Escherichia Coli O157 Research Articles

An Outbreak of Shiga Toxin-Positive Enteroaggregative Escherichia coli O104:H4 Related Hemolytic Uremic Syndrome in Turkey: A Multicenter Study

Introduction: Serious outbreaks of Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (STEC-HUS) have been reported globally. In 2011, Germany experienced a significant outbreak of HUS caused by enteroaggregative E. coli (EAEC) O104:H4 strain. Since then, no other outbreaks of this strain have been reported. This study aims to evaluate pediatric patients affected by the second documented worldwide outbreak of STEC-HUS (EAEC O104:H4 serotype) contaminating local drinking water. Methods: Medical records of patients hospitalized in five pediatric intensive care units (PICUs) diagnosed with STEC-HUS between July and September 2022 were evaluated retrospectively. Results: Eighteen patients (14 girls and 4 boys) were enrolled in the study. The median age was 7.4 (Interquartile range [IQR] 1.3–17) years. Abdominal pain was the most common symptom (100%). The mean duration between symptom onset and development of STEC-HUS was 3 days (IQ 1–9). EAEC O104:H4 serotype was detected in the stool samples of 8 patients. Neurological involvement was observed in 3 patients, cardiac involvement in 2 patients, and both in 1 patient. Two patients required respiratory support and dialysis was performed in 16 (88.8%) patients. Plasmapheresis was administered to 2 patients, and eculizumab was given to four. No mortality was reported during follow-up; the mean durations of PICU and hospital stays were 11.3 and 31.6 days, respectively. Conclusion: Outbreaks of HUS can have serious impacts on both mortality and morbidity. However, timely diagnosis and implementation of appropriate supportive care, including dialysis, respiratory support, and medical treatment for eligible patients, can lead to favorable outcomes.

Effects of shallot (Allium ascalonicum) powder supplementation on growth, intestinal morphology, immune stimulation, and intestinal bacteria in broiler chickens

Background and Aim: Antimicrobial resistance in poultry farms is a significant global public health concern that has led farmers to explore alternative antibiotics, such as prebiotics in poultry production. This study aimed to examine the antimicrobial activity of ethanolic shallot extract (ESE) and the effects of adding shallot powder (SP) to broiler feed on broiler growth, immune response to Newcastle disease virus (NDV) vaccination, and gastrointestinal tract bacteria. Materials and Methods: We determined the antimicrobial effects of ESE against Escherichia coli O157:H7 (EOH) and Lactobacillus acidophilus TISTR 2365 (L2365) using the agar well diffusion method. We used a complete randomized design to assign 120 1-day-old Arbor Acre chicks to six groups with four replicates of five broiler chickens over 42 days. The treatment groups were as follows: T1-basal diet (B) + NDV vaccination (positive control), T2-B (negative control), T3-B + 2 g SP per kg of feed, T4-B + 2 g SP per kg of feed + NDV, T5-B + 4 g SP per kg of feed, and T6-B + 4 g SP per kg of feed + NDV. Results: The minimum inhibitory concentrations of ESE on EOH and L2365 were 62.50 and 125.00 mg/mL, respectively. The body weight gain, average daily gain, and feed conversion ratio in the 4 g SP of T5 and T6 groups were significantly improved compared with the other groups (p < 0.05). The immune organ (IO) and thymus gland weights in the T4 group were significantly greater than those observed in the positive and negative control groups (p < 0.05). The IO weights of the bursae of Fabricius and spleen tended to be greater in the T4 group than in the other groups. T5 group broilers had the highest ratio of villus height to crypt depth. The humoral immunity titers against NDV vaccination were improved in the SP-supplemented groups compared with the non-supplemented groups (p > 0.05). SP supplementation reduced the levels of coliform (p < 0.05) and E. coli in the broiler intestine by adding 4 g of SP per kg of feed. However, L2365 was more tolerant to ESE in vitro and tended to increase in line with increased SP levels. Conclusion: ESE showed strong antimicrobial activity to reduce harmful bacteria, and SP supplementation may exhibit prebiotic effects to increase broiler chicken growth, immunity, and microbial balance. Keywords: broiler chickens, food security, immune stimulation, intestinal bacteria, intestinal morphology, shallot.

