Category Archives: Salmonella

Journal of Food Protection

During the early stages of aerobic composting, heat is generated and when the materials are self-insulating, extended exposure of pathogens to this heat source will lead to significant reduction, if not elimination, of the pathogens. However, when insufficient heat is applied to the composting materials, pathogens may survive. Under those conditions if the compost had contained material of animal origin or food waste, it would be considered untreated and would not be allowed in fields growing crops that may be consumed raw. However, alternative treatment processes are allowed, provided they are validated to meet the microbial standards stipulated in the Produce Safety final rule of the Food Safety Modernization Act and that the physical parameters of the process are documented to ensure that the conditions under which the process was validated have been met. Hence, this exploratory study was undertaken in a laboratory setting to determine the potential for application of aerosolized smoke to inactivate Salmonella in manure-based compost. Smoke generated from wood chips (oak or pecan) and introduced to the headspace of contaminated cow manure compost (≤3 log CFU/g) in sealed containers (35 g per container) resulted in no Salmonella detected by enrichment culture in 100% (0 of 14) of the samples after 18 to 48 h of exposure, whereas Salmonella in control samples remained at initial levels over the same time period. Shorter exposure times (6 h) to the smoke aerosols were less effective (11 of 24 samples positive by enrichment culture), and additional flushes with the wood smoke during this time failed to decrease the prevalence of contamination. Smoke aerosols generated from waste agricultural materials and held in containers with Salmonella-contaminated compost for 18 h significantly reduced the prevalence of the pathogen in samples compared with control samples (P < 0.05). The odds of not finding Salmonella in smoke-exposed compost were 14 (pine needles and rice hulls), 23 (cocoa hulls, orange rind, and peanut hulls), and 28 (sunflower hulls) times greater compared with samples not exposed to smoke. Many other variables remain to be examined (e.g., compost composition, compost maturity, and anaerobic conditions) to determine whether this approach could be universally applied to manure-based compost. Validation under field conditions will be required and may entail use of this approach in combination with suboptimal thermal conditions (<55°C).

Journal of Food Protection

Beef and veal products have been vehicles implicated in the transmission of Salmonella enterica, a gastroenteritis-causing bacteria. Recent regulatory samples collected from veal have indicated bob veal, or calves harvested within days of birth, have higher rates of Salmonella than samples collected from formula-fed veal, or calves raised 20 weeks on milk replacer formula before harvest. To investigate this problem, we collected samples from veal calf hides, preevisceration carcasses, and final carcasses at five veal processors that harvested bob or formula-fed veal or both. Prevalence and concentrations of Salmonellawere determined, and then the isolates were characterized for serovar and antibiotic susceptibility. Salmonella was more prevalent (P < 0.05) among bob veal than formula-fed veal hides, preevisceration carcasses, and final carcass (84.2 versus 15.6%, 62.8 versus 10.1%, and 12.0 versus 0.4%, respectively). Concentrations of Salmonella could be estimated by using regression order statistics on hides and preevisceration carcasses at two veal plants, with one harvesting bob veal and the other bob and formula-fed veal. The concentration of Salmonella on bob veal hides at the plants was 1.45 ± 0.70 and 2.04 ± 1.00 log CFU/100 cm², greater (P < 0.05) than on formula-fed veal hides, which was 1.10 ± 1.51 log CFU/100 cm². Concentrations on carcasses, however, were very low. Seventeen Salmonella serovars were identified among 710 isolates. Salmonella serovars London, Cerro, and Muenster were most common to bob veal and made up 50.7, 18.7, and 6.3% of the isolates, respectively, while serovar Montevideo (6.8% of isolates) was most common to formula-fed veal. Although bob veal had increased prevalence and concentrations of Salmonella, one group of formula-fed veal was found to harbor human disease–related antibiotic-resistant Salmonella serovars Heidelberg and the monophasic variant of Typhimurium (1,4,[5],12:i:−). Veal processors have made changes to improve the safety of veal, but further efforts are necessary from both bob and formula-fed veal to address Salmonella.

The Poultry Site

Dirty chick boxes at hatcheries can be a source of Salmonella, but the risk was still lower than expected in a study conducted at one US hatchery, according to Kathryn McCullough, a DVM candidate at North Carolina State University.

McCullough’s study was aimed at pinpointing where hatcheries need to focus their Salmonella-control efforts to prevent contamination of chicks with the pathogen.

“All of your breeder flocks are sending their eggs to the hatchery, and then those chicks hatching out are being disseminated… through the entire complex for that area. So, any disease measures that you can get under control at the hatchery are really going to have the biggest impact for that complex,” she told Poultry Health Today.

For the study, McCullough used boot swabs to sample chick boxes at a hatchery. Chicks were placed in clean boxes – boxes that were washed and dried – 2 days a week. Due to the hatchery’s schedule, however, dirty but dry boxes were used 2 other days because there wasn’t time to thoroughly wash and dry them.