Prevalence of Campylobacter spp., Escherichia coli, and Salmonella Serovars in Retail Chicken, Turkey, Pork, and Beef from the Greater Washington, D.C., Area

A total of 825 samples of retail raw meats (chicken, turkey, pork, and beef) were examined for the presence of Escherichia coli and Salmonella serovars, and 719 of these samples were also tested for Campylobacter spp. The samples were randomly obtained from 59 stores of four supermarket chains during 107 sampling visits in the Greater Washington, D.C., area from June 1999 to July 2000. The majority (70.7%) of chicken samples (n = 184) were contaminated with Campylobacter, and a large percentage of the stores visited (91%) had Campylobacter-contaminated chickens. Approximately 14% of the 172 turkey samples yielded Campylobacter, whereas fewer pork (1.7%) and beef (0.5%) samples were positive for this pathogen. A total of 722 Campylobacter isolates were obtained from 159 meat samples; 53.6% of these isolates were Campylobacter jejuni, 41.3% were Campylobacter coli, and 5.1% were other species. Of the 212 chicken samples, 82 (38.7%) yielded E. coli, while 19.0% of the beef samples, 16.3% of the pork samples, and 11.9% of the turkey samples were positive for E. coli. However, only 25 (3.0%) of the retail meat samples tested were positive for Salmonella. Significant differences in the bacterial contamination rates were observed for the four supermarket chains. This study revealed that retail raw meats are often contaminated with food-borne pathogens; however, there are marked differences in the prevalence of such pathogens in different meats. Raw retail meats are potential vehicles for transmitting food-borne diseases, and our findings stress the need for increased implementation of hazard analysis of critical control point (HACCP) and consumer food safety education efforts.     

Genotyping of Campylobacter spp. from retail meats by pulsed-field gel electrophoresis and ribotyping

AIMS: To determine the genetic relatedness of Campylobacter spp. from retail meat products, and compare the discriminatory power of pulsed-field gel electrophoresis (PFGE) and automatic ribotyping. METHODS AND RESULTS: A total of 378 Campylobacter isolates recovered from 159 raw meats (130 chicken, 25 turkey, three pork and one beef) sampled from 50 retail grocery stores of four supermarket chains in the Maryland suburban area from August 1999 to July 2000 were analysed by PFGE with SmaI, 120 isolates of which were also characterized by ribotyping with PstI using RiboPrinter system. A total of 148 unique PFGE patterns were identified, 91 of which were present in multiple Campylobacter isolates and 24 in multiple meat samples. Nineteen Campylobacter clones with identical PFGE patterns recurred frequently (up to nine times) throughout the sampling period. Comparing ribotyping with PFGE, we identified 44 PFGE patterns and 22 RiboGroups among the 120 isolates tested. Multiple PFGE patterns within one RiboGroup were commonly observed, as well as multiple RiboGroups within one PFGE pattern. CONCLUSIONS: Although Campylobacter present in retail meats were genetically diverse, certain clones persisted in poultry meats. PFGE had a greater discriminatory power than ribotyping, and the two methods were complementary in genotyping Campylobacter. SIGNIFICANCE AND IMPACT OF THE STUDY: Genomic DNA fingerprinting of Campylobacter confirmed diverse and recurrent Campylobacter clones in the retail meats, which provides additional data for a better understanding of the epidemiological aspect of Campylobacter infection.     

Comparison of the prevalences and antimicrobial resistances of Escherichia coli isolates from different retail meats in the United States, 2002 to 2008

