Contamination of retail foods, particularly turkey, from community markets (Minnesota, 1999-2000) with antimicrobial-resistant and extraintestinal pathogenic Escherichia coli

To assess the food supply as a possible vehicle for antimicrobial-resistant and extraintestinal pathogenic Escherichia coli (ExPEC), we defined the prevalence, density, clonal diversity, virulence characteristics, and antimicrobial resistance profiles of E. coli among diverse retail food items. A microbiological survey was undertaken of 346 food items (vegetables, produce, beef, pork, chicken, and turkey) purchased as a convenience sample from 16 retail markets within the Minneapolis-St. Paul area in 1999-2000, with selective cultures for E. coli and extensive molecular and phenotypic characterization of E. coli isolates. Meats, particularly turkey products, were often extensively contaminated with antimicrobial-resistant E. coli and ExPEC, to a much greater extent than were produce items, even those from farmer's markets. Moreover, meat-source E. coli differed substantially from produce-source E. coli with respect to phylogenetic background (more commonly from virulence-associated phylogenetic groups B2 or D), virulence genotype (more extensive), and antimicrobial resistance profile (more extensive). Molecular typing methods matched four turkey-source isolates to selected human clinical and fecal isolates representing the O7:K1:H-, O83:K1, and O73/O77:K52:H18 ("clonal group A") clonal groups of ExPEC. Meats purchased in grocery stores, particularly turkey products, are frequently contaminated with antimicrobial-resistant E. coli and ExPEC. Further study is needed regarding the origins and health consequences of these foodborne organisms, both to clarify the need for and to guide the possible development of appropriate regulatory and monitoring systems and preventive interventions.     

A survey of Campylobacter and other bacterial contaminants of pre-market chicken and retail poultry and meats, King County, Washington.

As part of a larger study to determine the flow of Campylobacter and Salmonella from food animals to humans during 1982-83, 1,936 swabs were collected for bacteriologic study from pre-market chickens, retail poultry, and other retail meats as well as from equipment and work surfaces used to process such foods. Of the 297 samples collected in a poultry processing plant, 56.6 per cent were positive for Campylobacter jejuni/coli (CJC), as were 23.1 per cent of the 862 retail chicken, and 17.2 per cent of the 29 retail game hen samples. CJC was found infrequently in retail turkey, pork, and beef samples. Contamination of retail and pre-market chicken with CJC appeared to increase as the week progressed, and in pre-market chicken, later in the day. Less than 5 per cent of the retail samples of poultry, beef, and pork were found to contain Yersinia or Salmonella. However, Salmonella was cultured from 14.8 per cent of the swabs taken from the processing plant with 68 per cent of 44 Salmonellas being isolated concurrently with CJC. Tetracycline resistance which was plasmid-mediated was the most common antibiotic resistance observed, and was carried by 23.8 per cent of all CJC isolates. Overall, 38.8 per cent of all CJC isolates were resistant to ampicillin, erythromycin, streptomycin, or tetracycline, either singly or in combination.     

Prevalence of verocytotoxigenic Escherichia coli in ground beef, pork, and chicken in southwestern Ontario

Samples of ground beef (225), pork (235) and chicken (200) were randomly selected from meat processing plants in the southwestern Ontario area. Supernatants of broth cultures of the samples were tested for verocytotoxins using a Vero cell assay. Neutralization of cytotoxic activity using antisera specific for three types of verocytotoxin (Verotoxin 1, Verotoxin 2 and Shiga-like toxin II) was performed on positive samples. Isolation of verocytotoxigenic Escherichia coli (VTEC) was attempted from positive samples. VTEC were confirmed as E. coli biochemically, tested for drug resistance, and serotyped. Based on neutralization studies, the prevalence of VTEC in beef and pork was at least 36.4% and 10.6%, respectively. This is much higher than has been reported from a survey of retail meats in which a method designed to detect only E. coli O 157.H7 was used. Isolations of VTEC were made from 10.4% of the beef samples and 3.8% of the pork samples. No VTEC were recovered from the chicken samples. The majority of VTEC isolates were susceptible to commonly used antimicrobial agents. A number of the serotypes of the VTEC isolates recovered have been associated with human disease; however, no VTEC of serotype O 157.H7 were isolated.     

