Short- and long-term impact of aseptic bathing strategies on the skin microbiome in ICU patients

Abstract

Bathing strategies with antiseptic agents, such as Chlorhexidine and Octenidine, have been widely adopted to mitigate infection risks in intensive care units (ICU). However, concerns exist regarding their long-term effects on skin microbiome structures and potential unintended consequences, including antibiotic cross-resistance. This longitudinal study characterized the compositional changes of the skin microbiome of ICU patients upon these two antiseptic bathing strategies when compared to standard water and soap bathing. Samples were collected in a three-armed cluster randomized decolonization trial (registration number DRKS00010475). Skin swabs from 5 different sites and three time points were analyzed by culture-based methods, 16S rRNA-gene amplicon sequencing and multiplex Taq-Man assays for detection of antimicrobial resistance genes (ARG). Our results show that Chlorhexidine bathing led to a sustained reduction of the bacterial biomass on different skin sites, as measured by both molecular and culture-based methods. Thereby, the microbial structures remained largely unaltered both in their diversity and their taxonomic composition. However, the loss of microbiome site-specificity observed on the skin of ICU patients remained unchanged independently from the bathing strategy applied and persisted even after discharge. None of the antiseptic bathing strategies led to an increase or accumulation of antibiotic-resistance determinants on any of the skin sites investigated in this study. Thus, this study suggests that daily patient bathing with 2% Chlorhexidine impregnated cloths or 0.08% Octenidine wash mitts does not impact skin microbiome structures and antibiotic resistance gene accumulation in ICU patients when compared to non-antiseptic water and soap bathing routine.

Keywords: Bathing; Critical illness; ICU; Skin microbiome.

Fig. 1

Quantitative analysis of the bacterial biomass on the skin after different bathing strategies. The scatter dot plots (with median) show the quantitative values obtained after 16S rRNA qPCR (A) and CFU counting (B), of the samples obtained from different skin sites at admission (T1), during ICU stay (T2) and after discharge (T3) (*p < 0.05; **p < 0.01; ***p < 0.001)

Fig. 2

Alpha-diversity metrics of the skin microbiota upon different bathing strategies. Shown is the Shannon index (box and whiskers plot with median, ∗ p < 0.05, ANOVA) for each of the skin sites (axillary vault (AV), hypothenar palm (HP) and gluteal crease (GC)) at each time point (T1, T2, T3) of the intervention with the different bathing strategies

Fig. 3

Site specificity of the bacterial communities on the skin as measured by beta-diversity metrics. Shown are the principal coordinate analyses of the β-diversity of the skin microbiome using Bray–Curtis distances for each of the skin sites in a healthy controls group (A) and in the ICU-patients cohort (B). The patients group samples were divided in the results obtained across the longitudinal study before (T1) and after intervention (T2: ICU stay; T3: after discharge). Pairwise comparisons between sites were made using Permanova tests. (WS: Water and soap; CHX: Chlorhexidine; OCT: Octenidine). Data for thse analysis of the healthy cohort was retrieved from Klassert et al. [5]

Fig. 4

Antibiotic resistance gene (ARG) detection on the skin microbiome of ICU patients. A Bar chart depicting the ARG expression across all samples of our ICU cohort. Bars represent percentage of samples with positive ARG detection in sites that were subjected (blue) and not subjected (green) to bathing. B mecA detection across different bathing strategies. Shown is the normalized mecA presence (% change to T1) during ICU-stay (T2) and after discharge (T3). Statistical evaluation (2-tailed t-test) was performed between washed and unwashed sites in each case (*p < 0.05). (W+S: Water and soap; CHX: Chlorhexidine; OCT: Octenidine)