Isolation and characterization of Escherichia coli O157:H7 from retail meats in Argentina

Between February and May 2000, 279 meat samples were collected from 136 retail stores in Gualeguaychú City, Argentina. Samples were assayed for Escherichia coli O157:H7 by selective enrichment in modified EC broth containing novobiocin, followed by immunomagnetic separation (IMS) and plating onto both sorbitol MacConkey agar supplemented with cefixime and potassium tellurite and a chromogenic medium. Eleven E. coli O157:H7 isolates were detected in 6 (3.8%) of 160 ground beef samples, in 4 (4.8%) of 83 fresh sausages, and in 1 (3.3%) of 30 dry sausages. E. coli O157:H7 was not isolated from five hamburger patties or one barbecue-type fresh sausage assayed. The isolates were tested for virulence-related genes. Ten additional Shiga toxin-producing E. coli (STEC) O157:H7 isolates of food origin, recovered from different locations in Argentina, were included for comparison purposes. All 21 isolates harbored both eae and EHEC-hlyA genes, and 12 (57.1%) encoded stx2/stx2vh-a. The isolates were of phage types 87 (seven strains), 14 (four strains), 4 (three strains), and 26 (one strain). Six strains were nontypable by phage typing. Pulsed-field gel electrophoresis (PFGE) revealed 19 XbaI-PFGE profiles. Fifteen (71%) strains were grouped in four clusters, which shared more than 80% of DNA restriction fragments. The enrichment culture method with IMS was a sensitive procedure to detect E. coli O157:H7 strains in retail meats. Some of the isolates from different stores presented a high clonal relatedness, as determined by XhaI-PFGE and phage typing, and harbored the virulence factors associated with human illness.     

Identification and antimicrobial resistance of extraintestinal pathogenic Escherichia coli from retail meats

Extraintestinal pathogenic Escherichia coli (ExPEC) causes a variety of infections outside the gastrointestinal tract. Retail meats are frequently contaminated with E. coli strains, and they might serve as a vehicle for transmitting ExPEC. A total of 1,275 E. coli isolates recovered from ground beef, ground turkey, chicken breasts, and pork chops obtained in Georgia, Maryland, Oregon, and Tennessee in 2006 were investigated for the presence of ExPEC by using multiplex PCR. Identified ExPEC isolates were assigned to serogroups and phylogenetic groups and then analyzed for antimicrobial susceptibility. Approximately 16% (200 of 1,275) of the E. coli isolates were identified as ExPEC, based on defined genetic criteria. The occurrence of ExPEC was highest in E. coli isolated from ground turkey (23.5%) and chicken breasts (20.2%), and less frequent in isolates from pork chops (8.3%) and ground beef (3.4%). Phylogenetic grouping revealed that most (66.5%) ExPEC isolates fell into the same phylogenetic groups (B2 and D) as did virulent human ExPEC strains. Among the 15 antimicrobial agents tested, resistance to tetracycline (67.0%), sulfisoxazole (59.5%), and streptomycin (46.0%) was most frequent. Most ExPEC isolates (n = 163 [81.5%]) were resistant to at least one antimicrobial agent, and more than half (n = 114 [57%]) exhibited resistance to at least three drugs. This study found that ExPEC strains, including antimicrobial-resistant strains, were frequent among E. coli recovered from retail meats, especially those from chicken and turkey products. These findings indicate a need to better understand the role of certain meat types as potential sources of human ExPEC infection.     

Occurrence and survival of verocytotoxin-producing Escherichia coli O157 in meats obtained from retail outlets in The Netherlands.

