Study Links Antibiotic Resistance to Exposure to Chlorhexidine Disinfectants

K. pneumoniae bacteria can become resistant to colistin

Klebsiella pneumoniae bacteria exposed to chlorhexidine-containing disinfectants can become resistant to colistin, a last-resort antibiotic often used against multidrug-resistant pathogens, according to a study published in Antimicrobial Agents and Chemotherapy.

In the study, investigators tested the hypothesis that K. pneumoniae could survive exposure to increased concentrations of chlorhexidine, and that these exposures might cause resistance to commonly used antibiotics. They selected specific strains of K. pneumoniae that were representative of isolates routinely found in the clinic.

Chlorhexidine is a common ingredient in several disinfectants used widely in the home and in health care settings, where it is a critical part of many infection-control practices.

While some K. pneumoniae strains died on exposure, others were able to survive at much higher concentrations of chlorhexidine than their parental strains. Some also gained resistance to colistin. The investigators found gene mutations in the exposed K. pneumoniae that conferred resistance to both compounds.

“Chlorhexidine is a critical part of current infection-control practices, and the development of increased resistance to this compound has potential implications for our ability to prevent infections during routine and emergency surgery, and during admission to hospitals,” said coauthor J. Mark Sutton, PhD, scientific leader at the National Infections Service, Public Health England in Salisbury, U.K.

The study data suggest that many bacterial pathogens may share the same or similar metabolic pathways. Specific selective pressures from antiseptics, such as chlorhexidine, may result in similar mutations in these pathways, conferring increased resistance in these different species of bacteria.

“If the same response is seen in hospitals, this might mean that we need to rethink how and where some types of critical disinfectants or antiseptics are used in the clinic,” Sutton said.

Sources: ASM; October 31, 2016; and AAC; October 31, 2016.