Mupirocin-resistant methicillin-resistant Staphylococcus aureus (MRSA) and vascular surgery

Aim 

An outbreak of mupirocin and methicillin resistant Staphylococcus aureus (MR-MRSA) occurred in a tertiary hospital, causing considerable disruption in a vascular unit. We investigated factors that might explain this large outbreak and areas for intervention to prevent a recurrence. 

Methods 

Cases of MRSA strain, spa type t127 or t922, were identified through databases, and healthcare records to describe affected patients in time, place and person. The adjusted matched odds ratio (amOR) for selected exposures in a matched case control study among hospital in-patients was calculated, using multivariable conditional logistic regression. 

Results 

Forty-one cases occurred over 18 months. Males predominated (78%), with a median age of 73 years. The specialty with the largest number of patients was vascular surgery with 18 cases (44%). Male sex (amOR=21; 95%CI 0.99-454), vascular surgery consultation (amOR=5.1; 95%CI 0.89-29), urinary catheterisation (amOR=12; 95%CI 0.98-154), occupational therapy (amOR=9.9; 95%CI 1.6-61) and length-of-stay (amOR=1.1; 95%CI 1.0-1.1 per additional overnight stay) were independently associated with an outbreak case. Control measures included; enhanced contact precautions, patient isolation/cohorting, ward closure, enhanced environmental decontamination and staff screening. 

Conclusion 

Vascular patients and those with underlying high dependency, i.e. urinary catheterisation and a requirement for occupational therapy had a higher risk of colonisation with MR-MRSA. Recording patient dependency prospectively, avoiding excessive bed occupancy, and a formal hospital policy on staff MRSA screening, are recommended to prevent/control future outbreaks in vascular units and elsewhere in hospitals.