OBJECTIVE
To characterize the relationship between chlorhexidine gluconate (CHG) skin concentration and skin microbial colonization.
DESIGN
Serial cross-sectional study.
SETTING/PARTICIPANTS
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.
METHODS
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.
RESULTS
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 species (26%) and gram-negative bacteria (20%). The adjusted odds of microbial recovery for every twofold increase in CHG skin concentration were 0.84 (95% CI, 0.80-0.87; < .001) for gram-positive bacteria, 0.93 (95% CI, 0.89-0.98; = .008) for species, 0.96 (95% CI, 0.91-1.02; = .17) for gram-negative bacteria, and 0.94 (95% CI, 0.84-1.06; = .33) for CPE. A threshold CHG skin concentration for reduced microbial detection was not observed.
CONCLUSIONS
On a cross-sectional basis, higher CHG skin concentrations were associated with less detection of gram-positive bacteria and species on the skin, but not gram-negative bacteria, including CPE. For infection prevention, targeting higher CHG skin concentrations may improve control of certain pathogens.