Serotype O157 Research Articles

Virulence and Antimicrobial Resistance Profiles of Shiga Toxin-Producing Escherichia coli from River Water and Farm Animal Feces near an Agricultural Region in Northwestern Mexico

Shiga toxin-producing Escherichia coli (STEC) are zoonotic enteric pathogens linked to human gastroenteritis worldwide. To aid the development of pathogen control efforts, the present study characterized the genotypic diversity and pathogenic potential of STEC recovered from sources near agricultural fields in Northwest Mexico. Samples were collected from irrigation river water and domestic animal feces in farms proximal to agricultural fields and were subjected to enrichment followed by immunomagnetic separation and plating on selective media for the recovery of the STEC isolates. Comparative genomic analyses indicated that the recovered STEC with the clinically relevant serotypes O157:H7, O8:H19, and O113:H21 had virulence genes repertoires associated with host cell adherence, iron uptake and effector protein secretion. Subsequent phenotypic characterization revealed multidrug resistance against aminoglycoside, carbapenem, cephalosporin, fluoroquinolone, penicillin, phenicol, and tetracycline, highlighting the need for improved surveillance on the use of antimicrobials. The present study indicated for the first time that river water in the agricultural Culiacan Valley in Mexico is a relevant key route of transmission for STEC O157 and non-O157 with a virulence potential. In addition, feces from domestic farm animals near surface waterways can act as potential point sources of contamination and transport of diverse STEC with clinically relevant genotypes.

Circumventing aglycon transfer en route to the synthesis of pentasaccharide thioglycoside donor for the chain extension of Plesiomonas shigelloides strain 302-73 (serotype O1) repeating unit

Herein we report a chemical synthesis of a pentasaccharide thioglycoside repeating unit of Plesiomonas shigelloides Strain 302-73 (Serotype O1), as a chain extension unit. In our synthetic endeavor we encountered multiple aglycon transfer reactions during glycosylations. This problem was obviated by employing a PMP group as a transient protecting group.

Identification and Genomic Analyses of a Multidrug Resistant Avian Pathogenic Escherichia coli Coharboring mcr-1, blaTEM-176 and blaCTX-M-14 Genes

The emergence and transmission of the colistin-resistance gene mcr and extended-spectrum β-lactamase (ESBL) encoding genes pose a significant threat to global public health. In recent years, it has been reported that mcr-1 and ESBL genes can coexist in single bacteria strain. The objective of this study was to characterize a multidrug-resistant (MDR) avian pathogenic Escherichia coli (APEC) isolate carrying mcr and ESBL encoding genes in China. A total of 200 APEC isolates were collected for antimicrobial susceptibility testing by Kirby–Bauer (K–B) disk method. The MDR strain EC012 were then further analyzed for minimum inhibitory concentrations, antimicrobials resistance genes (ARGs) detection, conjugation, and whole-genome sequencing (WGS). Among all APEC isolates determined by K–B disk method, strain EC012 was resistant to almost all the antimicrobials, including polymyxin B, cefotaxime, and ceftazidime. Moreover, EC012 harbored ARGs mcr-1, blaTEM-176, and blaCTX-M-14. WGS analysis revealed that EC012 belonged to epidemic APEC serotype O1:H16 and multilocus sequence type ST295. EC012 consisted of one chromosome and six plasmids, encoding a broad ARGs. The blaCTX-M-14, mcr-1 or blaTEM-176 genes were located on conjugative plasmids pEC012-1 or pEC012-5, respectively. These plasmids were successfully transferred to transconjugants and resulted in the resistance to polymyxin B, cefotaxime, and ceftazidime. This study indicated that APEC was a potential reservoir of colistin-resistance gene mcr-1 and ESBL encoding genes, and highlighted the necessity for enhanced monitoring of ARGs dissemination among bacteria from different origins.

Refining the Occurrence of Viral Encephalopathy and Retinopathy, Photobacteriosis, and Vibriosis in Connection with Seawater Physicochemical Parameters: A Five-Year Case Study