Escherichia coli isolates were recovered from the National Antimicrobial Resistance Monitoring System retail meat program and examined for antimicrobial susceptibility. Retail meat samples (n = 11,921) from four U.S. states collected during 2002 to 2008, consisting of 2,988 chicken breast, 2,942 ground turkey, 2,991 ground beef, and 3,000 pork chop samples, were analyzed. A total of 8,286 E. coli isolates were recovered. The greatest numbers of samples contaminated with the organism were chicken (83.5%) and turkey (82.0%), followed by beef (68.9%) and pork (44.0%). Resistance was most common to tetracycline (50.3%), followed by streptomycin (34.6%), sulfamethoxazole-sulfisoxazole (31.6%), ampicillin (22.5%), gentamicin (18.6%), kanamycin (8.4%), amoxicillin-clavulanic acid (6.4%), and cefoxitin (5.2%). Less than 5% of the isolates had resistance to trimethoprim, ceftriaxone, ceftiofur, nalidixic acid, chloramphenicol, and ciprofloxacin. All isolates were susceptible to amikacin. Compared to beef and pork isolates, the poultry meat isolates had a greater percentage of resistance to all tested drugs, with the exception of chloramphenicol, to which pork isolates had the most resistance. More than half of the turkey isolates (56%) were resistant to multidrugs (≥3 classes) compared to 38.9% of chicken, 17.3% of pork, and 9.3% of beef isolates. The bla(CMY) gene was present in all ceftriaxone- and ceftiofur-resistant isolates. The cmlA, flo, and catI genes were present in 45%, 43%, and 40% of chloramphenicol-resistant isolates, respectively. Most nalidixic acid-resistant isolates (98.5%) had a gyrA mutation in S83 or D87 or both, whereas only 6.7% had a parC mutation in either S80 or E84. The results showed that E. coli was commonly present in the retail meats, and antimicrobial resistance profiles differed according to the animal origin of the isolates.     

Prevalence and antimicrobial resistance of enterococcus species isolated from retail meats

From March 2001 to June 2002, a total of 981 samples of retail raw meats (chicken, turkey, pork, and beef) were randomly obtained from 263 grocery stores in Iowa and cultured for the presence of Enterococcus spp. A total of 1,357 enterococcal isolates were recovered from the samples, with contamination rates ranging from 97% of pork samples to 100% of ground beef samples. Enterococcus faecium was the predominant species recovered (61%), followed by E. faecalis (29%), and E. hirae (5.7%). E. faecium was the predominant species recovered from ground turkey (60%), ground beef (65%), and chicken breast (79%), while E. faecalis was the predominant species recovered from pork chops (54%). The incidence of resistance to many production and therapeutic antimicrobials differed among enterococci recovered from retail meat samples. Resistance to quinupristin-dalfopristin, a human analogue of the production drug virginiamycin, was observed in 54, 27, 9, and 18% of E. faecium isolates from turkey, chicken, pork, and beef samples, respectively. No resistance to linezolid or vancomycin was observed, but high-level gentamicin resistance was observed in 4% of enterococci, the majority of which were recovered from poultry retail meats. Results indicate that Enterococcus spp. commonly contaminate retail meats and that dissimilarities in antimicrobial resistance patterns among enterococci recovered from different meat types may reflect the use of approved antimicrobial agents in each food animal production class.     

Antimicrobial resistance of Campylobacter isolates from retail meat in the United States between 2002 and 2007

The emergence of antimicrobial resistance in Campylobacter spp. has been a growing public health concern globally. The objectives of this study were to determine the prevalence, antimicrobial susceptibility, and genetic relatedness of Campylobacter spp. recovered by the National Antimicrobial Resistance Monitoring System (NARMS) retail meat program. Retail meat samples (n = 24,566) from 10 U.S. states collected between 2002 and 2007, consisting of 6,138 chicken breast, 6,109 ground turkey, 6,171 ground beef, and 6,148 pork chop samples, were analyzed. A total of 2,258 Campylobacter jejuni, 925 Campylobacter coli, and 7 Campylobacter lari isolates were identified. Chicken breast samples showed the highest contamination rate (49.9%), followed by ground turkey (1.6%), whereas both pork chops and ground beef had <0.5% contamination. The most common resistance was to doxycycline/tetracycline (46.6%), followed by nalidixic acid (18.5%), ciprofloxacin (17.4%), azithromycin and erythromycin (2.8%), telithromycin (2.4%), clindamycin (2.2%), and gentamicin (<0.1%). In a subset of isolates tested, no resistance to meropenem and florfenicol was seen. C. coli isolates showed higher resistance rates to antimicrobials, with the exception of doxycycline/tetracycline, than those seen for C. jejuni. Pulsed-field gel electrophoresis (PFGE) fingerprinting resulted in 1,226 PFGE profiles among the 2,318 isolates, with many clones being widely dispersed throughout the 6-year sampling period.     

