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Escherichia coli serotype O157:H7 is a diarrheal agent and a significant cause of hemorrhagic colitis and the development of hemolytic uremic syndrome (HUS), mainly in infants. Early detection of contaminated food and water using reliable and fast tests is one of the strategies to prevent infections from E. coli O157:H7. Methods: Four quantitative polymerase chain reaction protocols (SYBR Green qPCR) were developed and validated to determine the presence of the bacteria according to its rfbE, stx1, and stx2 genes. Results: The results of the efficiencies were between 80% and 97% with a high linearity (R2 0.99). The cut-off limits for each primer sequence were 3.1667 × 10−2 ng µL−1 for two sequences of the serogroup O157 (primers rfbE and O157), 1.7228 × 10−3 ng µL−1 for stx1, and 3.5185 × 10−3 ng µL−1 for stx2. The inclusivity and the exclusivity of each gene, as well as the analytical precision and the positive and negative predictive value, were 100%. A contaminated meat matrix was evaluated, detecting up to 4 CFU g−1. Conclusions: SYBR Green qPCR protocols could be implemented to trace the presence of E. coli O157 in a routine analysis of ground beef or as an easy, rapid, sensitive, and specific diagnostic test while still considering microbiological tests to validate any inconclusive results.

Shiga toxin-producing Escherichia coli (STEC) strains have emerged as important foodborne patho-gens of global public health concern, causing life-threatening diseases. Animals and their products have been documented as important reservoirs for STECs, especially E. coli O157. The aim of this study was to investigate STECs from healthy and diarrhoeic sheep in Sanandaj, Iran. In the current study, a total of 81 sheep faecal samples were taken (22 from diarrhoeic sheep and 59 from healthy sheep). E. coli and subsequently STEC strains was detected according to standard protocol (cultural characterisation and PCR assays). Finally, the frequency of Shiga-toxin producing gene(s) (stx1, stx2), intimin (eaeA) and enterohaemolysin (hlyA) was detected among STEC isolates using duplex PCR. Totally, 42 E. coli were isolated from 81 faecal samples (51.85% contamination). Of these, 34 isolates (80.9%) were identified as STEC patotypes based on Sorbitol-MacConkey (SMAC) medium culturing and also the presence of stx1 and/or stx2. Of these, only 3 isolates (7.1%) were identified as serotype O157:H7 based on PCR assay. In addition, the results showed that STEC bacteria were sig-nificantly more prevalent in diarrhoeic samples than in healthy samples (50% vs. 22.1%). Overall, the PCR results showed that 33 (97%), 12 (35.3%) and 8 (23.5%) isolates carried stx1, stx2 and hlyA, respectively. The eaeA gene was not found in any isolate. The number of isolated STEC bacteria in spring (10 isolates) and winter (14 isolates) were significantly higher than those in summer (4 iso-lates) and autumn (6 isolates) (P=0.039). Also, the number of STEC in diarrhoea samples was signifi-cantly higher compared to non-diarrhoea samples (P=0.032). In conclusion, the present study re-vealed high prevalence rate of STEC including serotype O157:H7 and non-O157:H7 in sheep faeces which highlights the importance of sheep as a reservoir of STEC pathogen in Sanandaj region. Therefore, additional control and preventive measures must be undertaken to control the contamination by this pathogen.

Shiga toxin-producing Escherichia coli (STEC) strains have emerged as important foodborne pathogens of global public health concern, causing life-threatening diseases. Animals and their products have been documented as important reservoirs for STECs, especially E. coli O157. The aim of this study was to investigate STECs from healthy and diarrhoeic sheep in Sanandaj, Iran. In the current study, a total of 81 sheep faecal samples were taken (22 from diarrhoeic sheep and 59 from healthy sheep). E. coli and subsequently STEC strains was detected according to standard protocol (cultural characterisation and PCR assays). Finally, the frequency of Shiga-toxin producing gene(s) (stx1, stx2), intimin (eaeA) and enterohaemolysin (hlyA) was detected among STEC isolates using duplex PCR. Totally, 42 E. coli were isolated from 81 faecal samples (51.85% contamination). Of these, 34 isolates (80.9%) were identified as STEC patotypes based on Sorbitol-MacConkey (SMAC) medium culturing and also the presence of stx1 and/or stx2. Of these, only 3 isolates (7.1%) were identified as serotype O157:H7 based on PCR assay. In addition, the results showed that STEC bacteria were significantly more prevalent in diarrhoeic samples than in healthy samples (50% vs. 22.1%). Overall, the PCR results showed that 33 (97%), 12 (35.3%) and 8 (23.5%) isolates carried stx1, stx2 and hlyA, respectively. The eaeA gene was not found in any isolate. The number of isolated STEC bacteria in spring (10 isolates) and winter (14 isolates) were significantly higher than those in summer (4 isolates) and autumn (6 isolates) (P=0.039). Also, the number of STEC in diarrhoea samples was significantly higher compared to non-diarrhoea samples (P=0.032). In conclusion, the present study revealed high prevalence rate of STEC including serotype O157:H7 and non-O157:H7 in sheep faeces which highlights the importance of sheep as a reservoir of STEC pathogen in Sanandaj region. Therefore, additional control and preventive measures must be undertaken to control the contamination by this pathogen. [ABSTRACT FROM AUTHOR]

Rapid identification of Shiga toxin-producing Escherichia coli, or STEC, is of utmost importance to assure the innocuousness of the foodstuffs. STEC have been implicated in outbreaks associated with different types of foods however, among them, ready-to-eat (RTE) vegetables are particularly problematic as they are consumed raw, and are rich in compounds that inhibit DNA-based detection methods such as qPCR. In the present study a novel method based on Loop-mediated isothermal amplification (LAMP) to overcome the limitations associated with current molecular methods for the detection of STEC in RTE vegetables targeting stx1 and stx2 genes. In this sense, LAMP demonstrated to be more robust against inhibitory substances in food. In this study, a comprehensive enrichment protocol was combined with four inexpensive DNA extraction protocols. The one based on silica purification enhanced the performance of the method, therefore it was selected for its implementation in the final method. Additionally, three different detection chemistries were compared, namely real-time fluorescence detection, and two end-point colorimetric strategies, one based on the addition of SYBR Green, and the other based on a commercial colorimetric master mix. After optimization, all three chemistries demonstrated suitable for the detection of STEC in spiked RTE salad samples, as it was possible to reach a LOD50 of 0.9, 1.4, and 7.0 CFU/25 g for the real-time, SYBR and CC LAMP assays respectively. All the performance parameters reached values higher than 90 %, when compared to a reference method based on multiplex qPCR. More specifically, the analytical sensitivity was 100, 90.0 and 100 % for real-time, SYBR and CC LAMP respectively, the specificity 100 % for all three assays, and accuracy 100, 96 and 100 %. Finally, a high degree of concordance was also obtained (1, 0.92 and 1 respectively). Considering the current technological advances, the method reported, using any of the three detection strategies, demonstrated suitable for their implementation in decentralized settings, with low equipment resources.