Antimicrobial resistance of major foodborne pathogens from major meat products

The bacterial contamination of raw and processed meat products with resistant pathogens was studied. The raw samples included sheep (40), goat (40), pork (120), beef (80), and chicken (19) meat, and the processed samples included turkey filets (33), salami (8), readymade mincemeat (16), stuffing (22), and roast-beef (50). The samples were collected from retail shops in Northwestern Greece over a period of 3 years. The isolated pathogens were evaluated for susceptibilities to 19 antimicrobial agents used in humans. Out of 428 samples, 157 strains of Escherichia coli, 25 of Yersinia enterocolitica, 57 of Staphylococcus aureus, 57 of Enterococcus spp., 4 of Salmonella spp., and 3 of Campylobacter jejuni were isolated. Among the isolates 14.6% of the E. coli, 10.5% of S. aureus, 4% of Y. enterocolitica, 25% of Salmonella spp., and 42.1% of Enterococcus spp. were susceptible to antibiotics. E. coli from chicken exhibited high rates of resistance to ciprofloxacin (62.5%) followed by lamb/goat (10.9%), pork (15.7%), and beef (27.9%) meat. Resistance to nitrofurantoin dominated in the lamb/goat isolates (60%). Resistance to tetracycline predominated in pork (68.2%) and chicken (62.5%), and resistance to aminoglycosides dominated in lamb/goat meat isolates. S. aureus resistance to clindamycin predominated in lamb/goat isolates (50%), whereas resistance to ciprofloxacin predominated in the pork strains, but no resistance to methicillin was observed. Of the enterococci isolates 21.1% were resistant to vancomycin. High resistance to ampicillin (96%) was observed in Y. enterocolitica and all of the C. jejuni isolates were resistant to ampicillin, cephalothin, and cefuroxime. These results indicate that meat can be a source of resistant bacteria, which could potentially be spread to the community through the food chain.     

Antimicrobial resistance and resistance genes in Escherichia coli isolated from retail meat purchased in Alberta, Canada

This study analyzed antimicrobial resistance (AMR) and resistance genes in generic Escherichia coli isolated from retail meat samples purchased (2007-2008) in Alberta, Canada, and determined potential associations between resistance phenotypes and resistance genes with relation to the meat types. A total of 422 E. coli isolates from retail chicken, turkey, beef, and pork meats were tested for antimicrobial susceptibility. Multiplex PCRs were used to detect major resistance genes for tetracyclines [tet(A), tet(B), tet(C)], sulfonamides (sul1, sul2, sul3), aminoglycosides (strA/B, aadA, aadB, aac(3)IV, aphA1, aphA2), and β-lactamase (bla(CMY-2), bla(TEM), bla(SHV), bla(PSE-1)). Resistance to ciprofloxacin was not found in any isolate. Overall resistances to clinically important antimicrobials amoxicillin-clavulanic acid (16.8% of isolates) and ceftriaxone (12.6% isolates) were observed. These resistances were observed more frequently (p<0.0001) in chicken-derived E. coli than those from the other meat types. Resistance to multiple antimicrobials (≥ 5) was found in more chicken derived E. coli (32%) than E. coli from other meat types. The β-lactamase genes of clinical importance, including bla(CMY-2) and bla(TEM), were found in about 18% of poultry-derived E. coli and in only 5% of ground beef. The bla(CMY-2) gene was more likely to be found in E. coli from chicken than turkey, beef, or pork meats. The tet(A) gene was associated with bla(CMY-2), whereas bla(CMY-2) and bla(TEM) genes were associated with strA/B genes. Resistance genes for tetracycline, sulfonamides, and aminoglycosides were associated with the phenotypic expression of resistance to unrelated classes of antimicrobials. These data suggest the prevalence of AMR and select resistance genes were higher in poultry-derived E. coli. The multiple associations found between AMR phenotypes and resistance genes suggest a complex nature of resistance in E. coli from retail meat, and hence the use of a single antimicrobial could result in the selection of resistant E. coli not only to the drug being used but to other unrelated classes of antimicrobials as well.     