The marine environment and its physicochemical parameters play a pivotal role in the context of fish farming. Fundamental physicochemical factors of water, including temperature (T°C), salinity (S psu), dissolved oxygen (D.O. mg/l), and pH, exert a profound influence on the physiology of farmed aquatic animals and the composition of microbial communities. This study aimed to establish correlations between documented disease occurrences in sea bass intensive rearing and the prevailing physicochemical parameters of water. The objective was to analyse the significance of these parameters in disease outbreaks and develop a predictive model for the outbreak risk of key diseases. To this end, real-time physicochemical data were collected daily over five years (2011-2015) from two fish farms (A and B) located in the Gulf of Argostoli, island of Cephalonia, Western Greece. The focus was on incidences of Viral Encephalopathy and Retinopathy (VER), Photobacteriosis caused by Photobacterium damselae subsp. piscicida (PHDP) and Vibriosis caused by Vibrio anguillarum serotype O1 (VAO1). Statistically significant correlations were found between increasing water temperature and salinity and the occurrence of VER, PHDP, and VAO1 diseases. The reduction of dissolved oxygen, when combined with other parameters, synergistically triggered the manifestation of these three diseases. The study’s findings were discussed within the context of their potential to predict disease outbreaks based on fluctuations in the physicochemical parameters of water and anticipated climate change scenarios.

ORAL VACCINATION AGAINST YERSINIA RUCKERI: BIOMARKERS OF PROTEIN OXIDATION IN THE HEPATIC TISSUE OF RAINBOW TROUT (ONCORHYNCHUS MYKISS WALBAUM)

The aim of this study was to evaluate the one-month effect of oral vaccination against Yersinia ruckeri based on oxidative stress biomarkers in the hepatic tissue of rainbow trout (Oncorhynchus mykiss Walbaum). The vaccine consisted of three strains of Y. ruckeri (serotype O1) obtained from rainbow trout from different farms where fish showed clinical signs of enteric redmouth disease. The vaccine was produced at the Department of Fish Diseases, National Veterinary Research Institute in Pulawy (Poland) according to the process covered by patent no. P.428259. The concentrated vaccine was added to the fish feed. Treatment was administered three times at one-day intervals. Livers were sampled one month after immunisation. Our results show that immunisation with the anti-Yersinia vaccine did not alter the liver tissue of rainbow trout. aldehydic and ketonic derivatives of oxidatively modified proteins (OMP) were not significantly altered in the hepatic tissue of vaccinated fish prior to immunisation. One month after immunisation, the levels of ketonic derivatives of OMP in the hepatic tissue of untreated trout were reduced compared to the untreated group before immunisation. Similar to the untreated groups, the levels of ketonic derivatives of OMP in the hepatic tissue of the vaccinated group one month after immunisation were reduced compared to the vaccinated group before immunisation. A statistically non-significant decrease in the total antioxidant capacity (TAC) levels was observed between the values obtained in the untreated and vaccinated groups before vaccination and one month after vaccination. Understanding the role of oxidative stress in the tissues of vaccinated trout has important implications for understanding the complex physiological changes that occur during vaccination, and also for improving aquaculture practices to maximise tissue growth and health of vaccinated trout.

Induction of lipopolysaccharide during pregnancy will suppress IL-6 production but not activin B

During inflammation, proinflammatory cytokines are released by various immune cells including IL-6 and activin B. Production of proinflammatory cytokines can be suppressed by estradiol and an increase in estradiol can be found in pregnancy. The aim of this study was to determine the response of IL-6 and activin b in pregnant mice through LPS induction. There were two groups of mice consisting of 8 mice which were not pregnant and 13 pregnant mice in the 2nd week. Inflammation was induced by intraperitoneal injection of LPS Escherichia coli serotype O111:B4. After 4 hours of treatment, the mice serum was collected from their intracardiac blood to measure estradiol, IL-6 and activin B using ELISA. Pregnancy significantly reduced IL-6 levels (P=0.015) but there was no significant difference in estradiol (P=0.169) and activin B (P=0.583) levels. We also found that there was no association of E2 with IL-6 (P=0.637) and activin B (P=0.306). Pregnancy influences the inflammatory response, especially IL-6. This condition can occur because during pregnancy physiological changes occur in the body which involve various complex mechanisms in regulating the immune system.

Evaluation of the protective efficiency of an autogenous Vibrio anguillarum vaccine in lumpfish (Cyclopterus lumpus) under controlled and field conditions in Atlantic Canada

