Molecular characterization of Shiga toxin-producing Escherichia coli isolated from ruminant and donkey raw milk samples and traditional dairy products in Iran

Prevalence and Implications of Shiga Toxin-Producing E. coli in Farm and Wild Ruminants

Shiga-toxin-producing Escherichia coli (STEC) is a food-borne pathogen that causes human gastrointestinal infections across the globe, leading to kidney failure or even death in severe cases. E. coli are commensal members of humans and animals' (cattle, bison, and pigs) guts, however, may acquire Shiga-toxin-encoded phages. This acquisition or colonization by STEC may lead to dysbiosis in the intestinal microbial community of the host. Wildlife and livestock animals can be asymptomatically colonized by STEC, leading to pathogen shedding and transmission. Furthermore, there has been a steady uptick in new STEC variants representing various serotypes. These, along with hybrids of other pathogenic E. coli (UPEC and ExPEC), are of serious concern, especially when they possess enhanced antimicrobial resistance, biofilm formation, etc. Recent studies have reported these in the livestock and food industry with minimal focus on wildlife. Disturbed natural habitats and changing climates are increasingly creating wildlife reservoirs of these pathogens, leading to a rise in zoonotic infections. Therefore, this review comprehensively surveyed studies on STEC prevalence in livestock and wildlife hosts. We further present important microbial and environmental factors contributing to STEC spread as well as infections. Finally, we delve into potential strategies for limiting STEC shedding and transmission.

Occurrence of multiple drug-resistant Shiga toxigenic Escherichia coli in raw milk samples collected from retail outlets in South India

The prevalence of Shiga-toxigenic E. coli (STEC), harbouring multidrug-resistant genes in raw milk collected from household vendors and cooperative milk marketing societies in Ernakulam District, Kerala, India, has been investigated. A higher prevalence of STEC pathotypes, with 47.16% (20 out of 42 samples), was observed in raw milk. A total of 157 STEC isolates were identified, which included notorious pathoserotypes, E. coli O157 group (10.19%) and E. coli non-O157 group 5.73%). All of the tested STEC isolates were multidrug-resistant and showed resistance to at least six different antibiotics. Two of the isolates showed resistance to 14 different antibiotics tested. Cent percentage resistance was observed for Penicillin, Cefalexine, Rifampicin, Methicillin, and Novobiocin. We observed in phenotypic assays that 26.75% of STEC isolates are ESBL producers. The bla TEM gene, a characteristic marker for ESBL production, was detected in 42.85% of the isolates. The study points out the risk of virulent and multidrug-resistant STEC in raw milk and the need for stringent quality surveillance and assurance plans to alleviate the potential public health threat.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-021-05226-x.

Non-diarrhoeic pigs as source of highly virulent and multidrug-resistant non-typhoidal Salmonella

Food-producing animals act as reservoirs of non-typhoidal Salmonella (NTS) serovars with potential food safety and public health implications. The present cross-sectional study aimed at determining the prevalence of Salmonella serotypes in non-diarrhoeic pigs and characterizing the isolates using molecular tools. Salmonella isolates (n = 22) recovered from faecal samples of 194 randomly selected pigs were characterized for virulence and antimicrobial resistance and subtyped using XbaI-PFGE. The prevalence of Salmonella in apparently healthy non-diarrhoeic pigs was 11.3% (95%CI, 4.3-19.5%), with S. Weltevreden (81.8%) and S. Enteritidis (18.2%) being the serotypes detected. Salmonella isolates harboured virulence genes such as invA (100%), stn (100%), spvR/spvC (86.3%) and fimA (22.7%). Phenotypically, isolates showed sensitivity to chloramphenicol, levofloxacin and ciprofloxacin and resistance to tetracycline and ampicillin (100%), streptomycin (86.4%), amoxicillin-clavulanate (63.6%), cefotaxime (22.7%) and ceftriaxone (9.1%). Notably, 18.2% isolates were multidrug-resistant (≥ 3 antimicrobial class) with multiple antimicrobial resistance (MAR) index of 0.56-0.67 (18.2%), 0.44 (45.5%), 0.33 (31.8%) and 0.22 (4.5%). Genotypically, isolates carried various antibiotic resistance genes: ESBL (bla_TEM and bla_OXA), aminoglycoside (strA, strB and aadA1), sulphonamide (sul1, sul2 and dfrA1), tetracycline (tetA and tetB) and plasmid AmpC beta-lactamase (ACC, FOX, MOX, DHA, CIT and EBC). The present investigation emphasizes the epidemiological significance of PFGE typing in the detection of emerging strains of highly virulent and multidrug-resistant S. Weltevreden and S. Enteritidis in non-diarrhoeic pigs that pose serious public health implications in the pork supply chain environment. More extensive longitudinal study is warranted to provide epidemiological links between environmental reservoirs and animal and human infections in piggery settings.

Essential Oils from Indigenous Iranian Plants: A Natural Weapon vs. Multidrug-Resistant Escherichia coli

Aim of this study was to investigate the antimicrobial properties of herbal plant essential oils (EOs) from selected Iranian plant species such as Ferulago angulata, Zataria multiflora, Cuminum cyminum, and Mentha longifolia against antibiotic-resistant Escherichia coli (E. coli) strains. For this purpose, the Escherichia coli strains, isolated from raw cow’s milk and local dairy products (yogurt, cream, whey, cheese, and confectionery products) collected from different areas of Hamedan province, Iran, were investigated for their resistance to antibiotics (i.e., streptomycin, tetracycline, gentamicin, chloramphenicol, ciprofloxacin, and cefixime). Thus, the E. coli strains were tested for their susceptibility to the above-mentioned essential oils. Regarding antibiotics, the E. coli strains were highly sensitive to ciprofloxacin. In relation to essential oils, the most effective antibacterial activity was observed with Zataria multiflora; also, the bacteria were semi-sensitive to Cuminum cyminum and Mentha longifolia essential oils. All strains were resistant to Ferulago angulata essential oil. According to the results, the essential oil of Zataria multiflora can be considered as a practical and alternative antibacterial strategy to inhibit the growth of multidrug-resistant E. coli of dairy origin.

