In Vitro Studies on Antibiotic Susceptibility Pattern of Methicillin Resistant and Sensitive Staphylococcus aureus isolates

Background: Methicillin Resistant Staphylococcus aureus (MRSA) is a variant of Staphylococcus aureus which is resistant to all ß-lactams. Infections due to (MRSA) strains have been detected worldwide and it makes the treatment of common infections much more difficult. Objectives: This study was carried out to determine and compare the Antibiotic susceptibility patterns in Methicillin Resistant and Sensitive Staphylococcus aureus isolates (MRSA, MSSA). Material and methods: 395 clinical samples were collected from National Cancer Institute (NCI), Cairo, Egypt. Identification of all isolates and detection of its susceptibility was determined with Microscan system, standard biochemical tests and disc diffusion method using Kirby-Bauer disk diffusion method and the interpretation of the results was done using Clinical and Laboratory Standards Institute guidelines (CLSI). MRSA was detected using resistant to Cefoxitin and oxacillin. Results: Out of identified 408 isolates collected from all clinical samples, 43 isolates found to be Staphylococcus aureus were comprising 16 (37.2%) were MRSA strains and 27 (62.8%) were MSSA strains, 100% of MRSA and 77.8% of MSSA isolates were multidrug resistant (MDR). However, no Staphylococcus aureus strains were found to be resistant to vancomycin [100% VA sensitive], [MRSA and MSSA] were [38% and 56%] respectively sensitive to Synercid and [44%, 52%] respectively sensitive to Linezolid. MRSA isolates showed high level [100%] as resistance to antibiotic groups of ß-lactams. Conclusions: This study highlights the need for continuous surveillance of antibiotic susceptibility pattern of Methicillin resistant and sensitive Staphylococcus aureus with a view for selecting appropriate therapy.