Thermal injury of Yersinia enterocolitica

Abstract

Procedures were developed to evaluate thermal injury to three strains of Yersinia enterocolitica (serotypes 0:3, 0:8, and 0:17). Serotype 0:17 (atypical strain) was more sensitive to bile salts no. 3 (BS) and to sublethal heat treatment than the typical strains, 0:3 and 0:8. When the 0:3, 0:8, and 0:17 serotypes were thermally stressed in 0.1 M P04 buffer, pH 7.0, at 470C for 70, 60, and 12 mi, respectively, greater than 99% of the total viable cell population was injured. Injury was determined by the ability of cells to form colonies on brain heart infusion (BHI) agar, but not on Trypticase soy agar (TSA) plus 0.6% BS for serotypes 0:3 and 0:8 and TSA plus 0.16% BS for 0:17. Heat injury of serotype 0: 17 cells for 15 min in 0.1 M P04 buffer caused an approximate 1,000-fold reduction in cell numbers on selective media as compared with cells heated in pork infusion (PI), BHI broth, and 10% nonfat dry milk (NFDM). The extended lag and resuscitation period in BHI broth was 2.5 times greater for 0:17 cells injured in 0.1 M P04 than for cells injured in BHI or PI. The rate and extent of repair of Y. enterocolitica 0:17 cells in three recovery media were directly related to the heating menstruum used for injury. The use of metabolic inhibitors demonstrated that ribonucleic acid synthesis was required for repair, whereas deoxyribonucleic, cell wall, and protein synthesis were not necessary for recovery of 0:17 cells injured in 0.1 M P04 buffer, BHI, or PI. Inhibition of respiration by 2,4-dinitrophenol slowed repair only for 0:17 cells injured in 0.1 M P04 buffer, not for cells injured in PI or BHI. Yersinia enterocolitica and Y. enterocoliticalike organisms (atypical strains) have been isolated from a wide variety of foods as well as from environmental sources. In an extensive European survey, Leistner et al. (43) identified Y. enterocolitica in chicken meat, pork, and beef. Strains have been isolated from vacuum-packaged beef, lamb, and dark firm meat (pH 2 6.5) held under refrigeration (20, 26, 54), raw and pasteurized milk (32, 52), cheeses (51), mussels, ice cream, bananas, fish, ham, and sausage (41). They have also been isolated from pond and well water (11), streams, lakes (28), and drinking water (39). Only one foodborne outbreak caused by Y. enterocolitica has been documented (14), although food sources were implicated in other outbreaks (15, 29, 59). In 1976, an illness occurred among school children in Oneida County, New York (5). Chocolate milk was determined to be the common vector of transmission. Serotype 0:8 was isolated from an unopened carton of the milk and from the hospitalized children. Thirty-three children were hospitalized for suspected appendicitis, and 13 appendectomies were performed. Many treatments used in food processing and combinations of treatments may induce suble-thal damage to cells or spores (12). In addition, the production of bacterial end products such as organic acids in foods may cause sensitive bacterial cells to become stressed or injured. Therefore, unprocessed as well as pr...

Assessment of in vivo revival, growth, and pathogenicity of Escherichia coli strains after copper- and chlorine-induced injury

“…However, on extended incubation, enterotoxin levels were comparable to those produced by uninjured cultures. Somewhat similar studies on thermal injury and the process of repair in Y. enterocolitica (26), Campylobacterjejuni (24), S. aureus 3, and Salmonella typhimurium (36) have been reported. In these investigations, however, the revival process was studied in in vitro systems.…”

Efficacy of peroxy acetic acid in reducing Salmonella and Campylobacter spp. populations on chicken breast fillets

“…The lack of differences between the nonselective media (APC and TSA NA ) and the selective medium (BGS NA ) may be because of the absence of bile salts which are shown to inhibit recovery of cells from injury. Restaino et al. (1980) reported significant injury (>99%) in Yersinia enterocolitica serotypes subjected to sublethal heat injury (47°C for 70 min in 0.1 Mol phosphate buffer) in TSA containing 0.6% bile salts compared with the populations on TSA.…”

INJURY AND SURVIVAL OF AEROMONAS HYDROPHILA 7965 AND YERSINIA ENTEROCOLITICA 9610 FROM HIGH HYDROSTATIC PRESSURE

“…Sublethal injury ofA. hydrophila and Y. enterocolitica has been reported as a result of thermal treatment (Golden et al 1989;Restaino et al 1980) and exposure to preservatives (Moir and Eyles 1992;Palumbo et al 1995).…”