Coli O157 Research Articles

Foodborne disease outbreaks in flour and flour‐based food products from microbial pathogens in the United States, and their health economic burden

The most comprehensive and inclusive estimates for the economic burden of foodborne illness yield values as high as $97.4 billion USD annually. However, broad incidence and cost estimates have limited use if they cannot be attributed to specific foods, for the purposes of food safety control. In this study, we estimated the economic burden of foodborne illnesses resulting from flour and flour-based food products in the United States from the years 2001 to 2021. The outbreak, illness burden, and health economic data are combined to generate these estimates. Our model combined outbreak data with published Centers for Disease Control and Prevention multipliers to estimate the annual number of illnesses associated with flour-borne pathogens. We then integrated illness severity data with an updated economic model that accounts for costs related to medical care, productivity loss, loss of life, along with the quality of life loss that entails pain and suffering. In total, 752 cases and 223 hospitalizations from flour-related illnesses were reported from 2001 to 2021, with an average of 37.6 cases of reported cases annually. However, the actual number of cases, accounting for underreporting and underdiagnosis, can be as high as 19,440 annually. Pathogens involved in these outbreaks are Salmonella, E. coli O157:H7, and E. coli O121. Our estimates suggest average annual economic losses, including healthy years of life lost, of $108 and $258 million using two alternative models.

A Lab-on-a-Tube Biosensor Combining Recombinase-Aided Amplification and CRISPR-Cas12a with Rotated Magnetic Extraction for Salmonella Detection

Background: Foodborne pathogenic bacteria threaten worldwide public health, and simple bacterial detection methods are in urgent need. Here, we established a lab-on-a-tube biosensor for simple, rapid, sensitive, and specific detection of foodborne bacteria. Methods: A rotatable Halbach cylinder magnet and an iron wire netting with magnetic silica beads (MSBs) were used for simple and effective extraction and purification of DNA from the target bacteria, and recombinase-aided amplification (RAA) was combined with clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins12a(CRISPR-Cas12a) to amplify DNA and generate fluorescent signal. First, 15 mL of the bacterial sample was centrifuged, and the bacterial pellet was lysed by protease to release target DNA. Then, DNA-MSB complexes were formed as the tube was intermittently rotated and distributed uniformly onto the iron wire netting inside the Halbach cylinder magnet. Finally, the purified DNA was amplified using RAA and quantitatively detected by the CRISPR-Cas12a assay. Results: This biosensor could quantitatively detect Salmonella in spiked milk samples in 75 min, with a lower detection limit of 6 CFU/mL. The fluorescent signal of 102 CFU/mL Salmonella Typhimurium was over 2000 RFU, while 104 CFU/mL Listeria monocytogenes, Bacillus cereus, and E. coli O157:H7 were selected as non-target bacteria and had signals less than 500 RFU (same as the negative control). Conclusions: This lab-on-a-tube biosensor integrates cell lysis, DNA extraction, and RAA amplification in one 15 mL tube to simplify the operation and avoid contamination, making it suitable for low-concentration Salmonella detection.

Research on rapid detection technology of airborne pathogenic organisms based on up-conversion phosphor technology

Objective: To explore the application of up-conversing phosphor technology (UPT) to detect pathogenic organisms in the air. Methods: The performance of UPT was verified with Staphylococcus aureus, Yersinia pestis and Escherichia coli O157 as simulated strains, including stability, specificity, sensitivity and response time tests; Air particle sampler is used to collect air samples in the field microenvironment test chamber, and UPT is used for detection. At the same time, compared with the traditional culture method, the practicability of UPT is verified. Results: The coefficient of variation in laboratory was 9.62% and 8.02% when the concentration of 107 CFU/ml and 108 CFU/ml were detected by UPT. The results were less than the allowable target, and the detection system had good stability. The specificity of UPT was verified by Staphylococcus aureus. The results showed that no non-Staphylococcus aureus was detected, and the positive detection rate of different kinds of Staphylococcus aureus was 100%. The specificity of the detection system was good. The sensitivity of UPT for detecting Staphylococcus aureus was 104 CFU/ml. Detection sensitivity of Yersinia pestis ≥103 CFU/ml; The detection sensitivity of Escherichia coli O157 is ≥103 CFU/ml, and the response time of UPT to bacteria is within 15 min (all 10 min 15 s). The detection results of bacteria contentration in the air of the on-site microenvironment test cabin by UPT showed that when the concentration of Escherichia coli O157 in the air reached above 104 CFU/m3, the detection results of UPT were positive, and with the increase of air concentration, the numerical concentration measured by UPT showed an upward trend, which was positively correlated with the concentration of bacteria in the air. Conclusion: UPT may be feasible as a rapid method to evaluate the species and contentration of pathogenic organisms in the air.

