Phenotypic and molecular characterization of blaCTX-M-3 and blaCTX-M-55-producing monophasic Salmonella enterica serovar Typhimurium in Greece

Efthymia Protonotariou; Georgios Meletis; Theofilos Papadopoulos; Georgia Kagkalou; Areti Tychala; Marie Anne Chattaway; Georgia Mandilara; Satheesh Nair; Lemonia Skoura

doi:10.1016/j.jgar.2022.05.017

Phenotypic and molecular characterization of blaCTX-M-3 and blaCTX-M-55_-producing monophasic Salmonella enterica serovar Typhimurium in Greece

J Glob Antimicrob Resist. 2022 Sep:30:75-80. doi: 10.1016/j.jgar.2022.05.017. Epub 2022 May 28.

Authors

Efthymia Protonotariou¹, Georgios Meletis², Theofilos Papadopoulos³, Georgia Kagkalou², Areti Tychala², Marie Anne Chattaway⁴, Georgia Mandilara⁵, Satheesh Nair⁴, Lemonia Skoura⁶

Affiliations

¹ School of Medicine, Aristotle University of Thessaloniki; Department of Microbiology, AHEPA University Hospital, Thessaloniki, Greece. Electronic address: protonotariou@auth.gr.
² Department of Microbiology, AHEPA University Hospital, Thessaloniki, Greece.
³ Department of Microbiology and Infectious Diseases, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University, Thessaloniki, Greece.
⁴ Gastrointestinal Bacteria Reference Unit, National Infection Service, Public Health England, London, United Kingdom.
⁵ National Reference Centre for Salmonella, Faculty of Public Health Policies, School of Public Health, University of West Attica, Athens, Greece.
⁶ School of Medicine, Aristotle University of Thessaloniki; Department of Microbiology, AHEPA University Hospital, Thessaloniki, Greece.

PMID: 35640867
DOI: 10.1016/j.jgar.2022.05.017

Abstract

Objectives: To characterize three Salmonella enterica serovar Typhimurium strains using whole genome sequencing (WGS) and conventional methods. The isolates were recovered from three pediatric patients in Greece as part of the hospital's epidemiological surveillance system during 2016 to 2018.

Methods: Bacterial identification and antimicrobial susceptibility testing was performed using the VITEK 2 automated system, disc diffusion test, and MIC gradient test while serotyping by the slide agglutination method. Detection of resistance genes, eBurst groups (eBG), assignment to sequence types, single nucleotide polymorphism (SNP) typing, location and characterization of drug resistance regions, and in silico plasmid detection were carried out using WGS.

Results: All strains were identified as S. Typhimurium-monophasic, ST34, eBG1 with antigenic formula 1,4, [5], 12:i:-. They were phenotypically resistant to most antibiotics tested except piperacillin/tazobactam, imipenem, and co-trimoxazole. WGS revealed the chromosomally located genes encoding the ASSuT (ampicillin, streptomycin, sulfonamides, and tetracycline) resistant pattern in all three strains. WGS revealed extended spectrum ß-lactamase (ESBL) production in all three strains, the presence of blaCTX-M-3 on an IncI1 plasmid in two strains isolated in 2018, and the chromosomally encoded blaCTX-M-55 plus qnrS1 (resistance to ciprofloxacin) in the strain isolated in 2016. The two strains from 2018 were isolated from the same hospital ward and were genetically related.

Conclusions: The emergence of ESBL among S. 1,4,[5], 12:i:- is worrisome due to its increasing antimicrobial resistance phenotype, making clinical treatment difficult. WGS provides an alternative to traditional methods of identification and genomic characterisation of strains, and serves to better understand their epidemiological dynamics and bacterial pathogenesis.

Keywords: Antimicrobial resistance; CTX-M; Cefotaximases; ESBL; Monophasic Salmonella enterica serovar Typhimurium.

MeSH terms

Anti-Bacterial Agents* / pharmacology
Anti-Bacterial Agents* / therapeutic use
Drug Resistance, Bacterial* / genetics
Greece
Humans
Microbial Sensitivity Tests
Phenotype
Salmonella Infections* / microbiology
Salmonella typhimurium* / drug effects
Salmonella typhimurium* / genetics
Serogroup
beta-Lactamases* / genetics

Substances

Anti-Bacterial Agents
beta-Lactamases