沈阳市零售肉类大肠埃希菌与沙门菌污染调查

目的了解沈阳市不同类型市场零售肉类大肠埃希菌与沙门菌污染状况。方法2003年1~12月从沈阳市2个超市,6个农贸市场和10个街边市场,随机采集零售生肉类包括鸡肉、鸭肉、兔肉、猪肉和牛肉样品500份,应用常规方法检测其受大肠埃希菌(Escherichia coli)和沙门菌(Salmonella serovars)的污染情况,分析不同肉类品种、不同市场类型、不同季节对污染的影响。结果大肠埃希菌检出率在鸡肉、鸭肉和兔肉样品中均为100%,牛肉和猪肉样品中分别是89%和85%;沙门菌在鸡肉、鸭肉、兔肉样品中的检出率分别是61%,71%和83%,在猪肉和牛肉中分别是40%和48%。结论超市样品中2种微生物污染率最低,街边市场零售肉类污染率最高,农贸市场样品受污染程度居中。不同肉类以及不同市场类型2种微生物污染程度有明显差异,零售生肉是传播食源性疾病的主要潜在途径。切实有效的实施危害分析与关键控制点(HACCP)系统,提高消费者的食品安全性意识具有重要意义。     

Most Campylobacter subtypes from sporadic infections can be found in retail poultry products and food animals

The subtypes of Campylobacter isolates from human infections in two Danish counties were compared to isolates from retail food samples and faecal samples from chickens, pigs and cattle. During a 1-year period, 1285 Campylobacter isolates from these sources were typed by two methods: 'Penner' heat-stable serotyping and automated ribotyping (RiboPrinting). C. jejuni was the dominating species, but C. coli was more prevalent among food and chicken isolates (16%) compared to human isolates (4%). In total, 356 different combined sero-ribotypes (subtypes) were found. A large subtype overlap was seen between human isolates and isolates from food (66%), chickens (59%) and cattle (83%). This was verified by PFGE typing of 212 isolates representing selected subtypes. All frequent (n>3) subtypes found in food were also present in humans. Sixty-one per cent of the isolates from domestically acquired infections had subtypes that were also found in food as opposed to 31% of travel-associated infections. The results showed differences in the various Campylobacter populations, e.g. the Danish population as reflected in the domestically acquired infections and the Danish-produced food was more uniform than the isolates originating from outside the country. The study shows that most C. jejuni subtypes found in poultry food samples, broiler chickens, and cattle were represented in the domestically acquired cases, indicating that C. jejuni from these reservoirs are likely sources of human infections in Denmark.     

Salmonella enterica and Escherichia coli harboring blaCMY in retail beef and pork products

We estimated the proportion of retail beef and pork products containing bla(CMY)-mediated third-generation cephalosporin resistance in commensal Escherichia coli and Salmonella enterica. Samples were obtained from 50 grocery stores located in two U.S. states. From each store, 20 fresh meat products were purchased, including 7 packages of ground beef, 3 packages of beef steak, 6 packages of pork chops, and 4 packages of pork ribs. The resulting 1000 packages of fresh meat product were individually screened for the presence of E. coli or Salmonella harboring bla(CMY). Over 8% of all retail meat packages contained E. coli with bla(CMY), whereas 4% contained Salmonella and only 0.5% contained Salmonella with bla(CMY). Retail pork products more frequently yielded E. coli with bla(CMY) than did beef products (12.2% vs. 4.0%; p?=?0.06). Salmonella were also recovered more frequently from pork than beef (5.8% vs. 2.4%; p?相似文献   

Limited Dissemination of Extended-Spectrum β-Lactamase– and Plasmid-Encoded AmpC–Producing Escherichia coli from Food and Farm Animals,Sweden

