Vibrio vulnificus and Vibrio parahaemolyticus in U.S. retail shell oysters: a national survey from June 1998 to July 1999.

From June 1998 to July 1999, 370 lots of oysters in the shell were sampled at 275 different establishments (71%, restaurants or oyster bars; 27%, retail seafood markets: and 2%, wholesale seafood markets) in coastal and inland markets throughout the United States. The oysters were harvested from the Gulf (49%). Pacific (14%), Mid-Atlantic (18%), and North Atlantic (11%) Coasts of the United States and from Canada (8%). Densities of Vibrio vulnificus and Vibrio parahaemolyticus were determined using a modification of the most probable number (MPN) techniques described in the Food and Drug Administration's Bacteriological Analytical Manual. DNA probes and enzyme immunoassay were used to identify suspect isolates and to determine the presence of the thermostable direct hemolysin gene associated with pathogenicity of V. parahaemolyticus. Densities of both V. vulnifcus and V. parahaemolyticus in market oysters from all harvest regions followed a seasonal distribution, with highest densities in the summer. Highest densities of both organisms were observed in oysters harvested from the Gulf Coast, where densities often exceeded 10,000 MPN/g. The majority (78%) of lots harvested in the North Atlantic, Pacific, and Canadian Coasts had V. vulnificus densities below the detectable level of 0.2 MPN/g; none exceeded 100 MPN/g. V. parahaemolyticus densities were greater than those of V. vulnificus in lots from these same areas, with some lots exceeding 1,000 MPN/g for V. parahaemolyticus. Some lots from the Mid-Atlantic states exceeded 10,000 MPN/g for both V. vulnificus and V. parahaemolyicus. Overall, there was a significant correlation between V. vulificus and V. parahaemolyticus densities (r = 0.72, n = 202, P < 0.0001), but neither density correlated with salinity. Storage time significantly affected the V. vulnificus (10% decrease per day) and V. parahaemolyticus (7% decrease per day) densities in market oysters. The thermostable direct hemolysin gene associated with V parahaemolyticus virulence was detected in 9 of 3,429 (0.3%) V. parahaemolyticus cultures and in 8 of 198 (4.0%) lots of oysters. These data can be used to estimate the exposure of raw oyster consumers to V. vulnificus and V. parahaemolyticus.     

Effects of a commercial heat-shock process on Vibrio vulnificus in the American oyster, Crassostrea virginica, harvested from the Gulf Coast

Oysters (Crassostrea virginica) harvested from the Gulf Coast, containing 10(2) to 10(4) most probable number (MPN) per gram of Vibrio vulnificus, were subjected to a commercial heat-shock process. After 1 to 4 min at internal oyster meat temperatures exceeding 50 degrees C, shellstock oysters were shucked, chilled, washed, and packed. V. vulnificus and total bacterial levels in Gulf Coast oysters were significantly reduced from 1 to 4 logs in the finished product. Similar reductions were not observed in shellstock oysters that were subject to conventional processing. Under the National Shellfish Sanitation Program, heat shocking is an acceptable process to use to assist in the shucking of shellstock. This research revealed that the heat-shock process may also serve to significantly reduce V. vulnificus in summer Gulf Coast oysters.     

Campylobacter, Salmonella, Listeria monocytogenes, verotoxigenic Escherichia coli, and Escherichia coli prevalence, enumeration, and subtypes on retail chicken breasts with and without skin