Preparation of zein active films with antimicrobial and antioxidant properties by incorporating gallic acid loaded γ-CD-MOF for pork preservation

The growing concerns over food contamination caused by microorganisms, coupled with the worsening environmental impact of petroleum-based plastics have drawn significant attention to eco-friendly materials in food packaging. Herein, cyclodextrin-metal-organic framework (CD-MOF) was prepared as promising nanocarrier for the natural product gallic acid (GA). Then, the prepared material (GA@CD-MOF) was incorporated into zein matrix to obtain Zein-GA@CD-MOF films. Further studies showed that the composite films possessed great potential for food packaging, offering excellent UV-light blocking, water resistance, and mechanical properties. Notably, Zein-GA@CD-MOF films demonstrated superior antimicrobial activity (44.56%–77.97% against Escherichiacoli O157:H7 and 28.36%–59.49% against Salmonellaenterica) and sustained antioxidant properties for 100 days, which correlated with the sustainable release effect of GA. Furthermore, the exceptional biosafety of GA@CD-MOF has been confirmed through cytotoxicity and hemolysis assays. Pork preservation experiments illustrated that the obtained films could retard protein degradation, microorganism growth, and lipid oxidation, extending the shelf-life by 9 days at 4 °C. These findings suggest that Zein-GA@CD-MOF films has promising application prospects in pork preservation packaging.

Isolation and identification of Escherichia coli O157:H7 from houseflies (Musca domestica L) at cattle barns in Al-Qadisiyah Province, Iraq

Recent studies identified that Escherichia coli O157:H7 (ECO157H7) causes hemorrhagic colitis in humans, a rare spectrum of diarrheal illness. According to the findings of epidemiological investigations, cattle serve as the principal reservoirs for this bacterium. This study was conducted to understand the incidence of ECO157H7 in houseflies (HFs), a key disease vector. HFs (n = 40) were collected from cattle barns. The HFs were cultured on MacConkey (MC) agars, and any suspected colonies were grown on Eosin Methylene Blue (EMB) agar. EMB-based metallic sheen colonies were grown on specific media, such as sorbitol Chromagar (SCA) and cefixime tellurite sorbitol-MacConkey (CT–SMAC) agar. Sorbitol non-fermenting (SNF) isolates were subjected to a commercial latex agglutination kit to identify the existence of O157 group. The results recorded 31/40 (77.5%) E. coli isolates identified from HF samples. The findings revealed that only 18/31 (58%) were from the SNF isolates. The identities of the isolates were further examined by targeting the rfbO157 and fliCH7 genes, as genetic markers in a PCR method. The PCR results reported 10/18 (55.5%) and 12/18 (66.6%) isolates that carried the rfbO157 and fliCH7 genes, respectively. Our research revealed that HFs represent a harbor for the pathogenic E. coli. The ecology and way this bacterium spreads among animals and across the environment may depend heavily on the presence of ECO157H7 in agricultural environments.

Thiolated chitosan nanoparticles encapsulated nisin and selenium: antimicrobial/antibiofilm/anti-attachment/immunomodulatory multi-functional agent