Extended-spectrum β-lactamase (ESBL)– and plasmid-encoded ampC (pAmpC)–producing Enterobacteriaceae might spread from farm animals to humans through food. However, most studies have been limited in number of isolates tested and areas studied. We examined genetic relatedness of 716 isolates from 4,854 samples collected from humans, farm animals, and foods in Sweden to determine whether foods and farm animals might act as reservoirs and dissemination routes for ESBL/pAmpC-producing Escherichia coli. Results showed that clonal spread to humans appears unlikely. However, we found limited dissemination of genes encoding ESBL/pAmpC and plasmids carrying these genes from foods and farm animals to healthy humans and patients. Poultry and chicken meat might be a reservoir and dissemination route to humans. Although we found no evidence of clonal spread of ESBL/pAmpC-producing E. coli from farm animals or foods to humans, ESBL/pAmpC-producing E. coli with identical genes and plasmids were present in farm animals, foods, and humans.     

Associations between multidrug resistance, plasmid content, and virulence potential among extraintestinal pathogenic and commensal Escherichia coli from humans and poultry

The emergence of plasmid-mediated multidrug resistance (MDR) among enteric bacteria presents a serious challenge to the treatment of bacterial infections in humans and animals. Recent studies suggest that avian Escherichia coli commonly possess the ability to resist multiple antimicrobial agents, and might serve as reservoirs of MDR for human extraintestinal pathogenic Escherichia coli (ExPEC) and commensal E. coli populations. We determined antimicrobial susceptibility profiles for 2202 human and avian E. coli isolates, then sought for associations among resistance profile, plasmid content, virulence factor profile, and phylogenetic group. Avian-source isolates harbored greater proportions of MDR than their human counterparts, and avian ExPEC had higher proportions of MDR than did avian commensal E. coli. MDR was significantly associated with possession of the IncA/C, IncP1-α, IncF, and IncI1 plasmid types. Overall, inferred virulence potential did not correlate with drug susceptibility phenotype. However, certain virulence genes were positively associated with MDR, including ireA, ibeA, fyuA, cvaC, iss, iutA, iha, and afa. According to the total dataset, isolates segregated significantly according to host species and clinical status, thus suggesting that avian and human ExPEC and commensal E. coli represent four distinct populations with limited overlap. These findings suggest that in extraintestinal E. coli, MDR is most commonly associated with plasmids, and that these plasmids are frequently found among avian-source E. coli from poultry production systems.     

Endemic and epidemic lineages of Escherichia coli that cause urinary tract infections

Women with urinary tract infections (UTIs) in California, USA (1999-2001), were infected with closely related or indistinguishable strains of Escherichia coli (clonal groups), which suggests point source dissemination. We compared strains of UTI-causing E. coli in California with strains causing such infections in Montréal, Québec, Canada. Urine specimens from women with community-acquired UTIs in Montréal (2006) were cultured for E. coli. Isolates that caused 256 consecutive episodes of UTI were characterized by antimicrobial drug susceptibility profile, enterobacterial repetitive intergenic consensus 2 PCR, serotyping, XbaI and NotI pulsed-field gel electrophoresis, multilocus sequence typing, and phylogenetic typing. We confirmed the presence of drug-resistant, genetically related, and temporally clustered E. coli clonal groups that caused community-acquired UTIs in unrelated women in 2 locations and 2 different times. Two clonal groups were identified in both locations. Epidemic transmission followed by endemic transmission of UTI-causing clonal groups may explain these clusters of UTI cases.     

Integrated food chain surveillance system for Salmonella spp. in Mexico

Few developing countries have foodborne pathogen surveillance systems, and none of these integrates data from humans, food, and animals. We describe the implementation of a 4-state, integrated food chain surveillance system (IFCS) for Salmonella spp. in Mexico. Significant findings were 1) high rates of meat contamination (21.3%-36.4%), 2) high rates of ceftriaxone-resistant S. Typhimurium in chicken, ill humans, and swine (77.3%, 66.3%, and 40.4% of S. Typhimurium T isolates, respectively), and 3) the emergence of ciprofloxacin resistance in S. Heidelberg (10.4%) and S. Typhimurium (1.7%) from swine. A strong association between Salmonella spp. contamination in beef and asymptomatic Salmonella spp. infection was only observed in the state with the lowest poverty level (Pearson r = 0.91, p<0.001). Pulsed-field gel electrophoresis analysis of 311 S. Typhimurium isolates showed 14 clusters with 102 human, retail meat, and food-animal isolates with indistinguishable patterns. An IFCS is technically and economically feasible in developing countries and can effectively identify major public health priorities.     

