In-use contamination of a hospital-grade disinfectant

• Published in: American journal of infection control 2022-12, Vol.50 (12), p.1296-1301
• Main Authors: Boyce, John M., Havill, Nancy L.
• Format: Article
• Language: English
• Subjects: Disinfectant contamination; Disinfectants; Disinfectants - pharmacology; Disinfection; Drug Contamination; Genome sequencing; Hospitals; Humans; Quaternary ammonium compounds; Quaternary ammonium resistance; Serratia marcescens; Serratia marcescens - genetics
• ISSN: 0196-6553; 1527-3296
• DOI: 10.1016/j.ajic.2022.03.008

•An investigation documented contamination of an in-use hospital-grade disinfectant.•The disinfectant contained 9.3 × 104 CFU of S. marcescens and A. xylosoxidans.•Serratia was 102-fold less sensitive to fresh disinfectant than a control strain.•Whole genome sequencing of Serratia revealed sdeXY, sdeAB, smfY and sugE-like genes.•Contamination was due to failure to follow recommended disinfection protocols. Microbiological monitoring of disinfection of high-touch surfaces identified heavy growth of Serratia marcescens and Achromobacter xylosoxidans not present on surfaces before disinfection, suggesting contamination of the disinfectant used. An investigation included interview of the housekeeper involved, level of bacterial contamination of the in-use quaternary ammonium (Quat) disinfectant, bactericidal activity of the contaminated disinfectant, pulsed field gel electrophoresis of S.marcescens and Achromobacter isolates, survival of S. marcescens on dry surfaces, and genome sequencing to identify possible Quat resistance genes. The housekeeper, who seldom cleaned patient rooms, had used the disinfectant for months without emptying and drying the bucket between uses. The contaminated disinfectant contained 9.3 × 104 CFU of S. marcescens plus A. xylosoxidans. The log10 reduction of S. marcescens by fresh Quat was 102-fold lower than that achieved against a control strain (S. marcescens ATCC 13380). Genome sequencing of S. marcescens isolates identified the following genes previously shown to encode for efflux pumps associated with Quat resistance: sdeXY, sdeAB, smfY, and a sugE-like gene. Failure to follow existing guidelines and manufacturer's instructions for use resulted in contamination by A. xylosoxidans and by S. marcescens that possessed multiple genes associated with Quat resistance.