This study examined the prevalence, counts, and subtypes of Campylobacter, Salmonella, Listeria monocytogenes, verotoxigenic Escherichia coli (VTEC), and E. coli on raw retail chicken breast with the skin on versus the skin off. From January to December 2007, 187 raw skin-on chicken breasts and 131 skin-off chicken breasts were collected from randomly selected retail grocery stores in the Region of Waterloo, Ontario, Canada. Campylobacter isolates were recovered from a higher proportion of the skin-off chicken breasts, 55 (42%) of 131, than of the skin-on chicken breasts tested, 55 (29%) of 187 (P = 0.023). There was no difference in the proportion of Salmonella isolates recovered from the two meat types (P = 0.715): 40 (31%) of 131 skin-off chicken breasts versus 61 (33%) of 187 skin-on chicken breasts. L. monocytogenes isolates were recovered from a statistically lower proportion of the skin-off chicken breasts, 15 (15%) of 99, than of the skin-on chicken breasts, 64 (34%) of 187 (P = 0.001). There was no difference in the proportion of E. coli isolates recovered from the skin-off chicken breasts, 33 (33%) of 99, than from the skin-on chicken breasts, 77 (41%) of 187 (P = 0.204). VTEC was detected on a single skin-off chicken breast. Campylobacter jejuni was the most frequent species isolated on both types of chicken meat: skin-on, 48 (87%) of 55, and skin-off, 51 (94%) of 54. Salmonella serotypes Kentucky and Heidelberg and L. monocytogenes serotype 1/2a were the most frequently detected serotypes from both skin-off and skin-on chicken breasts. Although there appeared to be a trend toward higher enumeration values of these pathogens and E. coli on the skin-on chicken, the differences did not exceed 1 log. This study suggested that skin-off chicken breast may represent a higher risk of consumer exposure to Campylobacter, a similar risk for Salmonella, VTEC, and E. coli, and a lower risk for L. monocytogenes than skin-on chicken breast.     

Distribution of Listeria monocytogenes molecular subtypes among human and food isolates from New York State shows persistence of human disease--associated Listeria monocytogenes strains in retail environments

While there is considerable information available regarding Listeria monocytogenes contamination patterns in food processing plants, our understanding of L. monocytogenes contamination and transmission in retail operations is limited. We characterized 125 food, 40 environmental, and 342 human clinical L. monocytogenes isolates collected in New York State from 1997 to 2002 using automated ribotyping and hly allelic variation. All environmental isolates were obtained from retail establishments and the majority of food isolates (98 isolates) were obtained from foods that were prepared or handled at retail. Overall, food and/or environmental isolates from 50 different retail establishments were characterized. The 125 food and 40 environmental isolates were differentiated into 29 and 10 ribotypes, respectively. For 16 retail establishments, we found evidence for persistence of one or more specific L. monocytogenes strains as indicated by isolation of the same EcoRI ribotype from food or environmental samples collected in a given establishment on different days. The human isolates were differentiated into 48 ribotypes. Statistical analyses showed that two ribotypes were significantly (P < 0.0001) more common among food isolates as compared with human isolates. However, a total of 17 ribotypes found among the human clinical isolates were also found among the food and environmental isolates. We conclude that L. monocytogenes, including subtypes that have been linked to human disease, can persist in retail environments. Implementation of Listeria control procedures in retail operations, which process and handle products that permit the growth of L. monocytogenes, are thus a critical component of a farm-to-table L. monocytogenes control program.     

Density of total and pathogenic (tdh+) Vibrio parahaemolyticus in Atlantic and Gulf coast molluscan shellfish at harvest

The densities of total and pathogenic Vibrio parahaemolyticus in 671 samples of molluscan shellfish harvested in 1999 and 2000 from 14 sites in seven Gulf and Atlantic coast states were determined at 2-week intervals over a period of 12 to 16 months in each state. Changes in V. parahaemolyticus densities in shellfish between harvest and sample analysis were minimized with time and temperature controls. Densities were measured by direct plating techniques, and gene probes were used for identification. Total and pathogenic V. parahaemolyticus organisms were identified with probes for the thermolabile direct hemolysin (tlh) gene and the thermostable direct hemolysin (tdh) gene, respectively. An enrichment procedure involving 25 g of shellfish was also used for the recovery of pathogenic V. parahaemolyticus. The densities of V. parahaemolyticus in shellfish from all harvest sites were positively correlated with water temperature. Shellfish from the Gulf Coast typically had higher densities of V. parahaemolyticus than did shellfish harvested from the North Atlantic or mid-Atlantic coast. Vibrio parahaemolyticus counts exceeded 1,000 CFU/g for only 5% of all samples. Pathogenic (tdh+) V. parahaemolyticus was detected in approximately 6% of all samples by both procedures, and 61.5% of populations in the positive samples from the direct plating procedure were at the lower limit of detection (10 CFU/g). The frequency of detection of pathogenic V. parahaemolyticus was significantly related to water temperature and to the density of total V. parahaemolyticus. The failure to detect pathogenic V. parahaemolyticus in shellfish more frequently was attributed to the low numbers and uneven distribution of the organism.     

