MULTILOCUS SEQUENCE TYPING OF PENICILLIN NON-SUSCEPTIBLE S. PNEUMONIAE ISOLATES FROM INVASIVE INFECTIONS

Background and Aim:Worldwide spread of penicillin non-susceptible pneumococci (PNSSP) has created a serious problem in the treatment of pneumococcal infections. Monitoring of resistant clones is essential to antibiotic resistance surveillance. In this study, PNSSP isolates were typed using the Multilocus Sequence Typing (MLST) method.Methods:Various clinical samples were collected from patients with suspected pneumococcal disease and were cultured on sheep blood agar with 5% sheep blood. Suspected colonies were identified by biochemical and molecular assays. The penicillin susceptibility test was performed by serial broth microdilution method. MLST protocol was used to determine the molecular type of PNSSP isolates.Results:A total of 46 strains of S. pneumoniae were isolated from suspected clinical samples. Penicillin nonsusceptibility was detected in 12 (12/46) isolates. Molecular analysis showed that pneumococcus isolates clustered into five major clonal complexes and 42% (5/12) of the STs were novel.Conclusion:Our results showed that the majority of isolates (74%) are penicillin susceptible according to the recently revised S .pneumoniae breakpoints for penicillin. MLST analysis indicates that the high genetic diversity is among PNSP isolates.

Keywords:

penicillin non-susceptible pneumococci , molecular typing , multi locus sequence typing (MLST) , sequence type (ST) , clonal complex (CC)