YERSINIA ENTEROCOLITICA IN FOOD: RELATIONSHIP BETWEEN ITS ISOLATION ON CHROMOGENIC MEDIUM AND THE IN VITRO AUTOAGGLUTINATION TEST

MASTRODONATO ANNA CHIARA; FAVIER, GABRIELA I.; DI MARCO NATALIA; LUCERO ESTRADA, CECILIA S. M.; IRIARTE HEBE; ESCUDERO, MARÍA E.

SAN LUIS

Congreso; XIII Congreso Argentino de Microbiología General SAMIGE 2018; 2018

Yersinia enterocolitica is a widely distributed enteropathogen, with pigs as major reservoirs. This microorganism is associated to intestinal, extraintestinal and immunological manifestations. Humans are infected by consuming raw or inadequately thermally processed foods, or contaminated water.This species is classified into six biotypes (B):1A, 1B, 2, 3, 4, 5 and more than 60 serotypes (O). The virulence potential of Y. enterocolitica strains depends on the presence and expression of both chromosomal and plasmid (pYV)-borne genes. The B1A strains lack pYV but has some chromosomal virulence factors. YadA is a pYV-encoded adhesin that produces autoagglutination (AA) at 37°C, and is strongly linked to adherence to host cells and resistance to the bactericidal effect of serum. On the other hand, CHROMagarTM Yersinia enterocolitica allows differentiate pathogenic and nonpathogenic strains of this species by the different color of the colonies. The objective of this work was to evaluate the correlation between results observed on CHROMagarTM and the AA test for a collection of local Y. enterocolitica strains. Seventeen isolates of Y. enterocolitica were obtained by standard culture techniques from various foods purchased in retail stores of San Luis city, and identified by classicalbiochemical tests and Gram stain. Subsequently, the strains were cultured on CHROMagarTM at 30°C for 24 h and discriminated into pathogenic (1B, 2, 3, 4 or 5) and non-pathogenic (1A) isolates; moreover, AA test in trypticase soy broth (TSB) with incubation at 25 and 37°C for 24 h, was performed for each strain. The AA results showed that 35% (6/17) of the isolates were pYV+ carriers and there was a 100% correlation between CHROMagarTM and AA test. Our findings show that the isolation of Y. enterocolitica strains on chromogenic medium carried out simultaneously with a simple virulence indicator test as AA, might contribute to the presumptive differentiation of virulence plasmid-bearing and non-bearing Y. enterocolitica isolates.