BackgroundThe increase in the resistance of bacterial strains to antibiotics has led to research into the bactericidal potential of non-antibiotic compounds. This study aimed to evaluate in vitro antibacterial/ antibiofilm properties of nisin and selenium encapsulated in thiolated chitosan nanoparticles (N/Se@TCsNPs) against prevalent enteric pathogens including standard isolates of Vibrio (V.) cholerae O1 El Tor ATCC 14,035, Campylobacter (C.) jejuni ATCC 29,428, Salmonella (S.) enterica subsp. enterica ATCC 19,430, Shigella (S.) dysenteriae PTCC 1188, Escherichia (E.) coli O157:H7 ATCC 25,922, Listeria (L.) monocytogenes ATCC 19,115, and Staphylococcus (S.) aureus ATCC 29,733.MethodsThe synthesis and comprehensive analysis of N/Se@TCsNPs have been completed. Antibacterial and antibiofilm capabilities of N/Se@TCsNPs were evaluated through broth microdilution and crystal violet assays. Furthermore, the study included examining the cytotoxic effects on Caco-2 cells and exploring the immunomodulatory effects of N/Se@TCsNPs. This included assessing the levels of both pro-inflammatory (IL-6 and TNFα) and anti-inflammatory (IL-10 and TGFβ) cytokines and determining the gene expression of TLR2 and TLR4.ResultsThe N/Se@TCsNPs showed an average diameter of 136.26 ± 43.17 nm and a zeta potential of 0.27 ± 0.07 mV. FTIR spectroscopy validated the structural features of N/Se@TCsNPs. Scanning electron microscopy (SEM) images confirmed their spherical shape and uniform distribution. Thermogravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC) tests demonstrated the thermal stability of N/Se@TCsNPs, showing minimal weight loss of 0.03%±0.06 up to 80 °C. The prepared N/Se@TCsNPs showed a thiol content of 512.66 ± 7.33 µmol/g (p < 0.05), an encapsulation efficiency (EE) of 69.83%±0.04 (p ≤ 0.001), and a drug release rate of 74.32%±3.45 at pH = 7.2 (p ≤ 0.004). The synthesized nanostructure demonstrated potent antibacterial activity against various isolates, with effective concentrations ranging from 1.5 ± 0.08 to 25 ± 4.04 mg/mL. The ability of N/Se@TCsNPs to reduce bacterial adhesion and internalization in Caco-2 cells underscored their antibiofilm properties (p ≤ 0.0001). Immunological studies indicated that treatment with N/Se@TCsNPs led to decreased levels of inflammatory cytokines IL-6 (14.33 ± 2.33 pg/mL) and TNFα (25 ± 0.5 pg/mL) (p ≤ 0.0001), alongside increased levels of anti-inflammatory cytokines IL-10 (46.00 ± 0.57 pg/mL) and TGFβ (42.58 ± 2.10 pg/mL) in infected Caco-2 cells (p ≤ 0.0001). Moreover, N/Se@TCsNPs significantly reduced the expression of TLR2 (0.22 ± 0.09) and TLR4 (0.16 ± 0.05) (p < 0.0001).ConclusionIn conclusion, N/Se@TCsNPs exhibited significant antibacterial/antibiofilm/anti-attachment/immunomodulatory effectiveness against selected Gram-positive and Gram-negative enteric pathogens. However, additional ex-vivo and in-vivo investigations are needed to fully assess the performance of nanostructured N/Se@TCsNPs.

Shiga toxin-producing Escherichia coli O157:H7 outbreak associated with school field trips at a farm animal exhibit-Tennessee, September-October 2023.

In October 2023, the Tennessee Department of Health identified an outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 infections among elementary school students who attended school field trips to the same farm animal exhibit. Our aim was to determine STEC source and prevent additional illnesses by initiating epidemiologic, laboratory and environmental investigations. We identified cases using laboratory-based surveillance and by surveying caregivers of children who attended the exhibit. Probable cases were defined as illness with abdominal cramps or diarrhoea after attendance; confirmed cases were laboratory-confirmed STEC infection in an attendee or household contact. A site visit was conducted, and event organizers were interviewed. Human stool, animal faeces and environmental samples were tested for STEC O157:H7 by real-time polymerase chain reaction (PCR), culture and whole-genome sequencing (WGS). Approximately 2300 elementary school students attended the animal exhibit during 2 days. Field trip activities included contact with different farm animal species, drinking pasteurized milk outside animal enclosures and eating lunch in a separate building onsite. We received survey responses from 399 caregivers for 443 (19%) animal exhibit attendees. We identified 9 confirmed and 55 probable cases with illness onset dates during 26 September to 12 October. Seven children aged 1-7 years were hospitalized. Four children aged 1-6 years experienced haemolytic uraemic syndrome; none died. Laboratory testing identified STEC O157:H7 by culture from eight human stool samples with 0-1 allele difference by WGS. Three environmental samples had Shiga toxin (stx 2) genes detected by PCR, but no STEC isolates were recovered by culture. This is the largest reported STEC O157:H7 outbreak associated with an animal exhibit in Tennessee. We identified opportunities for educating school staff, event organizers and families about zoonotic disease risks associated with animal contact and published prevention measures.