Phenotypic and molecular characterizations of multidrug-resistant diarrheagenic E. coli of calf origin

Escherichia coli has become one of the most important causes of calf diarrhea. The aim of this study is to determine the patterns of antimicrobial resistance of E. coli isolates from six cattle farms and to identify prominent resistance genes and virulence genes among the strains isolated from the diarrhea of calves. Antimicrobial susceptibility tests were performed using the disk diffusion method, and PCR was used to detect resistance and virulence genes. The prevalence of multidrug resistant (MDR) E. coli was 77.8% in dairy cattle and 63.6% in beef cattle. There were high resistance rates to penicillin (100%, 100%) and ampicillin (96.3%, 86.4%) in E. coli from dairy cattle and beef cattle. Interestingly, resistance rate to antimicrobials and distribution of resistance genes in E. coli isolated from dairy cattle were higher than those in beef cattle. Further analysis showed that the most prevalent resistance genes were blaTEM and aadA1 in dairy cattle and beef cattle, respectively. Moreover, seven diarrheagenic virulence genes (irp2, fyuA, Stx1, eaeA, F41, K99 and STa) were present in the isolates from dairy cattle, with a prevalence ranging from 3.7% to 22.22%. Six diarrheagenic virulence genes (irp2, fyuA, Stx1, eaeA, hylA and F41) were identified in the isolates from beef cattle, with a prevalence ranging from 2.27% to 63.64%. Our results provide important evidence for better exploring their interaction mechanism. Further studies are also needed to understand the origin and transmission route of E. coli in cattle to reduce its prevalence.

Molecular Detection, Serotyping, and Antibiotic Resistance of Shiga Toxigenic Escherichia coli Isolated from She-Camels and In-Contact Humans in Egypt

This study aims to determine the prevalence of STEC in she-camels suffering from mastitis in semi-arid regions by using traditional culture methods and then confirming it with Serological and molecular techniques in milk samples, camel feces, as well as human stool samples for human contacts. In addition, an antibiotic susceptibility profile for these isolates was investigation. Mastitic milk samples were taken after California Mastitis Test (CMT) procedure, and fecal samples were taken from she-camels and human stool samples, then cultured using traditional methods to isolate Escherichiacoli. These isolates were initially classified serologically, then an mPCR (Multiplex PCR) was used to determine virulence genes. Finally, both camel and human isolates were tested for antibiotic susceptibility. Out of a total of 180 she-camels, 34 (18.9%) were mastitic (8.3% clinical and 10.6% sub-clinical mastitis), where it was higher in camels bred with other animals. The total presence of E. coli was 21.9, 13.9, and 33.7% in milk, camel feces, and human stool, respectively, whereas the occurrence of STEC from the total E. coli isolates were 36, 16, and 31.4% for milk, camel feces, and stool, respectively. Among the camel isolates, stx₁ was the most frequently detected virulence gene, while hlyA was not detected. The most detected virulence gene in human isolates was stx₂ (45.5%), followed by stx₁. Camel STEC showed resistance to Oxytetracycline only, while human STEC showed multiple drug resistance to Amoxicillin, Gentamycin, and Clindamycin with 81.8, 72.7, and 63.6%, respectively. Breeding camels in semi-arid areas separately from other animals may reduce the risk of infection with some bacteria, including E. coli; in contrast, mixed breeding with other animals contributes a significant risk factor for STEC emergence in camels.

Molecular detection of Shiga toxin-producing Escherichia coli (STEC) O157 in sheep, goats, cows and buffaloes

BACKGROUND

Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that causing serious public health consequences worldwide. The present study aimed to estimate the prevalence ratio and to identify the zoonotic potential of E. coli O157 isolates in slaughtered adult sheep, goats, cows and buffaloes.

MATERIALS AND METHODS

A total of 400 Recto-anal samples were collected from two targeted sites Rawalpindi and Islamabad. Among them, 200 samples were collected from the slaughterhouse of Rawalpindi included sheep (n = 75) and goats (n = 125). While, 200 samples were collected from the slaughterhouse of Islamabad included cows (n = 120) and buffalos (n = 80). All samples were initially processed in buffered peptone water and then amplified by conventional PCR. Samples positive for E. coli O157 were then streaked onto SMAC media plates. From each positive sample, six different Sorbitol fermented pink-colored colonies were isolated and analyzed again via conventional PCR to confirm the presence of rfbE O157 gene. Isolates positive for rfbE O157 gene were then further analyzed by multiplex PCR for the presence of STEC other virulent genes (sxt1, stx2, eae and ehlyA) simultaneously.

RESULTS

Of 400 RAJ samples only 2 (0.5%) showed positive results for E. coli O157 gene, included sheep 1/75 (1.33%) and buffalo 1/80 (1.25%). However, goats (n = 125) and cows (n = 120) found negative for E. coli O157. Only 2 isolates from each positive sample of sheep (1/6) and buffalo (1/6) harbored rfbE O157 genes, while five isolates could not. The rfbE O157 isolate (01) of sheep sample did not carry any of STEC genes, while the rfbE O157 isolate (01) of buffalo sample carried sxt1, stx2, eae and ehlyA genes simultaneously.

CONCLUSION

It was concluded that healthy adult sheep and buffalo are possibly essential carriers of STEC O157. However, rfbE O157 isolate of buffalo RAJ sample carried 4 STEC virulent genes, hence considered an important source of STEC infection to humans and environment which should need to devise proper control systems.