In 1996 and 1997, 2,941 fresh and processed meat products obtained from supermarkets and butcher shops in The Netherlands were examined for the presence of verocytotoxin-producing Escherichia coli of serogroup O157 (O157 VTEC). Additionally, the fate of O157 VTEC in raw meat products stored at low temperatures and the effect of different additives were evaluated. O157 VTEC strains were isolated from 6 (1.1%) of 571 samples of raw minced beef, 2 (0.5%) of 402 samples of raw minced mixed beef and pork, 1 (1.3%) of 76 samples of raw minced pork, 1 (0.3%) of 393 samples of other raw pork products, and 1 (0.3%) of 328 samples of cooked or fermented ready-to-eat meats. Other raw beef products (n = 223) and meat samples originating from poultry (n = 819), sheep or lamb (n = 46), or wild animals (n = 83) were all found to be negative for O157 VTEC. For the survival experiments we used tartaar (minced beef with a fat content of less than 10%) and filet americain (tartaar mixed with a mayonnaise-based sauce [80 to 20%]). The O157 VTEC strain tested was able to survive in tartaar and filet americain stored at -20, 0, 5, or 7 degrees C for 3 days. At both 7 and at 15 degrees C, O157 VTEC counts in tartaar and filet americain remained virtually unchanged throughout a storage period of 5 days. Addition of acetic acid (to pH 4.0), sodium lactate (1 and 2% [wt/wt]), or components of the lactoperoxidase-thiocyanate-hydrogen peroxide system to filet americain did not result in a reduction of viable O157 VTEC cells during storage at 7 or 15 degrees C. It was concluded that raw meat contaminated with O157 VTEC will remain a hazard even if the meat is held at low or freezing temperatures.     

Antimicrobial resistance and molecular subtyping of Campylobacter jejuni and Campylobacter coli from retail meats

Campylobacter isolates (n = 297; 202 C. jejuni and 95 C. coli isolates) recovered from 2,513 retail meat samples (chicken breasts, ground turkey, ground beef, and pork chops) were examined for antimicrobial susceptibility. The isolates were further analyzed for genetic relatedness by pulsed-field gel electrophoresis (PFGE) using SmaI and KpnI restriction enzymes, and a subset of isolates (n = 174) were subtyped by multilocus sequence typing (MLST). The resistance most frequently observed was that to doxycycline (27.6%), followed by ciprofloxacin (13.8%) and erythromycin (6.4%). All isolates were susceptible to gentamicin and meropenem. C. coli showed higher resistance to doxycycline than did C. jejuni (42.1 versus 20.8%) and lower resistance to ciprofloxacin than did C. jejuni (10.5 versus 15.3%). Erythromycin resistance was only observed in C. coli. PFGE using SmaI plus KpnI digestion generated 168 clusters from 297 isolates: 115 from C. jejuni and 53 from C. coli. MLST revealed 44 sequence types (STs) under 10 clonal complexes from 120 C. jejuni and 27 STs under two clonal complexes from 54 C. coli. There was a positive association between PFGE and STs; however, PFGE showed greater discriminatory power than MLST. Subtyping data did not correlate with antimicrobial resistance phenotypes.     

Isolation of Arcobacter spp. from retail meats and cytotoxic effects of isolates against vero cells

A survey of Arcobacter spp. was conducted over a 12-month period in Guadalajara, Mexico. A total of 135 samples (45 lean ground beef samples, 45 lean ground pork samples, and 45 chicken samples, including drumsticks, gizzards, and ground or chopped breast) were collected from local butcheries. The samples were enriched in Johnson-Murano enrichment medium and then streaked onto Johnson-Murano agar plates. Typical colonies were subjected to microscopic and biochemical identification followed by polymerase chain reaction confirmation of the genus Arcobacter. All isolates confirmed to be Arcobacter isolates were then inoculated into Eagle's minimum essential medium to determine their cytotoxicity against Vero cells. Arcobacter spp. were detected in 28.8, 51.1, and 40.0% of beef, pork, and chicken samples, respectively. From these samples, 101 isolates were confirmed to be Arcobacter spp. by polymerase chain reaction. Overall, the species most frequently identified was A. butzleri, followed by A. skirrowii. A. cryaerophilus was isolated only from pork meat. Ninety-five (95%) of the Arcobacter isolates produced a virulence mechanism against Vero cells, and 38 of them induced cell elongation, indicating enterotoxin production. Eighteen isolates produced the formation of vacuoles, and 39 produced both vacuolization and elongation. The vacuolization effect may be related to a vacuolizing toxin. The production of a vacuolizing toxin by Arcobacter spp. has not previously been reported. Results obtained in this study indicate that Arcobacter spp. may show cytotoxic effects other than the recognized enterotoxin production.     