RpoS Acts as a Global Repressor of Virulence Gene Expression in Escherichia coli O104:H4 and Enteroaggregative E coli.

In 2011, in Germany, Escherichia coli O104:H4 caused the enterohemorrhagic E coli (EHEC) outbreak with the highest incidence rate of hemolytic uremic syndrome. This pathogen carries an exceptionally potent combination of EHEC- and enteroaggregative E coli (EAEC)-specific virulence factors. Here, we identified an E coli O104:H4 isolate that carried a single-nucleotide polymorphism (SNP) in the start codon (ATG > ATA) of rpoS, encoding the alternative sigma factor S. The rpoS ATG > ATA SNP was associated with enhanced EAEC-specific virulence gene expression. Deletion of rpoS in E coli O104:H4 Δstx2 and typical EAEC resulted in a similar effect. Both rpoS ATG > ATA and ΔrpoS strains exhibited stronger virulence-related phenotypes in comparison to wild type. Using promoter-reporter gene fusions, we demonstrated that wild-type RpoS repressed aggR, encoding the main regulator of EAEC virulence. In summary, our work demonstrates that RpoS acts as a global repressor of E coli O104:H4 virulence, primarily through an AggR-dependent mechanism.

Lactic acid bacteria and spoilage bacteria: Their interactions in Escherichia coliO157:H7 biofilms on food contact surfaces and implications for beef contamination

AbstractThis research explores the interaction between Shiga toxin‐producing Escherichia coli (STEC) O157:H7 and bacteria species commonly found in beef processing environments, specifically Carnobacterium, Lactobacillus, Comamonas, Raoultella, and Pseudomonas. The study investigated how various environmental conditions impact the formation of biofilms and the ability of O157:H7 to transfer from multispecies biofilm onto beef surfaces. For this purpose, a mixture of lactic acid bacteria (LAB), spoilage bacteria (106 CFU/mL), and E. coli O157 (103 CFU/mL) were combined as follows: LAB (T1): Carnobacterium piscicola + Lactobacillus bulgaricus + O157:H7, an spoilage bacteria (T2): Comamonas koreensis + Raoultella terrigena + O157:H7, an spoilage bacteria (T3): Pseudomonas aeruginosa + C. koreensis strain + O157:H7 and only O157:H7 as control (T4). Multispecies biofilms were developed on thermoplastic polyurethane (TPU) and stainless steel (SS) coupons at 10 and 25°C for 6 days, washed and stored for 6, 30, and 60 days at wet (60%–90% RH) and dry (20%–50%, RH) conditions. To evaluate O157:H7 transfer, beef cubes (3 × 3 × 1 cm) were placed on the coupons, followed by a 50‐g weight (7.35 kPa). The experiment was repeated three times in triplicate for each strain combination. Results demonstrate that biofilms formed at 10°C were generally weaker (less biomass) than those at 25°C. Regardless of temperature, more viable O157:H7 cells were transferred to beef from moist biofilms on TPU surfaces. At 25°C, T3 biofilm exhibited the lowest O157:H7 transfer to beef by 1.44 log10 CFU/cm2 (p &lt; 0.01). At 10°C, none of the multispecies biofilm (T1–T3) affected the number of O157:H7 transfers to beef (p &gt; 0.05). Notably, O157:H7 was not detected on food contact surfaces with 30 and 60‐day‐old dry biofilms (T1–T4). Through enrichment, E. coli O157:H7 was recovered from multispecies biofilms T1, T2, and T3. Findings from this study imply that multispecies biofilms contribute to the persistence of O157:H7 under dry conditions, regardless of temperature. These results underscore the intricate influence of multiple environmental factors—including surface type, biofilm age, humidity, temperature, and the presence of other bacterial species—on the risk of beef contamination facilitated by biofilms.

