Mohammad Rahbar - Department of Microbiology, Iranian Reference Health Laboratory Research Center, Ministry of Health and Medical Education, Tehran, Iran
Mona Mohammadzadeh - Department of Microbiology, clinical Laboratory, Milad Hospital Tehran. Iran
Abed Zahedi bialvaei - Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
Alireza Dolatyar - Department of Microbiology, Iranian Reference Health Laboratory Research Center, Ministry of Health and Medical Education, Tehran, Iran

Background: Streptococcus pneumonia is one of the major causative agents of invasive disease such as pneumonia, sepsis, sinusitis, otitis media, meningitis, and bronchitis among children and predisposed adults. The aim of this study was to determine antibiotic resistance pattern in S.pneumoniae strains isolated from invasive specimens of patients admitted to Milad hospital. Methods: During of our study from 2010 to 2017 in total of 50 strains of S.pneumoniae was isolated from respiratory tract, blood, cerebrospinal fluid, peritoneal. Pleural effusion synovial fluid, bone aspiration, otiitis media sinusitis or other body sterile fluids. All isolates was confirmed by routinely laboratory methods. Antibiotic susceptibility testing for Oxacillin, Levofloxacin, Trimethoprim/ Sulfamethoxazol, Clindamycin, Azithromycin, Erythromycin, Vancomycin ,Cholramphenicol and Tetracycline was performed by gradient test (MIC –EtestBiomerux France) and evaluated according to the breakpoints of Clinical and Laboratory Standards Institute (CLSI M100 –S27).Data was analyzed using WHONET Software version 5.6). Results: Fifty isolates of S.pneumoniae strains was the subject of our study. The majority of strains were isolated from blood cultures. Age of patients ranged from three month to 77 years old.The result ofantimicrobial susceptibility testing showed that 88% of isolates were susceptible to vancomycin and 12% non-susceptible. The most of the resistance was observed for Oxacillin (98%), Erythromycin (72%), Azithromycin (70%), Trimethoprim/Sulfamethoxazole (64%), Tetracyclin (54%) and Clindamycin (52%) respectively. 34% of isolates had intermediate susceptibility against Trimethoprim/Sulfamethoxazole and 98% of isolates were susceptible for levofloxacin. Conclusion: Our study revealed a high rate of resistance among S.pneumoniae isolates to commonly used antibiotic such as penicillin and erythromycin .The most effective antibiotic for treatment of infection caused by S. pneumonia were levofloxacin and vancomycin respectively.

S.pneumoniae, Drug Resistance