Escherichia coli (E. coli) O157:H7 is considered a significant food-borne microorganism that causes food poisoning infections in humans every year. E. coli O157:H7 has various virulence factors such as Shiga-toxin encoding (Stx1 and Stx2). Meat and its products are considered the best meals that consumers eat every day worldwide, but meat and its products are exposed to contamination through unhygienic processing, handling, and storage. The aim of the study was the isolation of E. coli O157:H7 and detection of the uidA, Stx1, and Stx2 genes. 504 samples of meat and butchers’ shops were gathered from diverse areas in Mosul city. Classical and molecular biology techniques were used to isolate and identify E. coli O157:H7. The results appeared to indicate the total number of E. coli isolates in this study was 138 and the spread rate of E. coli O157:H7 isolated was 9.4% (13/138). The spread rate of E. coli O157:H7 was high in workers hands 4 (20%), while we did not detect E. coli O157:H7 in Machines. Additionally, all E. coli O157:H7 have the uidA, and Stx2 genes at 100%, while 92.3% of E. coli O157:H7 possess the Stx1 gene. The study concludes E. coli O157:H7 occurrences in meats and butchers’ shops and that all equipment and tools used were capable of transmitting E. coli O157:H7 to meats. Meats and butchers’ shops are a risk to humans who consume the uncooked meats.

Copyright of Etlik Veteriner Mikrobiyoloji Dergisi is the property of Veteriner Kontrol Merkez Arastirma Enstitusu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Escherichia coli (E. coli) O157:H7 is considered a significant food-borne microorganism that causes food poisoning infections in humans every year. E. coli O157:H7 has various virulence factors such as Shiga-toxin encoding (Stx1 and Stx2). Meat and its products are considered the best meals that consumers eat every day worldwide, but meat and its products are exposed to contamination through unhygienic processing, handling, and storage. The aim of the study was the isolation of E. coli O157:H7 and detection of the uidA, Stx1, and Stx2 genes. 504 samples of meat and butchers' shops were gathered from diverse areas in Mosul city. Classical and molecular biology techniques were used to isolate and identify E. coli O157:H7. The results appeared to indicate the total number of E. coli isolates in this study was 138 and the spread rate of E. coli O157:H7 isolated was 9.4% (13/138). The spread rate of E. coli O157:H7 was high in workers hands 4 (20%), while we did not detect E. coli O157:H7 in Machines. Additionally, all E. coli O157:H7 have the uidA, and Stx2 genes at 100%, while 92.3% of E. coli O157:H7 possess the Stx1 gene. The study concludes E. coli O157:H7 occurrences in meats and butchers' shops and that all equipment and tools used were capable of transmitting E. coli O157:H7 to meats. Meats and butchers' shops are a risk to humans who consume the uncooked meats. [ABSTRACT FROM AUTHOR]

It is necessary to understand the frequency of virulence factor-encoding genes in the assessment of the carriage proportion. Moreover, it is required in the characterization of major unique antigens that are useful in the development of effective immunological-based preventive measures. The current study aimed to evaluate the frequency of three encoding-virulence genes associated with Enterotoxigenic (ET) and Shigatoxigenic Escherichia coli (E. coli/EC) pathotypes (k99, stx1, and stx2) in North of Sistan and Baluchistan Province, Iran. The frequency of k99, stx1, and stx2 was determined via polymerase chain reaction among E. coli isolates collected from the feces of the clinically healthy suckling (n=50) and diarrheic calves (n=50). The k99 gene was absent in all isolates, and the frequencies of the E. coli containing stx1 and stx2 or both stx1 and stx2 were estimated at 8%, 14%, and 4%, respectively, in the clinically healthy suckling calves (P>0.05), compared to 24%, 16%, and 6% in diarrheic animals (p

1) Background: Uropathogenic E. coli (UPEC) is responsible for 70-90% of urinary tractinfections. On the other hand, E. coli producing Shiga toxin (STEC), the so-called Verotoxinproducing E. coli (VTEC), has two stx1 and stx2 genes (Producing Stx1 and Stx2 toxins). Since these genes are plasmidal and can be transmitted between E. coli strains, it is likely that stx1 and stx2 genes are also found in the Uropathogenic E. coli. Studies in different parts of the world indicate some cases of dangerous syndromes such as Haemolytic-Uraemic Syndrome (HUS)following urinary tract infections. Also, the incidence of urinary tract infections caused by Verotoxigenic E. coli strains is increasing. Therefore, the present study was conducted to investigate the presence of verotoxin genes in Uropathogenic E. coli; 2)Methods: A total of 180 clinical specimens were collected during five months. After diagnostic tests and differential biochemistry tests, 100 samples were confirmed as E. coli and the presence of stx2 and stx1 genes was investigated by Muliplex-PCR; 3) Results: The results showed that the prevalence rates of stx1 and stx2 genes were 15% and 13%, respectively, in UPEC samples examined in this study, which is in agreement with the results of few similar studies in Iran; and 4) Conclusions: It seems that the frequency of verotoxin genes in E. coli causing urinary tract infections in Kermanshah is more than the other parts of Iran. Therefore, the potential risks of these bacteria could not be ignored.

ABSTRACT: The present study was aimed at subtyping of Stx1 and Stx2 genes and characterization of antimicrobial resistance in 106 Shiga toxin-producing Escherichia coli (STEC) strains isolated from cattle and sheep feces. PCR was used to determine the subtypes, and the disk-diffusion method was used to evaluate the antimicrobial resistance. Ten antibiotics from five different classes were tested. Among the isolates of bovine origin, two subtypes of Stx1 (Stx1a and Stx1c), and four subtypes of Stx2 (Stx2a, Stx2b, Stx2c, and Stx2d) were identified. In isolates of sheep origin, two subtypes of Stx1 (Stx1a and Stx1c), and four subtypes of Stx2 (Stx2a, Stx2b, Stx2c, and Stx2 g) were identified. The results obtained suggest the presence of high diversity in Stx1 and Stx2 genes. Further, 96.6% (57/59) of bovine fecal strains and 89.4% (42/47) of sheep fecal strains showed resistance to at least one tested antibiotic. In both animal species, most strains were multidrug-resistant (MDR) (67.8% in cattle and 59.6% in sheep), with no significant difference between host animals. Adult animals were eight times more likely to have STEC with greater pathogenic potential. STEC with the highest pathogenic potential were three times more likely to be multidrug-resistant than STEC with the lowest pathogenic potential. The data reported in this study suggests the occurrence of strains with high potential pathogenicity in the region studied. Therefore, the ruminants of this region are carriers of strains that can cause infections in humans.

