Differentiation of Penicillin Susceptible and Nonsusceptible Streptococcus pneumoniae

Introduction: Streptococcus pneumoniae cause morbidity and mortality in infants and younger children. Because of high prevalence of penicillin resistance, rapid and reliable diagnostic techniques for penicillin non-susceptible S. pneumoniae (PNSSP) are important for prevention and treatment. We investigated the association of the restriction length polymorphism (RFLP) patterns for pbp2b to distinguish between penicillin susceptible and resistant S. pneumoniae isolates. Methods: In this study, a total of 70 pneumococcal isolates were collected from different clinical sources. MIC of these isolates was determined and pbp2b gene was amplified by PCR and they were digested by HaeІІІ enzyme. Results: Of the 70 isolates, 86% (60) and 14% (10) pneumococcal isolates were found to be PNSSP (penicillin intermediate S. pneumoniae (PISP) and penicillin resistant S. pneumoniae (PRSP)) and penicillin susceptible S. pneumoniae (PSSP). In addition, 10 RFLP patterns (A-J) which were based on the HaeІІІ digestion of pbp2b gene were observed. All PSSP isolates showed that they belonged to pattern D, whereas, all PNSSP showed 10 different patterns. Conclusion: In general, the present study suggests that RFLP can be a powerful tool in differentiation between the penicillin resistant and susceptible strains.