[Study on drug resistance and molecular epidemiology of Streptococcus pneumoniae isolated in Chongqing]

To investigate the prevalence and drug resistance of Streptococcus (S.) pneumoniae in patients infected in communities and molecular epidemiology with BOX-polymerase chain reaction (PCR) in Chongqing areas.

A total of 680 clinical specimens from sputum and throat/nasal swabs were collected from patients seen from September 2000 to March 2001. Antibiotic susceptibility was determined by agar dilution test. BOX-PCR was used for molecular typing of S. pneumoniae.

A total of 39 isolates of S. pneumoniae were collected with the isolation rate of 5.7%. Of the 34 S. pneumoniae strains, two showed low-level resistance to penicillin (MIC 0.125 mg/L), one to levofloxacin, but many to macrolide and clindamycin (nearly 70%). All the strains were susceptible to beta-lactams and vancomycin. BOX-PCR typing demonstrated a high discriminatory potential and easy to be accurately analysed. 35 S. pneumoniae strains (include ATCC49619) were divided into 25 distinct types, representing 29 subtypes with A (n = 3) as the predominant type. 2 penicillin-resistant strains were shown to be different types.

Penicillin resistant rate of S. pneumoniae was low in Chongqing, but macrolide and clindamycin resistant strains were common while BOX-PCR typing was a suitable technique to type S. pneumoniae. No dominant antibiotic resistant strains were found in Chongqing.