肉及肉制品中空肠弯曲菌的污染情况调查

我们对辽宁地区肉及肉制品进行弯曲杆菌属检查,发现12.9%(23/177)的样品为弯曲杆菌属阳性.经API Campy鉴定系统鉴定,其中26.1%(6/23)为空肠弯曲菌(C.jejuni)阳性,同时发现1株大肠弯曲菌.该调查证实,辽宁地区进出口的肉及肉制品中,存在空肠弯曲菌的污染,如果销售不当或再加工卫生不良,会对消费者的健康构成潜在威胁.     

Antimicrobial Resistance in Salmonella enterica Serovar Heidelberg Isolates from Retail Meats, Including Poultry, from 2002 to 2006

Salmonella enterica serovar Heidelberg frequently causes food-borne illness in humans. There are few data on the prevalence, antimicrobial susceptibility, and genetic diversity of Salmonella serovar Heidelberg isolates in retail meats. We compared the prevalences of Salmonella serovar Heidelberg in a sampling of 20,295 meats, including chicken breast (n = 5,075), ground turkey (n = 5,044), ground beef (n = 5,100), and pork chops (n = 5,076), collected during 2002 to 2006. Isolates were analyzed for antimicrobial susceptibility and compared genetically using pulsed-field gel electrophoresis (PFGE) and PCR for the bla_CMY gene. A total of 298 Salmonella serovar Heidelberg isolates were recovered, representing 21.6% of all Salmonella serovars from retail meats. One hundred seventy-eight (59.7%) were from ground turkey, 110 (36.9%) were from chicken breast, and 10 (3.4%) were from pork chops; none was found in ground beef. One hundred ninety-eight isolates (66.4%) were resistant to at least one compound, and 49 (16.4%) were resistant to at least five compounds. Six isolates (2.0%), all from ground turkey, were resistant to at least nine antimicrobials. The highest resistance in poultry isolates was to tetracycline (39.9%), followed by streptomycin (37.8%), sulfamethoxazole (27.7%), gentamicin (25.7%), kanamycin (21.5%), ampicillin (19.8%), amoxicillin-clavulanic acid (10.4%), and ceftiofur (9.0%). All isolates were susceptible to ceftriaxone and ciprofloxacin. All ceftiofur-resistant strains carried bla_CMY. PFGE using XbaI and BlnI showed that certain clones were widely dispersed in different types of meats and meat brands from different store chains in all five sampling years. These data indicate that Salmonella serovar Heidelberg is a common serovar in retail poultry meats and includes widespread clones of multidrug-resistant strains.     

Prevalence of Campylobacter spp. in turkey meat from a slaughterhouse and in turkey meat retail products

One hundred and forty-four samples of chilled turkey meat from six flocks, taken directly from the slaughterhouse, and 100 samples of turkey meat retail products were examined. Over one-quarter (29.2%) of the tested samples from the slaughterhouse were Campylobacter positive, showing high variability in the flocks. The lowest percentage of Campylobacter-positive samples was found in flocks I and III (8.3%), whereas, in flock VI, 91.7% of the samples were Campylobacter positive. Turkey meat retail products showed a prevalence of 34% for Campylobacter. Heat-treated meat was negative for Campylobacter. Quantitative studies of the samples taken at the slaughterhouse revealed a mean log range of 1.9-2.5 CFU g(-1)Campylobacter spp. Results from the quantification of retail products gave a mean log value of 2.1 CFU g(-1).     

Isolation of Escherichia coli O157:H7 from retail fresh meats and poultry.