A 1-year study of Escherichia coli O157 in cattle,sheep, pigs and poultry.

Samples of rectal faeces were collected immediately after slaughter from 400 cattle each month for a 1-year period and from 1000 each of sheep, pigs and poultry over the same period. Samples were examined for Escherichia coli O157 by enrichment culture in buffered peptone water with vancomycin, cefixime and cefsulodin followed by immunomagnetic separation and culture of magnetic particles onto cefixime tellurite sorbitol MacConkey agar. E. coli O157 was isolated from 752 (15.7%) of 4800 cattle, 22 (2.2%) of 1000 sheep and from 4 (0.4%) of 1000 pigs, but not from any of 1000 chickens. Of the cattle sampled. 1840 (38.4%) were prime beef animals, 1661 (34.6%) were dairy animals being culled and the status could not be determined for the other 1299 (27%) animals. E. coli O157 was found in 246 (13.4%) of the 1840 beef cattle and 268 (16.1%) of the 1661 dairy cattle. The monthly prevalence of E. coli O157 in cattle was 4.8-36.8% and was at its highest in spring and late summer. Seventeen of the 22 isolates from sheep were also made over the summer period. All E. coli O157 isolates from sheep and 749 (99.6%) of the 752 E. coli O157 isolates from cattle were verocytotoxigenic as determined by Vero cell assay and DNA hybridization, eaeA gene positive, contained a 92 kb plasmid and were thus typical of strains causing infections in man. In contrast isolates from pigs were non-toxigenic, eaeA gene negative and did not contain a 92 kb plasmid and would, therefore, be unlikely to be a source of infection for man.     

Antimicrobial-resistant campylobacter in the food chain in Mexico

Abstract We describe prevalence and antimicrobial susceptibility results for thermophilic Campylobacter isolates collected from humans, food, and food-animals in an integrated food chain surveillance network in Mexico. From 2003 to 2006, stool samples were collected from children with diarrhea at state sentinel hospitals. Concurrently, fecal samples from asymptomatic children in kindergartens, as well as raw chicken, pork and beef from retail outlets, and food-animal intestines from slaughterhouses were all collected in 65 cities from four different states. C. jejuni was identified with a standardized hippurate test. Hippurate negative, indoxyl acetate positive isolates were classified as Campylobacter spp. Susceptibility testing was performed by agar dilution according to Clinical and Laboratory Standards Institute guidelines. A total of 1,259 C. jejuni and 1,797 Campylobacter spp. isolates were recovered from 11,811 samples. Chicken was significantly more contaminated for both intestinal samples (93.6%) and meat products (58.3%), compared with swine (71.4%)/pork (14.6%) samples, and cattle (25.1%)/beef (5.3%) samples (p<0.001). Campylobacter was recovered from 5.1% of children with diarrhea and from 3.2% of asymptomatic children. Chicken was significantly more likely to harbor ciprofloxacin-resistant C. jejuni (85.8%) than swine (62.5%, OR=3.6), cattle (39.8%, OR=9.3), or humans (58.2%, OR=4.4). No significant differences were found for ciprofloxacin-resistant Campylobacter spp. among food-animals, but the rate in food-animals was significantly higher than in humans (84% vs. 56.7%, OR=4.0). Swine was significantly more likely to harbor erythromycin-resistant C. jejuni (14.8%) than chicken (3.5%, OR=4.9), cattle (1.8%, OR=9.3), or humans (3.0%, OR=5.7), and was associated with higher rates of erythromycin-resistant Campylobacter spp. (41.9%) than chicken (10.5%, OR=6.1) and humans (11.9%, OR=5.3). The high resistance rates to ciprofloxacin preclude the use of fluoroquinolones for treatment of campylobacteriosis in Mexico. Our results emphasize the need for ongoing and integrated surveillance of antimicrobial usage and antimicrobial susceptibility in humans and animals.     