杨凌及周边地区零售分割鸡肉中沙门菌污染状况及耐药和分型特征研究

目的研究陕西杨凌及周边地区零售分割鸡肉中沙门菌的污染状况及其药敏性、血清型和基于脉冲场凝胶电泳(PFGE)的基因型,为预警食源性沙门菌疾病暴发提供数据基础。方法采用GB 4789.4—2010《食品安全国家标准食品微生物学检验沙门氏菌检验》对陕西杨凌及周边地区采集的188份零售分割鸡肉中沙门菌进行分离和鉴定,并进行血清学分型。采用PFGE方法确定沙门菌DNA酶切电泳图谱,使用BioNumerics软件聚类分析电泳结果,确定沙门菌基因型。结果 188份零售分割鸡肉中共有34份(18.1%)样品检出沙门菌,农贸市场样品沙门菌检出率(24.6%,29/118)高于超市(7.1%,5/70)。鸡腿、鸡爪、鸡脖和鸡肝样品中沙门菌检出率高于鸡肠和鸡胗。34株沙门菌中共检出10种血清型,其中科瓦利斯沙门菌最为流行,高于德尔卑沙门菌和鼠伤寒沙门菌等,差异有统计学意义(P0.05)。分离株均对磺胺异噁唑、氯霉素、头孢噻呋和环丙沙星耐药,对甲氧苄啶/磺胺甲噁唑、萘啶酮酸、四环素、链霉素、氨苄西林和阿莫西林/克拉维酸的耐药率均在50%以上。34株沙门菌PFGE分型后可被分为11个簇,同一血清型菌株基本聚于同一大簇,同一时间、从相同市场采集的不同样品,其分离株PFGE型相似度均较高,表明分割鸡肉在加工或销售过程可能存在交叉污染。农贸市场分离菌株基因型多样性比较丰富。结论杨凌及周边地区零售分割鸡肉存在沙门菌污染,沙门菌血清型和基因型多样化,耐药菌株比例较高。     

Serotypes and typability of Campylobacter jejuni and Campylobacter coli isolated from poultry products

Campylobacter infection is one of the most common bacterial enteric pathogens. Campylobacter jejuni and Campylobacter coli infections are mostly food- and waterborne and especially poultry is often assumed to be an important source. The heat-stable serotyping system (the 'Penner' scheme) was used to study the serotype distribution of C. jejuni and C. coli isolated from different food products of poultry origin sampled from retail outlets in Denmark. A total of 156 isolates were serotyped, 85% of these were C. jejuni and 15% were C. coli. The most common C. jejuni serotypes were O:2 (30%), O:1,44 (12%) and the O:4-complex (8%). O:46 was the most frequent serotype among C. coli isolates. These serotypes are also common among Danish clinical isolates and isolates from broiler chickens and cattle. Differences in serotype distribution were seen for different kinds of poultry products. Isolates from chicken products covered a large selection of serotypes. In contrast, the majority of the isolates from other product groups (turkey, poussin, wild birds) were concentrated on 1-3 serotypes. Using the standard procedure for antigen preparation and serotyping, 25 of the 156 strains (16%) were nontypable. This rate of nontypable isolates is significantly higher than experienced for isolates from other sources than food products, i.e faecal samples from animals and humans. Subculturing and re-typing of the nontypable isolates improved the typability. After two, five and 10 subcultures 16, six and one isolate became typable, respectively. Only three isolates (2%) remained nontypable after 10 subcultures.     