Critical occurrence of verotoxgenic E.coli and non-typhoidal salmonella in some heat treated dairy products

Pathogenic strains of E.coli and Salmonella are common causes of foodborne illness and have been frequently isolated from inadequately heat-treated milk products in Mansoura city. The current study was performed to explore the prevalence of E.coli and Salmonella spp. in heattreated milk products intended for consumption in Mansoura university hospitals and hostels, as well as, to investigate their serotypes and virulence potential. Seventyfive samples of heat-treated milk products (Soft cheese, yoghurt, and processed cheese, 25 of each) were randomly gathered and directed to further investigation using conventional and molecular microbiology. Result revealed that 3(12%) of soft cheese samples harbored E.coli O146:H21, O26:H11 and O128:H2 serotypes and 2(8%) of yoghurt samples were contaminated with O128:H2 and O121:H7 serotypes while 3(12%) of processed cheese samples were positive for non-typhoidal Salmonella (NTS) serovars (Salmonella Typhimurium, Salmonella Infantis and Salmonella Essen). Virulence gene profiling reported that all E.coli isolates harbored eaeA gene and only E.coli O26:H11 and O121:H7 encoded stx2 (verotoxin) gene. Further, all Salmonella isolates harbored invA and stn genes, while only Salmonella Typhimurium and Salmonella Infantis encoded spvC gene. This study confirmed the existence of highly pathogenic verotoxogenic E.coli (VTEC) and NTS in investigated milk products which could be hazardous for public health and resident in Mansoura hospitals and hostels. Hence, the implementation of good hygienic practices together with hazard analysis, and risk-based preventive control measures are rigorously required in the process of HACCP plan to eliminate the risk of contamination that may occur during the manufacturing process.

Isolation and Antimicrobial Susceptibility Profile of Escherichia coli O157 : H7 from Raw Milk of Dairy Cattle in Holeta District, Central Ethiopia

A cross-sectional study was conducted in small, medium, and large-scale dairy farms of Holeta district to isolate, identify, and antimicrobial susceptibility profile of Escherichia coli O157 : H7 in raw milk of dairy cattle. A total of 210 lactating cows were selected for raw milk samples, and 19% (40/210) were found to be positive for E. coli whereas 5.2% (11/210) were confirmed as E. coli O157 : H7 positive using the Escherichia coli O157 latex test. Accordingly, all E. coli was highly susceptible to Ciprofloxacin (100%), Gentamycin (100%), Oxytetracycline (100%), and Tetracycline (63.63%). Furthermore, the resistance of 72.73%, 54.54%, 54.54%, and 45.45% was developed to Cefoxitin, Sulphamethoxazole, Cloxacillin, and Streptomycin, respectively. Factors such as parity, age, body condition, herd size, milk yield, udder hygiene, and udder lesion showed a statistically significant ( $p<0.05$ ) association with the occurrence of E. coli infection in dairy cattle. In conclusion, in this study, a higher prevalence of Escherichia coli O157 : H7 and its drug susceptibility profile is an alarm for the health of the public, and awareness creation to the farm owners and the community is recommended.

Uropathogenic Escherichia coli in the high vaginal swab samples of fertile and infertile women: virulence factors, O-serogroups, and phenotyping and genotyping characterization of antibiotic resistance

Transmission of urinary tract infections into the reproductive system is unavoidable. The present research was performed to assess the distribution of virulence genes, O-serogroups and antibiotic resistance properties of uropathogenic Escherichia coli (UPEC) strains isolated from the high vaginal swab samples of fertile and infertile women. A total of 460 high vaginal swab samples were taken from fertile and infertile women. Distribution of virulence factors and serogroups and antibiotic resistance properties of the E. coli isolates were assessed. Sixty-five out of 460 (14.13%) swab samples were positive for E. coli. Prevalences of E. coli in samples taken from fertile and infertile women were 13.63% and 14.58%, respectively. O1 (7.69%), O2 (6.15%) and O6 (6.15%) were the most frequently detected serogroups. The most frequently detected virulence genes were sfa (72.72%), afa (72.72%), cnf1 (72.72%) and fim (72.72%). The most commonly detected antibiotic-resistance genes were tetA (95.45%), CITM (88.63%), aac(3)-IV (86.36%) and sul1 (72.72%). UPEC strains harboured the highest prevalence of resistance against tetracycline (88.63%), ampicillin (79.54%), gentamicin (77.27%) and enrofloxacin (52.27%). Seventeen out of 26 (65.38%) UPEC strains isolated from infertile women were resistant toward more than ten antibiotic agents. Infertile women with a history of urinary tract infections had the higher prevalence of UPEC strains and also the other characters. High prevalence of the virulent and resistant UPEC strains in the high vaginal part of the infertile women with a history of urinary tract infections may show an important role of these pathogens as causes of female infertility. However, further research is required to confirm this hypothesis.

Antimicrobial resistance modulation of MDR E. coli by antibiotic coated ZnO nanoparticles

We evaluated three types of total six preparations against multidrug resistant E. coli i) three antibiotic coated ZnO nanoparticles (gentamicin coated nanoparticle-GNp; chloramphenicol coated nanoparticles-CNp; and both gentamicin & chloramphenicol coated nanoparticle-GCNp), ii) ZnO nanoparticle alone-Np, and iii) two antibiotics used in single (Gentamicin-G; and Chloramphenicol-C). A total of n = 200 sub-clinically positive mastitic milk samples of bovine origin were processed for isolation of MDR E. coli using microbiological and clinical laboratory & standard institute's protocols. ZnO Nps were prepared from zinc acetate dihydrate (Zn (CH₃COO)₂. 2H₂O), polyethylene glycol (C_2nH_4n+2O_n+1), and urea (CH₄N₂O) by standard chemical protocol. Nps were characterized by XRD and STEM analyses while coating of antibiotics on Nps was confirmed by UV-Visible spectrophotometric analysis. Analysis of variance and student t-test were applied at 5% probability using SPSS version 22 statistical software for inferences on obtained data. There was significantly (p < 0.05) lowest minimum inhibitory concentrations (MICs) and highest zone of inhibitions (ZOIs) in case of GCNp (10.42 ± 4.51 μg/mL & 22.00 ± 1.00 mm) followed by GNp (20.79 ± 8.95 μg/mL & 20.00 ± 1.00 mm) and then CNp (25.96 ± 8.95 μg/mL & 12.33 ± 0.57 mm). Percentage increase in ZOI were expressed as 135.8, 78.43, and 312.76% by GCNp when compared with that of G, C, and Np, respectively. GNp and CNp coated preparations exhibited 114.36 and 275.73% increase in ZOI than to that of G and C, respectively. Similar trend was found in percentage reduction of MICs of preparations. Highest filamentation, indicator of bacterial damage, of E. coli was noted at MIC of GCNp followed by GNp and CNp. The study concluded antibiotic coated ZnO nanoparticles significant candidates modulating antibiotic resistance in MDR E. coli.

