Shiga-toxigenic Escherichia coli from animal food sources in Mauritius: Prevalence, serogroup diversity and virulence profiles

Genetic and phylogenetic characterization of Shiga toxin-producing Escherichia coli and enteropathogenic E. coli from livestock in Jiangsu by using whole-genome sequencing

AIMS

There are knowledge gaps regarding STEC and EPEC strains in livestock in Jiangsu, China. This study aimed to evaluate the potential public health significance of STEC and EPEC strains isolated from livestock by determining the serotypes, virulence profiles, and genetic relationship with international STEC strains.

METHODS AND RESULTS

A total of 68 STEC and 37 EPEC strains were obtained from 231 fecal sheep samples and 70 fecal cattle samples. By using whole-genome sequencing (WGS) analysis, all STEC belonged to 15 O:H serotypes and the most prevalent serotypes were O6:H10 (19.1%), O155:H21 (14.7%), and O21:H25 (10.3%). The main Shiga toxin gene subtypes detected were stx1c (41.2%), stx1a (26.5%), stx2b (14.7%) and stx2k (14.7%). Only the STEC from cattle carried eae gene. Other adherence-associated or toxin-related genes, including lpfA (70.6%), iha (48.5%), subA (54.4%), and ehxA (33.8%), were found in STEC. All EPEC strains were bfpA-negative, and the predominant eae variants were eae-β1 (62.2%), eae-ζ (21.6%), and eae-θ (8.1%). The core-genome multi-locus sequence typing (cgMLST) analysis revealed nine scattered clusters in STEC and one dominant cluster in EPEC. The strains with the same serotypes, including O22:H8 and O43:H2 in the two towns, possessed a closely genomic distance. The core genome single nucleotide polymorphism (cgSNP) showed that part of STEC strains in this study were clustered with isolates possessing the same serotypes from the Netherlands, Sweden, and Xinjiang of China. Five serotypes of STEC isolates were associated with the clinical STEC strains from databases.

CONCLUSION

This study provided the diverse serotypes and the virulence genes profiles in STEC and EPEC strains. Local strains possessed widely diverse and scattered clusters by cgMLST. Closely genomic correlation with clinical isolates displayed that part of the STEC strains may threaten to public health.

SIGNIFICANCE AND IMPACT OF THE STUDY

Non-O157 STEC strains act as important pathogens for human infections. This study supports the increased surveillance work of non-O157 STEC rather than just O157 STEC in this region.

Whole-genome sequence analysis of Shiga toxin-producing Escherichia coli O157 strains isolated from wild deer and boar in Japan

The prevalence of Shiga toxin-producing Escherichia coli O157 (STEC O157) strains in wild deer and boar in Japan was investigated. STEC O157 strains were isolated from 1.9% (9/474) of the wild deer and 0.7% (3/426) of the wild boar examined. Pulsed-field gel electrophoresis (PFGE) analysis classified the wild deer and boar strains into four and three PFGE patterns, respectively. The PFGE pattern of one wild boar strain was similar to that of a cattle strain that had been isolated from a farm in the same area the wild boar was caught, suggesting that a STEC O157 strain may have been transmitted between wild boar and cattle. Clade analysis indicated that, although most of the strains were classified in clade 12, two strains were classified in clade 7. Whole-genome sequence (WGS) analysis indicated that all the strains carried mdfA, a drug resistance gene for macrolide antibiotics, and also pathogenicity-related genes similar to those in the Sakai strain. In conclusion, our study emphasized the importance of food hygiene in processing meat from Japanese wild animals for human consumption.

Role of Recent Therapeutic Applications and the Infection Strategies of Shiga Toxin-Producing Escherichia coli

