Antibiotics resistance in Streptococcus pneumoniae and correlates of pbp2b-gene amplicom profile to penicillin resistance
Objective To investigate the prevalence of penicillin and other antibiotics nonsusceptibility (including intermediate and resistant) among Pneumococci and to assess the correlation of pbp2b amplicon profiles to penicillin resistance in pneumococcal isolates by PCR and RFLP analysis. Method Susceptibility to antibiotics was determined by broth microdilution, E-test, and K-B disk. Primers pF and pR were used to amplify the pbp2b gene and its amplicon was subjected to HaeⅢ digestion. Results The percentage of nonsusceptilibity of S.pneumoniae to penicillin G raised from 9.9% in 1997 to 14.6% in 2000; pbp2b amplicon of 97.5% (39/40) pneumococcal isolates for which MICs of penicillin were ≤0.094μg/ml had one of three different susceptible restriction profiles, and 86.7% (26/30) isolates for which MICs were ≥ 0.12μg/ml had one of six. Low-concentration penicillin resistance (MICs=0.12μg/ml to 0.5μg/ml) was associated with sensitive HaeⅢ profiles (s1) in 4 isolates. Conclusion Penicillin and beta-lactams retained their activity against S.pneumoniae in Beijing. Restriction fragment length polymorphism (RFLP) analysis of pneumococcal pbp2b-specific amplicons is feasible for penicillin resistance screening. [