A total of 896 samples of retail fresh meats and poultry was assayed for Escherichia coli serogroup O157:H7 by a hydrophobic grid membrane filter-immunoblot procedure developed specifically to isolate the organism from foods. The procedure involves several steps, including selective enrichment, filtration of enrichment culture through hydrophobic grid membrane filters, incubation of each filter on nitrocellulose paper on selective agar, preparation of an immunoblot (by using antiserum to E. coli O157:H7 culture filtrate) of each nitrocellulose paper, selection from the filters of colonies which corresponded to immunopositive sites on blots, screening of isolates by a Biken test for precipitin lines from metabolites and antiserum to E. coli O157:H7 culture filtrate, and confirmation of isolates as Vero cell cytotoxic E. coli O157:H7 by biochemical, serological, and Vero cell cytotoxicity tests. E. coli O157:H7 was isolated from 6 (3.7%) of 164 beef, 4 (1.5%) of 264 pork, 4 (1.5%) of 263 poultry, and 4 (2.0%) of 205 lamb samples. One of 14 pork samples and 5 of 17 beef samples contaminated with the organism were from Calgary, Alberta, Canada, grocery stores, whereas all other contaminated samples were from Madison, Wis., retail outlets. This is the first report of the isolation of E. coli O157:H7 from food other than ground beef, and results indicate that the organism is not a rare contaminant of fresh meats and poultry.     

Microbiological quality and safety of zoo food.

Two types of commercial products for feeding zoo animals (a frozen meat product, referred to as zoo food, and a dry product, referred to as dry food) were microbiologically examined for spoilage organisms (aerobic, psychrotrophic, coliform, Escherichia coli, mold, and yeasts) and pathogens (Salmonella spp., Listeria monocytogenes, and Campylobacter jejuni). Levels of microorganisms in frozen ground zoo food were compared with those in frozen ground beef and frozen ground turkey meat. The level of microbial contaminants in frozen ground zoo meat was found to be similar to that in frozen ground beef and higher than that in frozen ground turkey meat. Sixty percent of the frozen zoo meat samples were Salmonella positive, and all of the samples were L. monocytogenes positive. Dry zoo food was documented to have microbial levels lower than those in frozen zoo meat; the pathogen levels were less than 1/25 g of food. Defrosting zoo meat at 10, 25, and 37 degrees C for 24 h showed that 10 degrees C is the best temperature for defrosting frozen ground zoo meat loaves (length, 9 in. [22.8 cm]; radius, 2 in. [5.1 cm]) without affecting the microbiological quality or safety of the product.     

Incidence of Campylobacter and Salmonella isolated from retail chicken and associated packaging in South Wales

AIMS: To investigate the incidence of Campylobacter and Salmonella contamination associated with supermarket and butchers' shop chicken and related packaging. METHOD AND RESULTS: Three hundred raw samples (whole chicken, chicken breast with skin or chicken pieces) were purchased on a monthly basis for seven months. Packaging associated with the chicken was also sampled to provide isolation data for external and whole packaging. Campylobacter and Salmonella were isolated from 68% and 29% of retail chicken, respectively. Campylobacter was isolated from 3% of external and 34% of whole packaging overall. Salmonella was absent from external packaging but was isolated from 11% of whole packaging. No significant trends in isolation rates of the organisms were obtained during the period of sampling. CONCLUSIONS: The food industry and consumers should be made aware of the potential risk of Campylobacter and Salmonella on both the external and internal surfaces of packaging in addition to chicken itself. SIGNIFICANCE AND IMPACT OF THE STUDY: Chicken and chicken packaging is a potential vehicle for the introduction of pathogens in retail and domestic kitchens and in particular for the cross-contamination of Campylobacter and Salmonella.     