Copyright of Archives of Razi Institute is the property of Institut Razi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rapid identification of Shiga toxin-producing Escherichia coli , or STEC, is of utmost importance to assure the innocuousness of the foodstuffs. STEC have been implicated in outbreaks associated with different types of foods however, among them, ready-to-eat (RTE) vegetables are particularly problematic as they are consumed raw, and are rich in compounds that inhibit DNA-based detection methods such as qPCR. In the present study a novel method based on Loop-mediated isothermal amplification (LAMP) to overcome the limitations associated with current molecular methods for the detection of STEC in RTE vegetables targeting stx 1 and stx 2 genes. In this sense, LAMP demonstrated to be more robust against inhibitory substances in food. In this study, a comprehensive enrichment protocol was combined with four inexpensive DNA extraction protocols. The one based on silica purification enhanced the performance of the method, therefore it was selected for its implementation in the final method. Additionally, three different detection chemistries were compared, namely real-time fluorescence detection, and two end-point colorimetric strategies, one based on the addition of SYBR Green, and the other based on a commercial colorimetric master mix. After optimization, all three chemistries demonstrated suitable for the detection of STEC in spiked RTE salad samples, as it was possible to reach a LOD50 of 0.9, 1.4, and 7.0 CFU/25 g for the real-time, SYBR and CC LAMP assays respectively. All the performance parameters reached values higher than 90 %, when compared to a reference method based on multiplex qPCR. More specifically, the analytical sensitivity was 100, 90.0 and 100 % for real-time, SYBR and CC LAMP respectively, the specificity 100 % for all three assays, and accuracy 100, 96 and 100 %. Finally, a high degree of concordance was also obtained (1, 0.92 and 1 respectively). Considering the current technological advances, the method reported, using any of the three detection strategies, demonstrated suitable for their implementation in decentralized settings, with low equipment resources., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Objective: Shiga-toxin producing Escherichia coli (STEC) is the most important foodborne bacterial pathogen worldwide and the bovine animals are assumed as a reservoir of this pathogen. The present study was conducted to assess the role of bovine animals as the source of STEC. Materials and methods: To assess the role of bovine animals as the source of STEC, we examined 100 samples (50 rectal swab and 50 beef samples) collected from the local beef slaughterhouses by cultural, morphological, biochemical tests and polymerase chain reaction. Finally, the drug resistance pattern of isolated organisms has been examined. Result: In the preliminary screening by polymerase chain reaction (PCR), E. coli was more prevalent in rectal swab (n=21/50) than beef samples (n=16/50). Among 39 isolated E. coli, 10 isolates were confirmed as STEC (Rectal swab=7, Beef=3) by PCR, where stx2 gene (n=7/10) was predominant than stx1 gene (n=3/10). Remaining 29 isolates did not react to stx primers in PCR. Presence of STEC in beef samples was significantly associated with the fecal contamination at P≤0.1 (0.074818) in Pearsons correlation coefficient method. In addition, most of the isolated STEC strains were resistant to one or more commonly used antimicrobials in the country. Conclusion: The bovine animals and its products could be an important source of multidrug-resistant STEC in the country. [J Adv Vet Anim Res 2018; 5(2.000): 218-225]

Escherichia coli is part of the normal microflora of the intestinal tract of humans and warm-blooded animals, but its presence in raw material and food of animal origin is considered as fecal contamination and can be very dangerous for consumers. The determination of the number of E. coli in raw material and food is important because among them can be pathogenic strains. The most dangerous strains are considered enterohemorrhagic E. coli as a causative agent of severe bloody diarrhea and hemorrhagic uremic syndrome in humans through the production of Shiga-toxin, which is the main virulence factor, responsible for disease. The aim of this study was to identify the prevalence of Shiga toxin-producing strains of E. coli (STEC) from swabs of beef and swine carcass in slaughterhouses in Ukraine and characterize their genes, which are responsible for pathogenic properties. A total of 230 samples of swabs from beef (130) and swine (100) carcasses were obtained from 5 slaughterhouses in Ukraine between 2012 and 2015. Samples of swabs from carcasses were randomly selected at the final point of the process after the final washing of the carcass from the following areas: distal hind limb, abdomen (lateral and medial) from swine carcasses, brisket, flank and flank groin areas from beef carcasses. All samples were examined by culture-dependent method, after that each positive isolate of STEC was analyzed by multiplex PCR to detect the stx1, stx2, and eae genes. Out of 230 collected samples, seven (7.2%) were contaminated with STEC. The highest prevalence of STEC was found in swabs from beef carcasses (8.1%) in comparison to swabs from swine carcasses (5.7%). The stx1 gene was the predominant gene detected in all STEC positive samples. The eae gene was found in one of the examined isolates from beef carcass. Three isolates from swabs of beef carcass carried both stx1 and stx2 genes, one isolate showed association between stx1 and eae genes, one isolate was positive for stx1 gene only. In swabs from swine carcasses (2 isolates) stx1 and stx2 genes were presented simultaneously. The results of this study suggested that fresh raw meat could be a potential vehicle for transmission of the Shiga toxin-producing strain of E. coli to humans. This is the first report of STEC prevalence in beef and swine carcasses in Ukraine and these data will be valuable for microbiological risk assessment and help the appropriate services to develop strategies to mitigate health risk.

Aim: To evaluation the effect of Lactobacillus acidophilus on Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 with detection of some virulence factors. Methods: Two hundred and fifty specimens (stool) from children under five years for both sexes were collected from some hospitals. All isolates were diagnosed according to morphological characteristics, biochemical tests. Monoplex pattern of PCR was used also for detection different genes in (7) Escherichia coli) O157:H7 (isolates; include 16SrRNA, eae, lifA, Stx1,Stx2 that encoded for ribosomal RNA, intimin, lymphocyte inhibitory factor, shiga toxins. Three types of probiotics strains were obtained, Lactobacillus fermentum, Lactobacillus plantarum and Lactobacillus acidophilus (ATCC4356). Minimum inhibitory concentration (MIC) of cell free supernatants of Lactobacillus acidophilus was determined by employing different dilutions (1/2, 1/4, 1/8, 1/16, 1/32), to detect the concentration of probiotic that will inhibit E.coli (O157:H7) growth. Results: Results showed, 210 (84%) samples were identified as E.coli from 250 samples. The result showed (7) isolates were identified as Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 and showed all isolates of O157:H7 were positive for 16SrRNA gene with (213bp) and eae with (741bp), lifA with (712bp), only Stx1 gene appeared in all isolates with (446bp) and no bands with Stx2. Current result showed only cell free culture supernatant of Lactobacillus acidophilus has inhibitory activity against all E.coli (O157:H7) isolates with different dilutions (1/2, 1/4, 1/8, 1/16, 1/32), while Lactobacillus fermentum, Lactobacillus plantarum have no effect against E.coli (O157:H7). The result showed the bacteriocin has inhibitory effect against E.coli (O157:H7), while organic acids and hydrogen peroxide haven't any role in inhibition. The (MIC) value was (1/8) which inhibits the bacterial growth of isolates. [ABSTRACT FROM AUTHOR]

