Hygiene indicator microorganisms for selected pathogens on beef, pork, and poultry meats in Belgium

Several bacterial indicators are used to evaluate hygiene during the meat slaughtering process. The objectives of this study were to assess the Belgian baseline data on hygienic indicators and the relationship between the indicators and zoonotic agents to establish hygiene indicator criteria for cattle, pig, and chicken carcasses and meat. The study used the results from the official Belgian surveillance plan from 2000 to 2003, which included the monitoring of Escherichia coli counts (ECC), Enterobacteriaceae counts (EC), aerobic colony counts (ACC), and Pseudomonas counts (PC). The sampling method was the wet and dry swabbing technique for cattle and pig carcasses and neck skin excision for broiler and layer chicken carcasses. The 75th and 95th percentiles of ECC were -0.20 and 0.95 log CFU/cm2 for cattle carcasses, 1.20 and 2.32 log CFU/cm2 for pig carcasses, and 4.05 and 5.24 log CFU/g for chicken carcasses. The ACC were 2.1- to 4.5-log higher than the ECC for cattle, pigs, and chickens. For cattle and pig carcasses, a significant correlation between ECC, EC, and ACC was found. ECC for pork and beef samples and EC in pig carcasses were significantly higher in samples contaminated with Salmonella. In poultry samples, ECC were in general higher for samples containing Salmonella or Campylobacter. Thus, E. coli may be considered as a good indicator for enteric zoonotic agents such as Salmonella for beef, pork, and poultry samples and for Campylobacter in poultry samples.     

A survey of food-borne pathogens in free-range poultry farms

A survey of the occurrence of Campylobacter, Salmonella, Listeria and Shiga toxin-producing E. coli was performed on 60 flocks of free-range chicken from 34 farms in the Basque Country (Northern Spain). Campylobacter was the most prevalent of the four pathogens, isolated in 70.6% of the farms, followed by L. monocytogenes (26.5%), and Salmonella (2.9%). No E. coli O157 or other STEC were isolated. In total 48 flocks from 26 farms were positive for at least one pathogen: 31 of them for a single pathogen (64.6%), and 17 for more than one species (35.4%). C. coli was more prevalent than C. jejuni (15 vs. 13 farms), and both species of Campylobacter were found in 3 farms. L. monocytogenes isolates were identified as serotype 4b complex, and the only Salmonella isolated was serovar Enteritidis. flaA PCR-RFLP performed on 91 Campylobacter isolates (36 C. jejuni and 55 C. coli) yielded 26 patterns, with higher diversity among the C. jejuni isolates. More than one pattern was found in 11 farms, and in 8 of them several patterns were found within the same flock. The findings of the present study suggest that the free-range rearing conditions described herein might have an advantageous effect on diminishing Salmonella but not on Campylobacter or L. monocytogenes flock contamination.     

腌制肉品的基本工艺

<正> 将食品以特殊的香辛料腌制后煮熟,即成为一系列既容易烹煮又营养丰富的菜肴。消费者购买这些食品后,只需短暂的加热即可食用,大大满足了今天高速生活节奏的市场要求。 可用以进行腌制的肉品有很多,最常用的是牛肉、鸡肉、海产品和其他禽肉类产品。一般生产腌制食品的工序包括真空翻滚、烤炉蒸煮、切割、冷冻和包装等,所用的机械设备则因应所要求的制成品而定。     