Antimicrobial susceptibility of Staphylococcus aureus from retail ground meats

The aim of this study was to characterize antimicrobial resistance in Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), recovered from raw retail meat products purchased in the Washington, D.C., area. From March to August 2008, 694 samples of ground beef (n = 198), ground pork (n = 300), and ground turkey (n = 196) were collected by random sampling from stores of three grocery chains. In total, 200 S. aureus isolates (29%) were recovered by direct plating. When tested for susceptibility to 22 antimicrobials, 69% of the S. aureus isolates were resistant to tetracycline, 26% to penicillin, 17% to ampicillin, 13% to methicillin, 8% to erythromycin, 4.5% to clindamycin, 1.5% to gentamicin, and 0.5% to chloramphenicol, oxacillin, cefoxitin, or quinupristin-dalfopristin. However, 27% of the isolates were susceptible to all tested antimicrobials. More turkey and pork isolates were resistant to ampicillin, penicillin, and tetracycline than were beef isolates (P < 0.05). Additionally, 17% of the turkey and 17% of the pork isolates were resistant to methicillin (MIC ≥ 16 μg/ml), whereas no beef isolates were resistant to the antimicrobial agent. A single MRSA (methicillin MIC > 32 μg/ml) isolate containing the mecA gene with additional resistance to erythromycin, clindamycin, oxacillin plus 2% NaCl, cefoxitin, ampicillin, penicillin, quinupristin-dalfopristin, tetracycline, and gentamicin was recovered from one pork sample. The presence of antimicrobial-resistant S. aureus, coupled with the relative lack of such studies in the United States, suggests that further investigations on MRSA in the food supply are needed despite the low rate of MRSA found in this particular study.     

Antimicrobial resistance in Escherichia coli isolated from retail milk-fed veal meat from Southern Ontario, Canada

This study estimated the prevalence of Escherichia coli isolates in fresh retail milk-fed veal scallopini pieces obtained from grocery stores in Ontario, Canada. In addition, the prevalence and antimicrobial resistance patterns were examined for points of public health significance. One hundred fifty-three milk-fed veal samples were collected over the course of two sampling phases, January to May 2004 and November 2004 to January 2005. E. coli isolates were recovered from 87% (95% confidence interval, 80.54 to 91.83%) of samples, and antimicrobial susceptibility testing was conducted on 392 isolates. The prevalence of resistance to one or more antimicrobials was 70% (274 of 392), while the resistance to five or more antimicrobials was 33% (128 of 392). Resistance to ceftiofur (2.8%), ceftriaxone (3.6%), nalidixic acid (12%), and ciprofloxacin (3.8%) alone or in combination was observed. Eighty-five resistance patterns were observed; resistance to tetracycline only (7.4%) was observed most frequently. Individual antimicrobial resistance prevalence levels were compared with grain-fed veal and retail beef data from samples collected in Ontario. In general, resistance to individual antimicrobials was observed more frequently in E. coli isolates from milk-fed veal than in isolates from grain-fed veal and beef. Resistance to one or more antimicrobials and to five or more antimicrobials in E. coli isolates was more frequent in isolates from milk-fed veal than in isolates from grain-fed veal and beef. This study provides baseline data on the occurrence of resistance in E. coli isolates from milk-fed veal that can be compared with data for other commodities. Additionally, E. coli resistance patterns may serve as an indicator of antimicrobial exposure.     

Isolation and characterization of the Shiga toxin gene (stx)-bearing Escherichia coli O157 and non-O157 from retail meats in Shandong Province, China, and characterization of the O157-derived stx2 phages

Infection by Shiga toxin (Stx)-producing Escherichia coli of non-O157 and O157 serotypes are rare in China, but infection by O157 serotype was found in Shandong Province and three other provinces in China. To understand the reason for these rare infections and to determine the safety of retail meats in Shandong Province, we examined the distribution of Shiga toxin gene (stx)-bearing E. coli in retail meats and characterized the isolated stx-bearing strains. We used hybridization with DNA probes and isolated stx1- and/or stx2-positive E. coli from 31 (58%) of 53 retail meat samples, with beef showing the highest frequency (68%). Of 42 stx-positive isolates, none belonged to O157. Using the O157-specific immunomagnetic bead technique, we isolated E. coli O157 carrying the eae and stx2 genes from eight beef samples (26%). These strains produced little or no Stx2 and carried a unique q gene. Replication of the stx2 phages was detected in these strains, whereas stx2 phage replication was not detected in our previous study in which we examined similar stx2-bearing E. coli O157 strains from other Asian countries. Analysis of E. coli C600 lysogenized with the stx2 phages found in this study suggests that the lack of Stx2 production is due to changes in non-q gene region(s) of the phage genome or chromosomal mutation(s) in the host. Our data and reports by other workers suggest it is necessary to determine if various stx2-bearing E. coli O157 strains producing Stx2 to varying degrees are distributed in meats in various locations in China.     

