Increasing usage of chlorhexidine in health care settings: blessing or curse? A narrative review of the risk of chlorhexidine resistance and the implications for infection prevention and control.

Chlorhexidine digluconate (CHG) is an antiseptic frequently used in hospitals to prevent healthcare-related infections. It is used in different formulations for skin antisepsis, oral care, patient bathing, and hand hygiene. Also, CHG impregnated vascular catheters and wound dressings contribute to increased exposure of hospital germs to this biocide. In the last decade, concerns are rising about decreasing susceptibility of microorganisms to CHG and its potential cross-resistance with antibiotics. This study reviewed the published data regarding the evidence of reduced CHG susceptibility, the cross-resistance with antibiotics, and the implications for infection control for S. aureus, coagulase-negative staphylococci, E. coli, K. pneumoniae, and P. aeruginosa. Despite incongruity in definitions of "resistance," increased CHG minimal inhibitory values of these pathogens have been described, and different mutations encoding for CHG efflux pumps have been identified. Clinical relevance of species with reduced susceptibility to CHG is debatable and cross-resistance with antibiotics remains controversial. However, some studies link the increased usage of CHG to multidrug resistance, and the potential cross-resistance with colistin for K. pneumoniae is of major concern. More research in this matter is necessary. For infection control, it is advisable to use CHG applications only for indications with a clear patient benefit. It is important to follow manufacturer's instructions, and exposure of microorganisms to sub-lethal CHG concentrations should be avoided.