Staffing deficits and workload have may a bearing on transmission of meticillin-resistant Staphylococcus aureus (MRSA) within intensive care units (ICUs). New MRSA acquistions may provide a clearer picture of the relationship between MRSA acquisition and staffing in the ICU setting.

To determine whether staffing and bed occupancy rates had an immediate or delayed impact on the number of new MRSA acquisitions in a well-staffed ICU, and whether these variables could be used as predictors of future MRSA acquisitions.

Data on new MRSA acquisitions in the ICU of a 796-bed metropolitan Australian hospital between January 2003 and December 2006 were used to build a model to predict the probabilility of actual new MRSA acquisitions in 2007. Cross validation was performed using receiver operator characteristic analysis.

Sixty-one new MRSA acquisitions (21 infections, 40 colonizations) were identified in 51 individual weeks over the study period. The number of non-permanent staffing hours was relatively small. The area under the curve in the cross-validation analysis was 0.46 [95% CI 0.25–0.67] which suggests that the model, built on data from 2003–2006, was not able to predict weeks in which new MRSA acquisitions occurred in 2007.

The risks posed by high workloads may have been mitigated by good compliance with infection control measures, nurse training and adequate staffing ratios in the ICU. Consequently, staffing policies and the infection control practices in the ICU do not need to be modified to address the rate of new MRSA acquisitions.