Drug resistant hospital bugs also learning to beat disinfectant

Dangerous multi-drug-resistant bacteria are also developing immunity to hospital disinfectants and antiseptics, according to new research presented today (Wednesday, 08 September 2004) at the Society for General Microbiology’s 155th Meeting at Trinity College Dublin.

Some of the most worrying microbes around, the drug-resistant bacteria known as MRSA (methicillin-resistant Staphylococcus aureus) have been discovered in heavily disinfected hospital locations such as catheters and on the disinfectant soap dispensers used in wards.

“As with the misuse of antibiotics, if bacteria are exposed continually to small amounts of the disinfectants and antiseptics which are supposed to kill them, they will eventually develop tolerance to them,” says Karen Smith from the University of Strathclyde who carried out the study. “Any bacteria that become tolerant to these common disinfectant and cleaning agents pose a huge threat to public health.”

The scientists discovered that different bacteria and different strains of the same bacteria have different levels of resistance to disinfectants and antiseptics. The researchers have found genes in some strains of MRSA which allow the bacteria to make pumps in their cells which remove the disinfectants from the cell to avoid damage.

“This study has enormous implications for clinical practice in hospitals and surgeries,” says Karen Smith. “We will be able to provide information on the effectiveness of biocides such as disinfectants and antiseptics which are used on drug-resistant bacteria. We will go on to study whether the bacteria that have become more tolerant to biocides are also more resistant to antibiotics, and whether antibiotic-resistant bacteria are more tolerant to biocides. Our results will help guide biocide use in hospitals.”

The researchers are now moving on to focus on the mechanisms used by bacteria to develop resistance to antimicrobial agents. Any information on how bacteria become resistant could be used to develop new antiseptics and disinfectants.