Bifidobacterium species isolated from animal feces and from beef and pork meat

Bifidobacteria were isolated from 122 of 145 samples of animal feces (from cattle, swine, sheep, goats, horses, rabbits, chickens, geese, and pigeons) from farms in France and Austria and from 92 of 955 production and processing chain samples of beef and pork (obtained at slaughter, cutting, and retail). Bacterial strains were identified to species by phenotypic numerical classification based on API 50CH and ID 32A tests and DNA-DNA hybridization. Bifidobacterium pseudolongum was present in 81% (99 of 122 samples) of all Bifidobacterium-positive fecal samples and predominated in samples from all animal species except those from swine from Austria. In these Austrian swine samples, the majority of strains were identified as Bifidobacterium thermophilum (78%), followed by B. pseudolongum (48%). The distribution of B. thermophilum and B. pseudolongum differed significantly between Austrian swine and cattle samples such as those collected along beef and pork production and processing chains. Bifidobacterium animalis was isolated from swine feces, and Bifidobacterium ruminantium was isolated from cow dung. Six fecal isolates (from cattle, swine, rabbits, goats, and horses) were identified as belonging to Bifidobacterium species of predominantly human origin: B. adolescentis, B. bifidum, and B. catenulatum. Only one other species, Bifidobacterium choerinum, was detected with low frequency in a pork processing chain. B. pseudolongum subsp. pseudolongum was predominant in pig feces, whereas B. pseudolongum subsp. globosum was predominant in feces from other animal species. Four strains closely related to both subspecies (58 to 61% DNA reassociation) formed a distinct genomic group. PCR techniques, which are more rapid and sensitive than culture-based methods, could be used to detect directly B. pseudolongum and B. thermophilum as indicators of fecal contamination along the meat processing chain.     

Prevalence and antibiotic resistance of Campylobacter spp. isolated from chicken meat, pork, and beef in Korea, from 2001 to 2006

A total of 770 samples of retail raw meat were examined for the presence of Campylobacter spp. The samples were obtained randomly from 232 retail stores in Korea from September 2001 to April 2006. The highest contamination rates were observed in chicken meat (220 181.4%] of 270 samples), whereas the rates of contamination in pork and beef were extremely low (1.6 and 1.2%, respectively). The antibiotic-resistant patterns of the 317 Campylobacter isolates were examined by the agar dilution method. Resistance to doxycycline was the most common (97.5%), followed by ciprofloxacin (95.9%), nalidixic acid (94.6%), tetracycline (94.6%), enrofloxacin (84.2%), and erythromycin (13.6%). All Campylobacter isolates from the retail raw meat were resistant to at least one of the six antibiotics tested, and 296 isolates (93.4%) showed multidrug (four or more antibiotics) resistance. This demonstrates that the multidrug-resistant Campylobacter species are widespread in meats in Korea. Therefore, further investigations will be needed to determine appropriate methods for eliminating Campylobacter contamination in industrial chicken production and food chains.     

Antimicrobial resistance among Campylobacter jejuni isolated from raw poultry meat at retail level in Denmark

Campylobacter jejuni isolated from raw poultry meat collected at retail shops in Denmark in the period 1996-2003 were tested for susceptibility to seven antimicrobial agents. The food samples consisted of raw chicken meat and other raw poultry meat of domestic or imported origin. The highest levels of resistance among C. jejuni were observed for tetracycline, nalidixic acid and ciprofloxacin, whereas macrolide resistance was rarely detected. C. jejuni originating from other poultry meat (mainly duck and turkey meat) exhibited the highest occurrences of antimicrobial resistance monitored; approximately one third of the isolates were tetracycline resistant (N=100). Among chicken meat isolates, the occurrence of tetracycline resistance was significantly higher (P<0.005) in C. jejuni isolated from imported chicken meat (N=88) than in C. jejuni from Danish chicken meat (N=367). The same tendency was observed for chloramphenicol, nalidixic acid and ciprofloxacin (P<0.05). The trends in resistance in the period 1996-2003 among C. jejuni isolates from chicken meat indicate a decrease in the occurrence of resistance towards fluoroquinolones. This may be due to reduced application of fluoroquinolones for food animals. Monitoring of the occurrence of antimicrobial resistance in C. jejuni isolated from raw uncooked poultry has been performed on a yearly basis since 1996, thus providing useful insight into consumer exposure to antimicrobial-resistant C. jejuni.     