Aim: This study describes the prevalence of Escherichia coli in frozen chicken meat intended for human consumption with emphasis on their virulence determinants through detection of the virulence genes and recognition of the extended-spectrum β-lactamase (ESBL) encoding genes (blaOXA and blaTEM genes). Materials and Methods: A total of 120 frozen chicken meat samples were investigated for isolation of E. coli. All isolates were subjected to biochemical and serological tests. Eight serotypes isolated from samples were analyzed for the presence of various virulence genes (stx1, stx2, and eae A genes) using multiplex polymerase chain reaction (PCR) technique. Moreover, the strains were evaluated for the ESBL encoding genes (blaTEM and blaOXA). Results: Overall, 11.66% (14/120) chicken meat samples carried E. coli according to cultural and biochemical properties. The most predominant serotypes were O78 and O128: H2 (21.5%, each), followed by O121: H7 and O44: H18. Molecular method detected that 2 strains (25%) harbored stx1, 3 strains (37.5%) stx2, and 3 strains (37.5%) both stx1 and stx2, while 1 (12.5%) strain carried eae A gene. Particularly, only O26 serotype had all tested virulence genes (stx1, stx2, and eae A). The results revealed that all examined 8 serotypes were Shiga toxin-producing E. coli (STEC). The ESBL encoding genes (blaTEM and blaOXA) of STEC were detected in 4 (50%) isolates by multiplex PCR. The overall incidence of blaTEM and blaOXA genes was 3 (37.5%) and 2 (25%) isolates. Conclusion: The present study indicates the prevalence of virulent and ESBL-producing E. coli in frozen chicken meat intended for hospitalized human consumption due to poor hygienic measures and irregular use of antibiotics. Therefore, the basic instructions regarding good hygienic measures should be adapted to limit public health hazard.

Aim: The aim of the present study was to determine the frequency of shiga-like toxin (stx1 and stx2) and drug resistance profiles food-borne Escherichia coli O157:H7 in Hatay province, Turkey. Methods: The presence of the virulence genes (stx1, stx2, hlyA) in a total of 150 E.coli isolates were studied with multiplex PCR. Results: A total of 327 salad samples were analyzed. E. coli O157:H7 was detected in 150 (45.8 %) out of 327 analyzed samples. Of these 150 isolates, the presence of hly-A gene was detected in 32 (21.3%) E.coli isolates. A total of five (15.6%) isolates in this 32 hlyA positive isolates had stx2 gene, two (6.3%) of them had stx1 gene and one (3.1%) of the isolates was found to be positive for both stx1 and stx2 genes. It was found that all E.coli O157:H7 isolates were resistant to erythromycin. While the highest rate of antibiotic resistance was observed for ampicillin (68.8%), no antibiotic resistance against cefuroxime, ciprofloxacin and cephaperasone was identified. Conclusions: The results obtained in our province showed that E.coli strains isolated from salad samples were found to have some important virulence genes such as stx1, stx2, and hlyA. The stx2 frequency was found to be higher than stx1 frequency. Also, it was observed that there was not any significant correlation between drug resistance profiles and presence of toxin genes in E.coli O157:H7 strains. As a result, increasing frequency of STEC O157 serotype among foodborne pathogens is a growing public health problem.

Aim: Wild birds are considered silent vectors of some zoonotic water and food borne pathogens of public health significance. Owing to the importance of Shiga toxin producing Escherichia coli (STEC) as the most pathogenic among the emerging diarrheagenic E. coli groups that can infect man; the present study was designed to detect the occurrence of STEC among wild birds in Egypt. Materials and Methods: A total of 177 intestinal content swab samples originating from five wild bird species were investigated for the presence of E. coli and STEC by standard culture methods. Suspect STEC isolates were further characterized by serotyping, random amplified polymorphic DNA polymerase chain reaction (RAPD PCR), antimicrobial resistance pattern and PCR detection of stx1, stx2, and eae genes. Results: A total of 30 suspect STEC isolates from 30 positive birds' samples were detected and identified on STEC CHROMagar (semi-captive pigeons, 15; house crows, 8; cattle egrets, 3; moorhens, 2; and house teals, 2). 25 isolates were grouped into 13 serogroups (O:20, O:25, O:26, O:27, O:63, O:78, O:111, O:114, O:125, O:128, O:142, O:153, and O:158), while five were rough strains. The distribution of STEC virulence genes among wild birds was as follows: 16 birds carried stx1 gene only (nine pigeons [28.1%], six crows [7.1%], and one cattle egret [5.6%]). stx1 and stx2 genes together were detected in four birds (one cattle egret [5.6%], two moorhens [6.1%], and one house teal, [10%]). Only one pigeon (3.1%) possessed the three alleles. Disk diffusion test results showed that cefixime was the most effective against STEC serotypes with (93.3%) sensitivity, followed by gentamycin (56.7%), and amoxicillin (50%). On the other hand, all the recovered STEC isolates were resistant to cefotaxime, doxycycline, cephalothin, and sulfisoxazole. RAPD fingerprinting using primers OPA-2 and OPA-9 showed that STEC isolates were heterogeneous; they yielded 30 and 27 different clusters, respectively. Conclusion: Wild birds carry STEC and may add to the contamination of the surrounding environment.

Objectives: This study was designed to assess the contamination of enterovirulent Escherichia coli with table eggs at Mansoura, Egypt. Materials and methods: A total of 100 commercially available table eggs were randomly collected from various groceries and supermarkets at Mansoura, Egypt. The samples were screened for the presence of E. coli through conventional bacteriological and biochemical analyses followed by confirmation by polymerase chain reaction. Results: Overall, 18% (n=18/100) samples were found to be contaminated with one or more E. coli isolates. All possible E. coli colonies (n=52) appeared on MacConkey agar plates during the screening process were picked for further analysis. Among the 52 suspected isolates, 24 were confirmed as E. coli, which were further serotyped using polyvalent E. coli antisera. In this study, 9 different E. coli serotypes namely O78, O114, O2, O44, O1, O125, O128, O124 and O26 were identified. Out of these 9 serological strains, 5 (O78, O2, O44, O125, O124 and O26) were positive for eae gene, and 3 (O44, O1 and O128) were positive for stx2 gene. Two serological strains (O44 and O1) were positive for both stx1 and eae genes, while O125 and O114 were positive for stx2 and eae genes. Two strains (O78 and O128) were found to be positive for all three genes (stx1, stx2 and eae). Conclusion: Ensuring hygienic measures can effectively reduce the microbial load from table eggs. [J Adv Vet Anim Res 2016; 3(1.000): 1-7]

The aim of this study was to identify virulent Shiga toxin-producing Escherichia coli (STEC) strains isolated from faecal samples of 100 clinically healthy calves. In the present study, a total of 100 Escherichia coli (E. coli) isolates from clinically healthy calves belonging to 6 different farms located in Khorasan Razavi province, Iran, were examined for presence of virulence genes characteristic for STEC strains.Duplex PCR assay was used in order to determine the presence of the stx1, and stx2 genes. The stx1 or stx2 positive isolates was later analyzed with primers specific for eaeA, hlyA genes. PCR assay was also conducted on these isolates for detection of O157: H7 serotype. Our results showed that 15 isolates (15%) were positive for stx1 gene, 19 isolates (19%) were positive for stx2 gene and 8 isolates (8%) were positive for both stx1, and stx2. Totally 26 isolates were positive for at least one of stx1or stx2 genes. Among 26 isolates, which were tested for the presence of eaeA and hlyA genes, 5 and 22 of them were positive for these genes, respectively. Four isolates were positive for both eaeA and hlyA genes. Among 26 isolates which were analyzed for genes coding O157 and H7 antigens, one and four isolates were positive for O157 and H7 antigen gene, respectively. None of the isolates were positive for both antigen genes. Faecal contamination due to poor hygiene is a risk factor in contamination of meat and milk products.