Lumpfish (Cyclopterus lumpus) have become the predominant cleaner fish species used in North American salmon aquaculture. Vibrio anguillarum is a frequent pathogen of lumpfish in Atlantic Canada, and current vaccines against local isolates conferred low to moderate efficacy. This study evaluated the safety and efficiency of a V. anguillarum autogenous vaccine under controlled and field conditions. Two safety trials were conducted following the Canadian Food Inspection Agency (CFIA) regulations before field trial testing. The first safety trial was a common garden assay, and 250 PIT-tsgged lumpfish were used for five treatments per tank (PBS-negative control, Lab vaccine-positive control, autogenous intraperitoneal (IP) vaccine, autogenous dip vaccine, autogenous dip-IP boosted vaccine) in triplicates. Weight, gross pathology, and IgM titers were evaluated to determine the vaccine’s safety. After 10 weeks post-vaccination (wpv), lumpfish were bath-challenged with a lethal dose (1.24 x 106 CFU/mL) of V. anguillarum serotype O2. Survival rate, IgM titers, memory immune response, and cross-immune protection were evaluated. The second safety trial was conducted using a double vaccine dose in two groups, PBS and autogenous IP. The gross pathology score indicated a normal immune response without tissue damage, and no mortality nor fish health issues were observed in the immunized animals. The IP route of administration conferred the highest protection against the V. anguillarum challenge. The autogenous vaccine conferred long-term immunity but did not confer cross-protection against V. anguillarum serotype O1. To evaluate the efficiency of the autogenous vaccine under field conditions, 58,976 naïve lumpfish (8-10 g) were IP immunized with either the autogenous vaccine or the commercial Forte micro IV vaccine. After 7 wpv, the lumpfish were equally distributed into eight sea cages and co-cultivated with Atlantic salmon smolts (60,000 per cage). Lumpfish IgM titers, tissue bacterial loads, mortality, and sea lice count on salmon were monitored. The autogenous vaccine and Forte vaccine confer acceptable protection to the lumpfish in sea cages. No significant difference was observed between lumpfish vaccinated with autogenous and commercial vaccines under field conditions.

One-pot rapid visual detection of E. coli O157:H7 by label-free AuNP-based plasmonic-aptasensor in water sample

Access to clean water for irrigation and drinking has long been a global concern. The need for fast, precise, and cost-effective methods to detect harmful bacteria like Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is high due to the potential for severe infectious diseases. Fortunately, recent research has led to developing and utilizing rapid bacterial detection methods. The creation of an aptamer-based biosensor (aptasensor) for the detection of E. coli O157:H7 using label-free aptamers and gold nanoparticles (AuNPs) is described in this study. The specific aptamers that can detect target bacteria are adsorbed on the surface of unmodified AuNPs to form the aptasensor. The detection is performed by target bacterium-induced aptasensor aggregation, which is associated with a red-to-purple color change under high-salt circumstances. We devised a quick and easy method for detecting bacteria using an anti-E. coli O157:H7 aptamer without the need for specialized equipment or pretreatment processes like cell lysis. The aptasensor could identify target bacteria with only as few as 250 colony-forming units (CFU)/ml in 15 min or less, and its specificity based on our test was 100%. This method not only provides a fast direct preparation process but also exhibits remarkable proficiency in promptly identifying the intended target with a heightened level of sensitivity and specificity. Therefore, it can serve as an intelligent tool for monitoring water reservoirs and preventing the transmission of infectious diseases associated with EHEC.

