Shiga Toxin-producing Strains Research Articles

Evolutionary genomic analyses of canine E. coli infections identify a relic capsular locus associated with resistance to multiple classes of antimicrobials.

Much of the human genomic epidemiology data available for E. coli mechanism discovery studies has been heavily biased toward shiga-toxin producing strains from humans and livestock. E. coli occupies many niches and produces a wide variety of other significant pathotypes, including some implicated in chronic disease. We hypothesized that since dogs tend to share similar strains with their owners and are treated with similar antibiotics, their pathogenic isolates will harbor unexplored AMR mechanisms of importance to humans as well as animals. By comparing over 1,000 genomes with in vitro antimicrobial susceptibility data from sick dogs across the US and Canada, we identified a strong multidrug resistance association with an operon that appears to have once conferred a type 1 capsule production system.

Phage Therapy Against Pathogenic Escherichia coli (O104:H4, O157:H7, and O26) Strains in Irrigation Water During Garden Cress (Lepidium sativum Linn.) Vegetation.

Fresh produce outbreaks have increased worldwide. Foodborne pathogens are transmitted mostly by contaminated water, and elimination is harder after the transmission. To eliminate pathogens in fresh produce, chemical prevention methods, including chlorine, can be used. However, the usage of chemicals poses a risk to human health, as well as environmental health. Therefore, alternative prevention methods that can be applied in the field should be investigated. This study aims to investigate an alternative method to prevent the pathogenic Escherichia coli strain O26 and Shiga toxin-producing strains O104:H4 and O157:H7 on freshly consumed garden cresses. In this study, garden cresses were treated with bacteriophages after becoming contaminated with pathogenic E. coli strains during growth. After 30 days, the leaves were collected and tested for the presence of E. coli. Its adherence on the leaf surface was investigated with scanning electron microscope (SEM). Although there were significant reductions in both total and biofilm-forming E. coli counts in pathogenic E. coli strain O26 and Shiga toxin-producing strains O104:H4 and O157:H7, which is also confirmed with the SEM images, the counts were not lowered to levels permitted by the EU. Therefore, results showed that phage therapy against pathogenic E. coli strains may be used as a biocontrol agent in combination with additional control measure.

Influence of temperature and pH on induction of Shiga toxin Stx1a in Escherichia coli.

Shiga toxin-producing strains represent pathogenic group that is of concern in food production. The present study evaluated forty-eight E. coli isolates (11 with intact stx gene, while remaining isolates presented only stx-fragments) for Shiga toxin production. The four most expressive stx-producers (O26, O103, O145, and O157) were selected to evaluate effects of pH (3.5, 4.5, and 7) and temperature (35, 40, and 50°C). After determining acid stress effects in media on Stx-induction, we mimicked "in natura" conditions using milk, apple, and orange juices. Only isolates that showed the presence of intact stx gene (11/48) produced Shiga toxin. In addition, acid pH had a role in down-regulating the production of Shiga toxin, in both lactic acid and juices. In contrast, non-lethal heating (40°C), when in neutral pH and milk was a favorable environment to induce Shiga toxin. Lastly, two isolates (O26 and O103) showed a higher capacity to produce Shiga toxin and were included in a genomic cluster with other E. coli involved in worldwide foodborne outbreaks. The induction of this toxin when subjected to 40°C may represent a potential risk to the consumer, since the pathogenic effect of oral ingestion of Shiga toxin has already been proved in an animal model.

Exploring the nature of interaction between shiga toxin producing Escherichia coli (STEC) and free-living amoeba - Acanthamoeba sp

Free-living amoebae (FLA) are widely distributed protozoa in nature, known to cause severe eye infections and central nervous system disorders. There is growing attention to the potential role that these protozoa could act as reservoirs of pathogenic bacteria and, consequently, to the possibility that, the persistence and spread of the latter may be facilitated, by exploiting internalization into amoebae. Shiga toxin-producing strains of Escherichia coli (STEC) are zoonotic agents capable of causing serious diseases, such as hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS). Cattle represent the main natural reservoir of STEC, which are frequently found also in other domestic and wild ruminants, often without causing any evident symptoms of disease. The aspects related to the ecology of STEC strains in animal reservoirs and the environment are poorly known, including the persistence of these microorganisms within niches unfavorable to survival, such as soils or waters. In this study we investigated the interaction between STEC strains of serotype O157: H7 with different virulence gene profiles, and a genus of a wild free-living amoeba, Acanthamoeba sp. Our results confirm the ability of STEC strains to survive up to 20 days within a wild Acanthamoeba sp., in a quiescent state persisting in a non-cultivable form, until they reactivate following some stimulus of an unknown nature. Furthermore, our findings show that during their internalization, the E. coli O157 kept the set of the main virulence genes intact, preserving their pathogenetic potential. These observations suggest that the internalization in free-living amoebae may represent a means for STEC to resist in environments with non-permissive growth conditions. Moreover, by staying within the protozoa, STEC could escape their detection in the vehicles of infections and resist to the treatments used for the disinfection of the livestock environment.

