Surveillance of bacterial resistance in community-acquired respiratory tract infection during 2005-2006 in China

Objective: To investigate antimicrobial resistance of bacterial pathogens isolated from community acquired respiratory tract infections to cefaclor and other 5 antimicrobial agents during 2005-2006. Methods: A total of 506 bacterial isolates were collected, including 280 strains of H. influenzae, 105 S. pneumoniae, 61 M. catarrhalis, 30 oxacillin-susceptible S. aureus (MSSA) and 30 beta-hemolytic Streptococcus from 6 hospitals. The strain identification confirmation and E-test were conducted in Beijing Hospital. Results: H. influenzae was isolated from 56.9% (115/202) of the patients with community-acquired pneumonia (CAP), and 64.5% (60/93) of the patients with acute exacerbation of chronic bronchitis (AECB). Results of susceptibility testing showed that the prevalence of penicillin-susceptible S. pneumoniae (PSSP) was 50.5%. About 31.4% of the S. pneumoniae isolates were penicillin-intermediate S. pneumoniae (PISP), and 18.1% of the S. pneumoniae isolates were penicillin-resistant S. pneumoniae (PRSP). The highest prevalence of penicillin-non-susceptible S. pneumoniae (PNSP) was found in Shanghai and Guangzhou (78.6%), followed by Sichuan (50%), Tianjin (46.7%), Zhejiang (37.5%) and Beijing (21.1%). Beta-lactamase was produced in 21.1% of H. influenzae isolates and93.4% of M. catarrhalis isolates. The 98.6%, 97.8%, 98.6%, and 85.8% of the H. influenzae isolates were susceptible to cefaclor, cefprozil, azithromycin, ampicillin and moxifloxacin respectively. The resistance rates of S. Pneumoniae, beta-hemolytic Streptococcus and MSSA to azithromycin were 94.3%, 60% and 56.7% respectively. The MIC values of cefaclor were 1-2 times lower than cefprozil against H. influenzae and M. catarrhalis. Conclusions: The resistance rate of S. pneumoniae to penicillin is increasing rapidly compared with the surveillance results in 2003. The prevalence of β-lactamase production was rising in H. influenzae and M. catarrhalis. The resistance rate of S. pneumoniae, beta-hemolytic Streptococcus and MSSA to azithromycin was high. Cefaclor still maintains good in vitro activity for most bacterial isolates (70%-100%) from community-acquired respiratory tract infections. It should be recommended as a good choice for mild to moderate community-acquired respiratory tract infections.