枯草芽孢杆菌CCTCC M207209对食源性病原菌的抑制作用

采用杯碟法、对峙培养法和平板对扣法分别检测了枯草芽孢杆菌CCTCC M207209的活菌菌碟、无菌体发酵液、多糖提取液、蛋白质粗提液及其挥发性气体产物对金黄色葡萄球菌、肠球菌、化脓链球菌、大肠杆菌、沙门氏菌等食源性病原菌的抑制作用。结果表明,枯草芽孢杆菌CCTCC M207209的活菌菌碟和发酵液对所有参试病原菌均有显著抑制作用;蛋白质粗提液对除化脓链球菌以外的所有病原菌有显著抑制作用;挥发性气体产物对所有病原菌均无抑制作用;所有抑菌活性物质对金黄色葡萄球菌的抑制作用最强,初步确定其为蛋白类物质。     

Antimicrobial activity of reuterin in combination with nisin against food-borne pathogens

Antimicrobial activity of reuterin individually or in combination with nisin against different food-borne Gram-positive and Gram-negative pathogens in milk was investigated. Reuterin (8 AU/ml) exhibited bacteriostatic activity against Listeria monocytogenes, whereas its activity was slightly bactericidal against Staphylococcus aureus at 37 degrees C. Higher bactericidal activity was detected against Escherichia coli O157:H7, Salmonella choleraesuis subsp. choleraesuis, Yersinia enterocolitica, Aeromonas hydrophila subsp. hydrophila and Campylobacter jejuni. A significant synergistic effect on L. monocytogenes and a slight additive effect on S. aureus after 24 h at 37 degrees C were observed when reuterin was combined with nisin (100 IU/ml). The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin against Gram-negative pathogens.     

An overview of microbial food safety programs in beef, pork, and poultry from farm to processing in Canada

Canada's vision for the agri-food industry in the 21st century is the establishment of a national food safety system employing hazard analysis and critical control point (HACCP) principles and microbiological verification tools, with traceability throughout the gate-to-plate continuum. Voluntary on-farm food safety (OFFS) programs, based in part on HACCP principles, provide producers with guidelines for good production practices focused on general hygiene and biosecurity. OFFS programs in beef cattle, swine, and poultry are currently being evaluated through a national recognition program of the Canadian Food Inspection Agency. Mandatory HACCP programs in federal meat facilities include microbial testing for generic Escherichia coli to verify effectiveness of the processor's dressing procedure, specific testing of ground meat for E. coli O157:H7, with zero tolerance for this organism in the tested lot, and Salmonella testing of raw products. Health Canada's policy on Listeria monocytogenes divides ready-to-eat products into three risk categories, with products previously implicated as the source of an outbreak receiving the highest priority for inspection and compliance. A national mandatory identification program to track livestock from the herd of origin to carcass inspection has been established. Can-Trace, a data standard for all food commodities, has been designed to facilitate tracking foods from the point of origin to the consumer. Although much work has already been done, a coherent national food safety strategy and concerted efforts by all stakeholders are needed to realize this vision. Cooperation of many government agencies with shared responsibility for food safety and public health will be essential.     

Antimicrobial resistance of Yersinia enterocolitica strains from human patients, pigs and retail pork in Switzerland

To obtain basic data for future resistance monitoring programs, 386 Yersinia enterocolitica strains from human patients, raw retail pork and pig feces were tested for their susceptibilities to 16 antimicrobial agents and two antimicrobial growth promoters (carbadox and olaquindox). No strains were resistant to ceftriaxone, cefuroxime, ciprofloxacine, gentamicin, kanamycin, neomycin or polymyxin. Although in Switzerland carbadox and olaquindox were used as growth promoters for pigs for over 25 years, all strains were susceptible to them. In contrast, there were high levels of resistance to ampicillin, cefalothin and amoxicillin/clavulanic acid. Less than 10% of clinical isolates and strains from pig feces were resistant to streptomycin, sulfonamide, trimethoprim/sulfamethoxazole, tetracyclin, trimethoprim and chloramphenicol, but strains from retail pork were all susceptible to these antimicrobial agents. This finding suggested that pork is probably not a major source of Y. enterocolitica that cause human infections in Switzerland. A difference between clinical isolates and strains from pork was also shown by serotyping. Clinical isolates frequently belonged to the O3 and O9 groups whereas these two serotypes were not found in strains from pork. Resistance to multiple antimicrobial agents was rare. When examined by pulsed field gel electrophoresis (PFGE), two strains of fecal origin with an identical pattern of resistance to six antimicrobial agents were shown to be unrelated. Of four clinical isolates with resistances to five antimicrobial agents, two were of the same pulsotype. Retrospectively, it was found that these strains came from two members of the same household and thus represented a mini-outbreak.     

