Robert H. Madden

A 1-year study was undertaken to determine the prevalence of Arcobacter spp. in raw milk and retail raw meats on sale in Northern Ireland. Retail raw poultry samples (n = 94), pork samples (n = 101...

To determine the principal points of microbial contamination of carcasses during beef carcass dressing in Northern Ireland, 190 carcasses were sampled by swabbing 1,000 cm2 of the brisket. A detail...

Recent evidence suggests that arcobacters, especially Arcobacter butzleri, are potential foodborne pathogens, but standardized detection methods have yet to be established. A study was undertaken t...

Aim: To investigate and compare the inherent resistance of 40 Salmonella serovars to heat, irradiation and high‐pressure stress. Methods and Results: D ₁₀ values for each of the three stresses were calculated for four serovars, chosen as representatives from a catalogue of 40. Based on these results, conditions for each stress were defined, which produced, on average, a three‐log reduction in viability. Heat stress (57°C for 13 min), high‐pressure stress (350 MPa for 10 min at 20°C) and irradiation stress (1·5 kGy at 20°C) were applied to all 40 serovars in the collection. Injury and loss of viability for all serovars were determined. Conclusions: Cluster analysis identified five groupings of isolates in terms of resistance to the applied stresses. The independent response of each isolate to all three stresses suggests that there is no relationship between resistances. Significance and Impact of the Study: Each serovar is inherently different. For modelling of real‐life food preservation processing the most resistant isolates for that process should be chosen. The results also emphasize the importance of including multiple stress resistant strains when food preservation systems apply multiple stresses.

Aims: Retail packs of fresh chicken in Northern Ireland were sampled to determine the frequency with which they were contaminated with Salmonella and Listeria spp. Methods: Packs of chicken were chos...

Preston broth and agar incubated at either 37 or 42°C have been widely used to isolate campylobacters from foodstuffs. The consequences of using either incubation temperature were investigated. Retail packs of raw chicken ( n = 24) and raw lamb liver ( n = 30) were purchased. Samples were incubated in Preston broth at 37 and 42°C and then streaked onto Preston agar and incubated as before. Two Campylobacter isolates per treatment were characterized. Poultry isolates were genotyped by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and flagellin PCR-restriction fragment length polymorphism, and lamb isolates were genotyped by RAPD only. In total, 96% of the poultry and 73% of the lamb samples yielded campylobacters. The lamb isolates were all Campylobacter jejuni , as were 96% of the poultry isolates, with the remainder being Campylobacter lari . The incubation temperature had no significant effect on the number of positive samples or on the species isolated. However, genotyping of the C. jejuni isolates revealed profound differences in the types obtained. Overall (from poultry and lamb), the use of a single incubation temperature, 37°C, gave 56% of the total number of RAPD C. jejuni genotypes, and hence, 44% remained undetected. The effect was especially marked in the poultry samples, where incubation at 37°C gave 47% of the PFGE genotypes but 53% were exclusively recovered after incubation at 42°C. Thus, the incubation temperature of Preston media selects for certain genotypes of C. jejuni , and to detect the widest range, samples should be incubated at both 37 and 42°C. Conversely, genotyping results arising from the use of a single incubation temperature should be interpreted with caution.

To standardize the assessment of the hygienic quality of beef carcasses in Northern Ireland (NI) abattoirs, swabbing techniques were evaluated. Six materials, including two commercially produced sw...