Effectiveness of steam pasteurization in controlling microbiological hazards of cull cow carcasses in a commercial plant.
The purpose of the study, carried out in a beef processing plant, was to evaluate the effectiveness of a new prototype for steam pasteurization treatment in controlling microbiological hazards. Samples were taken by swabbing randomly selected sites before and after pasteurization and again after chilling to obtain total aerobic counts (TAC), total coliform counts (TCC), and generic Escherichia coli counts (ECC) on Petrifilm plates and to determine the prevalence of Salmonella spp., Listeria monocytogenes, and E. coli O157:H7 using standard enrichment techniques. Escherichia coli and L. monocytogenes strains were tested for various factors associated with their virulence by using colony hybridization and polymerase chain reaction (PCR), respectively. Antimicrobial susceptibility was determined for each isolate that was potentially pathogenic to humans by using the disk-diffusion method. Mean values for TAC, TCC, and ECC were 2.18, 0.16, and 0.06 log10 CFU/cm2, respectively, before pasteurization; 1.17, 0.03, and 0.01 log10 CFU/cm2 after pasteurization; and 0.89, 0.02, and 0.01 log10 CFU/cm2 after chilling. Prevalence of L. monocytogenes, Salmonella spp., and E. coli O157:H7 on carcasses was 0.8%, 0.0%, and 0.0%, respectively, before pasteurization; 2.6%, 0.0%, and 0.0% after pasteurization; and 3.1%, 0.1%, and 0.0% after chilling. The prevalence of E. coli containing > or = 1 virulence gene was 14.7%. More specifically, 11.88% of the isolates obtained before pasteurization, 22.2% obtained after pasteurization, and 31.2% obtained after chilling had virulence genes. All L. monocytogenes isolates tested positive for the presence of 3 major virulence factors (hlyA, inlB, and plcB). Antibiograms showed that certain isolates were susceptible to all antibiotics, some showed an intermediate sensitivity, and others were multiresistant. Overall, these results suggest that steam pasteurization is an effective means of improving safety quality of beef carcasses. However, pasteurization may indirectly contribute to the growth of some pathogenic microorganisms, such as L. monocytogenes.
Corantin
Harold
H
Faculté de Médecine Vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, Québec.
Quessy
Sylvain
S
Gaucher
Marie-Lou
ML
Lessard
Louise
L
Leblanc
Danielle
D
Houde
Alain
A
D000003:Abattoirs / Q000592:standards; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development* / Q000302:isolation & purification / Q000472:pathogenicity; D002417:Cattle; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D024881:Drug Resistance, Bacterial; D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity; D005506:Food Contamination / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods* / Q000592:standards; D005516:Food Microbiology; D005525:Food-Processing Industry / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity; D008460:Meat / Q000382:microbiology* / Q000592:standards; D008826:Microbial Sensitivity Tests; D012475:Salmonella / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity; D013227:Steam; D014774:Virulence
D000900:Anti-Bacterial Agents; D013227:Steam