Effectiveness of icing as a postharvest treatment for control of Vibrio vulnificus and Vibrio parahaemolyticus in the eastern oyster (Crassostrea virginica)

The focus of this research was to investigate the efficacy of icing as a postharvest treatment for reduction of the levels of Vibrio vulnificus and Vibrio parahaemolyticus in commercial quantities of shellstock oysters. The experiments were conducted in June and August of 2006 and consisted of the following treatments: (i) on-board icing immediately after harvest; (ii) dockside icing approximately 1 to 2 h prior to shipment; and (iii) no icing (control). Changes in the levels of pathogenic Vibrio spp. during wholesale and retail handling for 2 weeks postharvest were also monitored. On-board icing achieved temperature reductions in all sacks in accordance with the National Shellfish Sanitation Program standard, but dockside icing did not meet this standard. Based on one-way analysis of variance, the only statistically significant relationship between Vibrio levels and treatment occurred for samples harvested in August; in this case, the levels of V. vulnificus in the noniced oysters were significantly higher (P < 0.05) than were the levels in the samples iced on-board. When analyzing counts over the 14-day storage period, using factorial analysis, there were statistically significant differences in V. vulnificus and V. parahaemolyticus levels by sample date and/or treatment (P < 0.05), but these relationships were not consistent. Treated (iced) oysters had significantly higher gaping (approximately 20%) after 1 week in cold storage than did noniced oysters (approximately 10%) and gaping increased significantly by day 14 of commercial storage. On-board and dockside icing did not predictably reduce the levels of V. vulnificus or V. parahaemolyticus in oysters, and icing negatively impacted oyster survival during subsequent cold storage.     

Comparison of antimicrobial resistance of Campylobacter jejuni isolated from humans, chickens, raw milk, and environmental water in Québec

This study compares the occurrence of antimicrobial resistance to erythromycin, ciprofloxacin, and tetracycline among 384 Campylobacter jejuni isolates from humans (245), fresh whole retail chickens (56), raw milk (33), and environmental water (41) collected between 2000 and 2003 in Québec, Canada. Resistance to ciprofloxacin was significantly more frequent in human isolates acquired abroad than in those acquired locally (50 versus 5.9%; P < 0.001); ciprofloxacin resistance was almost absent in water, chicken, and raw milk isolates. In contrast, resistance to erythromycin was significantly more common in chicken than in locally acquired human isolates (16 versus 3.0%, respectively; P < 0.001); no erythromycin resistance was found among water, raw milk, and human isolates acquired abroad. Resistance to tetracycline was significantly more common in chicken and human isolates acquired locally (58.9 and 45.8%, respectively) than in raw milk and water isolates (9.1 and 7.3%, respectively, P < 0.001). Tetracycline resistance was also observed in 44.4% of human isolates acquired abroad. No human isolate was resistant to both ciprofloxacin and erythromycin, but one chicken isolate was resistant to all three antimicrobial agents. Our results suggest that from 2000 to 2003 in Québec, antimicrobial resistance remained stable among locally acquired C. jejuni human clinical isolates and might even have decreased. However, the high erythromycin resistance rate observed among chicken isolates is concerning because of the risk of transmission of such isolates to humans. Additional studies are needed to monitor trends in antimicrobial resistance among food, environment, and human C. jejuni isolates as well as antibiotic use in animals.     