Molecular characterization of antimicrobial resistance and virulence genes of Escherichia coli isolates from bovine mastitis

Background and Aim:

Mastitis is a common and economically important disease in dairy cattle. It remains one of the most common reasons for the extensive use of antimicrobials in dairy farms leading to the emergence of antimicrobial-resistant pathogens. The aim of this study was to determine the patterns of antimicrobial resistance of Escherichia coli isolates from bovine mastitis and to identify prominent antimicrobial resistance and virulence genes among isolated strains.

Materials and Methods:

Antimicrobial susceptibility testing against six antibiotic groups, including tetracyclines, aminoglycosides, beta-lactams, macrolides, sulfonamides, and fluoroquinolones was performed using the disk diffusion method. PCR was performed on resistant isolates to detect resistance and virulence genes using commercially available primers.

Results:

Out of 216 milk samples cultured, 14 samples yielded E. coli isolates. All isolates (100%) were resistant to ampicillin, amoxicillin, procaine penicillin, streptomycin, oxytetracycline, and sulfamethoxazole-trimethoprim. Only one isolate (7%) was sensitive to gentamicin, and all isolates (100%) were sensitive to enrofloxacin and ciprofloxacin. All isolates carried at least one resistance gene against one or more of the major antibiotic groups. All isolates carried the ereA, tetG, tetE, and tetB genes, followed by tetA (93%), ampC (86%), strA (86%), sul1 (78%), tetD (71%), tetC (57%), aadA (57%), and strB (36%). The lowest percentage of isolates carried bla1 (17%) and bla2 (12%) genes, and none of the isolates carried the qnrA gene. Most of the isolates (93%) carried the Shiga toxin 1 virulence gene, followed by complement resistance protein (79%), intimin (64%), Shiga toxin 2 (36%), cytotoxic necrotizing factor (35%), aerotaxis receptor (21%), and type 1 fimbriae (15%).

Conclusion:

Results of this study indicate that the high percentages of E. coli isolate from bovine mastitis are resistant to two or more of the major antibiotic groups, irrespective of the presence or absence of relevant resistance or virulence genes.

Molecular Detection and Antimicrobial Resistance Patterns of Shiga Toxigenic Escherichia coli Isolated from Bovine Subclinical Mastitis Milk Samples in Kurdistan, Iran

Bovine subclinical mastitis is regarded as a devastating disease due to the economic costs imposed on dairy husbandry. Moreover, it is a hazard in the public sector in the cases of zoonotic bacteria because of the potential role of unpasteurized milk and dairy products to propagate the infectious agent to the human food chain. The present study aimed to evaluate the frequency, virulence content, and antimicrobial resistance profile of Shiga toxin-producing Escherichia coli (STEC) strains isolated from bovine subclinical mastitis in Kurdistan Province, West of Iran. A total of 400 bovine subclinical mastitis milk samples recognized in the California Mastitis Test were collected aseptically and analyzed for the presence of E. coli phenotypically and molecularly. The isolates were genotypically screened for stx1, stx2, and eae genes. Furthermore, O157:H7 STEC strain was searched among the isolates in a duplex polymerase chain reaction. The antimicrobial resistance scheme of the isolates was determined using the agar disk diffusion method. In general, 173 (43.25%) E. coli isolates were detected among which 39 (22.54%) isolates were STEC. The frequency of STEC virulence genotypes was stx2 (25 isolates, 64.10%), stx2+eae (6 isolates, 15.38%), stx1+stx2 (6 isolates, 15.38%), and stx1+stx2+eae (2 isolates, 5.12%). In addition, three O157: H7 strains were identified with the genetic content of stx1+stx2+eae (2 isolates) and stx1+stx2 (1 isolate). The most prevalent antimicrobial resistance was observed against streptomycin, tetracycline, and ampicillin. Gentamycin, amoxicillin-clavulanic acid, and trimethoprim-sulfadiazine were the most effective antibiotics against O157 strains, whereas gentamycin, ciprofloxacin, and nitrofurantoin were effective against non-O157 strains. The results revealed the significant role of STEC in bovine subclinical mastitis in the studied region. In addition, the distribution of O157:H7 strain and high prevalence of multidrug resistance among the isolates is a matter of concern. Therefore, there is a potential threat of human infection following the consumption of contaminated milk with STEC in Kurdistan Province, Iran.

Antimicrobial Effects of Zataria multiflora and Ocimum basilicum on Escherichia coli O157:H7 During Ripening of Traditional Lighvan Cheese

Background:

Escherichia coli O157:H7 is one of the most common causes of contamination in Lighvan cheese processing. Using from natural antimicrobial essential oils is applied method to decrease the rate of microbial contamination of dairy products. The present investigation was done to study the antimicrobial effects of Z. multiflora and O. basilicum essential oils on survival of E. coli O157:H7 during ripening of traditional Lighvan cheese.

Methods:

Leaves of the Z. multiflora and O. basilicum plants were subjected to the Clevenger apparatus. Concentrations of 0, 100 and 200 ppm of the Z. multiflora and 0, 50 and 100 ppm of O. basilicum essential oils and also 103 and 105 cfu/ml numbers of E. coli O157:H7 were used. The numbers of the E. coli O157:H7 bacteria were analyzed during the days 0, 30, 60 and 90 of the ripening period.

Results:

Z. multiflora and O. basilicum essential oils had considerable antimicrobial effects against E. coli O157:H7. Using the essential oils caused decrease in the numbers of E. coli O157:H7 bacteria in 90th days of ripening (P <0.05). Using from Z. multiflora at concentration of 200 ppm can reduce the survival of E. coli O157:H7 in Lighvan cheese.