A systematic literature review of milk consumption and associated bacterial zoonoses in East Africa.

Consumption of unsafe animal-source foods is the major cause of foodborne disease outbreaks in low-income countries. Despite current knowledge of the threat posed by raw milk consumption to human health, people in many countries in East Africa still consume unboiled milk. This literature review explored the association between milk consumption and the occurrence of five milk-borne bacterial zoonoses: brucellosis, salmonellosis, campylobacteriosis, Escherichia coli infections, and tuberculosis. A search for literature published up to 1 October 2021 was conducted through the Web of Science, PubMed, and Scopus databases, using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The selection process yielded 65 articles describing studies conducted in East Africa 2010-2021, which were carefully scrutinized. The most investigated pathogen was Brucella spp. (54.5%), followed by E. coli (18.2%), Salmonella spp. (12.1%), Mycobacterium spp. (6.1%), and E. coli O157: H7 (6.1%). The most common predisposing factors for potential milk-borne disease outbreaks were consumption of contaminated raw milk, inadequate cold storage along the milk value chain, poor milk handling practices, and lack of awareness of the health risks of consuming unpasteurized milk. Thus, a tailor-made training program is needed for all milk value chain actors to enhance the safety of milk sold in informal markets, and a One Health approach should be applied. Future studies should employ more advanced diagnostic techniques and countries in East Africa should invest in modern diagnostic tools and equipment, both in hospitals and in local rural settings where most cases occur.

Cefotaxime-, Ciprofloxacin-, and Extensively Drug-Resistant Escherichia coli O157:H7 and O55:H7 in Camel Meat.

The present study aimed to explore for the first time the occurrence and the antimicrobial resistance profiles of E. coli O157:H7 and O55:H7 isolates in camel meat in Egypt. Among the 110 camel meat samples examined using standardized microbiological techniques, 10 (9.1%) and 32 (29.1%) were positive for E. coli O157:H7 and E. coli O55:H7, respectively. In total, 24 isolates were verified as E. coli O157:H7, while 102 isolates were confirmed serologically as E. coli O55:H7. Multiplex PCR revealed the existence of eaeA, stx1, stx2, and EHEC-hlyA among E. coli O157:H7 and O55:H7 isolates (n = 126) at various percentages. According to their resistance against 14 antibiotics, 16.7% and 83.3% of O157:H7 isolates and 8.6% and 76.5% of O55:H7 isolates were classified into extensively drug-resistant and multi-drug-resistant, respectively, whereas 29.4% and 22.2% of E. coli isolates were resistant to cefotaxime and ciprofloxacin, respectively. The study results emphasize that camel meat may be a vehicle for multi- and extensively drug-resistant E. coli O157:H7 and O55:H7 strains, indicating a potential threat to public health. Further studies based on the molecular evidence of the antimicrobial resistance genes and enrolling a larger number of samples are recommended for a better understanding of the antimicrobial resistance phenomenon of camel-meat-originating pathogenic E. coli strains.

