2CS-CHXT Operon Signature of Chlorhexidine Tolerance among Enterococcus faecium Isolates

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Duarte, B (Author) Other; Pereira, AP (Author) Other; Freitas, AR (Author) Other; Coque, TM (Author) Other; Hammerum, AM (Author) Other; Hasman, H (Author) Other; Antunes, Patrícia (Author) FCNAUP; Peixe, L. (Author) FFUP; Novais, Carla (Author) FFUP

Journal

Title: Applied and Environmental Microbiology

Vol. 85

ISSN: 0099-2240

Publisher: American Society for Microbiology

Indexing

ISI Web of Knowledge - 7 Citations

Scopus - 7 Citations

Scientific classification

CORDIS: Health sciences

FOS: Medical and Health sciences

Other information

Authenticus ID: P-00R-BX0

DOI: 10.1128/aem.01589-19

Abstract (EN): Chlorhexidine (CHX) is a broad-spectrum antiseptic widely used in community and clinical contexts for many years that has recently acquired higher relevance in nosocomial infection control worldwide. Despite this, CHX tolerance among Enterococcus faecium bacteria, representing one of the leading agents causing nosocomial infections, has been poorly understood. This study provides new phenotypic and molecular data for better identification of CHX-tolerant E. faecium subpopulations in community and clinical contexts. The chlorhexidine MIC (MICCHX) distribution of 106 E. faecium isolates suggested the occurrence of tolerant subpopulations in diverse sources (human, animal, food, environment) and phylogenomic backgrounds (clades A1/A2/B), with predominance in Glade A1. They carried a specific variant of the 2CS-CHXT operon, identified here. It encodes glucose and amino acid-polyamine-organocation family transporters, besides the DNA-binding response regulator ChtR, with a P102H mutation previously described only in CHX-tolerant Glade A1 E. faecium, and the ChtS sensor. 2CS-CHXT seems to be associated with three regulons modulating diverse bacterial biological functions. Combined data from normal MIC distribution and 2CS-CHXT operon characterization support a tentative epidemiological cutoff (ECOFF) of 8 mg/liter to CHX, which is useful to detect tolerant E. faecium populations in future surveillance studies. The spread of tolerant E. faecium in diverse epidemiological backgrounds calls for the prudent use of CHX in multiple contexts. IMPORTANCE Chlorhexidine is one of the substances included in the World Health Organization's list of essential medicines, which comprises the safest and most effective medicines needed in global health systems. Although it has been widely applied as a disinfectant and antiseptic in health care (skin, hands, mouthwashes, eye drops) since the 1950s, its use in hospitals to prevent nosocomial infections has increased worldwide in recent years. Here, we provide a comprehensive study on chlorhexidine tolerance among strains of Enterococcus faecium, one of the leading nosocomial agents worldwide, and identify a novel 2CS-CI-IXT operon as a signature of tolerant strains occurring in diverse phylogenomic groups. Our data allowed for the proposal of a tentative epidemiological cutoff of 8 mg/liter, which is useful to detect tolerant E. faecium populations in surveillance studies in community and clinical contexts. The prediction of 2CS-CHXT regulons will also facilitate the design of future experimental studies to better uncover chlorhexidine tolerance among E. faecium bacteria.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12