Molecular Epidemiology and Virulence of Non-Typhoidal Salmonella in Armenia

Abstract

In this work, we analysed human isolates of nontyphoidal Salmonella enterica subsp. enterica (NTS), which were collected from salmonellosis cases in Armenia from 1996 to 2019. This disease became a leading food-borne bacterial infection in the region, with the younger age groups especially affected. The isolates were characterised by serotyping, Enterobacterial Repetitive Intergenic Consensus (ERIC-PCR) typing, and whole genome sequencing (WGS). The main serotypes were S. Typhimurium, S. Enteritidis, and S. Arizonae. ERIC-PCR indicated a high degree of clonality among S. Typhimurium strains, which were also multidrug-resistant and produced extended spectrum beta-lactamases. During the study period, the frequency of S. Typhimurium and S. Arizonae isolations decreased, but with the increase in S. Enteritidis and other NTS. A total of 42 NTS isolates were subjected to WGS and explored for virulence-related traits and the corresponding genetic elements. Some virulence and genetic factors were shared by all NTS serotypes, while the main differences were attributed to the serotype-specific diversity of virulence genes, SPIs, virulence plasmids, and phages. The results indicated the variability and dynamics in the epidemiology of salmonellosis and a high virulence potential of human NTS isolates circulating in the region.

Plasmid Profiling in Extended Spectrum β-Lactamase-Producing Human Isolates of Non-Typhoidal Salmonella

“…It was shown that bla CTX-M-5 gene is predominantly located on plasmids, small non-self-transferable or conjugative [3,5,6]. In our previous work, we demonstrated the high prevalence of in silico predicted plasmids (pCTXM5-1358 and pCTXM5-637) in bla CTX-M-5 -positive human S. Typhimurium ST328 isolates from Armenia [2]. Of note, these mobilizable plasmids have been associated with the clonal distribution of multidrug-resistant S. Typhimurium ST328 isolates in several FSU countries [6].…”

“…Of note, these mobilizable plasmids have been associated with the clonal distribution of multidrug-resistant S. Typhimurium ST328 isolates in several FSU countries [6]. Our previous work established a high degree of clonality among the human ESBL-producing S. Typhimurium isolates that have been circulating in Armenia for two decades [7]. In this study we explored the plasmid profile of human ESBL-producing S. Typhimurium isolates, presence of plasmid-encoded ESBL genes of bla CTX-M-2 phylogroup in these isolates, as well as assessed the frequency of plasmidmediated transfer of ESBL-producer phenotype.…”

“…Previously, we reported the high prevalence of ESBL-producer phenotype among Salmonella enterica subsp. enterica serovar Typhimurium (hereinafter referred to as S. Typhimurium) isolates collected from patients in Armenia between 1996 and 2016 [2]. Based on whole genome sequencing (WGS) data, we identified the presence of bla CTX-M-5 gene in human S. Typhimurium ST328 isolates displaying ESBLproducer phenotype and suggested that this phenotype is associated with plasmid-encoded CTX-M-5 production [2].…”

“…enterica serovar Typhimurium (hereinafter referred to as S. Typhimurium) isolates collected from patients in Armenia between 1996 and 2016 [2]. Based on whole genome sequencing (WGS) data, we identified the presence of bla CTX-M-5 gene in human S. Typhimurium ST328 isolates displaying ESBLproducer phenotype and suggested that this phenotype is associated with plasmid-encoded CTX-M-5 production [2]. The CTX-M-5 is a β-lactamase of bla CTX-M-2 phylogroup, which preferentially hydrolyses cefotaxime over ceftazidime and which is efficiently inhibited by clavulanic acid, tazobactam, and sulbactam [3,4].…”

“…A total of 42 human MDR S. Typhimurium isolates were tested for the phenotypic detection of ESBL-producers. Among these, 37 isolates from 1996-2014 were tested retrospectively to confirm the presence of ESBL-producer phenotype identified earlier [2], while 5 isolates from 2017 and 2019 were tested for the first time. The results indicated that there was no ESBL-producing isolates among the clinical S. Typhimurium isolates from 2017 and 2019.…”