Characterization of toxin genes and antimicrobial susceptibility of Staphylococcus aureus isolates from Louisiana retail meats

Staphylococcus aureus is a leading cause of food poisoning worldwide due to the production of heat-stable enterotoxins. Recently, the isolation of methicillin-resistant S. aureus (MRSA) from food animals and retail meats raised additional food safety concerns. In this study, we characterized 152 S. aureus isolates, including 22 MRSA recovered from Louisiana retail pork and beef meats, for the prevalence of nine enterotoxin and four other exotoxin genes by polymerase chain reaction and antimicrobial susceptibility testing by broth microdilution. Overall, 85% of S. aureus isolates were positive for at least one of six enterotoxin genes identified and 66% harbored two to four enterotoxin genes. The two most predominant ones were seg and sei (66% each), followed by seh (20%), sed (15%), sej (13%), and sea (1%). No isolates harbored enterotoxin genes seb, sec, or see, the toxic shock syndrome toxin 1 gene tst, or the exfoliative toxin genes eta or etb. Three MRSA isolates were the only ones harboring Panton-Valentine leucocidin. Resistances were common to penicillin (71%), ampicillin (68%), and tetracycline (67%), followed by erythromycin (30%), clindamycin (18%), oxacillin with 2% NaCl (14%), ciprofloxacin (13%), levofloxacin (13%), gentamicin (3%), quinupristin/dapfopristin (3%), chloramphenicol (2%), and moxifloxacin (1%). Multidrug resistance was commonly observed among MRSA isolates and S. aureus isolates from pork. This study demonstrated that S. aureus isolates found in Louisiana retail pork and beef meats possessed various enterotoxin genes and antimicrobial resistance profiles. Therefore, vigilant food safety practice needs to be implemented for people who handle raw meat products to prevent foodborne infections and intoxications due to S. aureus contamination.     

Prevalence of foodborne microorganisms in retail foods in Thailand

Worldwide, foodborne illness is often associated with consumption of meats and poultry products sold at retail markets. A cross-sectional retail food study was conducted in Bangkok, Thailand to assess the prevalence of bacterial pathogens on retail food samples. Raw chicken, beef, pork, and chicken eggs were purchased from fresh markets and supermarkets and tested for Salmonella spp., Campylobacter spp., Arcobacter spp., and Enterococcus spp. Suspect bacterial pathogens were isolated by differential culture and Salmonella species were serotyped. A total of 200 samples were collected from 50 markets between May and August 2003. Of the 200 samples tested, 121 (61%) were positive for at least one Salmonella spp. serogroup. A total of 175 Salmonella spp. were isolated. The most common serotype was Salmonella Anatum, followed by S. Corvallis and S. Derby. Campylobacter spp. were found in 31 (15.5%) of 200 samples. C. jejuni was isolated from 15% of fresh market chicken samples and 35% of supermarket chicken samples. Arcobacter spp. were isolated from 42 (21%) samples; fresh market chicken had significantly higher A. butzleri contamination than supermarket chicken. The presence of Enterococcus spp., an indication of fecal contamination, was detected in 188 (94%) samples, including 100% of the beef and pork sources. Few studies have examined retail food contamination in Thailand. In particular, the high prevalence of samples with Arcobacter spp. warrants further study to determine pathogenicity.     

Prevalence of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) on retail meat in Iowa

Several recent studies have indicated a high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in retail-available meat. However, few studies have investigated MRSA in meat in the United States. The aim of this study was to determine the presence of Staphylococcus aureus (S. aureus) on meat samples available at retail stores. Samples of fresh raw pork, chicken, beef, and turkey were purchased from 22 food stores throughout Iowa. S. aureus strains were isolated from 27 of 165 samples, giving an overall prevalence of 16.4%. Turkey, pork, chicken, and beef had individual S. aureus prevalence rates of 19.4%, 18.2%, 17.8%, and 6.9%, respectively. Two isolates of MRSA were isolated from pork, giving an overall prevalence of 1.2%. One MRSA isolate was positive for the PVL gene. Common spa types included t034, t337, t008, and t002. These results suggest that MRSA is present on low numbers of retail meat in Iowa.     

