Susceptibility of Nosocomial K. pneumoniae, P. aeruginosa, A. baumannii, and P. mirabilis Strains to a Chlorhexidine-Based Antiseptic Preparation

This study was performed to investigate activity of chlorhexidine-based antiseptic preparation «Dezin» against the following pathogens causing nosocomial respiratory tract infections (RTI) and urinary tract infections (UTI): Klebsiella pneumoniae (n=8), Pseudomonas aeruginosa (n=3), Acinetobacter baumannii (n=4) and Proteus mirabilis (n=3) isolated from patients in neurosurgery ICU in 2013, as well as reference strains of K. pneumoniae (n=1), P. aeruginosa (n=1), Escherichia coli (n=1), and Staphylococcus aureus (n=1). Antimicrobial activity of the antiseptic preparation was evaluated by microbial growth inhibition in planktonic state (microdrop) and protobiofilm-like state (cellulose patch). Distribution of tested strains by susceptibility of planktonic cells to chlorhexidine (expressed in minimal bactericidal concentration [MBC]) was the following (in order of increasing susceptibility): P. mirabilis (0.025%), P. aeruginosa (0.009%), K. pneumoniae (0.006%), A. baumannii (0.006%), E. coli (0.005%) и S. aureus (0.005%). Susceptibility of biofilmlike associations (on the surface of cellulose patches) to chlorhexidine was significantly decreased: 23 times in P. aeruginosa (MBC – 0.2%), 28 times in A. baumannii (MBC — 0.16%), 48 times in K. pneumoniae (MBC – 0.3%), 50 times in P. mirabilis (MBC — 1.3%), 128 times in E. coli (MBC — 0.6%), and 255 times in S. aureus (MBC — 1.3%). Based on the results, 1.5% chlorhexidine solution may be recommended as a measure to prevent nosocomial RTIs and UTIs in neurosurgery ICU patients.