Effects of salt reduction on the rheological and gelation properties of beef, pork and poultry meat batters

The gelation and rheological properties of beef, pork and poultry meat batters as affected by salt reduction (2·50, 1·25 and 0·00%) were studied by using a Haake rotational viscometer and a thermal scanning rigidity monitor. Beef batters showed a decrease in shear stress with the decrease in salt levels at both high and low shear rates. Pork batter showed a mixed behavior (no definite trend in shear stress versus shear rate) and the poultry meat batters showed a Bingham pseudoplastic behavior, except for the no-salt treatment. During heating the beef batters showed the highest G values followed by the pork and the poultry meat batters. The rigidity modulus profiles exhibited two major transition temperatures at 47-53°C and at 64-76°C. Beef batter with 2·50% salt developed the highest average G value (16·6 kPa) and the poultry batter with 2·50% salt the lowest (7·3 kPa).     

加工环境中单核细胞增生性李斯特菌耐药特征分析

目的分析在流通过程中加工环境来源的食源性李斯特菌耐药性及耐药基因携带情况,探讨加工环境对该菌的影响。方法收集2016~2017年分离自加工环境中的71株单核细胞增生性李斯特菌,利用微量肉汤稀释法对8种抗菌药物进行药物敏感性分析,并采用PCR鉴定11种耐药基因(tet A、tet M、tet S、erm A、erm B、erm C、mec A、aac(6’)-Ib、van A、van B、cfr)。结果 71株Lm对庆大霉素(11.27%)、氨苄西林(4.22%)、头孢他啶(98.59%)、环丙沙星(97.18%)、四环素(21.12%)、红霉素(15.49%)、林可霉素(92.96%)均具有不同程度的耐药性,对万古霉素敏感。其中以耐受3~6种抗菌药为主,耐药情况较为严重。耐药基因检测表明四环素类tet A,tet M为主要耐药基因,检出率高达50%以上,其次为红霉素类erm A、erm B、erm C,检出率约11%,氨基糖苷类aac(6’)-Ib的检出率为5.63%。结论加工环境单核细胞增生性李斯特菌的耐药性呈上升趋势,其耐药表型与耐药基因型并不完全一致,从而表明加工环境中存在影响单核细胞增生性李斯特菌耐药性因素,同时为食源性李斯特菌病的防治及预警提供参考依据。     

五种食源性致病菌多重PCR的条件优化和检出限分析

对沙门菌、金黄色葡萄球菌、大肠杆菌O157∶H7、单核增生李斯特菌和福氏志贺菌5种食源性致病菌的多重PCR反应条件进行优化并分析方法的DNA检测限。方法 根据沙门菌的invA基因、金黄色葡萄球菌的16S rDNA基因、大肠杆菌O157∶H7的eaeA基因、单核增生李斯特菌的hlyA基因和福氏志贺菌的ipaH基因设计5对特异性引物进行多重PCR,对反应条件包括镁离子浓度、引物浓度和退火温度进行优化试验,并确定该检测方法的检出限。结果 最佳反应条件为金黄色葡萄球菌、沙门菌和福氏志贺菌引物浓度为0.25μmol/L,单核增生李斯特菌引物浓度为0.4μmol/L,大肠杆菌O157∶H7引物浓度为0.3μmol/L,Mg²⁺浓度为2.25mmol/L,退火温度为60℃;在此条件下金黄色葡萄球菌、肠炎沙门菌、大肠杆菌O157∶H7、单核增生李斯特菌、福氏志贺菌的多重PCR的DNA检出限分别为6.4、32、32、800和160pg。结论 通过对5种引物的PCR条件进行优化和检出限的分析,为食品中该5种致病菌的快速检测奠定基础,对实际应用具有指导意义。     

