Evaluation of Routine Patient Bathing on the Reduction of Skin Colonization by Methicillin Resistant Staphylococcus aureus

Background: Patients with methicillin-resistant Staphylococcus aureus (MRSA) carriage are at increased risk for infection and may be a source for transmission. Chlorhexidine bathing of intensive-care unit patients has been shown to be effective means to reduce the burden of MRSA and other pathogens on skin. However, limited information is available regarding the efficacy of routine hospital bathing practices in reducing levels of MRSA on skin.

Objective: To determine whether routine hospital bathing practices are effective in decreasing levels of MRSA on skin.

Methods: We conducted a prospective study of 55 patients with MRSA nares colonization admitted to the Cleveland Veterans Affairs Medical Center. To assess the effect of bathing on the burden of MRSA, swab cultures were obtained from commonly examined sites (chest, abdomen, groin, hand and arm) before and after routine bathing. Patients with at least one positive skin culture were included in the analysis. The proportions of positive skin sites and mean numbers of colonies were compared before and after bathing. Bathing methods included showering and bed-baths. Both non-antimicrobial soap and antimicrobial soap containing 0.3% triclosan were used. Cultures were taken 1 hour, 6 hours, and 24 hours after bathing. Proportions of positive cultures were compared using Fisher’s exact test and mean numbers of colonies were compared using paired Student’s t test.

Results: Of 55 patients enrolled, 30 (54%) had at least one positive skin culture. Of the 120 skin culture sites, there was no significant difference in the percentages of positive cultures before versus after bathing (shower or bed bath) with non-antimicrobial soap (51% versus 44%, P= 0.37). However, the number of colonies recovered from skin was significantly reduced 1 hour after bathing (mean, 1.2 log CFU/swab versus 0.7 log CFU/swab, P<0.001). Use of antimicrobial soap containing 0.3% triclosan was associated with a non-significant reduction in the percentage of positive cultures at 6 hours after bathing, but no reduction at 24 hours after bathing.  

Conclusions: Routine bathing of MRSA carriers with non-antimicrobial soap or antimicrobial soap containing triclosan did not reduce the percentage of positive skin cultures, but there was a modest reduction in the burden of MRSA on skin. These findings suggest that routine hospital bathing practices have limited efficacy for removal of MRSA from skin.