هدف از مطالعه حاضر شناسایی سویه های حدت دار STEC جداشده از مدفوع 100 گوساله به ظاهر سالم می باشد. در مطالعه حاضر، 100 جدایه اشریشیا کلی از مدفوع گوساله های به ظاهر سالم متعلق به شش گله مختلف در استان خراسان رضوی از جهت حضور ژن های حدت مشخصه سویه های STEC مورد بررسی قرار گرفتند. جهت شناسایی ژن های stx1 و stx2 از روش داپلکس واکنش زنجیره ای پلیمراز استفاده گردید. سپس جدایه های مثبت از لحاظ ژن های stx1 و stx2 با پرایمرهای اختصاصی ژن های eaeA و hlyA مورد ارزیابی قرار گرفتند. هم چنین آزمون واکنش زنجیره ای پلیمراز جهت شناسایی سروتیپ O157: H7 بر روی این جدایه ها انجام گردید. نتایج مطالعه حاضر نشان داد که 15 جدایه (15%) دارای ژن stx1 و 19 جدایه (19%) دارای ژن stx2 و 8 جدایه (8%) حاوی هر دو ژن مذکور بودند. در کل 26 جدایه حاوی حداقل یکی از این دو ژن بودند. در بین این 26 جدایه که از لحاظ ژن های eaeA و hlyA مورد ارزیابی قرار گرفتند، 5 و 22 عدد آنها به ترتیب از لحاظ این ژن ها مثبت بودند. 4 جدایه نیز حاوی هر دو ژن eaeA و hlyA بودند. در بین این 26 جدایه که از لحاظ ژن های کد کننده آنتی ژن های O157 و H7 مورد ارزیابی قرار گرفتند، 1 و 4 عدد آنها به ترتیب از لحاظ این ژن ها مثبت بودند. 4 جدایه نیز حاوی هر دو ژن eaeA و hlyA بودند. هیچیک از جدایه ها حاوی هر دو ژن نبودند.

Objective: Shiga-toxin producing Escherichia coli (STEC) is the most important foodborne bacterial pathogen worldwide and the bovine animals are assumed as a reservoir of this pathogen. The present study was conducted to assess the role of bovine animals as the source of STEC. Materials and methods: To assess the role of bovine animals as the source of STEC, we examined 100 samples (50 rectal swab and 50 beef samples) collected from the local beef slaughterhouses by cultural, morphological, biochemical tests and polymerase chain reaction. Finally, the drug resistance pattern of isolated organisms has been examined. Result: In the preliminary screening by polymerase chain reaction (PCR), E. coli was more prevalent in rectal swab (n=21/50) than beef samples (n=16/50). Among 39 isolated E. coli, 10 isolates were confirmed as STEC (Rectal swab=7, Beef=3) by PCR, where stx2 gene (n=7/10) was predominant than stx1 gene (n=3/10). Remaining 29 isolates did not react to stx primers in PCR. Presence of STEC in beef samples was significantly associated with the fecal contamination at P≤0.1 (0.074818) in Pearson's correlation coefficient method. In addition, most of the isolated STEC strains were resistant to one or more commonly used antimicrobials in the country. Conclusion: The bovine animals and its products could be an important source of multidrug-resistant STEC in the country. [ABSTRACT FROM AUTHOR]

Stx1 toxin is one of the AB5 toxins of Shiga toxin-producing Escherichia coli (STEC) responsible for foodborne intoxication during outbreaks. The single-chain variable fragment (scFv) is the most common recombinant antibody format; it consists of both variable chains connected by a peptide linker with conserved specificity and affinity for antigen. The drawbacks of scFv production in bacteria are the heterologous expression, conformation and stability of the molecule, which could change the affinity for the antigen. In this work, we obtained a stable and functional scFv-Stx1 in bacteria, starting from IgG produced by hybridoma cells. After structural modifications, i.e., change in protein orientation, vector and linker, its solubility for expression in bacteria was increased as well as the affinity for its antigen, demonstrated by a scFv dissociation constant (KD) of 2.26 × 10-7 M. Also, it was able to recognize purified Stx1 and cross-reacted with Stx2 toxin by ELISA (Enzyme-Linked Immunosorbent Assay), and detected 88% of Stx1-producing strains using a rapid latex agglutination test. Thus, the scFv fragment obtained in the present work is a bacteria-produced tool for use in a rapid diagnosis test, providing an alternative for STEC diagnosis. [ABSTRACT FROM AUTHOR]

Aim: Wild birds are considered silent vectors of some zoonotic water and food borne pathogens of public health significance. Owing to the importance of Shiga toxin producing Escherichia coli (STEC) as the most pathogenic among the emerging diarrheagenic E. coli groups that can infect man; the present study was designed to detect the occurrence of STEC among wild birds in Egypt. Materials and Methods: A total of 177 intestinal content swab samples originating from five wild bird species were investigated for the presence of E. coli and STEC by standard culture methods. Suspect STEC isolates were further characterized by serotyping, random amplified polymorphic DNA polymerase chain reaction (RAPD PCR), antimicrobial resistance pattern and PCR detection of stx1, stx2, and eae genes. Results: A total of 30 suspect STEC isolates from 30 positive birds' samples were detected and identified on STEC CHROMagar (semi-captive pigeons, 15; house crows, 8; cattle egrets, 3; moorhens, 2; and house teals, 2). 25 isolates were grouped into 13 serogroups (O:20, O:25, O:26, O:27, O:63, O:78, O:111, O:114, O:125, O:128, O:142, O:153, and O:158), while five were rough strains. The distribution of STEC virulence genes among wild birds was as follows: 16 birds carried stx1 gene only (nine pigeons [28.1%], six crows [7.1%], and one cattle egret [5.6%]). Stx1 and stx2 genes together were detected in four birds (one cattle egret [5.6%], two moorhens [6.1%], and one house teal, [10%]). Only one pigeon (3.1%) possessed the three alleles. Disk diffusion test results showed that cefixime was the most effective against STEC serotypes with (93.3%) sensitivity, followed by gentamycin (56.7%), and amoxicillin (50%). On the other hand, all the recovered STEC isolates were resistant to cefotaxime, doxycycline, cephalothin, and sulfisoxazole. RAPD fingerprinting using primers OPA-2 and OPA-9 showed that STEC isolates were heterogeneous; they yielded 30 and 27 different clusters, respectively. Conclusion: Wild birds carry STEC and may add to the contamination of the surrounding environment. [ABSTRACT FROM AUTHOR]