Microbiological quality and safety of zoo food

Two types of commercial products for feeding zoo animals (a frozen meat product, referred to as zoo food, and a dry product, referred to as dry food) were microbiologically examined for spoilage organisms (aerobic, psychrotrophic, coliform, Escherichia coli, mold, and yeasts) and pathogens (Salmonella spp., Listeria monocytogenes, and Campylobacter jejuni). Levels of microorganisms in frozen ground zoo food were compared with those in frozen ground beef and frozen ground turkey meat. The level of microbial contaminants in frozen ground zoo meat was found to be similar to that in frozen ground beef and higher than that in frozen ground turkey meat. Sixty percent of the frozen zoo meat samples were Salmonella positive, and all of the samples were L. monocytogenes positive. Dry zoo food was documented to have microbial levels lower than those in frozen zoo meat; the pathogen levels were less than 1/25 g of food. Defrosting zoo meat at 10, 25, and 37 degrees C for 24 h showed that 10 degrees C is the best temperature for defrosting frozen ground zoo meat loaves (length, 9 in. [22.8 cm]; radius, 2 in. [5.1 cm]) without affecting the microbiological quality or safety of the product.     

Further Studies on Staphylococci in Meats, : III. Occurrence and Characteristics of Coagulase-positive Strains from a Variety of Nonfrozen Market Cuts

From 34 retail grocery stores and meat markets, 209 samples of nonfrozen meats were obtained and analyzed for coagulase-positive Staphylococcus aureus, employing six selective media. Sixty-seven (38.7%) of 173 samples obtained from 27 stores yielded S. aureus. No coagulase-positive S. aureus was isolated from 36 samples obtained from 7 of the stores. The 67 meats yielded 272 isolates from 10 different kinds of meats. There were 162 physiological strains represented when classified by store and 36 strains classified without regard to store of origin. The larger stores yielded fewer meats with staphylococci than the smaller stores. The meats from which S. aureus was recovered in the order of frequency of percentage recovery are as follows: chicken, pork liver, fish, spiced ham, round beef steak, hamburger, beef liver, pork chops, veal steak, and lamb chops. The following seven meats did not yield staphylococci: bologna, shucked oysters, olive and pickle loaf, salami, wieners, and chopped ham. Eighty-eight per cent of the isolates produced pigment, 85% were gelatinase positive, only 1 strain failed to form a precipitate on egg yolk agar, 92% formed deoxyribonuclease, 87% produced bound coagulase, 91% produced the α-hemolysin, 70% the δ-, 22% the β-, and 6% were nil in this regard. The isolates are compared with hospital and other food strains, and their possible source in the meats is discussed.     

Application of real-time PCR for quantitative detection of Campylobacter jejuni in poultry, milk and environmental water

Campylobacter jejuni is a leading human food-borne pathogen. The rapid and sensitive detection of C. jejuni is necessary for the maintenance of a safe food/water supply. In this article, we present a real-time polymerase chain reaction (PCR) assay for quantitative detection of C. jejuni in naturally contaminated poultry, milk and environmental samples without an enrichment step. The whole assay can be completed in 60 min with a detection limit of approximately 1 CFU. The standard curve correlation coefficient for the threshold cycle versus the copy number of initial C. jejuni cells was 0.988. To test the PCR system, a set of 300 frozen chicken meat samples, 300 milk samples and 300 water samples were screened for the presence of C. jejuni. 30.6% (92/300) of chicken meat samples, 27.3% (82/300) of milk samples, and 13.6% (41/300) of water samples tested positive for C. jejuni. This result indicated that the real-time PCR assay provides a specific, sensitive and rapid method for quantitative detection of C. jejuni. Moreover, it is concluded that retail chicken meat, raw milk and environmental water are commonly contaminated with C. jejuni and could serve as a potential risk for consumers in eastern China, especially if proper hygienic and cooking conditions are not maintained.     