Conclusion:

Using Z. multiflora and O. basilicum essential oils as good antimicrobial agents can reduce the risk of foodborne bacteria and especially E. coli O157:H7 in food products.

The First Isolation and Molecular Characterization of Shiga Toxin-Producing Virulent Multi-Drug Resistant Atypical Enteropathogenic Escherichia coli O177 Serogroup From South African Cattle

Atypical enteropathogenic E. coli (aEPEC) is a group of diarrhoeagenic Escherichia coli with high diversity of serogroups, which lack the bundle-forming pili (BFP) and genes encoding for shiga toxins. The aim of this study was to isolate, identify and determine virulence and antibiotic resistance profiles of aEPEC O177 strains from cattle feces. A total of 780 samples were collected from beef and dairy cattle and analyzed for the presence of E. coli O177. One thousand two hundred and seventy-two (1272) presumptive isolates were obtained and 915 were confirmed as E. coli species. Three hundred and seventy-six isolates were positively confirmed as E. coli O177 through amplification of rmlB and wzy gene sequences using multiplex PCR. None of these isolates harbored bfpA gene. A larger proportion (12.74%) of the isolates harbored hlyA gene while 11.20, 9.07, 7.25, 2.60, and 0.63% possessed stx₂, stx₁, eaeA, stx_2a, and stx_2d, respectively. Most of E. coli O177 isolates carried stx₂/hlyA (9.74%). Furthermore, 7.40% of the isolates harbored stx₁/stx₂ while 7.09% possessed stx₁/stx₂/hlyA genes. Only one isolate harbored stx₁/stx₂/hly/eaeA/stx_2a/stx_2d while 5.11% of the isolates harbored all the four major virulence genes stx₁/stx₂/hlyA/eaeA, simultaneously. Further analysis revealed that the isolates displayed varied antimicrobial resistance to erythromycin (63.84%), ampicillin (21.54%), tetracycline (13.37%), streptomycin (17.01%), kanamycin (2.42%), chloramphenicol (1.97%), and norfloxacin (1.40%). Moreover, 20.7% of the isolates exhibited different phenotypic multi-drug resistance patterns. All 73 isolates harbored at least one antimicrobial resistance gene. The aadA, streA, streB, erm, and tetA resistance genes were detected separately and/or concurrently. In conclusion, our findings indicate that environmental isolates of aEPEC O177 strains obtained from cattle in South Africa harbored virulence and antimicrobial resistance gene determinants similar to those reported in other shiga-toxin producing E. coli strains and suggest that these determinants may contribute to the virulence of the isolates.

Antibiotic-resistant Escherichia coli and Salmonella spp. associated with dairy cattle and farm environment having public health significance

Aim:

The present study was carried out to determine load of total bacteria, Escherichia coli and Salmonella spp. in dairy farm and its environmental components. In addition, the antibiogram profile of the isolated bacteria having public health impact was also determined along with identification of virulence and resistance genes by polymerase chain reaction (PCR) under a one-health approach.

Materials and Methods:

A total of 240 samples of six types (cow dung – 15, milk – 10, milkers’ hand wash – 10, soil – 10 water – 5, and vegetables – 10) were collected from four dairy farms. For enumeration, the samples were cultured onto plate count agar, eosin methylene blue, and xylose-lysine deoxycholate agar and the isolation and identification of the E. coli and Salmonella spp. were performed based on morphology, cultural, staining, and biochemical properties followed by PCR.The pathogenic strains of E. colistx1, stx2, and rfbO157 were also identified through PCR. The isolates were subjected to antimicrobial susceptibility test against 12 commonly used antibiotics by disk diffusion method. Detection of antibiotic resistance genes ereA, tetA, tetB, and SHV were performed by PCR.

Results:

The mean total bacterial count, E. coli and Salmonella spp. count in the samples ranged from 4.54±0.05 to 8.65±0.06, 3.62±0.07 to 7.04±0.48, and 2.52±0.08 to 5.87±0.05 log colony-forming unit/g or ml, respectively. Out of 240 samples, 180 (75%) isolates of E. coli and 136 (56.67%) isolates of Salmonella spp. were recovered through cultural and molecular tests. Among the 180 E. coli isolates, 47 (26.11%) were found positive for the presence of all the three virulent genes, of which stx1 was the most prevalent (13.33%). Only three isolates were identified as enterohemorrhagic E. coli. Antibiotic sensitivity test revealed that both E. coli and Salmonella spp. were found highly resistant to azithromycin, tetracycline, erythromycin, oxytetracycline, and ertapenem and susceptible to gentamycin, ciprofloxacin, and imipenem. Among the four antibiotic resistance genes, the most observable was tetA (80.51-84.74%) in E. coli and Salmonella spp. and SHV genes were the lowest one (22.06-25%).

Conclusion:

Dairy farm and their environmental components carry antibiotic-resistant pathogenic E. coli and Salmonella spp. that are potential threat for human health which requires a one-health approach to combat the threat.

Potential Hazards Associated with Raw Donkey Milk Consumption: A Review

Donkey milk can be used as a substitute for infants and children who suffer from cow milk proteins intolerance and multiple food hypersensitivity. Up to date, this is one of the main reasons why donkey milk has become a substantial area for reasearch, with an increase over the the last fifteen years. In donkey milk chain, risk analysis should be the object of particular attention because children are the main consumers of this food. In fact, this process is one of the main tool to achieve a high level of protection of human health and life; thus, the most important safety hazards should be monitored in order to attain this goal. This review focuses on the main hazards possibly present in raw donkey milk, including bacteria, fungal toxins, parasites, and chemical pollutants. Literature data have been considered, including some information that is not provided in the international literature. In the authors' opinion, the current scientific knowledge should be improved, with the aim of allowing a suitable risk assessment along the whole donkey milk chain. However, in the meantime, the competent authorithies must carry out more stringent official controls, with particular attention given to the level of primary production. The issue of a traceability system in donkey milk chain should be considered of paramount importance.