IMMUNOLOGICAL AND CYTOPATHOGENIC PROPERTIES OF LISTERIA MONOCYTOGENES ISOLATED FROM NATURALLY CONTAMINATED MEATS

Meat products have been implicated as the potential source of Listeria monocytogenes infection in humans. Here, we investigated the incidence of this organism in raw beef and poultry meat products and assessed their biochemical, immunological and cytopathogenic properties. Forty meat samples (20 beef and 20 poultry) were analyzed and the isolates were tested for sugar fermentation, hemolysin production, phospholipase activity, serotype profile, abilities to react with Listeria- specific monoclonal antibodies (MAbs) EM-7G1 and C11E9, and cytotoxic effects on hybridoma Ped-2E9 cells. Thirteen (6 beef and 7 poultry) meat samples (32.5%) were positive for L. monocytogenes. A total of 276 Listeria isolates were obtained, of which 182 (66%) were confirmed to be L. monocytogenes, 80 (29%) were L. innocua, 12 (4.3%) were L. welshimeri and 2 (0.7%) were identified as L. grayi. Fifty six percent of the L. monocytogenes isolates were serotype 4, while 42% were serotype 1, and 2% were untypeable. All but two L. monocytogenes isolates were hemolytic and phospholipase positive (99%). In the ELISA assay, MAb C11E9 showed reaction with L. monocytogenes isolates from all 13 positive meat samples (100%), while MAb EM-7G1 reacted positively with 12 of 13 positive meat samples (92.3%). Hemolysin-positive L. monocytogenes isolates were cytopathogenic to Ped-2E9 cells, while hemolysin-negative strains showed no effect. This study demonstrated that 32.5% of commercially purchased raw meat products were contaminated with cytopathogenic L. monocytogenes strains, and could be a potential source for infection in susceptible populations if these meats were not processed or cooked properly.     

生食动物性水产品中副溶血性弧菌和创伤弧菌污染状况分析

目的 了解生食动物性水产品中副溶血性弧菌和创伤弧菌污染状况。方法 采用随机抽样方法,在我国13个地区的餐饮店、零售店和批发市场采集生食动物性水产品,共计2 980份,对样品进行副溶血性弧菌和创伤弧菌检测。结果 生食动物性水产品中副溶血性弧菌检出率为14.7%(437/2 980),污染水平＞100 MPN/g的样品比例为2.9%(83/2 909);创伤弧菌检出率为3.5%(104/2 980)。采样于批发市场的样品中副溶血性弧菌检出率、污染水平＞100 MPN/g的样品比例和创伤弧菌检出率均高于餐饮店和零售店。第三季度副溶血性弧菌检出率、污染水平＞100 MPN/g的样品比例和创伤弧菌检出率最高。造成污染的主要原因包括原产地污染,储存不当及加工过程交叉污染。结论 生食动物性水产品中存在副溶血性弧菌和创伤弧菌的污染,其健康风险应引起关注,本次污染状况分析可为标准制修订提供理论依据。     

Antimicrobial resistance of Salmonella in raw retail chickens, imported chicken portions, and human clinical specimens

Salmonella isolates from raw, chilled, retail chickens (n = 434) sampled between 1998 and 2000 were tested for resistance to 12 antibiotics. Of 23 salmonellas isolated, 30% were susceptible and 30% were resistant or intermediately resistant to one antibiotic, 26% to two, and 13% to four or more. One Salmonella Saint-Paul and two Salmonella Typhimurium isolates were resistant to more than four antibiotics. Highest resistance rates were sulfonamide (52%), streptomycin (26%), tetracycline (22%), and ampicillin (17%). Isolates (n = 27) from frozen chicken portions (n = 150) imported from Brazil and Thailand (generally for manufacturing and catering) were also tested. Brazilian salmonellas showed no multiple resistance, but an isolate of Salmonella Virchow from Thai chickens was resistant to two antibiotics. This compared with 39% resistance to two or more antibiotics in nonimported isolates. Resistance patterns of both sets of chicken isolates were compared with human fecal clinical isolates (n = 274) submitted for routine examination at this hospital, and a greater similarity was found between the clinical and local isolates than with imported salmonellas. Sulfonamide resistance in imported salmonellas was lower than that of nonimported and clinical isolates. Resistance to one or more antimicrobial was found in 70% of nonimported raw retail chickens, 52% of imported chicken breast fillets, and 84% of human fecal isolates. Multiple resistance (to four or more antibiotics) is a much more limited problem.     