Antimicrobial resistance and virulence of Enterococcus faecalis isolated from retail food

Although enterococci are considered opportunistic nosocomial pathogens, their contribution to foodborne illnesses via dissemination through retail food remains undefined. In this study, prevalence and association of antimicrobial resistance and virulence factors of 80 Enterococcus faecalis isolates from retail food items were investigated. The highest rates of resistance were observed for lincomycin (73 of 80 isolates, 91%) and bacitracin (57 of 80 isolates, 71%), and lower rates of resistance (< or =40%) were found for chloramphenicol, ciprofloxacin, erythromycin, flavomycin, gentamicin, kanamycin, nitrofurantoin, penicillin, and tylosin. Overall resistance to antimicrobials was low for most isolates tested. Of the virulence factors tested, the majority of isolates were positive for ccf (78 of 80 isolates, 98%), efaAfs (77 of 80, 96%), and cpd (74 of 80, 93%). Isolates also commonly contained cob (72 of 80 isolates, 90%) and gelE (68 of 80, 85%). Very few isolates contained cylMBA (12 of 80 isolates [15%] for cylM and 9 of 80 isolates [11%] for both cylB and cylA) and efaAfm (2 of 80 isolates, 3%). Positive statistical associations (significance level of 0.05) were found between agg and tetracycline resistance, cylM and erythromycin resistance, and gelE and efaAfs and lincomycin resistance. The presence of the cylB and cylA alleles also was positively correlated with bacitracin and tetracycline resistance. Negative correlations were observed between many of the virulence attributes and resistance to ciprofloxacin, erythromycin, flavomycin, gentamicin, kanamycin, and tylosin. These data suggest that both positive and negative associations exist between antimicrobial resistance genes and virulence factors in E. faecalis isolates from foods commonly purchased from grocery stores.     

Antimicrobial resistance and genetic profiling of Escherichia coli from a commercial beef packing plant

The objective of this study was to investigate the extent of antimicrobial resistance and to genetically characterize resistant Escherichia coli recovered from a commercial beef packing plant. E. coli isolates were recovered by a hydrophobic grid membrane filtration method by direct plating on SD-39 medium. A total of 284 isolates comprising 71, 36, 55, 52, and 70 isolates from animal hides, washed carcasses, conveyers, beef trimmings, and ground beef, respectively, were analyzed. The susceptibility of E. coli isolates to 15 antimicrobial agents was evaluated with an automated broth microdilution system, and the genetic characterization of these isolates was performed by the random amplified polymorphic DNA (RAPD) method. Of the 284 E. coli isolates, 56% were sensitive to all 15 antimicrobial agents. Resistance to tetracycline, ampicillin, and streptomycin was observed in 38, 9, and 6% of the isolates, respectively. Resistance to one or more antimicrobial agents was observed in 51% of the E. coli isolates recovered from the hides but in only 25% of the E. coli from the washed carcasses. Resistance to one or more antimicrobial agents was observed in 49, 50, and 37% of the isolates recovered from conveyers, beef trimmings, and ground beef, respectively. The RAPD pattern data showed that the majority of resistant E. coli isolates were genetically diverse. Only a few RAPD types of resistant strains were shared among various sample sources. The results of this study suggest that antimicrobial-resistant E. coli isolates were prevalent during all stages of commercial beef processing and that considerably higher numbers of resistant E. coli were present on conveyers, beef trimmings, and ground beef than on dressed carcasses. This stresses the need for improving hygienic conditions during all stages of commercial beef processing and meatpacking to avoid the risks of transfer of antimicrobial-resistant bacteria to humans.     