Synergy between Iron Deficiency and Inflammation Adversely Affects Pregnancy

Iron is essential for maternal and fetal health during pregnancy. In many developing countries, nutritional deficiencies are common, with anemia affecting upwards of 60% of pregnancies. In addition, infection and inflammation, which are known to be detrimental to pregnancy, are also very prevalent in these regions. Even in high-resource countries, approximately 22% of pregnant women are anemic, and obesity and diabetes are common causes of maternal inflammation. Thus, iron deficiency and inflammation commonly co-exist. In our studies, we noted in mice a striking synergistic adverse interaction between maternal iron deficiency and inflammation that resulted in embryotoxicity, not observed in either condition alone. Considering the high global prevalence of concomitant iron deficiency and inflammation in pregnant women, the issue has outstanding translational importance. We induced iron deficiency in mice by feeding females an iron-poor diet (4ppm) for 1-3 weeks prior to mating and for the duration of pregnancy. This resulted in development of iron deficiency and anemia in both mothers and embryos by term [embryonic day (E)18.5] and placental iron concentrations decreased by half, compared to pregnancies fed control diet (100ppm iron). To model acute systemic maternal inflammation, pregnant females received a single moderate dose of LPS (E. coli serotype O55:B5, 0.5μg/g bodyweight subcutaneously), either in the “2nd” (E8.5) or “3rd” (E15.5) trimester. Embryos and placentas from the E8.5 LPS treatment were collected at E18.5, while those from the E15.5 LPS treatment were collected after 24h. Consistent with other reports, LPS injection alone resulted in some adverse pregnancy outcomes: injection on E8.5 in iron replete dams caused abortion in 22% of dams (total n=9 dams) and at E15.5 caused preterm birth in 50% of dams (n=8) but no embryo malformations or resorption were noted. In contrast, when pregnant dams were both iron-depleted and LPS-injected, we observed a striking synergistic effect resulting in embryo death and resorption in all E8.5 treated pregnancies (n=3 dams). In E15.5-treated pregnancies, 60% of embryos were dead and resorbing (n=42 embryos from 5 dams). This dramatic interaction between iron deficiency and inflammation has not been reported previously. Our data suggest the mechanism appears to be, at least in part, related to activation of the TNFα/TNF-R1 pathway and apoptosis of placental endothelial cells. To test the contribution of the TNFα/TNF-R1 pathway to adverse synergy between iron deficiency and inflammation, we generated endothelial TNF-R1 knockout (KO) mice using two different Cre drivers ( Tnfsfr1 f/f;VEC-Cre + or Tnfsfr1 f/f;Tie2-Cre +). Tnfsfr1 f/f and KO females were iron-depleted and mated with Tnfsfr1 f/fmales. Pregnant dams received a single subcutaneous dose of LPS at E15.5 and pregnancy outcomes were assessed after 24h. Embryos from KO dams were protected from LPS-induced embryotoxicity (30% death, n=7 dams) compared to embryos from WT dams (70% death, n=3 dams). Surprisingly, embryo genotype did not play a role in adverse synergy. Our data suggest that maternal TNFR signaling facilitates adverse interactions between iron deficiency and inflammation during pregnancy, which results in embryo death. These studies are ongoing and our results could provide a mechanistic explanation for known adverse outcomes in complicated human pregnancies, and eventually help inform interventions to optimize outcomes in such pregnancies

Study of the transfer of Shiga toxin-producing Escherichia coli during the slaughter of cattle using molecular typing combined with epidemiologic data

Investigation on the distribution and biological characteristics of Shiga-toxin producing Escherichia coli (STEC) during beef processing is essential for in-plant critical control points and food safety risk assessment. Serogroups and subtypes of stx genes of STEC strains isolated from beef processing lines were first investigated. Identification to cross-contamination among different sampling sites was further conducted by combining multilocus sequence typing (MLST) with the previous distribution and characterization data. The PCR-positive rate for STEC in 435 samples from two slaughter plants in China was 14.3% and the isolation rate for the 62 PCR positive and the entire set of 435 samples were 26% and 3.68% respectively. The existence of serotype O157:H7 (33%) and serogroups O121 (42%) and O26 (21%) as well as the high detection rate of high pathogenic gene stx2a (68%) in these serogroups indicated potential risk to the safety of beef. Traceability analysis showed that hide plays a critical role in cross-contamination between feces, lairage pens and post-washing carcasses from a molecular perspective. Intervening measures revolves around de-hiding should be involved in the in-plant safety control policy according to the tracing analysis.

Pharmacological Management of Cholera: A Century of Expert Opinions in Cecil Textbook of Medicine.

Cholera is a potentially lethal diarrheal disease produced by Vibrio cholerae serotypes O1 El Tor and O139. Known since antiquity, the condition causes epidemics in many areas, particularly in Asia, Africa, and South America. Left untreated, the mortality may reach 50%. The crucial therapeutic intervention is intravenous or oral rehydration and correction of acidosis, dyselectrolytemia, and renal impairment. Antibiotic use represents the main pharmacological intervention. What are the milestones of the antibiotics use recommended by experts for the pharmacological management of cholera in the past century? To determine the changes in the experts' approach to the management of cholera and particularly the use of antibiotics as presented in a widely used textbook in the United States. The chapters describing the management of cholera in the 26 editions of Cecil Textbook of Medicine published from 1927 through 2020. Sulfonamides were recommended in 1947, followed by the introduction of tetracyclines, chloramphenicol, and furazolidone in 1955. The options were restricted in 2000 to doxycycline. In the past decade, patients infected with strains known to have a degree a resistance to tetracyclines were treated with azithromycin or ciprofloxacin. Antibiotic use decreases the volume of stool and the duration of diarrhea but has not been considered lifesaving. Drugs with antimotility, antiemetic, or antisecretory properties are not useful. The utility of antibiotic use in cholera has been endorsed by experts, but only as an adjunct to rapid and complete fluid and electrolyte replacement.

Safety Properties of Escherichia coli O157:H7 Specific Bacteriophages: Recent Advances for Food Safety.

