Genotypic diversity of Salmonella ser. Abortusequi isolates from Argentina

Abstract

Summary Background Salmonella enterica subsp. enterica serovar Abortusequi (S. Abortusequi) is a serotype restricted to equines, which produces abortion outbreaks. Nowadays the disease is being reported in different countries including Argentina thus generating an important impact in the equine industry. Molecular characterization of the 95 kb virulence plasmid and the spvC gene of S. Abortusequi demonstrated their importance in the pathogenicity of the serotype. In the last decades, high clonality of S. Abortusequi was identified in Japan, Mongolia and Croatia. Objectives The aim of this work was to characterize S. Abortusequi isolates obtained in Argentina between 2011 and 2016 by virulence‐gene profiling and pulsed‐field gel electrophoresis. Study design Case report. Methods S. Abortusequi isolates were studied by virulence‐gene profiling and pulsed‐field gel electrophoresis. Results Four virulence profiles and nine pulsed‐field gel electrophoresis pulsotypes were identified among the 27 isolates included in the study. Different strains were found in the same outbreak and/or farm suggesting the presence of different sources of infection or mutation of isolates. Main limitations The number of related and nonrelated strains. More isolates may be necessary for a more intensive study. Conclusions Most strains presented the same virulence profile, being positive for all the studied genes except gipA and sopE1, which are involved in intestinal virulence. Only few isolates showed different results in the same outbreak or farm. Unlike other studies, our results demonstrate a considerable diversity of S. Abortusequi pulsed‐field gel electrophoresis pulsotypes, which suggests that different sources of infection may be involved within the same outbreak.

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“…Esto es particularmente importante cuando atendemos tormentas de abortos y potrillos neonatos enfermos: Chlamydia psittaci ha sido identificada como una causa de enfermedad respiratoria aguda en potrillos en Australia 4 y Salmonella enterica subsp. enterica serovar abortusequi ha re‐emergido como causa de aborto infeccioso en Argentina desde 2011 5 …”

“…This is of particular note when attending abortion storms and sick neonatal foals; Chlamydia psittaci having been identified as the cause of acute respiratory illness in foals in Australia, 4 and Salmonella enterica subsp. enterica serovar abortusequi re‐emerging as a cause of infectious abortion in Argentina since 2011 5 …”

“…enterica serovar abortusequi re-emerging as a cause of infectious abortion in Argentina since 2011. 5 Equine Influenza (EI) continues to act as one of the most important equine respiratory pathogens worldwide, but important findings from molecular characterisation of the virus that caused the 2018 Argentinian outbreak was field evidence of vaccine breakdown. Within the outbreak 61% of affected horses had received at least one dose of EI vaccine in the last 3 months and multiple amino acid changes at antigenic sites in the isolated virus, compared with vaccine strains, substantiated the potential for vaccine breakdown.…”

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“…enterica ser Abortusequi (S. Abortusequi), that manifests mainly as abortion in the mare, orchitis in stallions, and septicemia and polyarthritis in foals. It is a re-emerging disease, affecting negatively the equine production in Argentina (Bustos et al 2020).…”

“…(unpublished data), and PCR for Salmonella spp. from the vagina, placenta, and different organs of equine aborted fetuses as a fast approach for equine paratyphoid diagnosis (Bustos et al 2020).…”