Culture and nested PCR in the detection of pathogenic Yersinia enterocolitica strains from goat?s cheese

LAZARTE VALERIA S; LUCERO ESTRADA CECILIA STELLA MARYS; FAVIER GABRIELA ISABEL; ESCUDERO MARÍA ESTHER; VELÁZQUEZ LIDIA DEL CARMEN; STEFANINI DE GUZMÁN ANA MARÍA

San Luis

Jornada; XXIV Reunión Científica Anual de la Sociedad de Biología de Cuyo. IV reunión Científica de la Sociedad Argentina de Microscopía (SAMIC).; 2006

Sociedad de Biología de Cuyo

Cheese can be cause of food borne infections due to inadequate hygienic practices in its manipulation. The sensitivity of culture techniques and PCR for detecting pathogenic Yersinia enterocolitica strains in artificially contaminated goat´s cheese was assessed. Samples of 0.25 g each were placed in 225 ml of trypticase soy broth, modified Rappaport broth and a nutrient formula developed in our laboratory (3 samples per broth). They were inoculated with each one of three virulence plasmid - bearing Y enterocolitica strains: W 10240:9 (Belgium, reference strain). B2 0:9 (local origin, eggshell) and B3 0:3 (local origin, clinical sample), at 1 x 10e4 cfu/g (high inoculum. HI) and 1x 1Oe3 cfu/g (low inoculum, LI), and cultured at 25°C. At 0, 3 and 18 h, aliquots were withdrawn for counts on trypticase soy and Mac Conkey or cefsulodin-irgasan-novobiocin agars and for nested PCR directed to yadA gene. At time 0, Y. enterocolitica was detected in HI and LI samples by PCR. After 3 h, seven HI samples were positive by PCR and two of them showed characteristic colonics. Five LI samples were also positive by PCR. At 18 h, results were positive by both methods. Pathogenic and proteolytic bacteria were not detected in natural microflora.