Prevalence and antimicrobial resistance profile of Escherichia coli O157:H7 isolated from chickens and chicken meats from local poultry slaughterhouses in Nakhon Ratchasima Province, Thailand

This study sought to investigate the antimicrobial resistance profiles of Escherichia coli O157:H7 (EOH) isolated from chickens and chicken products at local poultry slaughterhouses in Nakhon Ratchasima Province, Thailand. EOH was isolated from cloacal swabs and chicken breast meat samples between January 2021 and June 2023. EOH were identified using a culture-based method and were confirmed on sorbitol MacConkey agar. Positive EOH isolates were tested via antimicrobial susceptibility testing and antimicrobial resistance profiles using the disk diffusion method and polymerase chain reaction. This study showed the prevalence of EOH isolated from chicken breast meat (11.47%) was higher than that of cloacal swab (9.32%). Most EOH isolates from cloacal swabs were resistant to oxytetracycline (65.38%), streptomycin (61.54%), amoxicillin (61.54%), and ampicillin (65.38%, and most EOH isolates from breast meat were resistant to oxytetracycline (78.12%), streptomycin (25%), amoxicillin (75%), and ampicillin (78.12%). In addition, 32 (55.17%) EOH isolates were multidrug resistant harbored the ESBL-TEM gene (65.38%), blaTEM (34.61%), int-1 (3.85%), or mcr-1 (0%). This is the first report of EOH isolated from chickens and chicken meats from domestic poultry slaughterhouses in Nakhon Ratchasima Province. Therefore, EOH is a public health concern in local poultry slaughterhouse processes in this area.

A Review on Ecoli 0157: H7 (EHEC)

Escherichia coli O157:H7 is an important food borne and water borne pathogen is first isolated in 1982, shiga toxin. producing Ecoli O157:H7 which causes diarrhea, hemorrhagic colitis and haemolytic uremic Syndrome in humans. Haemolytic uremic. Syndrome (Hus) is a Serious condition and upto 50% of Hus patients can develop renal acute dysfunction or blood pressure. Ecoli 0157:H7 infects the alimentary tract and induces abdominal cramps with hemorrhagic diarrhea and it can be transmitted by person to person through fecal shedding and 11%. of infection are estimated. Enterotoxigenic Escherichia coli(ETEC) strain are the main cause of the diarrheal disease problems. ETEC strains are the bacteria which cause the acute watery diarrhea in chinldren. Diarrheagenic Ecoli infection are more common in Africa countries. The occurance of antimicrobial resistance depends upon the type of antimicrobialagent,bacterial strain,dose,time and mode of ministration. some of Ecoli 0517:H7 occurs after taking the undercooked meat or deficiency pasteurized dairy products. And some of Ecoli 0157:H7 occurs due ro exposal to contaminated water from potable drinking sources,pools and lakes and foods such as inappropriate washed leafy green vegetables and fruits,apple juice and direct contact with contaminated animals. Ecoli 0157:H7 shiga toxin causes leukocyte aggregation,platelet aggregation,microthrombin formation, apoptosis of affected cells ,renal dysfunction. shiga toxin not only effect kidney but it can also effect in diffuse vasculitic injuries which cause the effect on multiple organ system and organ failure.

QIAstat-Dx gastrointestinal panel and Luminex xTAG gastrointestinal pathogen panel comparative evaluation.

