Surveillance of bacterial resistance in community-acquired respiratory tract infections 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 and 93.4% 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.