Effect of daily chlorhexidine bathing on the acquisition of methicillin-resistant Staphylococcus aureus in a medical intensive care unit with methicillin-resistant S aureus endemicity.

BACKGROUND

Universal decolonization is recommended in intensive care units (ICUs) that have unacceptably high rates of methicillin-resistant Staphylococcus aureus (MRSA) despite implementation of basic prevention strategies.

METHODS

An interrupted time series study was performed to evaluate the effect of daily chlorhexidine bathing on the acquisition of MRSA in a medical ICU with MRSA endemicity. There was a 14-month control period and a 16-month chlorhexidine bathing period. Segmented Poisson regression analysis was performed to assess the impact of daily chlorhexidine bathing on the incidence density of MRSA. Also, chlorhexidine susceptibility testing with polymerase chain reaction for the qacA/B gene was performed on MRSA isolates collected during the chlorhexidine bathing period.

RESULTS

There was a significant reduction in trend (-0.056; 95% confidence interval, -0.095 to -0.017; P = .005) of incidence density of MRSA despite a significant increase in both level and trend of MRSA prevalence rates during the chlorhexidine bathing period. However, there was no significant reduction in level of incidence density of MRSA during the interventional period. Minimum inhibitory concentration of chlorhexidine and the detection rates of the qacA/B gene for a total of 174 MRSA isolates did not increase during the chlorhexidine bathing period.

CONCLUSIONS

Daily chlorhexidine bathing resulted in a significantly decreasing trend of MRSA acquisition rates irrespective of increased MRSA prevalence rates in the medical ICU. There was no shift of chlorhexidine-resistant MRSA strains.