Antimicrobial drug resistance in Escherichia coli from humans and food animals, United States, 1950-2002

We conducted a retrospective study of Escherichia coli isolates recovered from human and food animal samples during 1950-2002 to assess historical changes in antimicrobial drug resistance. A total of 1,729 E. coli isolates (983 from humans, 323 from cattle, 138 from chickens, and 285 from pigs) were tested for susceptibility to 15 antimicrobial drugs. A significant upward trend in resistance was observed for ampicillin (p<0.001), sulfonamide (p<0.001), and tetracycline (p<0.001). Animal strains showed increased resistance to 11/15 antimicrobial agents, including ampicillin (p<0.001), sulfonamide (p<0.01), and gentamicin (p<0.001). Multidrug resistance (≥3 antimicrobial drug classes) in E. coli increased from 7.2% during the 1950s to 63.6% during the 2000s. The most frequent co-resistant phenotype observed was to tetracycline and streptomycin (29.7%), followed by tetracycline and sulfonamide (29.0%). These data describe the evolution of resistance after introduction of new antimicrobial agents into clinical medicine and help explain the range of resistance in modern E. coli isolates.     

Antimicrobial resistance of Escherichia coli O26, O103, O111, O128, and O145 from animals and humans

Susceptibilities to fourteen antimicrobial agents important in clinical medicine and agriculture were determined for 752 Escherichia coli isolates of serotypes O26, O103, O111, O128, and O145. Strains of these serotypes may cause urinary tract and enteric infections in humans and have been implicated in infections with Shiga toxin-producing E. coli (STEC). Approximately 50% of the 137 isolates from humans were resistant to ampicillin, sulfamethoxazole, cephalothin, tetracycline, or streptomycin, and approximately 25% were resistant to chloramphenicol, trimethoprim-sulfamethoxazole, or amoxicillin-clavulanic acid. Approximately 50% of the 534 isolates from food animals were resistant to sulfamethoxazole, tetracycline, or streptomycin. Of 195 isolates with STEC-related virulence genes, approximately 40% were resistant to sulfamethoxazole, tetracycline, or streptomycin. Findings from this study suggest antimicrobial resistance is widespread among E. coli O26, O103, O111, O128, and O145 inhabiting humans and food animals.     

Isolation and molecular characterization of Escherichia coli O157 from broiler and human samples

There is a lack of information about the role of poultry, specifically chicken, in transmission of Escherichia coli (E. coli) O157 and subsequent human illnesses. This study was therefore aimed at investigating the presence of E. coli O157 and its virulence genes in various samples collected from broiler chickens and humans in Eastern Turkey by culture, immunomagnetic separation (IMS), and polymerase chain reaction (PCR). The genetic relationship between broiler and human isolates was also examined by pulsed-field gel electrophoresis (PFGE). In the PCR analysis of sorbitol-negative isolates, E. coli O157 was identified in 0.1% (1/1000) and 0.4% (4/1000) of the liver and cecum samples of broiler chickens, respectively. On the other hand, none of the carcass samples were determined to be positive for E. coli O157. Overall, the results indicated that 12% (3/25) of the flocks were positive for E. coli O157. The differences between the flocks in terms of the positivity were determined to be statistically significant (p<0.001). Ten (2.7%) of 367 human stool samples were also positive for E. coli O157 in the PCR examination. None of the broiler and human E. coli O157 isolates possessed H7, shigatoxins 1-2, or enterohemolysin genes, whereas all the broiler isolates and one of the human isolates were positive for intimin gene. In the PFGE analysis, a total of eight different profiles (four from broiler and four from human isolates) were observed. However, there were no genetic relationships between broiler and human E. coli O157 isolates. It can be concluded that more detailed studies are needed in poultry to better understand the role of these species in the epidemiology of E. coli 0157 infections in humans.