Prevalence and antimicrobial resistance of enterococci isolated from retail fruits, vegetables, and meats

Although enterococci are considered opportunistic pathogens, they can be reservoirs of antimicrobial resistance. Antimicrobial resistance is increasingly important because of foodborne illnesses from meat and infections from produce. From 2000 through 2001, food items (vegetables, fruits, and meats) were obtained from grocery store chains in northern Georgia and cultured for the presence of enterococci; 47.7% (189 of 396) of these samples were positive for enterococci. For the fruits and vegetables, enterococci were cultured most often from tomatoes (9 of 27 samples, 33%) and radishes (10 of 11 samples, 91%), respectively. Among the meat items tested, enterococci were isolated from 95% (21 of 22) of the chicken samples, 73% (16 of 22) of the beef samples, 95% (20 of 21) of the turkey samples, and 68% (15 of 22) of the pork samples. The predominant species identified was Enterococcus faecalis (n = 80) from meat and Enterococcus casseliflavus (n = 66) from fruits and vegetables. Although high numbers of isolates were resistant to lincomycin (176 of 185 isolates, 95.1%) and bacitracin (150 of 185 isolates, 81.1%), very few isolates were resistant to salinomycin (2 isolates, 1.1%), penicillin (3 isolates, 1.6%), or nitrofurantoin (9 isolates, 4.9%). None of the isolates were resistant to linezolid or vancomycin. These data suggest that foods commonly purchased from grocery stores are a source of enterococci; however, overall resistance to antimicrobials is relatively low.     

猪肉源大肠杆菌分离鉴定及其生物被膜形成

为研究猪肉来源大肠杆菌分离菌株的生物被膜形成及相关基因表达变化,首先从生猪屠宰线、猪胴体表面及生鲜猪肉中采用选择平板和特异性聚合酶链式反应（polymerase chain reaction,PCR）分离鉴定大肠杆菌,采用微孔板结晶紫染色法评价分离菌株15 ℃培养72 h时生物被膜形成能力,进而选取代表菌株研究生物被膜形成过程中被膜量、胞外聚合物（extracellular polymeric substances,EPS）组成,以及基于反转录荧光定量PCR的成膜基因表达的变化。结果表明：共分离到猪肉源大肠杆菌31 株,包括生猪屠宰线11 株、猪胴体表面4 株、生鲜猪肉16 株;微孔板结晶紫染色结果显示,被膜形成能力存在明显菌株差异,64.52%菌株成膜能力较弱,选取其中1 株（D4-18）进行成膜过程研究;微孔板中菌株D4-18 15 ℃培养168 h过程中被膜量持续增加,培养72 h和168 h时,菌株D4-18分泌EPS,培养72 h时,papC、fimH、csgA基因表达量分别为0.095、0.933、0.435 copies/cm2,随着培养时间延长,松散型EPS中蛋白质及多糖含量、紧密型EPS中蛋白质含量极显著增加（P＜0.01）,培养168 h时,papC和fimH基因表达量增加,csgA基因表达量无显著变化,表明上述基因在大肠杆菌生物被膜形成过程中发挥了不同程度的调控作用。     

Effect of antimicrobial proteins from porcine leukocytes on Staphylococcus aureus and Escherichia coli in comminuted meats

Study is aimed to elucidate the effect of porcine leukocyte antimicrobial protein on the proliferation of Staphylococcus aureus and Escherichia coli inoculated in ground meats. The antimicrobial proteins were isolated from porcine blood using 0.2 M sodium acetate extraction and cation-exchange column chromatography. Antimicrobial protein preparation consisted predominantly of 7.5 and 6 kDa molecules. Immunoblotting demonstrated that the 7.5 kDa molecule displayed defensin immuno-reactivity, a unique blood granulocyte antimicrobial protein. Both 7.5 and 6 kDa molecules could decrease apparent proliferation of test cultures. Sterilization (121?°C, 30 min) and proteolytic enzymes (pepsin, trypsin, and chymotrypsin) could significantly decrease bacteriocidal activities of antimicrobial protein preparation. Furthermore, antimicrobial protein preparation enhanced exposure of intercellular nucleotide of test cultures. Antimicrobial protein preparation inhibition of S. aureus and E. coli growth was concentration and time dependence. Adding 160 μg/g antimicrobial protein preparation to ground ham meat and sausage mince could significantly (P<0.05) hurdle viable colony formation of test cultures at 6 and 12 h, respectively. Taken together, porcine leukocyte antimicrobial protein preparation has potential to inhibit proliferation of S. aureus and E. coli inoculated in ground meat via induction of bacterolysis, suggesting this antimicrobial protein preparation be an alternative natural bio-preservation source for ground meat products.     