Immunologic balance of regulatory T cell/T helper 17 responses in gastrointestinal infectious diseases: Role of miRNAs

Gastrointestinal Infectious diseases (GIDs) are the second cause of death worldwide. T helper17 cells (Th17) play an important role in GIDs through production of IL-17A, IL-17F, and IL-22 cytokines. Because of their increased activities in GID, Th17 and its inflammatory cytokines can inhibit the progression and eliminate the infection. Actually, although Th17 have the best performance in the acute phase, regulatory T cells (Treg cells) are enhanced in the chronic phase and infection progress through its suppressive function. In addition, Treg cells prevent undesirable inflammatory damages developed by immune system components. On the other hand, miRNAs have important roles in the regulation of immune responses to eliminate bacterial infections and protect host organisms from harmful effects. Actually, miRNAs can reinforce innate and adaptive immunity to remove infections. Of note, miRNAs can develop a regulatory network with the immune system. Additionally, miRNAs can also serve in favor of bacteria to reduce immune responses. Therefore, balance of immune responses in Treg and Th17 cells can influence outcome of many infectious diseases. In conclusion, there is an imbalance in the Treg/Th17 ratio in GIDs; importantly, sets of miRNAs, particularly miR155 and miR146, were determined to be involved clearly in GIDs.

Prevalence, identification of virulence factors, O-serogroups and antibiotic resistance properties of Shiga-toxin producing Escherichia coli strains isolated from raw milk and traditional dairy products

Background

Shiga-toxigenic Escherichia coli strains are one of the most important foodborne bacteria with an emergence of antibiotic resistance. Foodborne STEC strains are mainly associated with presence of certain virulence factors and O-seogroups. The present investigation was done to study the distribution of virulence factors, O-serogroups and antibiotic resistance properties of Shiga-toxigenic Escherichia coli isolated from milk and dairy products.

Methods

Six-hundred samples were randomly collected and immediately transferred to laboratory. All samples were cultured and E. coli strains were isolated. STEC strains were identified based on the presence of putative virulence factors and subtypes. STEC isolates were subjected to multiplex PCR and disk diffusion methods.

Results

One-hundred and eighty-one out of 600 samples (30.16%) harbored E. coli. Prevalence of STEC strains was 10.66%. O157 (43.75%) and O26 (37.50%) were the most frequently identified serogroups. Aac(3)-IV (100%), CITM (96.87%) and tetA (76.56%) were the most commonly detected antibiotic resistance genes. STEC strains had the highest prevalence of resistance against ampicillin (100%), gentamicin (100%) and tetracycline (96.87%).

Conclusions

Kashk and dough were negative for presence of E. coli strains. High prevalence of resistant-O157 strains and simultaneous presence of multiple virulence factors pose an important public health problem regarding the consumption of raw milk and dairy products.

Uropathogenic Escherichia coli in the Urine Samples of Iranian Dogs: Antimicrobial Resistance Pattern and Distribution of Antibiotic Resistance Genes

Resistant uropathogenic Escherichia coli is the most common cause of urinary tract infections in dogs. The present research was done to study the prevalence rate and antimicrobial resistance properties of UPEC strains isolated from healthy dogs and those which suffered from UTIs. Four-hundred and fifty urine samples were collected and cultured. E. coli-positive strains were subjected to disk diffusion and PCR methods. Two-hundred out of 450 urine samples (44.4%) were positive for E. coli. Prevalence of E. coli in healthy and infected dogs was 28% and 65%, respectively. Female had the higher prevalence of E. coli (P = 0.039). Marked seasonality was also observed (P = 0.024). UPEC strains had the highest levels of resistance against gentamicin (95%), ampicillin (85%), amikacin (70%), amoxicillin (65%), and sulfamethoxazole-trimethoprim (65%). We found that 21.50% of UPEC strains had simultaneously resistance against more than 10 antibiotics. Aac(3)-IV (77%), CITM (52.5%), tetA (46.5%), and sul1 (40%) were the most commonly detected antibiotic resistance genes. Findings showed considerable levels of antimicrobial resistance among UPEC strains of Iranian dogs. Rapid identification of infected dogs and their treatment based on the results of disk diffusion can control the risk of UPEC strains.

Genotyping of virulent Escherichia coli obtained from poultry and poultry farm workers using enterobacterial repetitive intergenic consensus-polymerase chain reaction

Aim

The aim of this study was to characterize virulent Escherichia coli isolated from different poultry species and poultry farm workers using enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) genotyping.

Materials and Methods

Fecal swabs from different poultry species (n=150) and poultry farm workers (n=15) were analyzed for E. coli and screened for virulence genes (stx1, stx2, eaeA, and hlyA) by multiplex PCR. Virulent E. coli was serotyped based on their "O" antigen and then genotyped using ERIC-PCR.

Results

A total of 134 E. coli isolates (122/150 from poultry and 12/15 from farm workers) were recovered. Virulence genes were detected in a total of 12 isolates. Serological typing of the 12 virulent E. coli revealed nine different serotypes (O2, O49, O60, O63, O83, O101, O120, UT, and Rough). ERIC-PCR genotyping allowed discrimination of 12 virulent E. coli isolates into 11 ERIC-PCR genotypes. The numerical index of discrimination was 0.999.

Conclusion

Our findings provide information about the wide genetic diversity and discrimination of virulent E. coli in apparently healthy poultry and poultry farm workers of Andhra Pradesh (India) based on their genotype.

Shiga (Vero)-toxin producing Escherichia coli isolated from the hospital foods; virulence factors, o-serogroups and antimicrobial resistance properties

BACKGROUND

According to the presence of the weak, diabetic and immunosuppressive patients in hospitals, hospital foods should have a high quality and safety. Cooking a lot of foods higher than daily requirement, storage of cooked foods in an inappropriate condition and presence of nurses and servants in distribution of food to patients are the main reasons caused contamination of hospital foods. Shiga toxigenic Escherichia coli is one of the common cause of food poisoning in hospitals. The present research was carried out to study the distribution of virulence factors, O-serogroups and antibiotic resistance properties in STEC strains recovered from Iranian hospital food samples.

METHODS

Five-hundred and eighty raw and cooked food samples were collected and immediately transferred to the laboratory. E. coli-positive strains were subjected to PCR and disk diffusion method.

