Examples of foodborne outbreaks traced to fresh fruits and vegetables can be found worldwide. The quantity of produce eaten per capita has been increasing steadily over the past two decades, creating a heightened potential for produce-related foodborne disease. A number of outbreaks identified during this time period were reviewed, with particular emphasis placed on incidents that have occurred in Canada. The collective information highlights the diversity of infectious agents and produce items involved, with a view to the prevention of fresh produce-related foodborne disease in the future.

The occurrence of Salmonella spp. in red-eared (Pseudemys scripta elegans) turtle eggs imported into Canada from Louisiana in June to September 1988 was examined. Of 28 lots tested, six (21%) lots from three of four exporters harbored salmonellae. Salmonella poona and Salmonella arizonae were frequently encountered in both fertile eggs and packaging moss. Turtles hatched in our laboratory from affected lots of eggs shed Salmonella in tank water for up to 11 months. Widespread use of gentamicin on turtle farms to produce Salmonella-free eggs for export apparently encouraged development of antibiotic resistance in bacterial strains. Of 37 Salmonella strains isolated in this study, 30 (81%) were gentamicin resistant. Such high levels of antibiotic-resistant salmonellae in turtle eggs pose a serious human health risk. Further marketing of turtle eggs and hatchlings should be curtailed until consistent production and distribution of Salmonella-free stocks can be assured.

A total of 689 Salmonella cultures isolated during 1986–1989 from Canadian agricultural products and from imported fish, shellfish, and reptiles were examined for resistance to a test panel of 11 antibiotics. The incidence of antibiotic resistance in strains from all sources seemingly increased during the study period, whereas the occurrence of resistance within individual sample categories fluctuated annually. Although poultry figured as a major reservoir of resistant salmonellae (53.4%), red meats and fish/shellfish also yielded substantial numbers of resistant strains. The range of streptomycin (27.1 to 48.7%) and tetracycline (24.3 to 37.8%) resistance among poultry and red meat isolates, and identification of meat isolates carrying chloramphenicol (0.4 to 9.1%) and ampicillin (3.4 to 11.4%) resistance codons was disquieting. Most of the multiply-resistant (≥ 2 antibiotics) strains belonged to somatic serogroups B and C, with poultry occurring as the principal reservoir of multiresistant phenotypes. Of the 27 resistance patterns encountered in this study, all but two contained a resistance determinant for streptomycin and/or tetracycline. These findings underscore a disturbing level of antibiotic resistant Salmonella in the food chain, and the need to reassess the alleged benefits of subtherapeutically medicated feeds in current animal husbandry practices.

Levels of Salmonella typhimurium phage-type 10 in Cheddar cheese implicated in a major Canadian foodborne outbreak ranged from 0.36 to 9.3 salmonellae/100 g. Such a low level contamination likely accounted for the uneven distribution of the organism among subsamples of individual lots. Coliform and Escherichia coli counts were within acceptable limits, whereas three of the 11 lots tested contained ≥105 Staphylococcus aureus per gram but no staphylococcal enterotoxins. Campylobacter and Yersinia spp. were not detected in any of the 12 lots examined. Ability of S. typhimurium to survive up to 8 months in Cheddar cheese stored at refrigerator temperature (5°C) underlines the inadequacy of current regulations requiring a 60-d storage of cheese manufactured from heat-treated (unpasteurized) milk before sale. Results underlined the greater sensitivity of selective enrichment in tetrathionate brilliant green (43°C) than in selenite cystine (35°C) for detection of Salmonella in cheese.

The prevalence of microwave ovens in North American homes has increased dramatically within the last decade. Although microwave ovens are primarily used for reheating of foods, they are now more commonly being applied to the cooking of raw foods. Although cooking of raw foods, according to manufacturers' instructions targets an organoleptically acceptable end product, the process does not address the microbiological safety of the cooked food. Seventeen microwave ovens from various commercial suppliers were used to cook naturally contaminated whole raw broilers (< or = 1.8 kg) and roasters (> 1.8 kg) according to manufacturers' instructions. Temperature probes (six per chicken) were used to measure the temperature of chickens immediately after cooking and during the holding period. Of 81 Listeria-positive raw broilers and 93 raw roasters, 1 (1.2%) and 9 (9.7%), respectively, yielded viable Listeria spp. after microwave cooking. Of these, two were undercooked (visual inspection), one was over the maximum weight stipulated by the oven manufacturer and another one was over the maximum weight and undercooked. A significantly greater proportion of contaminated cooked birds was observed with roasters than with broilers, where for one of these contaminated roasters, the temperature at all six measured sites was > or = 87 degrees C. Most of the postcook Listeria-positive birds were associated with 2 of the 17 microwave ovens. Factors such as wattage, cavity size, and the presence or absence of a turntable seemingly did not play a significant role in the survival of Listeria spp. in microwave-cooked chicken. However, the general inability of microwave ovens to uniformly heat chicken carcasses was noted. In order to promote greater safety of microwave-cooked foods, general recommendations for consumers are provided.