Antimicrobial resistance in Campylobacter, Salmonella, and Escherichia coli isolated from retail grain-fed veal meat from Southern Ontario, Canada

This study estimated the prevalence of Salmonella, Campylobacter, and Escherichia coli isolates in fresh retail grain-fed veal obtained in Ontario, Canada. The prevalence and antimicrobial resistance patterns were examined for points of public health significance. Veal samples (n = 528) were collected from February 2003 through May 2004. Twenty-one Salmonella isolates were recovered from 18 (4%) of 438 samples and underwent antimicrobial susceptibility testing. Resistance to one or more antimicrobials was found in 6 (29%) of 21 Salmonella isolates; 5 (24%) of 21 isolates were resistant to five or more antimicrobials. No resistance to antimicrobials of very high human health importance was observed. Ampicillin-chloramphenicolstreptomycin-sulfamethoxazole-tetracycline resistance was found in 5 (3%) of 21 Salmonella isolates. Campylobacter isolates were recovered from 5 (1%) of 438 samples; 6 isolates underwent antimicrobial susceptibility testing. Resistance to one or more antimicrobials was documented in 3 (50%) of 6 Campylobacter isolates. No Campylobacter isolates were resistant to five or more antimicrobials or category I antimicrobials. E. coli isolates were recovered from 387 (88%) of 438 samples; 1,258 isolates underwent antimicrobial susceptibility testing. Resistance to one or more antimicrobials was found in 678 (54%) of 1,258 E. coli isolates; 128 (10%) of 1,258 were resistant to five or more antimicrobials. Five (0.4%) and 7 (0.6%) of 1,258 E. coli isolates were resistant to ceftiofur and ceftriaxone, respectively, while 34 (3%) of 1,258 were resistant to nalidixic acid. Ciprofloxacin resistance was not detected. There were 101 different resistance patterns observed among E. coli isolates; resistance to tetracycline alone (12.7%, 161 of 1,258) was most frequently observed. This study provides baseline prevalence and antimicrobial resistance data and highlights potential public health concerns.     

Prevalence and characterization of typical and atypical Escherichia coli from fish sold at retail in Cochin, India

Escherichia coli is a common contaminant of seafood in the tropics and is often encountered in high numbers. The count of E. coli as well as verotoxigenic E. coli O157:H7 was estimated in 414 finfish samples composed of 23 species of fresh fish from retail markets and frozen fish from cold storage outlets in and around Cochin, India. A total of 484 presumptive E. coli were isolated, and their indole-methyl red-Voges-Proskauer-citrate (IMViC) pattern was determined. These strains were also tested for labile toxin production by a reverse passive latex agglutination method and checked for E. coli serotype O157 by latex agglutination with O157-specific antisera. Certain biochemical marker tests, such as methylumbelliferyl-beta-glucuronide (MUG), sorbitol fermentation, decarboxylase reactions, and hemolysis, which are useful for screening pathogenic E. coli, were also carried out. Results showed that 81.4% of the E. coli isolates were sorbitol positive. Among this group, 82% were MUG positive, and 14.46% of the total E. coli isolates showed human blood hemolysis. None of the isolates were positive for agglutination with E. coli O157 antisera nor did any produce heat-labile enterotoxin. This study indicates that typical E. coli O157 or labile toxin-producing E. coli is absent in the fish and fishery environments of Cochin (India). However, the presence of MUG and sorbitol-negative strains that are also hemolytic indicates the existence of aberrant strains, which require further investigation.     

Isolation of shiga toxigenic Escherichia coli from raw beef in Palestine

Shiga toxigenic Escherichia coli (STEC) isolated from raw beef samples in northern Palestine during a 1-year period were characterized for virulence genes by a polymerase chain reaction (PCR) assay and screened for their antibiotic resistance. STEC was identified in 44 (14.7%) of 300 raw beef samples. Twelve (27.3%) of the STEC isolates were serotype O157. Nine of those were isolated during summer. The majority of STEC isolates (70.5%) harbored both stx1 and stx2 genes, while the others harbored either stx1 or stx2. High levels of resistance against different antimicrobial agents were detected. Resistance to at least three drugs was found in 55% of the isolates.     

