Antimicrobial resistant profiles of Methicillin-resistant Staphylococcus aureus (MRSA) recovered from broiler chicken populations in Egypt

Little is still known about prevalence of methicillin resistant Staphylococcus aureus (MRSA) in broilers, so this study aimed to determine its prevalence, antibiogram patterns and the site of resistant genes using PCR. About 57 staphylococcal isolates of 78 samples (73%) recovered from broiler chicken were classified into coagulase positive staphylococci (CPS) (40.3%) and coagulase negative staphylococci (CNS) (59.6%). The CPS isolates were identified as MRSA (34.8%) and methicillin sensitive Staphylococcus aureus (MSSA) (65.2%) according to oxacillin resistance by disc diffusion method. The CPS isolates showed the highest rate of resistance to trimethoprim/sulphamethoxazole (100% and 93.3% for MRSA and MSSA respectively), erythromycin (100% and 93.3% for MRSA and MSSA respectively), oxacillin and cefoxitin (100%, 87.5% MRSA and 0%, 6.7% MSSA respectively), ceftriaxone (87.5% and 73.3% for MRSA and MSSA respectively) and amoxicillin (75% and 40% for MRSA and MSSA respectively). Moreover, the CNS showed resistance against trimethoprim/sulphamethoxazole with 85.3%, followed by 79.4% erythromycin, 55.9% ceftriaxone, 47% cefoxitin, 47% amoxicillin, and oxacillin (44%). PCR assay revealed that four (80%) of five MRSA isolates were harbored mecA gene. The screening of mecA, dfrA and ermC resistant genes was done on plasmid and chromosomal DNA of four MRSA isolates. All of them were chromosome linked genes, but none of these resistant genes were detected on plasmid DNA. All examined isolates (100%) contained ermC gene. In addition, the dfrA gene was detected in 2 (50%) out of the 4 isolates.