Quantitative Microbial Risk Assessment of Urban Wastewater Pertaining to Irrigation of Agricultural Products in Qom, Iran, in 2020

Introduction: The present study aims to evaluate adverse health effects caused by the use of wastewater for the irrigation of fields in Qom province, Iran.
 Materials and Methods: An environmental monitoring program was designed for 3 pathogens-Escherichia coli, Vibrio cholerae, and E. coli O157 and carried out on 120 samples from raw wastewater, effluent, and irrigated products with wastewater. In the next phase, exposure assessment and microbial risk assessment were performed using a questionnaire and interviewing 200 participants. 
 Results: Concentrations of E. coli, V. Cholerae, and E. coli O157:H7 in raw wastewater were determined to be 3.4 × 103 ± 500 cfu/100ml, 2.1 × 103 ± 100 cfu/100ml, and 312 cfu/100ml, respectively. Concentrations of E. coli, V. Cholerae, and E. coli O157:H7 in effluent were determined to be 2.1 × 103 ± 100 cfu/100ml, 0.8 × 103 ± 100 cfu/100ml, and 176 cfu/100ml, respectively. The conventional wastewater treatment system was effective in removing E. coli, V. Cholerae, and E. coli O157: H7 by 50%, 59%, and 43%, respectively. Crops irrigated with effluent contained 400 ± 250 cfu/100ml, 0.1 × 103 ± 0.019 cfu/100ml, and 52 cfu/100ml of E. coli, V. Cholerae, and E. coli O157:H7, respectively. According to the exposure scenarios, the total annual probability of infection in the studied population for E. coli, V. Cholerae, and E. coli O157:H7 was determined to be 8 × 10-2, 8 × 10-4, and 17 × 10-2, respectively.
 Conclusions: In irrigating agricultural crops with wastewater implementing wastewater safety plans (WWSP) is crucial.

Evidence for Porphyrin-Mediated Electron Transfer in the Radical SAM Enzyme HutW.

Bacteria that infect the human gut must compete for essential nutrients, including iron, under a variety of different metabolic conditions. Several enteric pathogens, including Vibrio cholerae and Escherichia coli O157:H7, have evolved mechanisms to obtain iron from heme in an anaerobic environment. Our laboratory has demonstrated that a radical S-adenosylmethionine (SAM) methyltransferase is responsible for the opening of the heme porphyrin ring and release of iron under anaerobic conditions. Furthermore, the enzyme in V. cholerae, HutW, has recently been shown to accept electrons from NADPH directly when SAM is utilized to initiate the reaction. However, how NADPH, a hydride donor, catalyzes the single electron reduction of a [4Fe-4S] cluster, and/or subsequent electron/proton transfer reactions, was not addressed. In this work, we provide evidence that the substrate, in this case, heme, facilitates electron transfer from NADPH to the [4Fe-4S] cluster. This study uncovers a new electron transfer pathway adopted by radical SAM enzymes and further expands our understanding of these enzymes in bacterial pathogens.

Molecular Evaluation of rfbE Gene Expression Changes under Different Creatinine Concentrations in Escherichia coli Strains Via Real-Time PCR

Background and objective. Escherichia coli (E. coli) O157: H7 as an enterohemorrhagic pathogen causes severe damage to the gastrointestinal tract and dangerous diseases in humans such as hemolytic uremic syndrome (HUS) and acute renal failure, which is associated with increased blood creatinine levels. This study aimed to evaluate antibiotic resistance of E. coli O157: H7 pathotypes to detect the virulence of gene rfbE and to study variations in its expression. Methods. The isolates were first inoculated on eosin methylene blue (EMB) agar and then identified using the Microgen kit and the presence of rfbE gene. Antibiotic susceptibility of the identified strains was tested by the disk diffusion technique, followed by inoculating E. coli O157: H7 strains at concentrations of 1, 3, and 6 mg dl–1 in BHI broth. DNA and RNA were then extracted from the bacteria, and cDNA was prepared from purified RNA. Then, the rfbE gene expression was evaluated using a real-time PCR approach, and the data were analysed with Rest software. Results. The research results revealed high resistance of isolated strains against some of the studied antibiotics, and variations in the expression of the rfbE gene were found to be different at different creatinine concentrations and at different time points. A significant decrease in variations in the rfbE gene expression was observed at low concentrations (1 mg dl-1), but, on the contrary, a significant increase in variations in the rfbE gene expression was found at higher concentrations (3 and 6 mg dl-1) (p<0.05). Conclusions. The rfbE gene is one of the factors affecting the bacterial virulence. We believe that a secondary increase in creatinine for any reason can exacerbate kidney disease and failure by affecting the rfbE gene expression while producing O antigen or bacterial endotoxin.