Shiga-toxin-producing Escherichia coli (STEC) is typically detected on food products mainly due to cross-contamination with faecal matter. The serotype O157:H7 has been of major public health concern due to the severity of illness caused, prevalence, and management. In the food chain, the main methods of controlling contamination by foodborne pathogens often involve the application of antimicrobial agents, which are now becoming less efficient. There is a growing need for the development of new approaches to combat these pathogens, especially those that harbour antimicrobial resistant and virulent determinants. Strategies to also limit their presence on food contact surfaces and food matrices are needed to prevent their transmission. Recent studies have revealed that bacteriophages are useful non-antibiotic options for biocontrol of E. coli O157:H7 in both animals and humans. Phage biocontrol can significantly reduce E. coli O157:H7, thereby improving food safety. However, before being certified as potential biocontrol agents, the safety of the phage candidates must be resolved to satisfy regulatory standards, particularly regarding phage resistance, antigenic properties, and toxigenic properties. In this review, we provide a general description of the main virulence elements of E. coli O157:H7 and present detailed reports that support the proposals that phages infecting E. coli O157:H7 are potential biocontrol agents. This paper also outlines the mechanism of E. coli O157:H7 resistance to phages and the safety concerns associated with the use of phages as a biocontrol.

Shiga toxin-producing Escherichia coli (STEC) in meat and leafy greens available in the Swedish retail market – Occurrence and diversity of stx subtypes and serotypes

Shiga toxin-producing Escherichia coli (STEC) is a major cause of foodborne illness, ranging from mild diarrhea to permanent kidney failure. This study summarizes the results of four surveys performed at different time periods, which investigated the occurrence and characteristics of STEC in beef, lamb and leafy greens available in the Swedish retail market. Such data is required when assessing the public health risk of varying types of STEC in different foods, and for establishing risk management measures. Samples from domestic and imported products were collected based on their availability in the retail market. The occurrence of STEC was investigated in 477 samples of beef, 330 samples of lamb and 630 samples of leafy greens. The detection of virulence genes (stx1, stx2, eae) was performed using real-time PCR followed by the isolation of bacteria from stx-positive enriched samples using immunomagnetic separation or an immunoblotting method. All STEC isolated from the food samples was further characterised in terms of stx subtyping and serotyping through whole genome sequencing. STEC was isolated from 2 to 14 % of beef samples and 20 to 61 % of lamb samples, depending on the region of origin. STEC was not isolated from samples of leafy greens, although stx genes were detected in 11 (2 %) of the samples tested. In total, 5 of the 151 sequenced STEC isolates from meat contained stx2 and eae, of which 4 such combinations had the stx2a subtype. The stx2 gene, stx2a in particular, is strongly associated with serious disease in humans, especially in combination with the eae gene. The isolates belonged to 20 different serotypes. Two isolates from beef and one from lamb belonged to the serotype O157:H7 and contained genes for stx2 and eae. Overall, several combinations of stx subtypes were found in isolates from beef, whereas stx1c, either alone or together with stx2b, was the dominant combination found in STEC from lamb. In conclusion, STEC was rare in whole meat samples of domestic beef in the Swedish retail market, whereas such bacteria were frequently found in minced meat and whole meat samples of imported beef and domestic and imported lamb. Although the number of isolates containing genes linked to an increased risk of severe disease was low, beef and lamb in the Swedish retail market is a common source of human exposure to potentially pathogenic STEC.

Physiological and Transcriptomic Analyses of Escherichia coli Serotype O157:H7 in Response to Rhamnolipid Treatment.

Rhamnolipid (RL) can inhibit biofilm formation of Escherichia coli O157:H7, but the associated mechanism remains unknown. We here conducted comparative physiological and transcriptomic analyses of cultures treated with RL and untreated cultures to elucidate a potential mechanism by which RL may inhibit biofilm formation in E. coli O157:H7. Anti-biofilm assays showed that over 70% of the E. coli O157:H7 biofilm formation capacity was inhibited by treatment with 0.25-1 mg/mL of RL. Cellular-level physiological analysis revealed that a high concentration of RL significantly reduced outer membrane hydrophobicity. E. coli cell membrane integrity and permeability were also significantly affected by RL due to an increase in the release of lipopolysaccharide (LPS) from the cell membrane. Furthermore, transcriptomic profiling showed 2601 differentially expressed genes (1344 up-regulated and 1257 down-regulated) in cells treated with RL compared to untreated cells. Functional enrichment analysis indicated that RL treatment up-regulated biosynthetic genes responsible for LPS synthesis, outer membrane protein synthesis, and flagellar assembly, and down-regulated genes required for poly-N-acetyl-glucosamine biosynthesis and genes present in the locus of enterocyte effacement pathogenicity island. In summary, RL treatment inhibited E. coli O157:H7 biofilm formation by modifying key outer membrane surface properties and expression levels of adhesion genes.

