Mechanisms of Tolerance and Resistance to Chlorhexidine in Clinical Strains of Klebsiella pneumoniae Producers of Carbapenemase: Role of New Type II Toxin-Antitoxin System, PemIK

• Published in: Toxins Vol. 12; no. 9; p. 566
• Main Authors: Bleriot, Ines, Blasco, Lucia, Delgado-Valverde, Mercedes, Gual-de-Torrella, Ana, Ambroa, Anton, Fernandez-Garcia, Laura, Lopez, Maria, Oteo-Iglesias, Jesus, Wood, Thomas K, Pascual, Alvaro, Bou, German, Fernandez-Cuenca, Felipe, Tomas, Maria
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 02.09.2020; MDPI
• Subjects: Anti-Infective Agents, Local - pharmacology; Antibiotics; Antimicrobial agents; Antitoxins; Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; beta-Lactamases - genetics; beta-Lactamases - metabolism; Biocides; Biofilms; Carbapenemase; Chlorhexidine; Chlorhexidine - pharmacology; Cloning; Colistin; Cross-resistance; Defense mechanisms; Drug Combinations; Drug resistance; Drug Resistance, Bacterial - genetics; Genes; Hospitals; Imipenem; Imipenem - pharmacology; Infections; Klebsiella; Klebsiella pneumoniae; Klebsiella pneumoniae - drug effects; Klebsiella pneumoniae - enzymology; Klebsiella pneumoniae - genetics; Klebsiella pneumoniae - growth & development; Metabolism; Molecular modelling; Nosocomial infection; Pathogens; PemI/PemK; persistence; Plasmids; Population; Time Factors; tolerance; toxin-antitoxin system; Toxin-Antitoxin Systems - genetics; Toxins; Toxins and antitoxins; β Lactamase; toxin-antitoxin system; persistence; cross-resistance; Klebsiella pneumoniae; tolerance; PemI/PemK
• ISSN: 2072-6651; 2072-6651
• DOI: 10.3390/toxins12090566

Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that the ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under chlorhexidine (CHLX) pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemI/PemK. We characterized this PemI/PemK TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).