Virtual Screening and In Vitro Experimental Verification of LuxS Inhibitors for Escherichia coli O157:H7.

Enterohemorrhagic Escherichia coli O157:H7 is an important foodborne pathogen that forms biofilms. In this study, three quorum-sensing (QS) inhibitors (M414-3326, 3254-3286, and L413-0180) were obtained through virtual screening, and their in vitro antibiofilm activities were validated. Briefly, the three-dimensional structure model of LuxS was constructed and characterized using the SWISS-MODEL. High-affinity inhibitors were screened from the ChemDiv database (1,535,478 compounds) using LuxS as a ligand. Five compounds (L449-1159, L368-0079, M414-3326, 3254-3286, and L413-0180) with a good inhibitory effect (50% inhibitory concentration <10 μM) on type II QS signal molecule autoinducer-2 (AI-2) were obtained using a AI-2 bioluminescence assay. The absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties predicated that the five compounds had high intestinal absorption levels (high) and plasma protein binding (absorbent strong) and did not inhibit the metabolism of CYP2D6 metabolic enzymes. In addition, molecular dynamics simulation showed that compounds L449-1159 and L368-0079 could not stably bind with LuxS. Thus, these compounds were excluded. Furthermore, surface plasmon resonance results showed that the three compounds could specifically bind to LuxS. IN addition, the three compounds could effectively inhibit the biofilm formation without affecting the growth and metabolism of the bacteria. Finally, the reverse transcription-quantitative PCR results showed that the three compounds downregulated the expression of the LuxS gene. Overall, these results revealed that the three compounds obtained through virtual screening could inhibit biofilm formation of E. coli O157:H7 and are potential LuxS inhibitors that can be used to treat E. coli O157:H7 infections. IMPORTANCE E. coli O157:H7 is a foodborne pathogen of public health importance. Quorum sensing (QS) is a form of bacterial communication that can regulate various group behaviors, including biofilm formation. Here, we identified three QS AI-2 inhibitors (M414-3326, 3254-3286, and L413-0180) that can stably and specifically bind to LuxS protein. The three QS AI-2 inhibitors inhibited biofilm formation without affecting the growth and metabolic activity of E. coli O157:H7. The three QS AI-2 inhibitors are promising agents for treating E. coli O157:H7 infections. Further studies to identify the mechanism of the three QS AI-2 inhibitors are needed to develop new drugs to overcome antibiotic resistance.

Influence of Biological and Environmental Factors in the Extraction and Concentration of Foodborne Pathogens using Glycan-Coated Magnetic Nanoparticles

Rapid detection of foodborne pathogens is essential to preventing foodborne illness outbreaks. Before detection can occur, however, it is often necessary to extract and concentrate bacteria. Conventional methods such as centrifugation, filtration, and immunomagnetic separation can often be time-consuming, ineffective, or costly when working with complex food matrices. This work used cost-effective glycan-coated magnetic nanoparticles (MNPs) for rapid concentration of Escherichia coli O157, Listeria monocytogenes, and Staphylococcus aureus. Glycan-coated MNPs were used to concentrate bacteria from both buffer solution and food matrices while examining the effect of factors including solution pH, bacterial concentration, and target bacterial species. In both pH 7 and reduced pH experiments, successful extraction of bacterial cells occurred in all food matrices and bacteria tested. In neutral pH buffer solution, bacteria were concentrated to 4.55 ± 1.17, 31.68 ± 6.10 and 64.27 ± 16.78 times their initial concentration (mean ± standard deviation) for E. coli, L. monocytogenes and S. aureus, respectively. Successful bacterial concentration occurred in several food matrices, including S. aureus in milk (pH 6), L. monocytogenes in sausage (pH 7), and E. coli O157 in flour (pH 7). The insights gained may facilitate future applications of glycan-coated MNPs to extract foodborne pathogens.