Differences in the Shiga Toxin (Stx) 2a Phage Regulatory Switch Region Influence Stx2 Localization and Virulence of Stx-Producing Escherichia coli in Mice.

Shiga toxin (Stx)-producing Escherichia coli (STEC) is a major cause of foodborne illness globally, and infection with serotype O157:H7 is associated with increased risk of hospitalization and death in the U.S. The Stxs are encoded on a temperate bacteriophage (stx-phage), and phage induction leads to Stx expression; subtype Stx2a in particular is associated with more severe disease. Our earlier studies showed significant levels of RecA-independent Stx2 production by STEC O157:H7 strain JH2010 (stx2astx2c), even though activated RecA is the canonical trigger for stx-phage induction. This study aimed to further compare and contrast RecA-independent toxin production in Stx2-producing clinical isolates. Deletion of recA in JH2010 resulted in higher in vitro supernatant cytotoxicity compared to that from JH2016ΔrecA, and the addition of the chelator ethylenediaminetetraacetic acid (EDTA) and various metal cations to the growth medium exacerbated the difference in cytotoxicity exhibited by the two deletion strains. Both the wild-type and ΔrecA deletion strains exhibited differential cytotoxicity in the feces of infected, streptomycin (Str)-treated mice. Comparison of the stx2a-phage predicted protein sequences from JH2010 and JH2016 revealed low amino acid identity of key phage regulatory proteins that are involved in RecA-mediated stx-phage induction. Additionally, other STEC isolates containing JH2010-like and JH2016-like stx2a-phage sequences led to similar Stx2 localization, as demonstrated by JH2010ΔrecA and JH2016ΔrecA, respectively. Deletion of the stx2a-phage regulatory region in the wild-type strains prevented the differential localization of Stx2 into the culture supernatant, a finding that suggests that the stx2a-phage regulatory region is involved in the differential ΔrecA phenotypes exhibited by the two strains. We hypothesize that the amino acid differences between the JH2010 and JH2016 phage repressor proteins (CIs) lead to structural differences that are responsible for differential interaction with RecA. Overall, we discovered that non-homologous stx2a-phage regulatory proteins differentially influence RecA-independent, and possibly RecA-dependent, Stx2 production. These findings emphasize the importance of studying non-homologous regulatory elements among stx2-phages and their influence on Stx2 production and virulence of STEC isolates.

