Yersinia enterocolitica IN FOOD: RELATIONSHIP BETWEEN ITS ISOLATION ON CHROMOGENIC MEDIUM AND THE In Vitro AUTOAGGLUTINATION TEST

MARÍA ESTHER ESCUDERO; HEBE IRIARTE; GABRIELA FAVIER; ANNA CHIARA MASTRODONATO; CECILIA LUCERO ESTRADA; DI MARCO NATALIA

San Luis

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

Asociación Argentina de Microbiología General

Yersinia enterocolitica is a widely distributed enteropathogen, with pigs as major reservoirs. Thismicroorganism is associated to intestinal, extraintestinal and immunological manifestations. Humansare 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). Thevirulence potential of Y. enterocolitica strains depends on the presence and expression of bothchromosomal and plasmid (pYV)-borne genes. The B1A strains lack pYV but has some chromosomalvirulence factors. YadA is a pYV-encoded adhesin that produces autoagglutination (AA) at 37°C, andis strongly linked to adherence to host cells and resistance to the bactericidal effect of serum. On theother hand, CHROMagarTM Yersinia enterocolitica allows differentiate pathogenic and nonpathogenicstrains of this species by the different color of the colonies. The objective of this work was to evaluatethe correlation between results observed on CHROMagarTM and the AA test for a collection of localY. enterocolitica strains. Seventeen isolates of Y. enterocolitica were obtained by standard culturetechniques 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 at30°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, wasperformed for each strain. The AA results showed that 35% (6/17) of the isolates were pYV+ carriersand there was a 100% correlation between CHROMagarTM and AA test. Our findings show that theisolation of Y. enterocolitica strains on chromogenic medium carried out simultaneously with a simplevirulence indicator test as AA, might contribute to the presumptive differentiation of virulenceplasmid-bearing and non-bearing Y. enterocolitica isolates.