The diagnosis of acute gastroenteritis is an ongoing clinical challenge in terms of identification of the etiologic agent, time to results, and appropriate treatment. Rapid detection of gastrointestinal pathogens is needed to improve patient care. This study evaluates the performance of the QIAstat-Dx gastrointestinal panel (Q-GP; Investigational Use Only) compared to the Luminex xTAG gastrointestinal pathogen panel (L-GPP; US-IVD). Using 245 stool specimens, we evaluated 10 different targets including rotavirus, norovirus, Salmonella, Shigella, Campylobacter, Giardia, Cryptosporidium, Escherichia coli O157, enterotoxigenic E. coli (ETEC), and Shiga toxin-producing E. coli (STEC). For the viral targets, the percent positive agreement (PPA) for rotavirus was 100% (n = 19) and that for norovirus was 91% (20/22). For the parasitic targets, the PPA was 100% for Giardia and Cryptosporidium (n = 18 and n = 23, respectively). The PPA was 96% for Salmonella (22/23) and Campylobacter (22/23), and the PPA for Shigella was 100% (n = 23). For the E. coli targets, a PPA of 94% was achieved for STEC (32/34) and 96% for ETEC (24/25). We did not assess PPA for the E. coli O157 target as the Q-GP O157 call is stx dependent. The negative percent agreement across all targets was 99.1%. Our study suggests that QIAstat-Dx GP provides comparable results to Luminex GPP based on the analysis of targets found on both panels.

Selection of a diagnostic tool for microbial water quality monitoring and management of faecal contamination of water sources in rural communities

The aim of the current study was to evaluate, validate and select microbial water quality monitoring tools to establish their suitability and feasibility for use in rural communities. The monitoring of water quality was performed at three different levels: i) basic level focusing on sanitary inspection and hydrogen sulphide (H2S) test; ii) intermediate level via enumeration of faecal indicator bacteria (faecal coliforms, Escherichia coli, Enterococcus spp. and Clostridium perfringens); and iii) advanced level based on qPCR detecting host-associated genetic markers (BacHum, BacCow, Cytb, Pig-2-Bac, and BacCan) and pathogens (Vibrio cholerae, Escherichia coli O157:H7, and Shiga toxin-producing Escherichia coli). A positive correlation was recorded between sanitary risk and faecal coliforms (r = 0.613 and p < 0.002), E. coli (r = 0.589 and p < 0.003), and Enterococcus spp. (r = 0.625 and p < 0.003). The H2S test showed positive correlations with sanitary risk score (r = 0.623; p < 0.003), faecal coliforms (r = 0.809; p < 0.001), E. coli (r = 0.779; p < 0.001) and Enterococcus spp. (r = 0.799; p < 0.001). Similar correlation patterns were also found with advanced techniques used for detecting host-associated genetic markers, excepted between Clostridium perfringens, and Pig-2-Bac (pig), BacCan (dog), and V. cholerae. The H2S test and sanitary inspections are therefore suitable and cost-effective tools to capacitate rural areas at household level for the monitoring of faecal contamination and management of water sources.

Notes from the Field: Multistate Outbreak of Escherichia coli O157:H7 Infections Linked to a National Fast-Food Chain - United States, 2022.

Notes from the Field: Multistate Outbreak of Escherichia coli O157:H7 Infections Linked to a National Fast-Food Chain - United States, 2022.

Predictive Population Dynamics of Escherichia coli O157:H7 and Salmonella enterica on Plants: a Mechanistic Mathematical Model Based on Weather Parameters and Bacterial State.