Adding a selective enrichment step to the iQ-Check real-time PCR improves the detection of Salmonella in naturally contaminated retail turkey meat products

AIMS: The aim of this study was to compare the real-time iQ-Check Salmonella kit (Bio-Rad) with the immunocapture assay RapidCheck Salmonella method, and a conventional culture method (FSIS, USDA) in detecting Salmonella in naturally contaminated turkey meat products. This study was also designed to determine if a selective enrichment step might improve the real-time detection of Salmonella. METHODS AND RESULTS: Using the culture method, Salmonella was recovered from 49 out of 99 retail turkey meat samples collected. RapidCheck failed to detect 11 Salmonella samples that were positive by the culture method. The iQ-Check real-time PCR also failed to detect three samples that were positive by the culture method. However, when carried out after a selective enrichment step, the iQ-Check real-time PCR detected all 49 Salmonella samples recovered by the culture method. The iQ-Check real-time PCR detected the presence of Salmonella in some samples that were not recovered by the culture method. CONCLUSIONS: Adding a selective enrichment step to the iQ-Check real-time PCR improves the detection of Salmonella in naturally contaminated turkey meat samples. SIGNIFICANCE AND IMPACT OF THE STUDY: The iQ-Check Salmonella real-time PCR can be used as a rapid method to monitor Salmonella in turkey meat, together with conventional culture methodology.     

Incidence and relationship of group D streptococci with other indicator organisms in meats.

Raw and processed meats were analyzed for presumptive group D streptococci using KF streptococcus agar. Counts were compared with coliform, presumptive Escherichia coli, and Enterobacteriaceae counts but no meaningful relationships were observed. Results indicated that group D streptococci and E. coli type I were principally contaminants from the packing plant, rather than at retail level. The predominating group D streptococcus in both beef and pork cuts was Streptococcus faecalis, while in processed meat (bologna), the predominating group D streptococci were Streptococcus faecium var. durans and Streptococcus faecium. Streptococcus bovis was not detected among the isolates from any meat samples. Marked differences were noted in numbers of group D streptococci in processed meat from different manufacturers. The results did not support the use of group D streptococci as alternative indicator organisms for meats. However, the association of group D streptococci with packing plant contamination may prove to be of value.     

Detection of Salmonella spp. in retail raw food samples from Vietnam and characterization of their antibiotic resistance

A study was conducted to examine the levels of Salmonella spp. contamination in raw food samples, including chicken, beef, pork, and shellfish, from Vietnam and to determine their antibiotic resistance characteristics. A total of 180 samples were collected and examined for the presence of Salmonella spp., yielding 91 Salmonella isolates. Sixty-one percent of meat and 18% of shellfish samples were contaminated with Salmonella spp. Susceptibility of all isolates to a variety of antimicrobial agents was tested, and resistance to tetracycline, ampicillin/amoxicillin, nalidixic acid, sulfafurazole, and streptomycin was found in 40.7%, 22.0%, 18.7%, 16.5%, and 14.3% of the isolates, respectively. Resistance to enrofloxacin, trimethoprim, chloramphenicol, kanamycin, and gentamicin was also detected (8.8 to 2.2%). About half (50.5%) of the isolates were resistant to at least one antibiotic, and multiresistant Salmonella isolates, resistant to at least three different classes of antibiotics, were isolated from all food types. One isolate from chicken (serovar Albany) contained a variant of the Salmonella genomic island 1 antibiotic resistance gene cluster. The results show that antibiotic resistance in Salmonella spp. in raw food samples from Vietnam is significant.     

Recovery of different Listeria ribotypes from naturally contaminated, raw refrigerated meat and poultry products with two primary enrichment media.