Prevalence and Antimicrobial Resistance of Escherichia coli in Chicken Meat and Edible Poultry Organs Collected from Retail Shops and Supermarkets of North Western Province in Sri Lanka

Escherichia coli is a commensal bacterium that lives in human and animal intestines. Shiga toxin-producing strains of E. coli STECs are responsible for most food-related E. coli infections. Pathogenic E. coli transmits to human bodies due to the consumption of contaminated, raw, or undercooked food. This study was conducted to identify the prevalence of E. coli contamination in edible poultry meat and meat organs in the North Western Province of Sri Lanka. A total of 250 samples consisting of chicken meat (n = 144) and edible organs (n = 106) were collected from retail shops (n = 181) and supermarkets (n = 69), in both Kurunegala and Puttlam districts. The prevalence of E. coli from 250 chicken meat samples was 66.80% (167/250); E. coli prevalence at retail shops (66.85%) was higher than that at supermarkets (66.67%) and was not statistically significant. E. coli prevalence in chicken meat and edible organs was 65.73% and 69.16%, respectively. Molecular confirmation for the positive samples was done through polymerase chain reaction (PCR) using previously designed primers. An antibiotic susceptibility test was performed according to CLSI using nine antibiotics: ampicillin, amoxicillin, chloramphenicol, ceftazidime, ciprofloxacin, cephalexin, erythromycin, gentamicin, and tetracycline. Most isolates were resistant to erythromycin (80.84%) and amoxicillin (76.05%), while the least resistance was observed for gentamicin (4.79%). This study indicates the potential public health risk associated with chicken sold at retail and supermarket levels in the North Western Province of Sri Lanka.

Assessment of Food Safety and Foodborne Zoonotic Bacterial and Fungal Pathogens in Pig Meat Sold in Slaughterhouses of Kinshasa, Democratic Republic of the Congo

Foods produced from animals are major reservoirs for many of the foodborne pathogens such as Campylobacter species, non-Typhi serovars of Salmonella enterica, Shiga toxin-producing strains of Escherichia coli and Listeria monocytogenes. The zoonotic potential of foodborne pathogens, as well as their ability to produce toxins that cause disease or even death, are enough to highlight the gravity of the situation. In this research, it is evidenced that animals act as vehicles in transmission of foodborne pathogens such as Candida albicans, Citrobacter freundii, Escherichia coli, Enterobacter agglomerrans, Klebsiella oxytoca, Proteus mirabilis, Salmonella spp, Shigella dysenteriae, Staphylococcus aureus and Yersinia enterocolitica. their impact, and their current status. This study contributes to improving the health of the meat consumed by the Kinoise population and popularization of national and international opinion about the dangers posed by the consumption of these meats if there is infection. Matete market with 42.8% of samples contaminated with Staphylococcus aureus, three out of six samples may be declared unfit for human consumption and samples from other sites may also be declared unfit for consummation because the bacterial count revealed were above the threshold recommended by the FAO. These were 33.3 % (case 2/6) of samples contaminated with Staphylococcus aureus, Central Market 33.3% Staphylococcus aureus and Salmonella spp), Gambela 33.3% (Staphylococcus aureus and Salmonella spp), Liberté market 20% contaminated with Salmonella spp samples. Since no effective interventions have eliminated these pathogenic bacteria from animals and food, we indicated that they will continue to cause outbreaks and deaths around the world.