Growth and stress resistance variation in culture broth among Listeria monocytogenes strains of various serotypes and origins

Twenty-five Listeria monocytogenes strains of various serotypes and sources, including clinical and food isolates associated with the same outbreaks, were characterized and compared based on growth rates and heat and acid death rates. Growth was monitored in tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) at 4 and 30 degrees C for 32 days and 20 h, respectively. Heat and acid stress responses in TSBYE heated to 55 degrees C or acidified to pH 3.0 with lactic acid were evaluated for 240 or 120 min, respectively. Extensive variation in growth and stress resistance was observed among the tested strains. Growth rate differences were less evident at 30 than at 4 degrees C, where growth rates (log CFU per milliliter per day) ranged from 0.28 to 0.43. Thermal and acid death rates (log CFU per milliliter per minute) ranged from -0.023 to -0.052 and from -0.012 to -0.134, respectively. Serotype appeared to play a significant role (P < 0.05) only with respect to the heat resistance of the organism. Serotype 4b isolates as a group had lower heat resistance than did isolates representing all other serotypes combined. Although no clear origin-related (food versus clinical) trends were observed under the tested conditions, outbreak-related isolates of serotype 4b had lower acid death rates (higher acid resistance) (P < 0.05) than did the rest of the strains belonging to this serotype. Strain Scott A exhibited slow growth at 4 degrees C and low acid resistance, behavior that was distinct among both clinical and serotype 4b isolates. The results of this study highlight the risks associated with extrapolation to other strains of findings obtained with only one strain of L. monocytogenes. This information should be useful when test strains are to be selected for the evaluation of antimicrobial alternatives in ready-to-eat meat and other food products and when risk assessments are to be conducted.     

Characterization of Listeria monocytogenes isolated from retail foods

Listeria monocytogenes isolates recovered from retail ready-to-eat (RTE) meats, raw chickens and fresh produce were characterized by serogroup identification using PCR, genotyping using pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. Five L. monocytogenes serogroups were identified. Of the 167 isolates 68 (41%) belonged to serogroup 1/2b, 3b; 53 (32%) belonged to serogroup 4b, 4d, 4e; 43 (26%) belonged to serogroup 1/2a, 3a; 2 (1.2%) belonged to serogroup 1/2c, 3c; and 1 (0.6%) belonged to serogroup 4a, 4c. PFGE generated 120 patterns which correlated well with PCR serogrouping. Most L. monocytogenes isolates were resistant to sulfonamide (73%) and some were resistant to tetracycline (8.4%) and ciprofloxacin (1.8%). Tetracycline resistance was conjugatively transferable and the tet(M) gene was identified in 14 tetracycline-resistant isolates as well as their transconjugants. These findings indicate that L. monocytogenes present in food were diverse, and that resistance to one or more antibiotics among these isolates was common. In addition, the presence of potential serotype 4b in all food categories is of public health concern, as serotype 4b has been the serotype most frequently associated with human listeriosis.     