Indigenous microbial community governs the survival of Escherichia coli O157:H7 in constructed wetlands

The survival pattern of Escherichia coli O157:H7 (E. coli O157:H7) and its regulatory factors in natural environments have been widely studied. However, there is little information about the survival of E. coli O157:H7 in artificial environments, especially in wastewater treatment facilities. In this study, a contamination experiment was performed to explore the survival pattern of E. coli O157:H7 and its central control factors in two constructed wetlands (CWs) under different hydraulic loading rates (HLRs). The results showed that the survival time of E. coli O157:H7 was longer in the CW under the higher HLR. Substrate ammonium nitrogen and available phosphorus were the main factors that influenced the survival of E. coli O157:H7 in CWs. Despite the minimal effect of microbial α-diversity, some keystone taxa, such as Aeromonas, Selenomonas, and Paramecium, governed the survival of E. coli O157:H7. In addition, the prokaryotic community had a more significant impact on the survival of E. coli O157:H7 than the eukaryotic community. The biotic properties had a more substantial direct power on the survival of E. coli O157:H7 than the abiotic factors in CWs. Collectively, this study comprehensively disclosed the survival pattern of E. coli O157:H7 in CWs, which is an essential addition to the environmental behavior of E. coli O157:H7, providing a theoretical basis for the prevention and control of biological contamination in wastewater treatment processes.

Maturation of pathogenic biofilms induces enhanced resistance against gaseous chlorine dioxide.

Biofilms are surface-associated microbial clusters embedded in extracellular polymeric substances. Biofilms formed on food-contact surfaces create challenges for the food industry due to their increased tolerance to antimicrobial agents and disinfectants. This study aimed to evaluate the effect of the biofilm maturation period on their resistance to gaseous ClO2. Listeria monocytogenes, Salmonellaserotype Typhimurium, and Escherichia coli O157:H7 biofilms formed on stainless steel (SS) and high-density polyethylene (HDPE) surfaces were investigated. The total cell mass and protein content significantly increased (P<.05) between the second and the fifth day of maturation, and the biofilms' resistance to gaseous ClO2 increased as they matured. Generally, the cell counts of 0-day-old L. monocytogenes, Salm. Typhimurium, and E. coli O157:H7 biofilms on SS and HDPE reduced below the detection limit (0.48 log CFU/cm2) within 5min. The cell counts of 2-day-old biofilms of the three pathogens were reduced by 6.22 to over 7.52 log, while those of 5-day-old biofilms were reduced by 3.64 to over 6.34 log after 20min of treatment with 30 ppmv of gaseous ClO2. Therefore, as resistance increases with biofilm maturation, daily gaseous ClO2 treatment would maximize the antimicrobial efficacy of the cleaning strategy against biofilms.

Occurrence and antimicrobial resistance pattern of E. coli O157:H7 isolated from foods of Bovine origin in Dessie and Kombolcha towns, Ethiopia.

E. coli are frequently isolated food-borne pathogens from meat, milk, and their products. Moreover, there has been a significant rise in the antimicrobial resistance patterns of E. coli O157:H7 to commonly used antibiotics. A cross-sectional study was conducted from October 2019 to July 2021 to estimate prevalence and identify associated factors of E. coli and E. coli O157:H7 and to determine antibiotic resistance pattern of E. coli O157:H7 from foods of bovine origin in Dessie and Kombolcha towns. A total of 384 samples were collected. Systematic and simple random sampling techniques were employed for sampling carcasses and milking cows, respectively. E. coli and E. coli O157:H7 were detected according to recommended bacteriological protocols. E. coli O157:H7 strains were evaluated for in vitro antimicrobial susceptibility using agar disk diffusion method. Both descriptive and inferential statistical techniques were applied to analyze the data. Overall prevalence rates of E. coli and E. coli O157:H7 were 54.7% and 6.5%, respectively. Highest prevalence rates of E. coli (79.6%) and E. coli O157:H7 (16.7%) were obtained from carcass swabs and milk tank samples, respectively. Unlike E. coli O157:H7, a statistically significant difference in the E. coli prevalence (P<0.05) was observed among the different sample types. Multidrug resistance was observed among all isolates of E. coli O157:H7. All E. coli O157:H7 isolates (100.0%) were susceptible to Ampicillin, Sulfamethoxazole-trimethoprim, and Norfloxacin. On the contrary, all of the isolates (100%) were resistant to Penicillin G, Vancomycin, and Oxacillin. The current study indicated that different foods of bovine origin in the study area were unsafe for human consumption. Hence, good hygienic production methods should be employed to ensure the safety of foods of bovine origin.

