الگوي مقاومت آنتي بيوتيكي و پروفاژ تايپينگ سويه هاي استافيلوكوكوس اوريوس مقاوم به متي سيلين جدا شده از مرغ داري هاي كرج در سال 1391

Antibiotic Resistance Pattern and Prophage Typing of Methicillin Resistant Staphylococcus aureus Strains Isolated from Chicken Husbandries in Tehran

Abstract Background and objective: Staphylococcus aureus is a common cause of infection among human and animals and known as community-acquired and nosocomial pathogen. Most of the isolates contain lysogenic phages which are responsible for production of various virulence factors. All staphylococcus isolates are classified in 6 groups according to their sensitivity to 27 known lysogenic phages. The aim of this study was to analyze different prophage types, antibiotic resistance pattern and detection of mecA gene in meticilin resistant S. aureus (MRSA) strains isolated from a poultry farm in Karaj. Materials and methods: Totally 110 isolates of MRSA from poultry samples were collected from 1 laying flocks in Karaj. All isolates were identified at the species level using specific primers. Susceptibility to 19 antibiotics was determined using disc diffusion method according to guidelines of Clinical Laboratory and Standard institute (CLSI). Minimum inhibitory concentration (MIC) of oxacillin and vancomycin in MRSA isolates were also detected using Etest according to CLSI recommendation. Primers for identification of 6 classes of prophages were used in a Multiplex-PCR assay. Plaque and spot assays were used to show the presence of lysogenic prophages. mecA gene was detected using specific primers. Results: Using PCR all isolates were confirmed as MRSA. The highest antibiotic resistance was observed to penicillin (100%) and followed by ciprofloxacin (100%), erythromycin (100%), amikacin (100%) and kanamycin (100%). None of the isolates were resistant to fusidic acid, nitrofurantoin, vancomycin, linezolid and synercid. Very high (MIC?128 µg/ml) levels resistance to oxacillin was observed in 83.5 % of the isolates. Four different prophage types were found in MRSA isolates. Out of the total MRSA isolates, 81 and 19 percent of the isolates contained 4 and 3 different prophage types, respectively. Conclusion: High diversity of prophage phages was found in MRSA isolates. Prophage segment from SGF prophage type was common in the MRSA isolates indicating the ability of these isolates to produce enterotoxins and other virulence factors. High prevalence of different classes of prophages encoding a variety of virulence factors and high oxacillin resistance provide an important role for phages in the evolutionary development of virulence factors and also diversity in methicillin resistance cassette in MRSA isolates. Presence of these highly virulent isolates with high resistance to first and second lines of treatments is a potential treat for public health.