Mechanisms of Tolerance and Resistance to Chlorhexidine in Clinical Strains of <i>Klebsiella pneumoniae</i> Producers of Carbapenemase: Role of New Type II Toxin-Antitoxin System, PemIK
Ines Bleriot,
Lucia Blasco,
Mercedes Delgado-Valverde,
Ana Gual-de-Torrella,
Anton Ambroa,
Laura Fernandez-Garcia,
Maria Lopez,
Jesus Oteo-Iglesias,
Thomas K. Wood,
Alvaro Pascual,
German Bou,
Felipe Fernandez-Cuenca,
Maria Tomas
Affiliations
Ines Bleriot
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Lucia Blasco
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Mercedes Delgado-Valverde
Clinical Unit for Infectious Diseases, Department of Microbiology and Medicine, Microbiology and Preventive Medicine, Hospital Universitario Virgen Macarena, University of Seville, Biomedicine Insititute of Seville (IBIS), 41009 Seville, Spain
Ana Gual-de-Torrella
Clinical Unit for Infectious Diseases, Department of Microbiology and Medicine, Microbiology and Preventive Medicine, Hospital Universitario Virgen Macarena, University of Seville, Biomedicine Insititute of Seville (IBIS), 41009 Seville, Spain
Anton Ambroa
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Laura Fernandez-Garcia
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Maria Lopez
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Jesus Oteo-Iglesias
Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA) the Behalf of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), 28003 Madrid, Spain
Thomas K. Wood
Department of Chemical Engineering, Pennsylvania State University, University Park, PA 16801, USA
Alvaro Pascual
Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA) the Behalf of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), 28003 Madrid, Spain
German Bou
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
Felipe Fernandez-Cuenca
Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA) the Behalf of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), 28003 Madrid, Spain
Maria Tomas
Microbiology Department-Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), 15006 A Coruña, Spain
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 Klebsiella pneumoniae 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 K. pneumoniae 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).