鸡肉源沙门氏菌血清型、药敏性及部分耐药基因研究

目的:研究432株分离于陕西省杨凌及周边城市零售鸡肉中沙门氏菌的血清型分布、药敏性及其与(氟)喹诺酮类抗菌药物抗性相关耐药基因的流行状况。方法:按照玻片凝集法鉴定血清型,使用临床和实验室标准协会推荐的琼脂稀释法测定沙门氏菌的药敏性,聚合酶链式反应(polymerase chain reaction,PCR)方法确定沙门氏菌中与(氟)喹诺酮类抗生素耐药相关基因。结果:432株沙门氏菌中除36株血清型未定外,其余396株沙门氏菌共涵盖37个血清型,其中鼠伤寒沙门氏菌(Salmonella typhimurium,检出率17.93%)、汤普森沙门氏菌(Salmonella thompsons,检出率12.88%)、埃森沙门氏菌(Salmonella essen,检出率8.84%)和婴儿沙门氏菌(Salmonellainfants,检出率6.57%)等血清型比较常见。沙门氏菌对磺胺异噁唑(耐药率89.81%)耐药最为普遍,对磺胺甲噁唑、萘啶酮酸、四环素、氨苄西林、氯霉素和阿莫西林-克拉维酸等抗生素的耐药率均在50%以上。aac(6’)-Ib-cr基因检出率(16.67%)最高,qnr B、qnr S和qnr A的检出率分别为10.19%、6.71%和1.62%,且该4种基因在不同血清型菌株中分布不同。菌株携带qnr和aac(6’)-Ib-cr基因越多,对(氟)喹诺酮类和氨基糖苷类协同耐药性越强。结论:陕西省杨凌及周边城市零售鸡肉源沙门氏菌的血清型种类繁多,耐药比较普遍。     

Antimicrobial resistance types and genes in Salmonella enterica infantis isolates from retail raw chicken meat and broiler chickens on farms

Salmonella enterica subsp. enterica serotype Infantis isolates from retail raw chicken meat (n = 98) and broiler chickens on farms (n = 70) were examined for antimicrobial susceptibility and antimicrobial resistance genes. A total of 15 antimicrobial resistance types, 14 in meat and 10 in broiler isolates, were identified, and 9 of the 15 types were indistinguishable between meat and broiler isolates. Resistance to both oxytetracycline and dihydrostreptomycin accounted for 94.0% of the resistance types in meat and broiler isolates, and each type harbored aadA1 within 1.0 kb of class 1 integron and tetA. Of nalidixic acid resistance types, point mutations at 87Asp (GAC) to Tyr (TAC) in the quinolone resistance-determining region of gyrA was detected in 10 of 13 meat isolates and at 87Asp to Asn (AAC) in four of seven broiler isolates. These findings suggest that the antimicrobial resistance of Salmonella Infantis in retail chicken meat predominantly originates from broiler chickens.     

Vibrio parahaemolyticus, Vibrio vulnificus and microorganisms of fecal origin in mussels (Mytilus galloprovincialis) sold in the Puglia region (Italy)

Mytilus galloprovincialis is one of the most commonly consumed of all bivalve molluscs. The consumption of raw bivalve molluscs has caused outbreaks of food poisoning due to Vibrio parahaemolyticus and Vibrio vulnificus. This paper reports the results of a survey on the presence of V. parahaemolyticus, V. vulnificus fecal coliform bacteria, Escherichia coli and Salmonella spp. in 600 M. galloprovincialis samples collected from retail outlets in the Puglia region. V. parahaemolyticus and V. vulnificus were found in 47 (7.83%) and 17 (2.83%) of the samples, respectively. One sample (0.16%) was contaminated with Salmonella spp. but no relationship was observed between vibrios and fecal coliforms and E. coli. There were no significant differences among vibrios present in bivalve molluscs during the 3-year survey.     

2018年广州市水产品中创伤弧菌和河弧菌检测分析

目的 了解为期一年的监测中广州市水产品创伤弧菌和河弧菌污染水平、菌株携带毒力基因和分子分型情况。方法 对广州市水产品中创伤弧菌和河弧菌进行分离鉴定,毒力基因鉴定和肠道细菌基因间重复序列聚合酶链式反应(Eric-PCR)。结果 创伤弧菌阳性率为10.4%(31/298),河弧菌为5.0%(15/298)；用PCR法检测创伤弧菌毒力溶血素基因vvhA全部阳性,vcgC/E和16S rRNA A/B分型结果显示,共有CB型、EA型和CA型3种基因型别。河弧菌毒力相关基因vfh、toxR全部阳性,hupO携带率为60.0%(9/15)、vfp携带率为80.0%(12/15)；Eric-PCR扩增出8～14条100～2 000 bp之间的条带,将15株河弧菌在相似系数为0.8处分为5个群11个类型。结论 广州市水产品中创伤弧菌和河弧菌污染情况较严重,大部分菌株携带毒力基因,Eric-PCR结果显示15株河弧菌在亲缘关系上具有相关性,应加强防控。     