Ribotoxic Shiga toxins are the primary cause of hemolytic uremic syndrome (HUS) in patients infected with Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC), a pathogen class responsible for epidemic outbreaks of gastrointestinal disease around the globe. HUS is a leading cause of pediatric renal failure in otherwise healthy children, resulting in a mortality rate of 10% and a chronic morbidity rate near 25%. There are currently no available therapeutics to prevent or treat HUS in STEC patients despite decades of work elucidating the mechanisms of Shiga toxicity in sensitive cells. The preclinical development of toxin-targeted HUS therapies has been hindered by the sporadic, geographically dispersed nature of STEC outbreaks with HUS cases and the limited financial incentive for the commercial development of therapies for an acute disease with an inconsistent patient population. The following review considers potential therapeutic targeting of the downstream cellular impacts of Shiga toxicity, which include the unfolded protein response (UPR) and the ribotoxic stress response (RSR). Outcomes of the UPR and RSR are relevant to other diseases with large global incidence and prevalence rates, thus reducing barriers to the development of commercial drugs that could improve STEC and HUS patient outcomes. [ABSTRACT FROM AUTHOR]

Two enzyme-linked immunosorbent assay (ELISA) kits were evaluated for their effectiveness in detecting and differentiating between Shiga toxin 1 and 2 (Stx1 and Stx2) produced by Shiga toxin-producing E. coli (STEC) inoculated into food and water samples. Each kit incorporated monoclonal antibodies previously determined to bind all known Stx1 or Stx2 subtypes with the exception of Stx2b. Four different sample types, including ground beef, Romaine lettuce, pond water, and pasteurized milk were inoculated with Stx1a-, Stx2a-, or Stx1a- and Stx2a-producing STEC strains, enriched using modified tryptic soy broth (containing mitomycin C) for 6, 16, and 22 h, and tested using the ELISA kits in the presence of a bacterial protein extraction reagent (B-PER™). The two Shiga toxin types were readily detected and distinguished for all tested sample types. There was good overall sensitivity, specificity, variance, and reproducibility for the two ELISA kits and they should prove useful for application in food testing. [ABSTRACT FROM AUTHOR]

Cattle are considered a reservoir of Shiga toxin-producing Escherichia coli (STEC). There is no information about the presence of antibodies against Shiga toxins in Brazilian bovine serum. Using ELISA, all sera tested showed antibodies against the two main STEC virulence factors; Stx1 and Stx2. Neutralizing antibodies against Stx1 and/or Stx2 were detected in all but one serum. In conclusion, our results indicated that these animals had been exposed to STEC producing both toxins. [ABSTRACT FROM AUTHOR]

Escherichia coli O157 related foodborne illnesses continue to be one of the most important global public health problems in the world. This study aims to determine E. coli O157 prevalence in 375 chicken meat parts and giblets. The samples were collected randomly from several supermarkets and butchers in Diyarbakir, a city in southeast Turkey. They were analyzed and confirmed using the immunomagnetic separation (IMS), vitek® 2 microbial identification system and polymerase chain reaction (PCR) method. this study also aims to detect the presence of fliCH7, eaeA, stx1, stx2 and hlyA genes by using PCR. The overall E. coli O157 prevalence in chicken meat parts and giblets was 1.3%. all of the E. coli O157 isolates carried rfbEO157 and eaea genes; but not any fliCH7 and hlyA genes. The E. coli O157 isolates obtained from drumstick and breast meat carried either stx1 or stx2 genes, which were related to important virulence factors of the disease. [ABSTRACT FROM AUTHOR]

Both ricin and Shiga holotoxins display no ribosomal activity in their native forms and need to be activated to inhibit translation in a cell-free translation inhibition assay. This is because the ribosome binding site of the ricin A chain (RTA) is blocked by the B subunit in ricin holotoxin. However, it is not clear why Shiga toxin 1 (Stx1) or Shiga toxin 2 (Stx2) holotoxin is not active in a cell-free system. Here, we compare the ribosome binding and depurination activity of Stx1 and Stx2 holotoxins with the A1 subunits of Stx1 and Stx2 using either the ribosome or a 10-mer RNA mimic of the sarcin/ricin loop as substrates. Our results demonstrate that the active sites of Stx1 and Stx2 holotoxins are blocked by the A2 chain and the B subunit, while the ribosome binding sites are exposed to the solvent. Unlike ricin, which is enzymatically active, but cannot interact with the ribosome, Stx1 and Stx2 holotoxins are enzymatically inactive but can interact with the ribosome. [ABSTRACT FROM AUTHOR]

Shiga toxin-producing Escherichia coli (STEC) is recognised as toxin producing group of E. coli and one of the most significant foodborne pathogens worldwide. The aim of this study was to detect STEC and determine virulence gene profiles of these pathogens in different kinds of meat and products in Iran. For this reason a total of 182 samples of minced beef, mutton, chicken meat, chicken feet and mechanically separated chicken meat were collected from retail markets for detection of STEC by PCR method. Of the 72 E. coli isolated from examined samples, 29 of them were STEC. The highest presence of STEC was detected in minced beef (23.5%) followed by chicken feet (15%), mutton (13.3%), mechanically separated chicken meat (12.5%) and chicken meat (5.5%) respectively. In addition the results of PCR assay indicated that 21 (72.4%) and 4 (13.7%) of isolates carried stx2 and eaeA genes respectively. However, according to the results stx2 was the most prevalent gene detected in all kinds of examined samples. Our findings showed that evaluation of the prevalence and virulence factors of this pathogen seems necessary considering the increasing importance of STEC as one of the most significant foodborne pathogens. [ABSTRACT FROM AUTHOR]

Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3) on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to the endoplasmic reticulum. The enzymatically active part of the A-moiety is then translocated to the cytosol, where it inhibits protein synthesis and in some cell types induces apoptosis. Protection of cells can be provided either by inhibiting binding of the toxin to cells or by interfering with any of the subsequent steps required for its toxic effect. In this article we provide a brief overview of the interaction of Shiga toxins with cells, describe some compounds and conditions found to protect cells against Shiga toxins, and discuss whether they might also provide protection in animals and humans. [ABSTRACT FROM AUTHOR]

Escherichia coli O157:H7 with the ability to produce shiga-like toxin was isolated from beef, cattle,chicken, and human feces. Due to its importance to human health, it is necessary to identify the genesencoding the production of shiga-like toxin, stx1 and stx2 respectively to further understand the pathogenesis.Isolation of E. coli was done on Eosin Methylene Blue Agar (EMBA), followed by identification on SorbitolMacConkey Agar (SMAC), latex agglutination test, and H7 antiserum test, respectivelly. The existence ofgenes stx1 and stx2 in E. coli O157:H7 was confirmed molecularly using PCR method with specific primersLP 30/31 and LP 43/44, Stx2 (F)/Stx2 (R) respectively. Escherichia coli O157:H7 was isolated from 22 outof 344 samples (6,4%). Some isolates showed gene stx1 and stx2 was detected in two isolates as indicatedby a 384 bp band (stx1 gene), 584 bp and 1588 bp bands (stx2 gene) respectivelly. The results indicatedthat local isolates E. coli O157:H7 are potential as a zoonoses agent.