RESULTS

Thirty-nine out of 580 (6.72%) hospital food samples were contaminated with E. coli. Raw (20%) and cooked meat (6%) were the most commonly contaminated samples. Raw samples had the higher prevalence of E. coli (P <0.01). Samples which were collected in the summer season had the highest prevalence of bacteria (64.10%). Significant difference was seen between the prevalence of EHEC and AEEC subtypes (P <0.01). The most commonly detected virulence factors in both EHEC and AEEC subtypes were stx1 and eae. The most commonly detected serogroups were O26 (43.75%) and O157 (25%) and there were no positive results for O103, O145, O91, O113 and O128 serogroups. Aac (3)-IV (100%), CITM (100%) and tetA (62.50%) were the most commonly detected antibiotic resistance genes. STEC strains harbored the highest levels of resistance against ampicillin (93.75%), gentamycin (93.75%), tetracycline (87.50%) and ciprofloxacin (81.25%). All of the STEC strains were resistant to at least 3 antibiotics, while the prevalence of resistance against more than 12 antibiotics were 12.50%.

CONCLUSIONS

High presence of O157 serogroups, EHEC strains and animal-based antibiotics in cooked foods showed insufficiency of cooking time and temperature in the kitchens of hospitals. Judicious prescription of antibiotics and attentions to the principles of food safety can reduce the risk of resistant and virulent strains of STEC in hospital foods.

Enterohemorrhagic Escherichia coli O157 in milk and dairy products from Libya: Isolation and molecular identification by partial sequencing of 16S rDNA

Aim:

The aim of this work was to isolate and molecularly identify enterohemorrhagic Escherichia coli (EHEC) O157 in milk and dairy products in Libya, in addition; to clear the accuracy of cultural and biochemical identification as compared with molecular identification by partial sequencing of 16S rDNA for the existing isolates.

Materials and Methods:

A total of 108 samples of raw milk (cow, she-camel, and goat) and locally made dairy products (fermented cow’s milk, Maasora, Ricotta and ice cream) were collected from some regions (Janzour, Tripoli, Kremiya, Tajoura and Tobruk) in Libya. Samples were subjected to microbiological analysis for isolation of E. coli that was detected by conventional cultural and molecular method using polymerase chain reaction and partial sequencing of 16S rDNA.

Results:

Out of 108 samples, only 27 isolates were found to be EHEC O157 based on their cultural characteristics (Tellurite-Cefixime-Sorbitol MacConkey) that include 3 isolates from cow’s milk (11%), 3 isolates from she-camel’s milk (11%), two isolates from goat’s milk (7.4%) and 7 isolates from fermented raw milk samples (26%), isolates from fresh locally made soft cheeses (Maasora and Ricotta) were 9 (33%) and 3 (11%), respectively, while none of the ice cream samples revealed any growth. However, out of these 27 isolates, only 11 were confirmed to be E. coli by partial sequencing of 16S rDNA and E. coli O157 Latex agglutination test. Phylogenetic analysis revealed that majority of local E. coli isolates were related to E. coli O157:H7 FRIK944 strain.

Conclusion:

These results can be used for further studies on EHEC O157 as an emerging foodborne pathogen and its role in human infection in Libya.

Vegetables and Restaurant Salads as a Reservoir for Shiga Toxigenic Escherichia coli: Distribution of Virulence Factors, O-Serogroups, and Antibiotic Resistance Properties

Close contact of vegetables with soil, polluted water, and animal manure and unsanitary conditions during processing of restaurant salads led us to study the distribution of virulence factors, O-serogroups, and antibiotic resistance properties in Shiga toxigenic Escherichia coli (STEC) isolated from vegetables and salads. Samples of vegetables and salad (n = 420) were collected and evaluated for the presence of E. coli using culture and a PCR assay. Total prevalence of E. coli in studied samples was 49.5%. E. coli was found in 49.6% of vegetable samples and 49% of salad samples. Leek and traditional salad had the highest incidence of E. coli. Significant differences in the incidence of E. coli were found between the hot and cold seasons. Of the 149 E. coli isolates from vegetable samples, 130 (87%) were STEC, and of the 59 E. coli isolates from salad samples, 50 (84%) were STEC. The most commonly detected virulence factors were stx1 and eaeA. A significant difference was found between the frequency of the attaching and effacing and the enterohemorrhagic E. coli subtypes. Serogroups O26 (46% of isolates), O157 (14%), O121 (10%), and O128 (9%) were the most commonly detected serogroups among the STEC strains. The tetA, sul1, aac(3)-IV, dfrA1, blaSHV, and CITM antibiotic resistance genes were found in 96, 47.7, 90, 51, 27, and 93% of isolates, respectively. The highest levels of resistance were found against ampicillin (96.6% of isolates), tetracycline (87%), and gentamicin (90%). This study shows the importance of vegetables and salads as potential sources of E. coli infection.

Detection of virulence factors and antimicrobial resistance patterns in shiga toxin-producing Escherichia coli isolates from sheep

Abstract: In order to detect virulence factors in Shiga toxin-producing Escherichia coli (STEC) isolates and investigate the antimicrobial resistance profile, rectal swabs were collected from healthy sheep of the races Santa Inês and Dorper. Of the 115 E. coli isolates obtained, 78.3% (90/115) were characterized as STEC, of which 52.2% (47/90) carried stx1 gene, 33.3% (30/90) stx2 and 14.5% (13/90) both genes. In search of virulence factors, 47.7% and 32.2% of the isolates carried the genes saa and cnf1. According to the analysis of the antimicrobial resistance profile, 83.3% (75/90) were resistant to at least one of the antibiotics tested. In phylogenetic classification grouped 24.4% (22/90) in group D (pathogenic), 32.2% (29/90) in group B1 (commensal) and 43.3% (39/90) in group A (commensal). The presence of several virulence factors as well as the high number of multiresistant isolates found in this study support the statement that sheep are potential carriers of pathogens threatening public health.

