Control of methicillin-resistant Staphylococcus aureus in a burn unit: role of nurse staffing.

We investigated retrospectively the spread of methicillin-resistant Staphylococcus aureus (MRS) in a burn unit. During 8 months, 34% of the patients acquired MRS, and transmission continued despite barrier isolation precautions and treatment of colonized personnel with topical intranasal antibiotics. Several findings suggested MRS was spread primarily by contact transmission involving personnel: case-control comparison showed burn size to be the major host risk factor for colonization; correlation analysis of environmental factors revealed a significant (p = 0.001) association of new cases with increased patient load and with staffing by overtime or temporary nurses; and environmental sampling yielded few colonies of MRS. The outbreak halted following implementation of control measures, among which assignment of separate nurses to colonized patients appeared to be essential. The association of different nurse staffing variables with persistence then eradication of MRS suggests nurse staffing may have been an important factor in staphylococcal transmission.