Monoclonal antibodies (MAbs) have been employed either for diagnosis or treatment of infections caused by different pathogens. Specifically for Shiga toxin-producing Escherichia coli (STEC), numerous immunoassays have been developed for STEC diagnosis, showing variability in sensitivity and specificity when evaluated by reference laboratories, and no therapy or vaccines are currently approved. Thus, the aim of this work was the characterization of the interaction between MAbs against Stx1 and Stx2 toxins and their neutralizing abilities to enable their use as tools for diagnosis and therapy. The selected clones designated 3E2 (anti-Stx1) and 2E11 (anti-Stx2) were classified as IgG1. 3E2 recognized the B subunit of Stx1 with an affinity constant of 2.5 × 10−10 M, detected as little as 6.2 ng of Stx1 and was stable up to 50 ºC. In contrast, 2E11 recognized the A subunit of Stx2, was stable up to 70 ºC, had a high dissociation constant of 6.1 × 10−10 M, and detected as little as 12.5 ng of Stx2. Neutralization tests showed that 160 ng of 3E2 MAb inhibited 80% of Stx1 activity and 500 µg 2E11 MAb were required for 60% inhibition of Stx2 activity. These MAb amounts reversed 25 to 80% of the cytotoxicity triggered by different STEC isolates. In conclusion, these MAbs show suitable characteristics for their use in STEC diagnosis and encourage future studies to investigate their protective efficacy.

Stx1 toxin is one of the AB5 toxins of Shiga toxin-producing Escherichia coli (STEC) responsible for foodborne intoxication during outbreaks. The single-chain variable fragment (scFv) is the most common recombinant antibody format; it consists of both variable chains connected by a peptide linker with conserved specificity and affinity for antigen. The drawbacks of scFv production in bacteria are the heterologous expression, conformation and stability of the molecule, which could change the affinity for the antigen. In this work, we obtained a stable and functional scFv-Stx1 in bacteria, starting from IgG produced by hybridoma cells. After structural modifications, i.e., change in protein orientation, vector and linker, its solubility for expression in bacteria was increased as well as the affinity for its antigen, demonstrated by a scFv dissociation constant (KD) of 2.26 × 10−7 M. Also, it was able to recognize purified Stx1 and cross-reacted with Stx2 toxin by ELISA (Enzyme-Linked Immunosorbent Assay), and detected 88% of Stx1-producing strains using a rapid latex agglutination test. Thus, the scFv fragment obtained in the present work is a bacteria-produced tool for use in a rapid diagnosis test, providing an alternative for STEC diagnosis.

Objectives: This study was designed to assess the contamination of enterovirulent Escherichia coli with table eggs at Mansoura, Egypt. Materials and methods: A total of 100 commercially available table eggs were randomly collected from various groceries and supermarkets at Mansoura, Egypt. The samples were screened for the presence of E. coli through conventional bacteriological and biochemical analyses followed by confirmation by polymerase chain reaction. Results: Overall, 18% (n=18/100) samples were found to be contaminated with one or more E. coli isolates. All possible E. coli colonies (n=52) appeared on MacConkey agar plates during the screening process were picked for further analysis. Among the 52 suspected isolates, 24 were confirmed as E. coli, which were further serotyped using polyvalent E. coli antisera. In this study, 9 different E. coli serotypes namely O78, O114, O2, O44, O1, O125, O128, O124 and O26 were identified. Out of these 9 serological strains, 5 (O78, O2, O44, O125, O124 and O26) were positive for eae gene, and 3 (O44, O1 and O128) were positive for stx2 gene. Two serological strains (O44 and O1) were positive for both stx1 and eae genes, while O125 and O114 were positive for stx2 and eae genes. Two strains (O78 and O128) were found to be positive for all three genes (stx1, stx2 and eae). Conclusion: Ensuring hygienic measures can effectively reduce the microbial load from table eggs. [ABSTRACT FROM AUTHOR]

Shiga toxin 1 (Stx1) and Shiga toxin 2 (Stx2) differ regarding receptor affinity, cellular toxicity and clinical outcome. To this date, it is not clarified in detail why the subtypes display these differences. Even though the crystal structures of Stx1 and Stx2 share overall similarities, significant differences were found in the C-terminal end of the A-subunits. The aim of this study was to investigate the role of the C-terminal end of the A-subunit in complex stability and retrograde transport by generating truncated mutants where 2, 4, 6 and 8 amino acids were removed from the C-terminal end of Stx1A and Stx2A. The results obtained show that removal of 6 or 8 amino acids from the Stx1A C-terminus abolishes the AB5 complex integrity, while removing up to 8 amino acids from Stx2A does not affect the complex in vivo (in the bacteria). We also present results showing different levels of A1-subunit in HeLa cells after exposure to Stx1, Stx2 and their truncated mutants. [ABSTRACT FROM AUTHOR]

Ribotoxic Shiga toxins are the primary cause of hemolytic uremic syndrome (HUS) in patients infected with Shiga toxin-producing enterohemorrhagic Escherichia coli (STEC), a pathogen class responsible for epidemic outbreaks of gastrointestinal disease around the globe. HUS is a leading cause of pediatric renal failure in otherwise healthy children, resulting in a mortality rate of 10% and a chronic morbidity rate near 25%. There are currently no available therapeutics to prevent or treat HUS in STEC patients despite decades of work elucidating the mechanisms of Shiga toxicity in sensitive cells. The preclinical development of toxin-targeted HUS therapies has been hindered by the sporadic, geographically dispersed nature of STEC outbreaks with HUS cases and the limited financial incentive for the commercial development of therapies for an acute disease with an inconsistent patient population. The following review considers potential therapeutic targeting of the downstream cellular impacts of Shiga toxicity, which include the unfolded protein response (UPR) and the ribotoxic stress response (RSR). Outcomes of the UPR and RSR are relevant to other diseases with large global incidence and prevalence rates, thus reducing barriers to the development of commercial drugs that could improve STEC and HUS patient outcomes.

