ABSTRACT
This study investigated the occurrence, concentration and key characteristics of Listeria monocytogenes in beef chain samples (n=1100) over a 2-year period (July 2007-June 2009). Listeria monocytogenes was isolated from bovine hides (27%), pre-chill carcasses (14%) and ground beef (29%), but not from ready-to-eat (RTE) beef. The concentration of the pathogen in the majority (95%) of contaminated samples was low and detected by enrichment only. The highest concentrations recovered (100-200 CFU/g) were in ground beef samples. The most commonly isolated serotype group was 1/2a (58%) followed by 4b (12%), 1/2b (10%) and 1/2c (6%). A small portion (<5%) isolates had demonstrated resistance to key anti-microbials including ampicillin, vancomycin and gentamycin which are recommended treatment options for listeriosis. Pulsed-field gel electrophoresis showed indistinguishable profiles for a number of isolates recovered from the hide and carcass (after slaughter and dressing) of the same animals, highlighting the role of hides as a source of contamination. Equally, indistinguishable pulsotypes for isolates recovered at different stages and time points (up to 6 months apart) in the beef chain demonstrated the persistence of specific clones in the factory, process and distribution environments. Overall, the study demonstrated a high prevalence of clinically significant L. monocytogenes entering and progressing along the beef chain and highlights the needs to control cross-contamination during beef processing and distribution and the need for thorough cooking of raw beef products.
Subject(s)
Cattle/microbiology , Listeria monocytogenes , Meat/microbiology , Abattoirs , Animals , Drug Resistance, Bacterial , Food Contamination/analysis , Food Microbiology , Humans , Ireland/epidemiology , Listeria monocytogenes/drug effects , Listeria monocytogenes/isolation & purification , Listeriosis/epidemiology , Polymerase Chain ReactionABSTRACT
The study investigated the prevalence, concentration and characteristics of Salmonella spp. in the Irish beef chain. A total of 900 samples including bovine hides, carcasses and ground beef were examined for the pathogen over a 2-year study (July 2007-June 2009). Salmonella prevalence was low in all sample types; bovine hide (0.75%, 3 of 400); carcasses (0.25%, 1 of 400); and ground beef (3%, 3 of 100). All positive samples contained the pathogen in low concentrations (<10 CFU per cm(2) or per g). Serovars recovered were S. Dublin from hide and carcasses and S. Braenderup in ground beef. All isolates were susceptible to 13 anti-microbials. The study highlights that Salmonella can be found at low levels at all stages of beef chain production, processing and retail and that there is a need for multiple hurdle interventions and practices along the beef chain, which will reduce consumer exposure to this pathogen.
Subject(s)
Cattle Diseases/microbiology , Food Handling , Food Microbiology , Meat/microbiology , Salmonella/isolation & purification , Abattoirs , Animals , Cattle , Cattle Diseases/epidemiology , Colony Count, Microbial/veterinary , Electrophoresis, Gel, Pulsed-Field/veterinary , Food Contamination , Ireland/epidemiology , Prevalence , Serotyping/veterinaryABSTRACT
The aim of this study was to develop a universal cultural protocol, which could facilitate the growth of 17 species and 3 subspecies of Campylobacter. Enrichment media including Campylobacter Enrichment Broth (CEB) and Bolton Broth were tested against a panel of Campylobacter strains (n=53) encompassing 17 species and 3 subspecies, under a gas atmosphere containing hydrogen (2.5% O(2), 7% H(2), 10% CO(2), and 80.5% N(2)). The impact of enrichment conditions on cell motility was also investigated using fluorescent microscopy. Membrane filtration was examined as a means of selectively recovering Campylobacter from enrichment media on two different non-selective agars, Anaerobe Basal Agar (ABA) and Tryptose Blood Agar (TBA). The results showed that enrichment in CEB for 24 h at 37°C under a modified gas atmosphere followed by centrifugation and membrane filtration onto ABA allowed recovery of all species (53 strains) of Campylobacter from inoculated meat samples. After 24 h enrichment, there were higher levels of motile Campylobacter in CEB than in Bolton broth and it is proposed that this attribute aided the passage of the Campylobacter through the membrane filter. The results of this study provide a simple, but effective method for the growth and recovery of a wide range of diverse Campylobacter spp. from a meat matrix using common cultural parameters.
Subject(s)
Bacteriological Techniques/methods , Campylobacter/growth & development , Culture Techniques/methods , Meat/microbiology , Animals , Campylobacter/isolation & purification , Campylobacter/metabolism , Cattle , Culture Media/metabolismABSTRACT
A combination of factors including changes in the agri-food chain, social changes, advances in detection and reporting systems coupled with bacterial adaptation and evolution have in recent years lead to the emergence of a number of zoonotic microorganisms in the food and water chain. These include multi-antibiotic resistant bacteria, verocytotoxigenic Escherichia coli, parasites such as Cyclospora on fruit, and Cyrptosporidium and Giardia in water, Enterobacter sakazakii in infant milk formula, and emergent species of Campylobacteraceae. In this paper, Enterohaemorrhagic E. coli and Campylobacteraceae are taken as examples of emergent pathogens in the meat chain. Specific factors which may have lead to their emergence are deliberated, in addition to an overview of tools for their detection and tracking, and their epidemiology and survival characteristics. Approaches to managing and controlling emergent pathogens in the agri-food chain are also discussed.
