptible to most antibiotics, with resistance rate of < 5% (16/313, H. influenza; 4/86, M. catarrhalis). The mean productions of β-lactamase in H. influenza and M. catarrhalis were 13.1% (41/313) and 91.7% (79/86), respectively.
Conclusions: The percentage of PRSP increased significantly, and the resistance rates of community-acquired respiratory tract pathogens to common antibiotics such as macrolide and cephalosporins increased gradually. New fluoroquinolones such as moxifloxacin showed a high antimicrobial activity against most of the respiratory pathogens.