Prevalence of Shiga toxin-producing Escherichia coli in ground beef and cattle feces from King County,Washington

Shiga toxin-producing Escherichia coli (STEC) is increasingly recognized as a common cause of diarrhea. STEC infection is a major public health threat because of its ability to cause serious and potentially life-threatening illnesses. The main reservoirs of STEC are believed to be the intestinal tracts of animals. Several studies have investigated the prevalence of STEC in various food items. The objective of this study was to determine the prevalence of STEC in the Seattle ground beef supply. In addition, the relative amount of STEC contamination between stores was compared, and possible differences between types of ground beef based on fat content (9, 16, and 23%) were investigated. A survey of Stx-I and/or Stx-II genes in fecal samples from cattle at a local slaughterhouse was also conducted. Of 296 ground beef samples tested from area retail grocery stores, 16.8% were positive for the presence of the toxin genes. Our data showed that there was no statistically significant difference (P > 0.05) in the prevalence of STEC between the ground beef samples of different fat contents and between grocery store chains. Of the 103 cattle fecal samples tested, 19 (18.4%) were found positive for the presence of Stx-I and/or Stx-II genes. The presence of a rather high percentage of STEC in the food supply in the absence of large number of cases suggests that not all STEC lineages are pathogenic for humans.     

Incidence of enterohemorrhagic Escherichia coli, Escherichia coli O157, Salmonella, and Listeria monocytogenes in retail fresh ground beef, sprouts, and mushrooms

The objective of this study was to determine the prevalence of enterohemorrhagic Escherichia coli (EHEC), E. coli O157, Salmonella, and Listeria monocytogenes in retail food samples from Seattle, Wash. A total of 2,050 samples of ground beef (1,750 samples), mushrooms (100 samples), and sprouts (200 samples) were collected over a 12-month period and analyzed for the presence of these pathogens. PCR assays, followed by culture confirmation were used to determine the presence or absence of each organism. Of the 1,750 ground beef samples analyzed, 61 (3.5%) were positive for EHEC, and 20 (1.1%) of these were positive for E. coli O157. Salmonella was present in 67 (3.8%) of the 1,750 ground beef samples. Of 512 ground beef samples analyzed, 18 (3.5%) were positive for L. monocytogenes. EHEC was found in 12 (6.0%) of the 200 sprout samples, and 3 (1.5%) of these yielded E. coli O157. Of the 200 total sprout samples, 14 (7.0%) were positive for Salmonella and none were positive for L. monocytogenes. Among the 100 mushroom samples, 4 (4.0%) were positive for EHEC but none of these 4 samples were positive for E. coli O157. Salmonella was detected in 5 (5.0%) of the mushroom samples, and L. monocytogenes was found in 1 (1.0%) of the samples.     

Phenotypic and genetic characterization of antimicrobial resistance in Salmonella serovars isolated from retail meats in Alberta, Canada

This study determined the prevalence of Salmonella serovars, antimicrobial resistance (AMR) and resistance genes in Salmonella isolated from retail meats purchased in Alberta, Canada. Samples were collected during one year period (May 2007–April 2008) on weekly basis from 19 census divisions in Alberta. A total of 564 samples including chicken (n = 206), turkey (n = 91), beef (n = 134) and pork (n = 133) were purchased. Salmonella were recovered from chicken (40%), turkey (27%) and pork (2%) samples and was not found in ground beef. A total of 21, 8, and 3 different serovars were recovered from chicken, turkey and pork meats, respectively. Salmonella Hadar was most common in chicken whereas S. Heidelberg was common in turkey meat. Overall 29% (32/110) of isolates were susceptible to tested antimicrobials and resistance to ciprofloxacin, amikacin and nalidixic acid was not found in any isolate. Multiresistance (≥2 antimicrobials) was found in 56% of isolates. Resistance to amoxicillin–clavulanic acid (AMC), ceftiofur (TIO), and ceftriaxone (CRO) was found in about 21% of chicken and 25% of turkey isolates. Resistance to either of tetracycline (TET), streptomycin (STR) or ampicillin (AMP) was unconditionally associated with S. Hadar but resistance to either of TET, AMP, AMC, TIO, CRO or cefoxitin was associated with S. Heidelberg. The strA/B (42% isolates), tet(A) (28% isolates), bla_CMY-2 (21% isolates) and bla_TEM (17% isolates) were the most common resistance genes found. The bla_CMY-2 and bla_TEM genes were unconditionally associated with S. Heidelberg; tet(A) and strA/B with S. Hadar and tet(B) gene with S. Kentucky. The strA/B genes were not associated with S. Heidelberg. Our data suggests that the prevalence of Salmonella serovars varied by the meat type and that AMR and resistance genes varied by the Salmonella serovars.     