Trace Detection of E. coli O157:H7 Cells by an Au Nanoparticle-Based SERS Aptasensor

Drinking polluted water can cause deadly diseases, and clean water is becoming increasingly scarce in the environment. Various pathogens in water will affect environmental safety and human health, so it is necessary to detect pathogens with sensitivity, specificity, simplicity, and celerity. Here, we designed a surface-enhanced Raman scattering (SERS) adaptive sensor based on rolling cycle amplification (RCA), in which the introduced Au nanoparticle-based SERS aptasensor could transform the concentration signal of Escherichia coli into a Raman signal, realizing the sensitive analysis of E. coli O157:H7 (E. coli O157:H7). In this strategy, the magnetic beads were modified with double-stranded DNA (dsDNA) to recognize E. coli and initiate RCA. In the presence of E. coli, one strand of dsDNA will recognize it and unchained from dsDNA and the other strand of dsDNA will act as a trigger for RCA. Then, the RCA reaction was initiated. A large number of SERS probes can be attached to RCA products to achieve a strong Raman signal. Under the optimal conditions, we obtained a low limit of detection (LOD = 0.3 CFU/mL) and a wide detection range (102–107 CFU/mL). Also, this SERS aptasensor can complete the detection within 45 min. It can be concluded that this SERS aptasensor has wide application prospects in food safety inspections, environmental monitoring, and clinical diagnosis, as it can provide a fast, sensitive, and one-pot platform for bacterial detection.

Survival of Inoculated Campylobacter jejuni and Escherichia coli O157:H7 on Kale During Refrigerated Storage

Campylobacter and pathogenic Escherichia coliillnesses have been attributed to the consumption of fresh produce. The leafy green, kale, is increasingly consumed raw. In comparison to other leafy greens, kale has a longer shelf-life. Due to the extended shelf-life of kale, it is warranted to examine the survival of pathogenic Campylobacter jejuni and E. coli O157:H7 inoculated on the surface of kale stored in a controlled environment at 4 ± 1.4°C, and average humidity of 95 ± 1.9% over a 23-day period. At predetermined time points (days 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, and 21), inoculated kale was destructively sampled and the surviving bacteria determined by serial dilution and plating onto Tryptic soy agar, Charcoal cefoperozone deoxycholate agar, and Eosin methylene blue for total aerobic bacteria, C. jejuni, and E. coli O157:H7, respectively. Enrichment and PCR were used for detection when pathogens were not detected using serial dilution and plating. Aerobic heterotrophic bacteria increased over the 23-day period, in contrast, significant declines in the inoculated pathogens were observed. Inoculated E. coli O157:H7 survived longer on kale (up to 19 d); in comparison, C. jejuni was undetectable by day 13 using enrichment and PCR or plating. In conclusion, C. jejuni and E. coli O157:H7 declined on fresh kale over time when held at refrigerated temperatures but were still detected during the majority of the time when the kale would likely still be considered edible by consumers.

Occurrence of Escherichia Coli O157:H7 in lactating cows and dairy farm environment and the antimicrobial susceptibility pattern at Adami Tulu Jido Kombolcha District, Ethiopia