Shiga Toxin-Producing Escherichia coli in Diarrheic Neonatal Dairy Calves: Matching Small Intestinal and Fecal Isolates in Terms of Isolation Rates and Antimicrobial Resistance

Background: Shiga toxin-producing strains have been considered remarkable diarrheagenic agents and foodborne pathogens. Several studies have mentioned the role of some Shiga toxin-producing Escherichia coli (STEC) strains in diarrhea and dysentery in calves. Enteropathogenic E. coli (EPEC) have also been isolated from diarrheic calves. Generally, the culture and antibiogram results obtained from fecal samples are used to select antibiotics to treat calf diarrhea. However, the value of such a sampling method has not been evaluated yet. Objectives: This study aimed to evaluate the clinical utility of fecal sample cultures for isolating STEC and EPEC in calf diarrhea by comparing them with small intestine samples. Materials and Methods: The small intestine and fecal samples were simultaneously collected from 35 diarrheic calves. Small intestine samples were collected under the ultrasonographic guide. A total of 70 confirmed E. coli isolates were screened by the multiplex polymerase chain reaction to detect genes encoding Shiga toxin1 (stx1), Shiga toxin2 (stx2), intimin (eae), and hemolysin (E-hly). We also compared the presence of class 1 and 2 integrons and antimicrobial resistance properties in the STEC and EPEC isolates recovered from the small intestine and fecal samples. Finally, the presence of important STEC/EPEC serogroups, including O26, O103, O111, O113, O145, and O157 in isolates from both samples, was determined as well. Results: STEC strains were detected in 25.7%, and 20% of E. coli isolates obtained from the small intestine and fecal samples, respectively. The stx1 was the sole Shiga toxin subtype detected among STEC in intestinal and fecal isolates. EPEC was detected only in one and two E. coli isolates from the small intestine and fecal samples, respectively. Conclusion: A numerically higher prevalence of STEC was observed in the small intestine compared to fecal samples; there was no significant difference in the frequencies of STEC and EPEC isolates between the small intestine and fecal samples. The results indicated that the fecal sample, as a non-invasive and practical method, could be used for isolating STEC and EPEC in calf diarrhea. The antibiogram showed the presence of a high degree of multi-drug resistance among the isolates.

Molecular detection and phylogenetic analysis of a Shiga toxin-producing strain Escherichia coli (partial rfbE and fliCh7 gene), serotype O157:H7 isolated from a living chicken of a traditional market in Indonesia

The objective of this study was to identify a Shiga toxin-producing strain Escherichia coli partial rfbE and fliCh7 gene of O157:H7 isolated from a faeces sample collected from a live chicken in a traditional market in Bogor, Indonesia. The isolate was investigated using multiplex polymerase chain reaction (PCR) to detect stx1, stx2, rfbE, and fliCh7 gene of STEC O157:H7. Then, sequencing was applied to identify the antigen markers, which are the rfbE and fliCh7 genes. In the present study, the isolate which was obtained from a live chicken was successfully identified as STEC O157:H7 strain. This conclusion was based on multiplex PCR and a nucleotide sequence analysis. This pathogen was not only found in the live chicken, but it was further suggested that the rfbE and fliCh7 genes can be used as alternative targets for molecular identification of this pathogen.

Zoonotic potential of Escherichia coli in Poultry Intestinal Contents in Ismailia City, Egypt with special reference to Shiga toxin-producing (STEC) strains

Zoonotic potential of Escherichia coli in Poultry Intestinal Contents in Ismailia City, Egypt with special reference to Shiga toxin-producing (STEC) strains

Zoonotic Potential of Escherichia Coli in Poultry Intestinal Contents in Ismailia City, Egypt with Special Reference to Shiga Toxin-Producing (STEC) Strains