#3740 AFTER ALL A TYPICAL HUS

Abstract Background and Aims Typical Hemolytic Uremic Syndrome (HUS) is a thrombotic microangiopathy (TMA) characterized by the triad of acute renal failure, hemolytic anemia and thrombocytopenia. TMAs are classified into: Inherited or primary acquired (atypical HUS), secondary or infection associated. Infection with Shiga-toxin–producing Escherichia coli (E. coli), mainly of serotype O157:H7, is the most common cause of typical HUS, but other serotypes have been rarely associated such as Enteroagregative Escherichia coli (EAEC) serotype O104:H4. Method Case Report Results We report a case of a 51-years-old male with past medical history of arterial hypertension (treated with Perindopril) and IgGk Multiple Myeloma (MM) diagnosed 10 years prior submitted to two bone marrow autotransplants (9 and 4 years prior) and multiple chemotherapy agents including Carfilzomib-Pomalidomide-Dexamethasone (last cycle 4 days before the onset of symptoms). One week after returning from a trip to Brazil, he was admitted to the emergency department with a two-day history of non-bloody diarrhea (4-5 liquid stools per day) and asthenia, with similar positive familiar epidemiology. He denied abdominal pain, fever, nausea or vomiting. At physical examination, he was hypertensive (177/90 mmHg), anuric (12,5 ml/h), dehydrated and apyretic. Abdominal palpation was painless and there were no signs of peritoneal irritation. Laboratory tests showed hemoglobin 10.5 g/dl, new onset thrombocytopenia (261 000/uL » 21 000/uL), kidney disfunction (serum creatinine (sCr) 0.74 mg/dL to 9 mg/dL and serum urea (sU) 41 mg/dL to 260 mg/dL), hyperkaliemia (6 mEq/L) and metabolic acidosis (pH 7,39 and bicarbonate 18.4 mEq/L). LDH was 1949 U/L, C-reactive protein 30.6 mg/L, procalcitonin 3.77 ng/mL, haptoglobin <0.07 g/L and with normal complement levels (C3 and C4). Schistocytes were present in peripheral blood smear. The diagnosis of Acute Kidney Injury related with TMA was established and the patient was transferred to the Nephrology ward and urgent hemodialysis was started. Exhaustive study was performed showing normal renal ultrasound, non-nephrotic proteinuria (1.6 g/g), urinalysis showed leukocyturia and erythrocyturia. Autoimmune study including PR3-ANCA, MPO-ANCA, anti-GBM antibody, Anti-dsDNA antibody, anti-beta 2-glycoprotein I antibodies, anticardiolipin antibodies, anti-ADAMTS13 antibodies and ADAMTS13 activity, as well as study of complement C5, C'3, C'4, factor B, H and I, anti-factor H ac, AH 50 and CH50b were unremarkable. Blood and urine culture and antistreptolysin O titers were negative. Specific stool cultures for E. coli O157, Shigella, Salmonella, Yersinia and Campylobacter were negative. Stool evaluation for parasites were also negative. Viral serology for HIV, HBV, HCV and Plasmodium tests were negative. PCR stool was required due to high suspicion of E.coli infection. The suspicion of a Carfilzomib induced TMA was also raised, while molecular techniques results were awaited. MM was stable and treatment was held until recovery of kidney function. During hospitalization the patient recovered diuresis and creatinine decreased. On the 11th day of hospitalization, he was discharged but still depended on hemodialysis. Finally, stool PCR techniques identified aatA and aggR genes associated with EAEC O104:H4 allowing the diagnosis of acquired infectious HUS rather than drug-related TMA. One week after discharge, the dialysis was stopped due to sCr 3 mg/dL. Four months later, he resumed Carfilzomib and kidney function remained stable with sCr 0.9 mg/dL, despite sustained proteinuria of 1.2 g. Conclusion The authors emphasize the importance of considering other causes of TMA when E.coli O157 infection is excluded, namely drug-related causes (as Carfilzomib) or less frequent infectious agents such as EAEC O104:H4. This case reveals the importance of requesting PCR in the stool even when the E.coli test is negative. This is of particular relevance in immunosuppressed patients. This diagnosis allowed continuing MM treatment.

Immunoinformatics aided design of a peptide‐based kit for detecting Escherichia coliO157:H7 from food sources

AbstractFood and water‐borne enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a zoonotic bacterium that causes gastroenteritis and other human diseases. It has also been linked to chronic foodborne diseases with high mortality rates worldwide, particularly in children. Hence, this study was carried out to designed a peptide base kit for quick detection of E. coli in food. A peptide‐based rapid detection kit was designed using an immunoinformatic technique and some antigenic target genes (stx1A, stx2B, escC, fliC, and eae). The antigenic gene sequences retrieved were screened for antigenicity, transmembrane topology, B‐cells and helper T‐cells. Selected epitopes were joined with appropriate linkers to form a chimeric protein which consists of five B‐cell epitopes, five interleukin‐4 (IL‐4) inducer epitopes and five interleukin‐10 (IL‐10) inducer epitopes. The improved and optimized chimeric protein sequence was cloned in‐silico in a suitable expression host, E. coli‐strain K12. The designed peptide refined and validated tertiary structure was molecularly docked with the tertiary structures of each antigenic target gene. The physicochemical properties of the chimeric protein showed that the construct has an amino acid length of 295 amino acids, a molecular weight of 29.876 kiloDalton (kDa), an aliphatic index of 75.05 and an instability index of 14.82 which confers stability. The construct was hydrophilic with a GRAVY value of −0.261 and had a considerable half‐life of 4.4 h (mammalian reticulocytes, in vitro), >20 h (yeast, in vivo) and >10 h (E. coli, in vivo). Conclusively, the final construct has successfully met the design requirements for the development of a lateral flow kit, which has the potential to provide fast and efficient detection of E. coli O157:H7. However, it is the additional validation through the vitro and in vivo techniques needed to confirm that this designed peptide based test kit.

Vibrio Phage VMJ710 Can Prevent and Treat Disease Caused by Pathogenic MDR V. cholerae O1 in an Infant Mouse Model.