Frequency and antimicrobial resistance of Salmonella serotypes on beef carcasses at small abattoirs in Jalisco State, Mexico

The prevalence and antimicrobial resistance of Salmonella serotypes on beef carcasses from four small abattoirs in Jalisco State, Mexico, were investigated during a 10-month period. Following U.S. Department of Agriculture Food Safety and Inspection Service protocols, Salmonella was isolated from 78 (15.4%) beef carcasses (n = 505) after the final carcass water wash. Isolation frequency differed by establishment (P < 0.05) and was higher (P < 0.05) during the wet season (May through September) for all establishments. Thirteen Salmonella serotypes and four serogroups (partially serotyped isolates) were identified. The most prevalent were Salmonella enterica Give (24.4%), Salmonella Typhimurium (17.9%), and Salmonella Group B (14.1%). Antimicrobial susceptibility was tested against 11 drugs, and results indicated that 46.2% of the isolates were resistant to tetracycline, 42.3% were resistant to streptomycin, 23.1% were resistant to chloramphenicol, 21.8% were resistant to trimethoprim-sulfamethoxazole, and 19.2% were resistant to gentamicin. No resistance to ceftriaxone or ciprofloxacin was observed, and 33% of the isolates were resistant to three or more antimicrobials. Although Salmonella Give was the most prevalent serotype, 95% of the isolates of this serotype were susceptible to all antimicrobials tested. Antimicrobial resistance was more common in Salmonella Typhimurium, and 93% (13 of 14) of the isolates of this serotype were resistant to at least five antimicrobials. The frequency of multidrug-resistant Salmonella isolates differed among establishments (P < 0.05) and may be related to the origin of the cattle presented for harvesting. These findings highlight the need for control measures to reduce Salmonella prevalence on beef carcasses in small abattoirs in Mexico and for strategies to ensure the cautious use of antimicrobials in animal production to prevent and control the spread of antimicrobial-resistant foodborne pathogens.     

2007—2008年西安地区鸡肉源沙门氏菌相关特性分析

目的:研究260株2007—2008年分离于西安市零售鸡肉中沙门氏菌的药敏性、血清型和基因型,以确保食品安全。方法:使用临床实验室标准化委员会(the Clinical and Laboratory Standards Institute,CLSI)推荐的琼脂稀释法测定沙门氏菌的药敏性;世界卫生组织(WHO)推荐的玻片凝集法测定沙门氏菌的血清型;使用美国疾病预防控制中心推荐的脉冲场凝胶电泳法确定沙门氏菌的DNA酶切图谱,BioNumerics软件分析电泳结果,确定沙门氏菌的基因型。结果:沙门氏菌对萘啶酮酸、环丙沙星、左氧氟沙星、加替沙星、氨苄西林、阿莫西林-克拉维酸、头孢哌酮、头孢曲松和头孢西丁的耐药率分别为81.4%、29.2%、22.4%、21.8%、34.6%、37.7%、32.6%、23.1%和1.9%。260株沙门氏菌共涵盖21个血清型,以肠炎沙门氏菌(Salmonella Enteritidis)、舒卜拉沙门氏菌(S.Shubra)、印第安纳沙门氏菌(S.Indiana)、鼠伤寒沙门氏菌(S.Typhimurium)、丘古沙门氏菌(S.Djugu)、德尔卑沙门氏菌(S.Derby)、维尔肖沙门氏菌...