Characterization of 5 Episodes of Vancomycin Nonsusceptible Streptococcus Pneumoniae From Clinical Isolates in Tehran, Iran

Abstract

Background: Streptococcus pneumoniae is an important bacterial pathogen in children and older adults. It is associated with the highest case fatality rates in patients with pneumonia and meningitis. Objectives: In the present study, we determined the phenotypic and genotypic properties of a vancomycin nonsusceptible S. pneumoniae isolates from clinical specimens in Tehran, Iran. Methods: Five pneumococcal isolates were included in the study from different clinical specimen in 2 hospitals in Tehran (Milad and Sina), Iran. Antimicrobial susceptibility tests of pneumococcal isolates were performed by the broth microdilution method according to CLSI guideline, and the presence of vanA gene was detected by PCR. Results: During the study period, 5 S. pneumoniae isolates resistance to vancomycin were identified. Vancomycin minimum inhibitory concentrations (MIC) ranged from 2 µg/mL to 16 µg/mL. All the isolates were resistant to cefotaxime and erythromycin. Moreover, only 1 isolate was susceptible to penicillin. PCR results showed that all isolates were negative for vanA gene. Conclusions: Our results demonstrated that an alarming rate of vancomycin resistant pneumococci may result from the uncontrolled use of vancomycin and self-medication. Moreover, multiple drug resistant pneumococci were observed especially in cefotaxime and erythromycin, which may be a major health problem in Iranian patients.