BackgroundFood-borne pathogens are the foremost causes of food-borne human illness in the world. Escherichia coli O157:H7 (E. coli O157:H7) is one of the major food-borne pathogenic bacteria around the world. Though evidence is lacking; especially in developing countries like Ethiopia, the potential health impact of E. coli O157:H7 can be high where food production, handling and consumption is often taking place under unhygienic conditions. In Ethiopia, studies reported E. coli and E. coli O157: H7 from food of animal origin, mainly meat and milk, and also animal surfaces and feces. The objective of the present study was to investigate the occurrence of E. coli O157:H7 in raw milk and the dairy production farm environment and further assess the antimicrobial resistance pattern of the bacterium.MethodsSamples of milk from individual lactating cows’ and dairy farm environmental samples (feces, water and manure) were collected at Adami Tulu Jido Kombolcha district (ATJKD) and analyzed for the presence of E. coli O157:H7. Standard microbiological techniques including culture, biochemical testing and serological test were performed to isolate and identify the bacterium. The bacterial isolates were evaluated for antimicrobial susceptibility patterns using disk diffusion method. A questionnaire was used to collect possible factors affecting E. coli O157:H7 occurrence.ResultsThe overall prevalence of E. coli O157:H7 was 4.7% (19/408) (95% CI: 2.6; 6.7). Out of 19 E. coli O157:H7 isolates, 4/50, 7/154, 2/50, and 6/154 were from water, milk, manure, and feces samples, respectively. From potential risk factors considered in this study area, floor type, cleaning of pens, milking location and hand washing during the time of milking were significantly associated with the occurrence of E. coli O157:H7. The antimicrobial susceptibility pattern indicated varying degrees of resistance. All of the isolates were found to be resistant ampicillin, cephalothin, and rifampin, and 100% susceptibility was observed against the drugs: chloramphenicol, ciprofloxacin, gentamicin, nalidixic acid, kanamycin, and tetracycline. Concerning streptomycin, 63.15% of the isolates were susceptible and 36.8% showed intermediate susceptibility.ConclusionsThe occurrence of multi-drug resistance E. coli O157:H7 observed both in lactating cows and in dairy farm environments can sustain a continuous transmission of the bacteria. The occurrence of multidrug-resistant E. coli o157:H7could hamper the control and prevention efforts.

Molecular Detection of Salmonella spp. and E. coli non-O157:H7 in Two Halal Beef Slaughterhouses in the United States.

The aim of this study was to estimate the prevalence of pathogenic bacteria on halal beef carcasses and environmental surfaces in two halal beef slaughterhouses in the United States. To evaluate halal beef slaughter operations, 144 beef carcass samples (pre- and post-evisceration), and 24 environmental site samples (slaughter hall floor, brisket saw, and offal's table) were collected in two halal beef slaughterhouses during June to September 2017. All carcass and environmental samples were analyzed for the presence of Salmonella spp., Escherichia coli O157:H7, and shiga toxin-producing E. coli (non-O157 STEC). Results revealed that Salmonella spp. was isolated and confirmed for the presence of invA gene in 5/36 samples (13.8%) and 5/36 samples (13.8%) at pre-evisceration in plants A and B, respectively. Salmonella spp. was isolated in 2/9 samples (5.6%) of plants A and was not detected in any sample at post-evisceration process. E. coli O157:H7 was not detected in any sample collected from plant A and B. E. coli non-O157 was isolated and confirmed for the presence of virulence genes in 4/36 samples (11.1%) and 2/36 samples (5.5%) at post-evisceration in plants A and B, respectively. Salmonella spp. was detected based on the presence of the Salmonella&amp;nbsp;invA gene in the slaughter hall floor (4/4) and the offal's table (2/4) samples using multiplex polymerase chain reaction (mPCR). In plant B, Salmonella spp. was also confirmed in the slaughter hall floor (2/4) and brisket saw (2/4) samples. On the other hand, one isolate of E. coli O157:H7 and one non-O157 STEC were obtained from the slaughter hall floor of plant A. The E. coli O157:H7 isolate was positive for stx1, stx2, eaeA, and EHEC-hly genes. Two isolates of non-O157 STEC (2/4) were detected in the environmental site samples, one from the slaughter hall floor, and one from an offal's table sample of plant B. These data can be used to inform food safety interventions targeting halal meat operations in the southeastern United States.

Evaluation of Precision Livestock Technology and Human Scoring of Nursery Pigs in a Controlled Immune Challenge Experiment.