Animal Reservoirs of Shiga Toxin-Producing Escherichia coli

Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

Use of mild irradiation doses to control pathogenic bacteria on meat trimmings for production of patties aiming at provoking minimal changes in quality attributes

The objectives of the present work were to assess the use of moderate doses of gamma irradiation (2 to 5 kGy) and to reduce the risk of pathogen presence without altering the quality attributes of bovine trimmings and of patties made of irradiated trimmings. Microbiological indicators (coliforms, Pseudomonas spp and mesophilic aerobic counts), physicochemical indicators (pH, color and tiobarbituric acid) and sensory changes were evaluated during storage. 5 kGy irradiation doses slightly increased off flavors in patties. Two pathogenic markers (Listeria monocytogenes and Escherichia coli O157:H7) were inoculated at high or low loads to trimming samples which were subsequently irradiated and lethality curves were obtained. Provided that using irradiation doses ≤2.5 kGy are used, reductions of 2 log CFU/g of L. monocytogenes and 5 log CFU/g of E. coli O157:H7 are expected. It seems reasonable to suppose that irradiation can be successfully employed to improve the safety of frozen trimmings when initial pathogenic bacteria burdens are not extremely high.

Virulence factors, serogroups and antimicrobial resistance properties of Escherichia coli strains in fermented dairy products

Background

From a clinical perspective, it is essential to know the microbial safety of fermented dairy products. Doogh and kashk are fermented dairies. These products are used by millions of people but their microbial qualities are unknown. Shiga toxin producing Escherichia coli (STEC) is one of the most commonly detected pathogens in the cases of food poisoning and food-borne illnesses. The present investigation was carried out in order to study the molecular characterization and antimicrobial resistance properties of STEC strains isolated from fermented dairy products.

Methods

Six hundred fermented dairy samples were collected and immediately transferred to the laboratory. All samples were cultured immediately and those that were E. coli-positive were analyzed for the presence of O157 , O26, O103, O111, O145, O45, O91, O113, O121 and O128 STEC serogroups, tetA, tetB, blaSHV, CITM, cmlA, cat1, aadA1, dfrA1, qnr, aac (3)-IV, sul1 and ereA antibiotic resistance genes and stx1, stx2, eaeA, ehly, cnf1, cnf2, iutA, cdtB, papA, traT, sfaS and fyuA virulence factors using PCR. Antimicrobial susceptibility testing was performed also using disk diffusion methodology with Mueller–Hinton agar.

Results

Fifty out of 600 (8.33%) dairy samples harbored E. coli. In addition, yoghurt was the most commonly contaminated dairy. O157 (26%) and O26 (12%) were the most commonly detected serogroups. A significant difference was found between the frequency of Attaching and Effacing E. coli and Enterohaemorrhagic E. coli (P <0.05). Stx1 (44%), eae (36%), papA (32%) stx2 (30%), and ehly (28%) were the most commonly detected virulence factors. The genes encode resistance against tetracycline (tetA and tetB) (76% and 70%, respectively), cephalothin (blaSHV) (38%), ampicillin (CITM) (36%) and gentamicin (aac (3)-IV) (32%) were the most commonly detected. High resistance levels to tetracycline (84%), penicillin (46%), ampicillin (38%) and streptomycin (36%) were observed.

Conclusion

Fermented dairy products can easily become contaminated by antibiotic resistant STEC strains. Our findings should raise awareness about antibiotic resistance in Iran. Clinicians should exercise caution when prescribing antibiotics, especially in veterinary treatments.

Incidence of Shiga toxin-producing Escherichia coli serogroups in ruminant's meat

To assess the presences of Escherichia coli, its serogroups, virulence factors and antibiotic resistance properties in ruminant's meat, a total of 820 raw meat samples were collected and then evaluated using culture, PCR and disk diffusion methods. Totally, 238 (29.02%) samples were positive for presence of Escherichia coli. All of the isolates had more than one virulence gene including Stx1, Stx2, eaeA and ehly. All investigated serogroups were found in beef and sheep and all except O145, O121 and O128 were found in goat. The O91, O113, O111, O103, O26 and O157 serogroups were found in camel. Totally, aadA1-blaSHV combination was the most predominant antibiotic resistance gene. The highest resistance of STEC strains was seen against penicillin while resistance to nitrofurantoin and ciprofloxacin was minimal. These findings showed that health care and meat inspection should be reconsidered in Iranian slaughterhouses and butchers.

Characterization of non-O157 shiga toxin-producing Escherichia coli isolates from healthy fat-tailed sheep in southeastern of Iran

The objectives of this study were to determine the presence and prevalence of non-O157 shiga toxin-producing Escherichia coli (STEC) isolates from faeces of healthy fat-tailed sheep and detection of phylogenetic background and antibiotic resistance profile of isolates. One hundred ninety-two E. coli isolates were recovered from obtained rectal swabs and were confirmed by biochemical tests. Antibiotic resistance profiles of isolates were detected and phylogenetic background of isolates was determined according to the presence of the chuA, yjaA and TspE4.C2 genetic markers. The isolates were examined to determine stx (1), stx (2) and eae genes. Non-O157 STEC isolates were identified by using O157 specific antiserum. Forty-three isolates (22.40 %) were positive for one of the stx (1), stx (2) and eae genes, whereas 10.42 % were positive for stx (1), 19.38 % for eae and 2.60 % for stx (2) gene. None of the positive isolates belonged to O157 serogroup. Twenty isolates possessed stx ( 1 ) were distributed in A (six isolates), B1 (13) and D (one) phylogroups, whereas stx (2) positive isolates fell into A (three isolates) and B1 (two) phylogenetic groups. Eighteen isolates contained eae gene belonged to A (five isolates), B1 (seven) and D (six) phylogroups. The maximum and minimum resistance rates were recorded against to penicillin and co-trimoxazole respectively. The positive isolates for stx (1), stx (2) and eae genes showed several antibiotic resistance patterns, whereas belonged to A, B1 and D phylogroups. In conclusion, faeces of healthy sheep could be considered as the important sources of non-O157 STEC and also multidrug-resistant E. coli isolates.