Shiga toxins consist of an A-moiety and five B-moieties able to bind the neutral glycosphingolipid globotriaosylceramide (Gb3) on the cell surface. To intoxicate cells efficiently, the toxin A-moiety has to be cleaved by furin and transported retrogradely to the Golgi apparatus and to the endoplasmic reticulum. The enzymatically active part of the A-moiety is then translocated to the cytosol, where it inhibits protein synthesis and in some cell types induces apoptosis. Protection of cells can be provided either by inhibiting binding of the toxin to cells or by interfering with any of the subsequent steps required for its toxic effect. In this article we provide a brief overview of the interaction of Shiga toxins with cells, describe some compounds and conditions found to protect cells against Shiga toxins, and discuss whether they might also provide protection in animals and humans.

Purpose: To characterize the prevalence of hemolytic Shiga toxin-producing Escherichia coli (STEC) with a multidrug-resistant pattern in different age groups in Abeokuta, Nigeria. Methods: Nonrepetitive E. coli isolates were collected from 202 subjects with or without evidence of diarrhea. Each isolate was biochemically identified and antimicrobial susceptibility testing was performed using the disk diffusion method. A sorbitol fermentation test of all the E. coli isolates was done and the minimum inhibitory concentration of suspected STEC was measured by the standard broth microdilution method to determine antibiotic resistance. The genotypes of stx1, stx2, and hlyA were determined by polymerase chain reaction assay. Results: The majority of subjects were aged $40 years (41.6%) and were female (61.9%). Of the 202 subjects, 86.1% had STEC isolates (P,0.05). A high rate of STEC isolates resistant to amoxicillin (90.6%), cefotaxime (77.7%), and cefuroxime (75.7%) was observed. Resistance to amoxicillin, gentamicin, and cefotaxime was demonstrated with a minimum inhibitory concentration .16 μg/mL in 13.9%, 11.4%, and 10.4% of the isolates, respectively. The prevalence of stx1, stx2, and hlyA was 13.9%, 6.9%, and 2.0%, respectively; 5.5% of stx1 were in the 0–10-year-old age group, 3.5% of stx2 were aged $40 and above, and 1.0% of the hlyA isolates were in the 0–10-year-old age group. Conclusion: The prevalence of virulent STEC is a public health concern. The use of polymerase chain reaction assay should aid quick detection of this virulent serotype and help curb the severe epidemic of human diseases associated with STEC infections. [ABSTRACT FROM AUTHOR]

In order to isolate and characterize E. coli producing shigatoxins (STEC) pathogenic to humans in samples of meat and cheese type mines frescal marketed in the southwestern region of the state of Goiás, were evaluated 24 samples of frescal cheese, as contamination by STEC. Found an isolate of STEC originating from a frescal cheese. So animal foods marketed in Goias are possible sources of contamination STECs pathogenic for humans. [ABSTRACT FROM AUTHOR]

Rectal swabs of 198 Holstein × Gir crossbred beef cattle from 34 milk farms in the central west of Brazil were analyzed from August 2010 to February 2011. Strains of shiga toxin-producing Escherichia coli (STEC) were isolated from 72.73 % (144/198) of the animals, on over 97 % of the surveyed properties. The molecular characterization indicated the most common toxin gene s tx1 in 70.88 % of the animals (202/285), followed by 18.95 % (54/285) s tx1/ sxt2, and 10.18 % (29/285) stx2. The presence of STEC in animals together with the probable risk factors based on a questionnaire was evaluated in the owners of the evaluated animals. Results showed that the animal category 'calves' and production/technification scale 'low' of the farm were related to high STEC prevalence in cattle. The season did not significantly affect the presence of STEC in cattle. The STEC strains are considered a major pathogen, causing severe and potentially lethal diseases in humans such as hemorrhagic colitis and hemolytic uremic syndrome. This high prevalence of STEC in dairy cattle poses a significant risk to public health, since these microorganisms can contaminate products intended for human consumption, e.g., water, raw and pasteurized milk, meat products, dairy products, and/or products of plant origin. [ABSTRACT FROM AUTHOR]

Abstract: This study determined the prevalence, serotypes and virulence genes distribution of non-O157 Shiga toxin-producing Escherichia coli in meat products collected from butchers shops and supermarkets in Mansoura city, Egypt. We have characterized 18 non-O157 STEC strains among the identified 100 E. coli isolates recovered from the examined 87 meat product samples. The prevalence of non-O157 STEC strains in fresh beef, ground beef and beef burger samples were 11.1% (3/27), 16.7% (5/30), and 33.3% (10/30), respectively. The eighteen non-O157 STEC isolated strains were serotyped into seven (38.9%) O111:H8, six (33.3%) O26:H11, two (11.1%) O111:H–, and one (5.56%) for each of O55:H7, O126:H5 and O128:H2. PCR assays for different virulence genes showed that nine (50%), eleven (61.1%), and nine (50%) strains carry stx1, stx2, and eae genes, respectively. The distribution of shiga toxin genes among the isolated strains indicated that seven (38.9%) strains harbored stx1 only, nine (50%) strains harbored stx2 only, and two (11.1%) strains harbored both stx1 and stx2. The eae gene was present in association with five (27.8%), three (16.7%), and one (5.6%) strains that harbored stx1 only, stx2 only, and both stx1 and stx2, respectively. This study concluded that the examined meat products, particularly beef burger, consumed in Egypt are considerably contaminated with a variety of non-O157 STEC serotypes, and hence consumption of such products may constitute a potential health risk for consumers. [Copyright &y& Elsevier]

Background and Objectives: Shiga toxin-producing Escherichia coli (STEC) strains are human pathogens linked to hemorrhagic colitis and hemolytic uremic syndrome. Shiga toxins (Stx1 and Stx2) are the major virulence factors of these strains. The aim of this work was to study the prevalence and distribution of stx1 and stx2 gene in E. coli O157:H7 and non-O157:H7 strains isolated from cattle in Shiraz, Iran. Materials and Methods: Four hundred and twenty samples consisted of recto-anal mucosal swabs were collected from cattle. They were checked for the presence of the stx1 and stx2 gene using multiplex-PCR every 1 week over a 1-year period (2007-2008). Results: A total of 146 strains carrying the stx1 and stx2 gene were isolated from 51 (12.14%) cattle. Overall, 15 (3.57%) were identified as O157:H7 and 131 (31.19%) revealed to be non-O157:H7. Both stx2 and stx1 genes were detected in 51 (34.93%) STEC isolates. Genotypes stx1 and stx2 were detected in 15 (10.27%) and 78 (53.42%) respectively. Seasonal distribution of stx genes revealed high percentage of positive animals in warm seasons. The gene sequence similarity ranged from 94 to 100%. Conclusion: Frequency of stx1 and stx2 in animals and its relation to human disease is not well understood in Iran. The high prevalence of STEC in cattle seems to parallel that which is usually observed in warm seasons and it also parallels occurrence of human STEC. The higher prevalence of the stx2 gene than stx1 in strain populations isolated from cattle indicates a risk alert of E. coli O157:H7 being shed by cattle in these populations. Appropriate measures are now needed to prevent the spread of this life-threatening foodborne disease in our country.