Isolation rates for Listeria monocytogenes and the other Listeria spp. typically improve when samples are enriched in more than one primary enrichment medium. This study evaluated the abilities of two primary enrichment media, University of Vermont-modified Listeria enrichment broth (UVM) and Listeria repair broth (LRB), to recover different ribotypes of Listeria spp. from raw meat and poultry samples. Forty-five paired 25-g retail samples of ground beef, pork sausage, ground turkey, and chicken (160 samples) underwent primary enrichment in UVM and LRB (30 degrees C for 24 h) followed by secondary enrichment in Fraser broth (35 degrees C for 24 and 40 h) and plating on modified Oxford agar. After 24 h of incubation of 35 degrees C, 608 Listeria colonies from selected positive samples were biochemically confirmed as L. monocytogenes (245 isolates), L innocua (276 isolates), and L. welshimeri (89 isolates) and then ribotyped with the automated Riboprinter microbial characterization system (E. I. du Pont de Nemours & Co., Inc.). Thirty-six different Listeria strains comprising 16 L. monocytogenes (including four known clinical ribotypes), 12 L. innocua, and 8 L. welshimeri ribotypes were identified from selected positive samples (15 samples of each product type; two UVM and two LRB isolates per sample). Twenty-six of 36(13 L. monocytogenes) ribotypes were detected with both UVM and LRB, whereas 3 of 36 (1 L. monocytogenes) and 7 of 36 (3 L. monocytogenes) Listeria ribotypes were observed with only UVM or LRB, respectively. Ground beef, pork sausage, ground turkey, and chicken yielded 22 (8 L. monocytogenes), 21 (12 L. monocytogenes), 20 (9 L. monocytogenes), and 19 (11 L. monocytogenes) different Listeria ribotypes, respectively, with some Listeria ribotypes confined to a particular product. More importantly, major differences in both the number and distribution of Listeria ribotypes, including previously recognized clinical and nonclinical ribotypes of L. monocytogenes, were observed when 10 UVM and 10 LRB isolates from five samples of each product were ribotyped. When a third set of six samples per product type was examined from which two Listeria isolates were obtained by using only one of the two primary enrichment media, UVM and LRB failed to detect L. monocytogenes (both clinical and nonclinical ribotypes) in two and four samples, respectively. These findings stress the importance of using more than one primary enrichment medium and picking a sufficient number of colonies per sample when attempting to isolate specific L. monocytogenes strains during investigations of food-borne listeriosis.     

Isolation of<Emphasis Type="Italic">Arcobacter butzleri</Emphasis> and<Emphasis Type="Italic">A. cryaerophilus</Emphasis> in samples of meats and from meat-processing plants by a culture technique and detection by PCR

A pilot survey of sources of contamination with arcobacters (representing a potential risk for humans) was done in a wide range of samples involved various kinds of meat (beef, pork, meat products, chilled chickens, etc.) from a retail level and domestic farming. Sanitary practices in slaughterhouses and production lines were checked in two different plants (a beef and pork production and a chicken processing plant). The method is based on a selective enrichment to isolate suspect strains, in combination with a PCR technique specific for arcobacters. The choice of a suitable enrichment broth and a plating agar was made with the use of pure bacterial strains and by means of real meat samples seeded with Arcobacter butzleri. The PCR technique was optimized to allow differentiation of a 1223 bp product, typical of the genus Arcobacter, and a product of 686 bp, specific for A. butzleri a total number of 198 samples were tested, of that 33 (17%) were found to be positive for the genus Arcobacter but only 22 (11%) for A. butzleri.     

Carriage of four bacterial pathogens by beef cattle in Northern Ireland at time of slaughter

AIMS: To determine the prevalence of four bacterial zoonotic pathogens in beef cattle at time of slaughter in Northern Ireland (NI), in order to assess their potential for reducing beef safety. METHODS AND RESULTS: Faeces were collected postmortem from beef cattle (n =220) at seven EU registered abattoirs. Standard enrichment culturing methods were employed, plus immunomagnetic enrichment in the case of Escherichia coli O157:H7. Campylobacter spp. were found in 52 samples (24.8%), Listeria monocytogenes in 10 (4.8%), E. coli O157:H7 in 2 (0.9%) whilst Salmonella spp. were isolated from six out of 200 samples (3.0%). Five salmonellas were Salmonella Chandans and one was Salmonella Liverpool. CONCLUSIONS: Campylobacter spp. were the most frequently isolated pathogen, despite being relatively rare in beef. Genotyping showed the campylobacters to be very diverse, indicating cattle encounter campylobacters from many sources. The remaining three pathogens, which are associated with meats, occurred at relatively low frequencies, especially E. coli O157:H7. The Salmonella serovars found rarely infect humans. SIGNIFICANCE AND IMPACT OF THE STUDY: The low prevalence of E. coli O157:H7 in NI beef cattle was confirmed and the reasons for this merit further study. The four pathogens should have little impact on beef quality.