Avian colibacillosis can affect birds of all ages. It is now one of the major causes of economic losses in the poultry industry, as well as a public health risk all over the world.This study aimed to determine the occurrence of E. coli in market-age poultry and the risk of its zoonotic infections in Ismailia city, Egypt. A total of 350 samples were collected from the intestinal contents of the slaughtered poultry (100 farm chickens, 100 backyard chickens, 50 ducks, 50 geese, and 50 turkeys) in Ismailia City. On the other hand, a total of 200 samples were collected from humans at outpatient clinics (100 stool samples and 100 urine samples) from the same investigated area. Samples were examined using bacteriological and molecular examination for genus-specific and virulence gene detection. Results revealed that the isolation rates of E. coli were 70% in farm chickens and turkeys, 88% in backyard chickens, 86% in domestic ducks, 72% in geese. Of avian E. coli isolates, the rates of Shiga toxin-producing E. coli (STEC) strains were 91.4%, 96.6%, 90.9%, 41.7%, and 51.4%% in farm chickens, backyard chickens, ducks, geese, and turkey respectively. In humans, the isolation rate of E. coli was 42% in urine samples and 66% in stool samples. The human STEC isolates were higher in stool samples (26%) than in urine samples (6%). The isolation rates of E. coli were significantly higher in persons who were in contact with poultry than in persons who were not in contact with poultry (p ≤ 0.01). In conclusion, the high isolation rates of STEC and detection with similarities of some E. coli virulence genes (It, St, eaeA, Stx1, and Stx2 genes) from poultry intestinal contents and human samples indicated a significant risk of zoonotic transmission of E. coli via food chain in the investigated area.

Frecuencia de contaminación y de serotipos de Salmonella enterica y Escherichia coli en una operación integrada de matanza y deshuese de bovinos

El objetivo fue determinar la frecuencia de contaminación y la diversidad de serotipos de Salmonella enterica (SE) y Escherichia coli (EC) en diferentes etapas de los procesos de matanza y deshuese de bovinos. Se tomaron muestras de heces, canales y cortes primarios (100 de cada tipo) en un rastro Tipo Inspección Federal ubicado en Mexicali, Baja California. EC no se analizó en heces, por ser esta bacteria parte de la microbiota intestinal. La identidad de las cepas se confirmó por métodos bioquímicos y por PCR: genes taxonómicos invA y gadA, para SE y EC, respectivamente. En EC se investigó también la presencia de genes asociados con los principales patotipos. SE tuvo una frecuencia de 34 % en heces, 3 % en canales y 2 % en cortes, siendo Montevideo el serotipo predominante (72.5 % del total de cepas). EC se detectó en canales (34 %) y en cortes (11 %), en concentraciones promedio de 0.012 y 0.33 log UFC cm-2, respectivamente. Aunque varios de los serotipos de EC identificados están asociados con cepas enterotoxigénicas o productoras de toxinas tipo Shiga, ninguno portaba factores de virulencia característicos de estos patotipos. En resumen, las canales y cortes de bovino no son una fuente relevante de cepas patógenas de EC. En contraste, los bovinos constituyen un importante reservorio de SE, lo cual representa un riesgo para la salud pública. Se requieren estudios genómicos sobre el perfil de virulencia y los genes asociados con infecciones subclínicas en cepas de SE provenientes de animales aparentemente sanos

IDENTIFICATION OF FOOD PATHOGENS AND DETERMINATION OF THEIR DISTRIBUTION LEVEL IN UKRAINIAN FOOD PRODUCTS OF ANIMAL AND PLANT ORIGIN BY PCR METHOD

The foodborne pathogens cause serious public health problems in each country. In this regard, microbiological investigation is included in food safety management of the food chain. Molecular methods and mostly polymerase chain reaction (PCR) are considered highly sensitive, specific and rapid methods for pathogens detection from raw material and food. This study describes the using of specially designed and highly specific primers for PCR to identify 5 common and especially dangerous causeve agents of food poisoning and disease and to determine their level of distribution in food of animal and plant origin. The studies included the identification of methicillin-resistant Staphylococcus aureus (MRSA) and Cronobacter spp. (E. sakazakii) from raw milk, Shiga toxin-producing strains of Escherichia coli (STEC) from beef and swine carcasses, Bacillus cereus and Clostridium perfringens from various types of plant and animal raw materials and products of its processing - fruits, vegetables, berries, dried and preserved products, food concentrates, half-canned food. A total of 397 food samples were investigated to detect these pathogens using classical bacteriological methods and PCR. It was found that the distribution of foodborne pathogens in the studied products of animal and plant origin was as follows: Staphylococcus aureus (MRSA) and Cronobacterspp. (E. sakazakii) in raw cow milk in 6.5% and 19.4% of cases, respectively; shiga-toxin-producing Escherichia coli (STEC) from beef and pork carcasses in 8.1% and 5.7%; Bacillus cereus and Clostridium perfringens from different types of plant and animal raw materials and their processing products averages 27.5 % and 7.7 %, respectively. The advantages of molecular biological methods to which the PCR method relates, include their speed, as well as the specificity of identification of microorganisms by the features of genetic regions of genes that carry information about their pathogenicity factors. It has been found that the rate of detection of these pathogens when using the PCR method in comparison with classical methods increases at least 5-9 times. This data will be useful for assessing microbiological risk and will help authorities develop strategies to reduce consumer health risks.