生牛肉中沙门菌的血清型鉴定与耐药性检测

目的了解新疆地区生牛肉中沙门菌的血清型和耐药状况。方法采用沙门菌诊断血清试剂盒检测血清型,微量肉汤稀释法检测分离菌株的耐药性。结果 28株牛肉源沙门菌共检出11种血清型,其5种优势血清型分别为伦敦沙门菌(17.9%)、德尔卑沙门菌(10.7%)、伤寒沙门氏菌(10.7%)、甲型副伤寒沙门菌(10.7%)和阿贡纳沙门菌(10.7%);沙门菌对10种抗菌药物耐药结果显示菌株对甲氧苄啶、氯霉素、四环素的耐药率最高,分别为100%、92.9%和75%,对氟苯尼考最为敏感,耐药率为7.1%。所有的菌株可耐2种或2种以上的抗生素。结论新疆地区牛肉源沙门菌存在一定的致病性,耐药状况比较严重。     

Antimicrobial packaging of raw beef,pork and turkey using silver‐zeolite incorporated into the material

This study determined the efficacy of silver‐zeolite impregnated into wrapping paper to reduce the bacterial growth on raw beef, pork and turkey cuts. This was compared with that of regular butcher paper. The samples were inoculated with Pseudomonas putida (psychrotrophic spoilage bacterium) and stored on 4% silver‐zeolite and regular butcher paper for up to 4 days at 4 °C and 10 °C. Results showed that P. putida on the beef, pork and turkey samples did not increase in numbers after exposure to all paper packaging at 4 °C during the 4 days of storage. At 10 °C storage temperature, logarithmic growth patterns for the organisms were seen on all paper packaging. However, the growth rate was slower for the organisms on the silver‐zeolite paper. Storage on the silver‐zeolite paper accounted for one log cfu/sample mean reduction in viable cell count for the beef, pork and turkey samples when compared with the samples stored on the butcher paper at 3 days.     

Occurrence of the vancomycin-resistant genes vanA, vanB, vanCl, vanC2 and vanC3 in Enterococcus strains isolated from poultry and pork

It is suspected that the use of avoparcin as a feeding antibiotic for the fat stock contributes to development of cross-resistance against vancomycin and teicoplanin. After isolating enterococci strains from poultry and pork meat by cultivation on citrate azide Tween carbonate agar (CATC) and screening the vancomycin resistance on Columbia colistin nalidixic acid agar (CNA, supplemented with 5% sheepblood and 5 mg vancomycin/l) the polymerase chain reaction (PCR) was used for the detection of the vancomycin resistance genes vanA (‘high level’), vanB (‘moderate high level’), vanC1, vanC2 and vanC3 (‘low level’). Out of 1643 E.-isolates from 115 poultry and 50 pork samples, 420 isolates could be identified as vancomycin resistant, 202 isolates of which carry the vanA, one isolate both the vanA and the vanC1, 38 isolates the vanC1, 14 isolates the vanC2, nine isolates both the vanC1 and the vanC3 gene and 156 isolates carry no gene. The vanB gene was not found in these isolates. Comparing vanA-positive food isolates with those from different human sources by means of the pulsed field gel electrophoresis (PFGE) it could clearly be demonstrated that they do not show homological fingerprints according to the source of origin. It is therefore unlikely that there is a close genetic relationship between isolates from animal foodstuff and humans.     

Prevalence and antimicrobial resistance of Campylobacter isolated from retail raw chicken and beef meat, Tehran, Iran

Campylobacter spp. is a leading cause of human diarrhea. The common source of infection is contaminated food, particularly poultry. The veterinary use of antimicrobial drugs has been suggested to be largely responsible for resistance in human isolates of this zoonotic pathogen. From April to October 2004, 241 samples of chicken and beef meat for sale in retail outlets in Tehran (Iran) were analyzed for the presence of Campylobacter. Totally, 88 (36.5%) Campylobacter strains were isolated. Campylobacter was isolated from a significantly larger number of chicken (63%) than beef (10%) meat (P < 0.0001). Susceptibilities of 72 strains were determined for eight antimicrobial drugs using the disk diffusion assay. Resistance to nalidixic acid was the most common finding (75%), followed by resistance to ciprofloxacin (69.4%), tetracycline (45.8%), amoxicillin (11.1%), streptomycin (4.2%), chloramphenicol (2.8%) and gentamicin (1.4%). None of the isolates was resistant to erythromycin. Multidrug resistance was seen in 75% of the Campylobacter strains.