Weather affects key aspects of bacterial behavior on plants but has not been extensively investigated as a tool to assess risk of crop contamination with human foodborne pathogens. A novel mechanistic model informed by weather factors and bacterial state was developed to predict population dynamics on leafy vegetables and tested against published data tracking Escherichia coli O157:H7 (EcO157) and Salmonella enterica populations on lettuce and cilantro plants. The model utilizes temperature, radiation, and dew point depression to characterize pathogen growth and decay rates. Additionally, the model incorporates the population level effect of bacterial physiological state dynamics in the phyllosphere in terms of the duration and frequency of specific weather parameters. The model accurately predicted EcO157 and S. enterica population sizes on lettuce and cilantro leaves in the laboratory under various conditions of temperature, relative humidity, light intensity, and cycles of leaf wetness and dryness. Importantly, the model successfully predicted EcO157 population dynamics on 4-week-old romaine lettuce plants under variable weather conditions in nearly all field trials. Prediction of initial EcO157 population decay rates after inoculation of 6-week-old romaine plants in the same field study was better than that of long-term survival. This suggests that future augmentation of the model should consider plant age and species morphology by including additional physical parameters. Our results highlight the potential of a comprehensive weather-based model in predicting contamination risk in the field. Such a modeling approach would additionally be valuable for timing field sampling in quality control to ensure the microbial safety of produce. IMPORTANCE Fruits and vegetables are important sources of foodborne disease. Novel approaches to improve the microbial safety of produce are greatly lacking. Given that bacterial behavior on plant surfaces is highly dependent on weather factors, risk assessment informed by meteorological data may be an effective tool to integrate into strategies to prevent crop contamination. A mathematical model was developed to predict the population trends of pathogenic E. coli and S. enterica, two major causal agents of foodborne disease associated with produce, on leaves. Our model is based on weather parameters and rates of switching between the active (growing) and inactive (nongrowing) bacterial state resulting from prevailing environmental conditions on leaf surfaces. We demonstrate that the model has the ability to accurately predict dynamics of enteric pathogens on leaves and, notably, sizes of populations of pathogenic E. coli over time after inoculation onto the leaves of young lettuce plants in the field.

Isolation, Characterization, and Comparative Genomic Analysis of Bacteriophage Ec_MI-02 from Pigeon Feces Infecting Escherichia coli O157:H7.

The most significant serotype of Shiga-toxigenic Escherichia coli that causes foodborne illnesses is Escherichia coli O157:H7. Elimination of E. coli O157:H7 during food processing and storage is a possible solution. Bacteriophages have a significant impact on bacterial populations in nature due to their ability to lyse their bacterial host. In the current study, a virulent bacteriophage, Ec_MI-02, was isolated from the feces of a wild pigeon in the United Arab Emirates (UAE) for potential future use as a bio-preservative or in phage therapy. Using a spot test and an efficiency of plating analysis, Ec_MI-02 was found to infect in addition to the propagation host, E. coli O157:H7 NCTC 12900, five different serotypes of E. coli O157:H7 (three clinical samples from infected patients, one from contaminated green salad, and one from contaminated ground beef). Based on morphology and genome analysis, Ec_MI-02 belongs to the genus Tequatrovirus under the order Caudovirales. The adsorption rate constant (K) of Ec_MI-02 was found to be 1.55 × 10-8 mL/min. The latent period was 50 min with a burst size of almost 10 plaque forming units (pfu)/host cell in the one-step growth curve when the phage Ec_MI-02 was cultivated using the propagation host E. coli O157:H7 NCTC 12900. Ec_MI-02 was found to be stable at a wide range of pH, temperature, and commonly used laboratory disinfectants. Its genome is 165,454 bp long with a GC content of 35.5% and encodes 266 protein coding genes. Ec_MI-02 has genes encoding for rI, rII, and rIII lysis inhibition proteins, which supports the observation of delayed lysis in the one-step growth curve. The current study provides additional evidence that wild birds could also be a good natural reservoir for bacteriophages that do not carry antibiotic resistance genes and could be good candidates for phage therapy. In addition, studying the genetic makeup of bacteriophages that infect human pathogens is crucial for ensuring their safe usage in the food industry.

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.

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.

Antimicrobial Profiles and Conventional PCR Assay of Shiga Toxigenic Escherichia coli O157:H7 (STEC) Isolated from Cattle Slaughtered at Bedele Municipal Abattoir, South West Ethiopia.