Soil pH and microbial diversity constrain the survival of E. coli in soil

The presence of Eschericia coli (E. coli) leads to potential outbreaks of disease, demonstrating the importance of understanding how such organisms survive in secondary environments such as soil. Biotic and abiotic soil characteristics play a role in E. coli survival, but it remains unclear how these two aspects interact with survival and whether it is linked to toxin genes. Here we evaluated the survival of three E. coli O157:H7strains: Shiga toxin-producing E. coli, its mutant without stx genes and strain without virulence genes in 4 distinct Chinese soils. To further disentangle the effects of microbial diversity, soils were manipulated to generate a gradient of microbial diversity (10−1, 10−6, and a sterile soil [γ-irradiated control]). Overall, our results showed the E. coli O157:H7 survival time decreased in all treatments, ranging from 8.23 ± 5.42 to 62.33 ± 35.80 days. The fastest decline was with the Shiga toxin-producing strain at 10−1 dilution, whereas the strain without virulence genes, persisted the longest 178 days in the γ sterilized control. These results confirmed the importance of biodiversity upon E. coli invasion and revealed virulence genes negatively influenced survival. The negative correlation between community niche or niche breadth of soil communities and survival, indicated that resource competition also was the major driver of E. coli O157:H7 survival. Moreover, path analyses revealed that soil pH exerted a critical role on the persistence of E. coli O157:H7, higher pH values produced longer survival time in each strain. These conclusions are of relevance for agricultural situations, where anthropogenic influences lead to decreased soil diversity, increased soil pH and resource input through manure application, which can potentially increase the survival time of E. coli O157:H7, the expanding the window of opportunity for food contamination.

Effects of Shiga-Toxin Producing Strains of Escherichia coli (STEC), Lead and Bisphenol A Mixture on Kidney and Spleen of Whistler Mice

Human exposure to shiga toxin producing strains of Escherichia coli (STEC), and environmental contaminants such as lead and bisphenol A (BPA) are on the increase globally. This research work was aimed at investigating the effect of these contaminants on the kidney and spleen of Whistler mice when acting singly and in combination. A total of 24 mice (6 groups of 4 mice each) were obtained and feed with STEC, lead and BPA, either singly or in combination, using oral-gastric gavage at a concentration of 5.9 × 10 5 CFU/ml/bw/day, 60 µg/kg/bw/day and 10 µg/kg/bw/day respectively, for 7 days. After treatment, the mice were sacrificed, and the kidney and spleen observed microscopically by established methods. The results of the current study shows that mice, when administered only STEC, developed interstitial infiltration and congestion of the kidney and spleen respectively, while BPA and Lead, when acting independently, caused durable damages to both organs. Upon administration of two or more of these contaminants together, a somewhat different outcome was recorded, mild damage on both the kidney and spleen. The result therefore shows that exposure to microbial and chemical contaminants singly or together could have grave consequences, and efforts should be made to reduce exposure to these contaminants.

Isolation of Shiga toxin-producing strains of Escherichia coli from beef and swine carcasses and the characterization of their genes

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

Abundant production of exopolysaccharide by EAEC strains enhances the formation of bacterial biofilms in contaminated sprouts

ABSTRACTEnteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu. The exopolysaccharide was identified as colanic acid (CA). Unexpectedly, Shiga-toxin producing EAEC strain 227-11 produced 3-6-fold higher levels of CA than the 042 strain, suggesting differential regulation of the CA in the two strains. The presence of CA was accompanied by the formation of large biofilm structures on the surface of sprouts. The wcaF-wza chromosomal locus was required for the synthesis of CA in EAEC 042. Deletion in the glycosyltransferase wcaE gene abolished the production of CA in 042, and resulted in diminished adherence to sprouts when co-cultured at ambient temperature. In conclusion, this work suggests that copious production of CA may contribute to persistence of EAEC in the environment and suggests a potential explanation for the large Shiga toxin-producing EAEC outbreak in 2011.

