Epidemiology and antibiotic resistance of Staphylococcus aureus at the Avicenne Military Hospital, Marrakesh (2017–2024)

Background: Staphylococcus aureus is a Gram-positive coccus responsible for a variety of infections ranging from mild skin and soft tissue infections to severe invasive diseases. The emergence and spread of methicillin-resistant Staphylococcus aureus (MRSA) has become a significant public health concern, complicating treatment and infection control efforts worldwide. Methods: We performed a retrospective descriptive study at the microbiology department of the Avicenne Military Hospital of Marrakesh over a seven-year period from July 2017 to December 2024. We included every Staphylococcus aureus strains isolated from all clinical specimens of hospitalized patients and outpatients. Bacterial identification and antibiotic susceptibility testing were performed using standard microbiological techniques, including automated systems and diffusion methods, following CASFM/EUCAST guidelines. Data were analyzed using Microsoft Excel 2019. Results: Among 7738 specimen collected Staphylococcus aureus represented 8.1% (n=626). MRSA accounted for 11.41% of isolates. Surgical departments made up the majority of isolates (37%). Pus and related specimens were the most frequent sample types (43%). As for antibiotic resistance, MRSA strains exhibited 100% resistance to penicillin and cefoxitin, and high resistance rates to tetracycline (48%), macrolides (42%) and aminoglycosides (up to 45%) while retaining full susceptibility to vancomycin and 96% susceptibility to linezolid. On the other hand, MSSA strains demonstrate a 92% resistance rate to penicillin while mostly conserving susceptibility to other antibiotics. Conclusion: Our study underlines the continuing burden of Staphylococcus aureus particularly MRSA strains. To limit the spread of such resistant strains a continued surveillance with strict infection control practices and rational antibiotic use are critical.