The objectives were to determine the sensitivity, specificity, and cutoff values of a visual-based precision livestock technology (NUtrack), and determine the sensitivity and specificity of sickness score data collected with the live observation by trained human observers. At weaning, pigs (n = 192; gilts and barrows) were randomly assigned to one of twelve pens (16/pen) and treatments were randomly assigned to pens. Sham-pen pigs all received subcutaneous saline (3 mL). For LPS-pen pigs, all pigs received subcutaneous lipopolysaccharide (LPS; 300 μg/kg BW; E. coli O111:B4; in 3 mL of saline). For the last treatment, eight pigs were randomly assigned to receive LPS, and the other eight were sham (same methods as above; half-and-half pens). Human data from the day of the challenge presented high true positive and low false positive rates (88.5% sensitivity; 85.4% specificity; 0.871 Area Under Curve, AUC), however, these values declined when half-and-half pigs were scored (75% sensitivity; 65.5% specificity; 0.703 AUC). Precision technology measures had excellent AUC, sensitivity, and specificity for the first 72 h after treatment and AUC values were &gt;0.970, regardless of pen treatment. These results indicate that precision technology has a greater potential for identifying pigs during a natural infectious disease event than trained professionals using timepoint sampling.

Joint-detection of Salmonella typhimurium and Escherichia coli O157:H7 by an immersible amplification dip-stick immunoassay

To explore the superiority of multifunctional nanocomposites and realize the joint-detection of foodborne pathogens, an immersible amplification dip-stick immunoassay (DSIA) was exploited for the sensitive detection of Salmonella typhimurium (S. typhi) and Escherichia coli O157:H7 (E. coli O157:H7). Saving for the basic colorimetric performance, the reporter molecule of CoFe2O4 (CFO) possesses multivalent elements (Co2+/3+, Fe2+/3+) as well as multifunction of superior catalase-like activity and magnetic properties. By dint of the catalytic activity of CFO, a directly immersible amplification can be simply achieved to endure the DSIA with an intensive signal and a dual-visible mode for the determination of S. typhi and E. coli O157:H7. In virtue of the magnetic separation and enrichment capability of the CFO, the DSIA can perform a matrix-interference-free detection and obtain a dynamic detection range of 102–108 CFU/mL and a low assay limit of 102 CFU/mL. Moreover, the DSIA has reasonable recovery rates for contamination monitoring of two target bacteria in milk and beef samples. Our research provides a persuasive supplement for the application of multifunctional nanocomposites in the ongoing dip-stick immunoassay and an alternative strategy for the efficient detection of foodborne pathogens.

Detection of uidA, stx1, and stx2 Genes in Escherichia coli O157:H7 Isolated from Cattle Faecal Matter and River Water

Cattle can harbour enterohaemorrhagic Escherichia coli O157:H7 serotype in their faecal matters. This study aimed to isolate E. coli O157:H7 from the intestinal digesta, cattle dungs and water; and assess the antibiotic susceptibility and production of shiga toxins by the isolates. The counts of viable bacteria and faecal coliforms in 13 each of intestinal digesta and cattle dung and the 12 water samples were determined using nutrient agar and Eosin methylene blue agar respectively. Sorbitol MacConkey agar (SMAC) was used to screen for E. coli O157:H7 among the 38 E. coli isolates. PCR amplification of uidA genes was used to authenticate the isolates as enterohaemorrhagic E. coli O157:H7 serotype while amplification of stx1 and stx2 showed the production of shiga toxins. The antibiotic susceptibility patterns of the isolates were determined using standard disk diffusion method. The count of viable bacteria and faecal coliform was highest in the intestinal digesta followed by cattle dungs. There was 100% susceptibility to ofloxacin coupled with 100% resistant to augmentin by all the 8 E. coli O157 and 10 non-O157 isolates. The E. coli O157 isolates were more susceptible to ciprofloxacin, gentamicin, ampicillin and cefuroxime than non-O157 isolates but were less susceptible to nitrofurantoin and ceftazidime than non-O157. Eight (44.4%) out of the 18 presumptive E. coli O157 on SMAC amplified uidA genes and were confirmed as E. coli O157. They were isolated only from intestinal digesta and cattle dung. The prevalence of stx1 and stx2 genes among the E. coli O157 was 37.5% and 12.5% respectively. It is concluded from this study that intestinal digesta and cattle dung harboured E. coli O157: H7 some of which possessed shiga toxin.