Shiga Toxin Producing Strains of Escherichia coli (STEC) Associated with Beef Products and Its Potential Pathogenic Effect

Shiga Toxin Producing Strains of Escherichia coli (STEC) Associated with Beef Products and Its Potential Pathogenic Effect

Identification of Shiga toxin in patients with acute intestinal infections in the presence of mono- and mixed-O-antigens of pathogens

To investigate the time course of changes in the detection rates and levels of Shiga toxin antigen (STA) in their stool and middle-molecule circulating immune complexes (CICs) containing IgG (IgG CIC) in patients with acute intestinal infections (AIIs) in the presence of the body's circulation of mono- and mixed-LPS/O-antigens of intestinal pathogens. A total of 147 patients aged 15 to 55 years who had been hospitalized with AIIs were examined. The diagnosis was bacteriologically verified in 19% of the patients; in the others, it was confirmed by the detection of LPS/O-antigens of Shigella, Salmonella, Yersinia, and Campylobacter in their stool by means of the reaction of coagglutination (RCA) on glass slides. Plates for RCA displayed STA in the fecal and IgG CIC samples. Mono- and mixed infections were detected in 32 and 68%, respectively. The RCA plates exhibited STA in 25.2% of the fecal samples and in 90.5% of the IgG CIC ones from patients with AIIs and did not in those from donors. In monoinfection, the detection rates and levels of STA in the feces became lower in the course of the disease and remained unchanged in IgG CIC and the levels of STA also decreased in the feces, but increased in IgG CIC in mixed infection. In 25.2% of the patients with early AIIs, their stools show free STA; its detection rate and levels are significantly higher in mixed infections than those in monoinfection. The level of STA in serum IgG CIC was significantly higher in mixed infection, suggesting an active immune response to the pathogen. Given that the Shiga toxin-producing strains are present in patients with AIIs, caution should be exercised in the choice of an antibacterial drug to prevent horizontal gene transfer and to enhance toxin production and the body's intoxication. One of the advantages of RCA is the possibility of rapidly changing the spectrum of test systems, depending on the region of their application and the epidemiological situation.

Contribution of cropland to the spread of Shiga toxin phages and the emergence of new Shiga toxin-producing strains

A growing interest in healthy eating has lead to an increase in the consumption of vegetables, associated with a rising number of bacterial outbreaks related to fresh produce. This is the case of the outbreak in Germany, caused by a O104:H4 enteroaggregative E. coli strain lysogenic for a Stx phage. Temperate Stx phages released from their hosts occur as free particles in various environments. This study reports the occurrence of Stx phages in vegetables (lettuce, cucumber, and spinach) and cropland soil samples. Infectious Stx2 phages were found in all samples and many carried also Stx1 phages. Their persistence in vegetables, including germinated sprouts, of Stx phage 933 W and an E. coli C600 (933 W∆stx::gfp-cat) lysogen used as surrogate, showed reductions below 2 log10 units of both microorganisms at 23 °C and 4 °C over 10 days. Higher reductions (up to 3.9 log10) units were observed in cropland soils at both temperatures. Transduction of a recombinant 933 W∆stx::kan phage was observed in all matrices. Protecting against microbial contamination of vegetables is imperative to ensure a safe food chain. Since the emergence of new Stx strains by Stx phage transduction is possible in vegetable matrices, methods aimed at reducing microbial risks in vegetables should not neglect phages.

Whole genome sequencing of diverse Shiga toxin-producing and non-producing Escherichia coli strains reveals a variety of virulence and novel antibiotic resistance plasmids

The genomes of a diverse set of Escherichia coli, including many Shiga toxin-producing strains of various serotypes were determined. A total of 39 plasmids were identified among these strains, and many carried virulence or putative virulence genes of Shiga toxin-producing E. coli strains, virulence genes for other pathogenic E. coli groups, and some had combinations of these genes. Among the novel plasmids identified were eight that carried resistance genes to aminoglycosides, carbapenems, penicillins, cephalosporins, chloramphenicol, dihydrofolate reductase inhibitors, sulfonamides, tetracyclines and resistance to heavy metals. Two of the plasmids carried six of these resistance genes and two novel IncHI2 plasmids were also identified. The results of this study showed that plasmids carrying diverse resistance and virulence genes of various pathogenic E. coli groups can be found in E. coli strains and serotypes regardless of the isolate's source and therefore, is consistent with the premise that these mobile elements carrying these traits may be broadly disseminated among E. coli.