Efficacy of an aerosol-resistant pepsin powder used in artificial digestion for the detection of Trichinella larvae in meat.

Trichinellosis is an important worldwide foodborne zoonosis. The gold standard test to detect Trichinella spp. larvae in muscle samples of animals intended for human consumption is the artificial digestion method. Handling and dispensing of conventional pepsin powder present significant safety risks for analysts. The use of pepsin powder that is resistant to aerosolization should alleviate these safety concerns. The aim of this study was to compare the efficacy of an aerosol-resistant pepsin powder to conventional pepsin powder in the artificial digestion method. Proficiency samples of pork diaphragm containing specific numbers of viable Trichinella spiralis larvae were tested in two laboratories. The results revealed that aerosol-resistant pepsin was simple, effective and convenient to use, and showed good solubility and larval recovery that met the requirements of the European Union regulation EU 2015/1375. Overall, the efficacy of the aerosol-resistant pepsin was comparable to the conventional pepsin and safer for analysts.

Comparison of spontaneous antibiotic resistance frequency of Salmonella Typhimurium growth in glucose amended continuous culture at slow and fast dilution rates.

The objective of the study was to determine the frequency of spontaneous acquisition of resistance to select antibiotics by Salmonella Typhimurium (ST) when grown in glucose amended continuous flow culture at slow (D = 0.025 h(-1)) or fast (D = 0.27 h(-1)) dilution rates. The bacterium was grown in LB minimal medium (pH 6.25) containing no antibiotics. Upon achieving steady state, samples were plated to tryptic soy agar (TSA) alone or supplemented (per ml) with 2 and 16 microg oxytetracycline, 4 and 16 microg tetracycline, 2 and 64 microg kanamycin, and 0.25 and 2 microg enrofloxacin. Regardless of growth rate, CFU of resistant ST from the TSA containing antibiotics was less than 2 x 10(1) except for 2 microg kanamycin and 0.25 microg enrofloxacin treatments (higher than 1 x 10(9) and 4 x 10(7) CFU of resistant ST for trials 1 and 2, respectively). Frequency of recovering resistant ST from the TSA containing the higher antibiotic concentrations was less than 1 in 10(9) for all antibiotics, but was higher on the media containing 2 microg kanamycin and 0.25 microg enrofloxacin at both slow and fast growth rates. In general, minimal susceptibility differences were detected for isolates from slow and fast dilution rates.

Potential for the spread of Escherichia coli O157, Salmonella, and Campylobacter in the lairage environment at abattoirs.

Prevalences of Escherichia coli O157, Salmonella spp., and Campylobacter spp. were examined in 270 swabs taken from selected sites along the unloading-to-slaughter routes of animal movement in lairages of six commercial abattoirs, three for cattle and three for sheep. The overall prevalences of the pathogens in the respective lairage environments were compared with those for 270 swabs from the pelts of 90 lambs examined in the present study and 270 swabs from the hides of 90 cattle examined in a previous study that were slaughtered at the same abattoirs on the same days. Also, the results obtained were analyzed with the aim of identifying critical points at which animal-environment-animal transfer of the pathogens in lairages occurs. The results showed that (i) the overall prevalences of E. coli O157, Salmonella spp., and Campylobacter spp. were 27.2, 6.1, and 1.1%, respectively, in cattle lairages and 2.2, 1.1, and 5.6%, respectively, in sheep lairages; (ii) the overall prevalences of the three pathogens on cow hides (28.8, 17.7, and 0%, respectively) and sheep pelts (5.5, 7.8, and 0%, respectively) were higher than the overall prevalences in the respective lairage environments; (iii) the most frequently contaminated sites in cattle lairages were holding pen floors (50% of swabs positive for one or more pathogens), entrance gates of stun boxes (27.8% of swabs positive for one or more pathogens), and stun box floors (22.2% of swabs positive for one or more pathogens); (iv) the most frequently contaminated sites in sheep lairages were unloading ramp floors, holding pen floors, and water troughs (33.3, 22.2, and 22.2%, respectively); and (v) overall, cattle lairages and cow hides were more frequently contaminated with the pathogens than were lamb lairages and lamb pelts. Further research is needed to develop strategies for the incorporation of pathogen control in lairages into integrated microbial meat safety systems.