Shiga toxin producing Escherichia coli O157:H7 (STEC) is considered the most prevalent food borne pathogen that has gained increasing attention worldwide in recent years. A cross-sectional study was carried out at Bedele Municipal abattoir on cattle that were reported healthy from detailed ante-mortem inspections and having various body conditions scores. A total of 516 samples were collected and examined after enriched in modified peptone water. Following an enrichment, the samples were plated onto MacConkey agar and then onto Eosin methylene blue agar. Finally after a few similar procedures, 14 E. coli O157:H7 (STEC) isolates were confirmed through latex agglutination test. The collected data were analyzed using SPSS version 20 statistical software. This study finding revealed that the overall prevalence of E. coli O157:H7 out of 516 samples was found to be 2.7%. However, on sample type basis, the prevalence of E. coli O157:H7 from feacal samples, carcass swabs, butcher hand swabs and knife swabs were 4.7%, 3.3%, 1.1% and 1.1%, respectively. It was also found that that the prevalence of E. coli O157:H7 was significantly affected by age groups of slaughtered cattle (p<0.05). Moreover, in vitro antimicrobial susceptibility test result on average showed that almost all of E. coli O157:H7 isolates were highly susceptible to kanamycin and no resistance was shown to ciprofloxacin and gentamicin. Finally, the conventional PCR detection of stx1, st2 and hylA genes revealed that only 21.4% and 14.3% were found to contain stx1 and hylA genes respectively. To wrap up, this study showed that Shiga toxin producing E. coli O157:H7 (STEC) isolates were found with almost low overall prevalence rate from all sample sources in this study site. Therefore, improving abattoir facilities and slaughter house workers' personal hygiene are recommended to curtail E. coli O157:H7 meat contamination in this abattoir.

Prevalence of Shiga Toxin Producing Enterohemorrhagic Escherichia coli O157:H7 Isolated from Chicken Meat in Northern Punjab, Pakistan

Prevalence of Shiga Toxin Producing Enterohemorrhagic Escherichia coli O157:H7 Isolated from Chicken Meat in Northern Punjab, Pakistan

Pseudomonas fluorescens group bacterial strains interact differently with pathogens during dual-species biofilm formation on stainless steel surfaces in milk.

In order to develop strategies for preventing biofilm formation in the dairy industry, a deeper understanding of the interaction between different species during biofilm formation is necessary. Bacterial strains of the P. fluorescens group are known as the most important biofilm-formers on the surface of dairy processing equipment that may attract and/or shelter other spoilage or pathogenic bacteria. The present study used different strains of the P. fluorescens group as background microbiota of milk, and evaluated their interaction with Staphylococcus aureus, Bacillus cereus, Escherichia coli O157:H7, and Salmonella Typhimurium during dual-species biofilm formation on stainless steel surfaces. Two separate scenarios for dual-species biofilms were considered: concurrent inoculation of Pseudomonas and pathogen (CI), and delayed inoculation of pathogen to the pre-formed Pseudomonas biofilm (DI). The gram-positive pathogens used in this study did not form dual-species biofilms with P. fluorescens strains unless they were simultaneously inoculated with Pseudomonas strains. E. coli O157:H7 was able to form dual-species biofilms with all seven P. fluorescens group strains, both in concurrent (CI) and delayed (DI) inoculation. However, the percentage of contribution varied depending on the P. fluorescens strains and the inoculation scenario. S. Typhimurium contributed to biofilm formation with all seven P. fluorescens group strains under the CI scenario, with varying degrees of contribution. However, under the DI scenario, S. Typhimurium did not contribute to the biofilm formed by three of the seven P. fluorescens group strains. Overall, these are the first results to illustrate that the strains within the P. fluorescens group have significant differences in the formation of mono-or dual-species biofilms with pathogenic bacteria. Furthermore, the possibility of forming dual-species biofilms with pathogens depends on whether the pathogens form the biofilm simultaneously with the P. fluorescens group strains or whether these strains have already formed a biofilm.