Contamination of Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam

From March 2000 to September 2001, 608 samples of retail meat (136 pork, 70 beef, 202 chicken, and 200 ducks) and 110 samples of retail shrimp from six provinces of the Mekong Delta in Vietnam were collected individually and examined for the prevalence of Salmonella. Of the 718 samples examined, 243 (33.8%) were Salmonella positive. Salmonella was isolated from 69.9% of the pork samples, 48.6% of the beef samples, 21.0% of the chicken meat samples, 22.3% of the duck meat samples, and 24.5% of the shrimp samples. From 261 Salmonella isolates, 24 different serovars were identified. The predominant serovars of the isolates were Salmonella Derby, Salmonella Weltevreden, and Salmonella London in pork; Salmonella Weltevreden, Salmonella London, and Salmonella Dessau in beef; Salmonella Emek, Salmonella Typhimurium, and Salmonella Dessau in chicken meat; Salmonella Lexington, Salmonella Derby, and Salmonella Dessau in duck meat; and Salmonella Weltevreden, Salmonella Tennessee, and Salmonella Dessau in shrimps. Salmonella Bovismorbificans, Salmonella Derby, Salmonella Dessau, and Salmonella Weltevreden were the most common serovars in all the samples examined. These results indicate a high rate of contamination by Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam.     

乌鲁木齐市零售牛羊肉中沙门氏菌的调查

目的通过对乌鲁木齐零售牛羊中的沙门氏菌检测分离并分型,了解乌鲁木齐市牛羊肉的污染状况。方法按照沙门氏菌检验国家标GB/T 4789.1-2010对乌鲁木齐零售牛羊肉检测分离并进行血清型分型。结果2013~2014年共检测535份零售牛羊肉样品,共分离得到30株沙门氏菌,总体感染率为5.6%,羊肉的感染率为6.5%,牛肉感染率为4.3%,经血清分型鉴定可以分为5个血清群,12个血清型主要有哈达尔沙门氏菌、伦敦沙门氏菌、肠炎沙门氏菌、姆班达卡沙门氏菌和哈瓦那沙门氏菌等。结论新疆乌鲁木齐地区零售牛羊肉中存在沙门氏菌污染,沙门氏菌菌株为不同的表型,需要加强对零售牛羊肉市场的卫生检疫,防控沙门氏菌疾病。     

2010—2012年新疆乌鲁木齐地区零售生肉中沙门菌污染情况调查

通过对2010—2012年新疆乌鲁木齐地区零售生肉中沙门菌的检测分析,了解沙门菌污染情况,掌握乌鲁木齐地区零售肉品中沙门菌污染动态变化。方法 按照沙门菌检验国家标准GB/T 4789.1—2010对乌鲁木齐地区的零售肉(鸡肉、羊肉、牛肉、猪肉)检测分离沙门菌并进行血清型分型。结果 2010—2012年共检测1406份零售生肉样品,生鸡肉的感染率达到9.14%,生猪肉为9.06%,生羊肉为8.05%,生牛肉为6.44%,检测共分离得到123株沙门菌,经血清型鉴定可以分为4个血清群,7种血清型,分别为肠炎沙门菌(n=17)、萨奥沙门菌(n=9)、塔西沙门菌(n=8)、乌干达沙门菌(n=6)、康科德沙门菌(n=3)、汤姆逊沙门菌(n=3)和德尔卑沙门菌(n=2),未定型沙门菌75株。结论 新疆乌鲁木齐地区零售肉类中存在沙门菌污染,沙门菌菌株为不同的表型,地区内生肉品中沙门菌污染不容忽视,需要加强对零售肉市场的卫生检疫,防控沙门菌病。