Occurrence of Yersinia enterocolitica in Raw and Pasteurized Milk

Abstract

Raw milk (100 samples) and pasteurized milk (100 samples) were assayed for presence of Yersinia enterocolitica, using four different enrichment and post-enrichment techniques. Isolation of Y. enterocolitica was made on MacConkey agar and Cefsulodin-Irgasan-Novobiocin (CIN) agar directly from incubated broths containing the milk, and after treatment of enrichment broths with a potassium hydroxide solution. Twelve samples of raw milk and one of pasteurized milk contained Y. enterocolitica. Nearly all isolates were found after KOH treatment. All isolates except that obtained from the pasteurized milk sample produced detectable levels of heat-stable enterotoxin. However, none of the 13 isolates agglutinated in WA-SAA, an antiserum specific for virulent Y. enterocolitica.

A Turkey survey of hygiene indicator bacteria and Yersinia enterocolitica in raw milk and cheese samples

“…Epidemiological studies in food microbiology revealed that refrigerated food stored over a long period pose an additional risk, because Yersinia, as a psychrotrophic microbe, is able to grow at temperatures as low as 0°C (Hanna, Zink, Carpenter, & Vanderzant, 1976). These microorganisms have been isolated in different countries from raw milk: in Australia (Ibrahim & Mac Rae, 1991;Hughes, 1979), Canada (Schiemann, 1978), France (Vidon & Delmas, 1981), Ireland (Walker & Gilmour, 1986), Italy (Franzin, Fantino, & Vidotto, 1984) and USA (Moustafa, Ahmed, & Marth, 1983) but, the incidence of Y. enterocolitica in derived dairy products was rarely reported (Hamama, Marrakchi, & el Othmani, 1992;Schiemann, 1978). The first, food-associated outbreak of yersiniosis occurred in New York, where over 220 individuals were stricken with acute intestinal illness after consumption of contaminated milk (Black et al, 1978).…”

Bacterial quality of raw milk investigated by Escherichia coli and isolates analysis for specific virulence-gene markers

“…and Yersinia enterocolitica in farm bulk tank milk (BTM) (Lovett, Francis, & Hunt, 1987;McManus & Lanier, 1987;Moustafa, Ahmed, & Marth, 1983;O'Donnell, 1995;Rahn et al, 1997;Rohrbach, Draughon, Davidson, & Oliver, 1992;Steele et al, 1997).…”

Milk and dairy products

“…Schiemann and Toma (1978) recovered Y. enterocolitica only from 1 of 165 samples of pasteurized dairy products produced in Ontario, Canada. Similarly, Moustafa et al (1983) recovered Y. enterocolitica from 1% of pasteurized milk samples examined, while Tibana et al (1987) recovered the pathogen from 13.7% of pasteurized milk samples produced in Rio de Janeiro, Brazil. Twenty-two of the 41 isolates were capable of producing heat-stable toxin in culture media but not in sterile whole milk.…”

“…High prevalence was also reported for goat milk (Jensen and Hughes, 1980;Walker and Gilmour, 1986). However, strains of Y. enterocolitica possessing virulent characteristics, or biotypes and serovars associated with human illness, are rarely isolated from raw milk (Moustafa et al, 1983;Jayarao and Henning, 2001), although non-virulent serotypes are.…”

“…Surveys to determine the prevalence of Yersinia enterocolitica in raw milk have been conducted in many countries, including Australia, Canada, Brazil, Czechoslovakia, France, Japan, and the United States (Schiemann and Toma, 1978;Hughes, 1979;Vidon and Delmas, 1981;Delmas, 1983;Moustafa et al, 1983). Prevalence varied between 10% and 81.4%.…”