Influence of whole-body washing of critically ill patients with chlorhexidine on Acinetobacter baumannii isolates

Background Acinetobacter baumannii is 1 of the most important nosocomial pathogens and the causative agent of numerous types of infections, especially in intensive care units (ICUs). Our aim was to evaluate the effect of 2% chlorhexidine gluconate (CHG) whole-body washing of ICU patients on A baumannii in a tertiary care hospital. Methods During the 6-month intervention period, 327 patients were subjected to whole-body bath with 2% CHG-impregnated wipes. bla _IMP (active on imipenem), bla _VIM (Verona integron-encoded metallo-ß-lactamase), and bla _oxacillinase (OXA) of A baumannii were typed. Isolates were genotyped by pulsed-field gel electrophoresis. Minimum inhibitory concentrations (MIC) to CHG were determined by the agar dilution method and drug susceptibility determined using the broth microdilution method. Biofilm formation was determined by crystal violet staining. Results We analyzed 80 isolates during the baseline period and 69 isolates during the intervention period. There was a decrease in the MIC ₅₀ and MIC ₉₀ values for CHG for isolates (8 mg/L and 16 mg/L, respectively). All isolates typed positive for OXA _51-like and 86% typed positive for OXA _24-like pulsed-field gel electrophoresis identified 2 main clone types. During the intervention period the frequency of clone A decreased and that of clone B increased. Both clones were OXA _24-like positive. Conclusions The A baumannii isolates recovered from patients who received body washing with 2% CHG presented with a significant decrease in CHG MIC values associated with a change in clonality correlating with increased biofilm production.