Brote de gastroenteritis en una guardería causado por una cepa de Salmonella enterica serovar Typhimurium portadora del plásmido híbrido de resistencia-virulencia pUO-StVR2
Epidemiological and microbiological study of a salmonellosis outbreak, affecting 22 children in a nursery school in Oviedo (Spain).
Attack rates and epidemic curves were determined, and bacterial typing methods were applied.
The outbreak was attributed to a Salmonella enterica serovar Typhimurium strain, belonging to an emergent type characterized by the presence of a hybrid virulence-resistance plasmid of 125-130 kb, named pUO-StVR2. The attack rate of confirmed cases vs.
possible cases was 27.2% vs. 23.5% for the children and 0 vs. 26.5% for the staff of the affected center. The source of the infection could not be identified. Nevertheless, according to the evolution of the cases over time, the transmission route was likely to be personal contact between the staff and children, which facilitates fecal-oral dissemination. All but one of the 27 isolates analyzed (from 22 patients) showed identical features: R-profile, plasmid-profile, RAPD-type, PFGE-type; all were non-phage-typeable, with the exception of a DT104b isolate. pUO-StVR2 is probably a derivative of the virulence plasmid pSLT from the LT2 type strain that acquired an R-region complex (ACSSuT/blaOXA-catA1-strA/B-aadA1-sul1-sul2-tet[B]), in which the blaOXA-aadA1 genes are part of the variable region of a class 1 integron.
This outbreak is an example of how a Salmonella enterica serovar Typhimurium strain belonging to a type that is probably endemic in Spain can be transferred to the community and affect a susceptible population.
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ABSTRACT: During a screening of Salmonella enterica in foods of animal origin four isolates of serovar Typhimurium carrying hybrid virulence-resistance plasmids were detected. Three of them, one from pork and two from chicken meat, contained pUO-StVR2, a derivative of the pSLT virulence plasmid with the blaOXA-1, catA1, aadA1, sulI and tet(B) genes, which confer resistance to ampicillin, chloramphenicol, streptomycin-spectinomycin, sulfonamides and tetracycline, respectively. The fourth isolate, from pork, harbored a pUO-StVR2 variant (termed ν8) with an additional dfrA10 gene responsible for resistance to trimethoprim. This gene is part of the orf513-dfrA10-qacEΔ1-sul1 element characteristically found in complex class 1 integrons. Pulsed-field gel electrophoresis identified two XbaI-BlnI combined profiles: X2-B2 generated from the three pUO-StVR2 isolates, and X12-B17 shown by the pUO-StVR2-ν8 isolate. The same profiles have also been found in clinical and ill pig isolates, supporting chicken and pork meat as vehicles for transmission of Typhimurium carrying pUO-StVR2-like plasmids.Food Research International 03/2012; 45(2). DOI:10.1016/j.foodres.2011.04.014 · 2.82 Impact Factor
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ABSTRACT: Five variants of a resistant derivative of pSLT (termed pUO-StVR2) were detected in clinical isolates of Salmonella enterica serovar Typhimurium recovered in Spain. The structure of these variants revealed the involvement of IS1, IS26 and Tn21-like transposition, as well as homologous recombination in the generation of deletions, inversions and insertions which, depending on the variant, affected an orf of unknown function, genes encoding a possible iron acquisition system, and/or resistance properties. These variants, which appeared at a relatively low frequency, can be used as a model to understand the co-selection mechanisms which are helping to maintain multidrug resistance in bacterial pathogens, despite the structural instability of the responsible DNA.Infection Genetics and Evolution 01/2015; 29:99-102. DOI:10.1016/j.meegid.2014.11.010 · 3.02 Impact Factor