Safety characterization of Yersinia enterocolitica strains isolated from raw milk in Western Algeria

Yersinia enterocolitica, an important food-borne enteric pathogen is associated with various clinical manifestations ranging from self-limited gastroenteritis to more invasive syndrome such as terminal ileitis and mesenteric lymphadenitis. The main aim of this study was to investigate the incidence of Y. enterocolitica in milk samples. For this purpose, one hundred (100) samples of raw cow’s milk were collected from the western Algeria region. Seventeen (17) isolates were obtained. All these isolates belong to Y. enterocolitica biotype 1A and were ystB positive. Heat resistance and antibiotic susceptibility of these isolates were also investigated. The heat resistance D-value (decimal reduction time) and heat sensitivity ZT values (increase in temperature leads to a ten-fold reduction of the D value) of Y. enterocolitica in BHI broth showed that D55, D60 and D65 were 1.34, 0.85 and 0.62 min, respectively. The obtained Z value was 29.98°C and antibiotic resistance profiles of 17 isolates were evaluated. All the isolates were susceptible to 13 of the 30 tested antibiotic, resistance was noted for eight different antibiotics, among are them Ampicillin and 3rd generation Cephalosporins. The presence of chromosomal ystB gene virulence and antibiotic susceptibility indicate that these isolates from raw milk are potentially able to cause human foodborne illnesses and highlights the role of milk as a transmission vehicle of potentially pathogenic Y. enterocolitica strains, with consequent risks for consumer’s health via the consumption of raw milk and derivatives.