Shiga toxin-producing Escherichia coli (STEC) is a global foodborne bacterial pathogen that is often accountable for colon disorder or distress. STEC commonly induces severe diarrhea in hosts but can cause critical illnesses due to the Shiga toxin virulence factors. To date, there have been a significant number of STEC serotypes have been evolved. STECs vary from nausea and hemorrhoid (HC) to possible lethal hemolytic-based uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP). Inflammation-based STEC is usually a foodborne illness with Shiga toxins (Stx 1 and 2) thought to be pathogenesis. The STEC's pathogenicity depends significantly on developing one or more Shiga toxins, which can constrain host cell protein synthesis leading to cytotoxicity. In managing STEC infections, antimicrobial agents are generally avoided, as bacterial damage and discharge of accumulated toxins are thought the body. It has also been documented that certain antibiotics improve toxin production and the development of these species. Many different groups have attempted various therapies, including toxin-focused antibodies, toxin-based polymers, synbiotic agents, and secondary metabolites remedies. Besides, in recent years, antibiotics' efficacy in treating STEC infections has been reassessed with some encouraging methods. Nevertheless, the primary role of synbiotic effectiveness (probiotic and prebiotic) against pathogenic STEC and other enteropathogens is less recognized. Additional studies are required to understand the mechanisms of action of probiotic bacteria and yeast against STEC infection. Because of the consensus contraindication of antimicrobials for these bacterial pathogens, the examination was focused on alternative remedy strategies for STEC infections. The rise of novel STEC serotypes and approaches employed in its treatment are highlighted.

Rapid and highly sensitive pathogen detection by real-time DNA monitoring using a nanogap impedimetric sensor with recombinase polymerase amplification

Fast detection of pathogens is important for protecting our health and society. Herein, we present a high-performance nanogap impedimetric sensor for monitoring nucleic acid amplification in real time using isothermal recombinase polymerase amplification (RPA) for rapid pathogen detection. The nanogap electrode chip has two pairs of opposing gold electrodes with a 100 nm gap and was fixed to a PCB. Then, the nanogap impedimetric sensor was immersed in RPA reaction solution for the detection of E. coli O157:H7, and target DNA amplification was evaluated through bulk solution impedance changes using impedance spectroscopy every minute during RPA. In addition, target gene amplification in the sample solution during RPA was confirmed with a 2% DNA agarose gel. Our nanogap impedimetric sensor can detect down to a single copy of the eae A gene in gDNA extracted from E. coli O157:H7 as well as a single cell of pathogenic E. coli O157:H7 strain within 5 min during direct RPA, which was performed with the pathogen itself and without the extraction and purification of target gDNA. The miniaturized nanogap impedimetric sensor has potential as a cost-effective point-of-care device for fast and accurate portable pathogen detection via real-time nucleic acid analysis.

Advanced molecular characterization of enteropathogenic Escherichia coli isolated from diarrheic camel neonates in Egypt

BACKGROUND AND AIM

Camels are important livestock in Egypt on cultural and economic bases, but studies of etiological agents of camelid diseases are limited. The enteropathogen Escherichia coli is a cause of broad spectrum gastrointestinal infections among humans and animals, especially in developing countries. Severe infections can lead to death. The current study aimed to identify pathogenic E. coli strains that cause diarrhea in camel calves and characterize their virulence and drug resistance at a molecular level.

MATERIALS AND METHODS

Seventy fecal samples were collected from diarrheic neonatal camel calves in Giza Governorate during 2018-2019. Samples were cultured on a selective medium for E. coli, and positive colonies were confirmed biochemically, serotyped, and tested for antibiotic susceptibility. E. coli isolates were further confirmed through detection of the housekeeping gene, yaiO, and examined for the presence of virulence genes; traT and fimH and for genes responsible for antibiotic resistance, ampC, aadB, and mphA. The isolates in the important isolated serotype, E. coli O26, were examined for toxigenic genes and sequenced.

RESULTS

The bacteriological and biochemical examination identified 12 E. coli isolates from 70 fecal samples (17.1%). Serotyping of these isolates showed four types: O26, four isolates, 33.3%; O103, O111, three isolates each, 25%; and O45, two isolates, 16.7%. The isolates showed resistance to vancomycin (75%) and ampicillin (66.6%), but were highly susceptible to ciprofloxacin, norfloxacin, and tetracycline (100%). The structural gene, yaiO (115 bp), was amplified from all 12 E. coli isolates and traT and fimH genes were amplified from 10 and 8 isolates, respectively. Antibiotic resistance genes, ampC, mphA, and aadB, were harbored in 9 (75%), 8 (66.6%), and 5 (41.7%), respectively. Seven isolates (58.3%) were MDR. Real-time-polymerase chain reaction of the O26 isolates identified one isolate harboring vt1, two with vt2, and one isolate with neither gene. Sequencing of the isolates revealed similarities to E. coli O157 strains.

CONCLUSION

Camels and other livestock suffer various diseases, including diarrhea often caused by microbial pathogens. Enteropathogenic E. coli serotypes were isolated from diarrheic neonatal camel calves. These isolates exhibited virulence and multiple drug resistance genes.