Relationship between chlorhexidine gluconate concentration and microbial colonization of patients' skin.

To characterize the relationship between chlorhexidine gluconate (CHG) skin concentration and skin microbial colonization. Serial cross-sectional study. Adult patients in medical intensive care units (ICUs) from 7 hospitals; from 1 hospital, additional patients colonized with carbapenemase-producing Enterobacterales (CPE) from both ICU and non-ICU settings. All hospitals performed routine CHG bathing in the ICU. Skin swab samples were collected from adjacent areas of the neck, axilla, and inguinal region for microbial culture and CHG skin concentration measurement using a semiquantitative colorimetric assay. We used linear mixed effects multilevel models to analyze the relationship between CHG concentration and microbial detection. We explored threshold effects using additional models. We collected samples from 736 of 759 (97%) eligible ICU patients and 68 patients colonized with CPE. On skin, gram-positive bacteria were cultured most frequently (93% of patients), followed by On a cross-sectional basis, higher CHG skin concentrations were associated with less detection of gram-positive bacteria and