Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Outbreaks in a Surgical Ward in Kano State

Healthcare-associated outbreaks of methicillin-resistant Staphylococcus aureus (MRSA) in surgical wards cause significant patient harm and require rapid epidemiological investigation to contain spread. This outbreak investigation study examined a cluster of MRSA surgical site infections that occurred in the surgical ward of Aminu Kano Teaching Hospital, Kano State, in the North West geopolitical zone of Nigeria. Twelve patients who underwent elective surgeries between February and April 2024 developed post-operative MRSA wound infections within 30 days. Environmental swabs, staff nasal swabs, and clinical isolates were collected and processed. MRSA isolates were typed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) to determine clonal relationships. Eleven of twelve clinical isolates and four of 28 staff nasal swabs shared an identical PFGE pattern, indicating a single clone responsible for the outbreak. MLST revealed the isolates belonged to sequence type ST22, a community-associated MRSA lineage with known nosocomial transmission capacity. The implicated healthcare worker was traced to a scrub nurse with asymptomatic nasal carriage. Decolonization of the carrier, reinforced hand hygiene, and enhanced surgical site preparation protocols successfully terminated the outbreak. The study demonstrates the power of molecular typing in outbreak resolution and recommends routine MRSA surveillance cultures and rapid molecular typing capacity at all tertiary surgical centres in Nigeria. Keywords: MRSA, outbreak investigation, surgical ward, Kano, molecular typing.