Cholera, a disease of antiquity, is still festering in developing countries that lack safe drinking water and sewage disposal. Vibrio cholerae, the causative agent of cholera, has developed multi-drug resistance to many antimicrobial agents. In aquatic habitats, phages are known to influence the occurrence and dispersion of pathogenic V. cholerae. We isolated Vibrio phage VMJ710 from a community sewage water sample of Manimajra, Chandigarh, in 2015 during an outbreak of cholera. It lysed 46% of multidrug-resistant V. cholerae O1 strains. It had significantly reduced the bacterial density within the first 4-6 h of treatment at the three multiplicity of infection (MOI 0.01, 0.1, and 1.0) values used. No bacterial resistance was observed against phage VMJ710 for 20 h in the time-kill assay. It is nearest to an ICP1 phage, i.e., Vibrio phage ICP1_2012 (MH310936.1), belonging to the class Caudoviricetes. ICP1 phages have been the dominant bacteriophages found in cholera patients' stools since 2001. Comparative genome analysis of phage VMJ710 and related phages indicated a high level of genetic conservation. The phage was stable over a wide range of temperatures and pH, which will be an advantage for applications in different environmental settings. The phage VMJ710 showed a reduction in biofilm mass growth, bacterial dispersal, and a clear disruption of bacterial biofilm structure. We further tested the phage VMJ710 for its potential therapeutic and prophylactic properties using infant BALB/c mice. Bacterial counts were reduced significantly when phages were administered before and after the challenge of orogastric inoculation with V. cholerae serotype O1. A comprehensive whole genome study revealed no indication of lysogenic genes, genes associated with possible virulence factors, or antibiotic resistance. Based on all these properties, phage VMJ710 can be a suitable candidate for oral phage administration and could be a viable method of combatting cholera infection caused by MDR V. cholerae pathogenic strains.

Rapid and accurate detection of Shiga toxin-producing Escherichia coli (STEC) serotype O157 : H7 by mass spectrometry directly from the isolate, using 10 potential biomarker peaks and machine learning predictive models.

Introduction. The different pathotypes of Escherichia coli can produce a large number of human diseases. Surveillance is complex since their differentiation is not easy. In particular, the detection of Shiga toxin-producing Escherichia coli (STEC) serotype O157 : H7 consists of stool culture of a diarrhoeal sample on enriched and/or selective media and identification of presumptive colonies and confirmation, which require a certain level of training and are time-consuming and expensive.Hypothesis. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a quick and easy way to obtain the protein spectrum of a microorganism, identify the genus and species, and detect potential biomarker peaks of certain characteristics.Aim. To verify the usefulness of MALDI-TOF MS to rapidly identify and differentiate STEC O157 : H7 from other E. coli pathotypes.Methodology. The direct method was employed, and the information obtained using Microflex LT platform-based analysis from 60 clinical isolates (training set) was used to detect differences between the peptide fingerprints of STEC O157 : H7 and other E. coli strains. The protein profiles detected laid the foundations for the development and evaluation of machine learning predictive models in this study.Results. The detection of potential biomarkers in combination with machine learning predictive models in a new set of 142 samples, called 'test set', achieved 99.3 % (141/142) correct classification, allowing us to distinguish between the isolates of STEC O157 : H7 and the other E. coli group. Great similarity was also observed with respect to this last group and the Shigella species when applying the potential biomarkers algorithm, allowing differentiation from STEC O157 : H7Conclusion. Given that STEC O157 : H7 is the main causal agent of haemolytic uremic syndrome, and based on the performance values obtained in the present study (sensitivity=98.5 % and specificity=100.0 %), the implementation of this technique provides a proof of principle for MALDI-TOF MS and machine learning to identify biomarkers to rapidly screen or confirm STEC O157 : H7 versus other diarrhoeagenic E. coli in the future.

Molecular epidemiology, clinical features and significance of Shiga toxin detection from routine testing of gastroenteritis specimens

After introduction of faecal multiplex PCR that includes targets for stx1 and stx2 genes, we found stx genes were detected in 120 specimens from 111 patients over a 31-month period from 2018-2020 from a total of 14,179 separate tests performed. The proportion of stx1 only vs stx2 only vs stx1 and stx2 was 35%, 22% and 42%, respectively. There were 54 specimens which were culture positive, with 33 different serotypes identified, the predominant serotype being O157:H7 (19%). Eighty-two patients had clinical data available; we found a high rate of fever (35%), bloody diarrhoea (34%), acute kidney injury (27%), hospital admission (80%) and detection of faecal co-pathogens (23%). Only one patient developed haemolytic uraemic syndrome. We found no significant association with stx genotype and any particular symptom or complication. We found a significant association of serotypes O157:H7 and O26:H11 with bloody stool, but no significant association with any other symptom or complication.