Gastroenterology
Stephan Strobel, Lewis Spitz, Stephen D. Marks in Great Ormond Street Handbook of Paediatrics, 2019
Infection with E coli is a common, world-wide problem, particularly in developing countries. It is from faecal–oral transmission. E coli are gram-negative motile bacilli, which are some of the most common flora of the healthy large intestine. The pathogenic organisms each have one of four properties that the organisms in the normal flora do not possess. These are intestinal wall invasion, enterotoxin and cytotoxin production, or adherence to the bowel wall. Enterotoxin producing E coli (ETEC) produce heat labile (similar to cholera toxin) and heat stable toxins, which result in profuse diarrhoea.Enteroadherent (EPEC) E coli (tEPEC and aEPEC) infection with its attaching and effacing (A/E) lesions is a major agent in infantile diarrhoea.Enteroinvasive E coli (EIEC) produce the same toxin as the shiga toxin from Shigella dysenteriae. They are spread through contaminated food and water, but can also pass from person to person.Enterohaemorrhagic E coli (EHEC) such as E coli 0157 produce cytotoxin. They are transmitted from cattle, and are often acquired from undercooked fast food.
Common Infections in the Nursing Home Setting
Thomas T. Yoshikawa, Shobita Rajagopalan in Antibiotic Therapy for Geriatric Patients, 2005
Some diarrheas are diagnosed by assay of toxin in stool. For C. difficile, the diagnosis hinges primarily on the demonstration of toxins A or B in diarrheal stool specimens. Stools should not be sent in patients without diarrhea as asymptomatic carriage of toxin-producing C. difficile is common in nursing home residents. The toxin assays are 70-90% sensitive to detect the organism, particularly if multiple specimens are sent. Similarly, stool shiga-toxin can be detected in residents with £. coli 0157:H7 infection. Stool culture for C. difficile is not useful as non-toxin-producing strains are commonly found in the stool of healthy persons, and many laboratories no longer perform the test. Endoscopy is not a substitute for stool toxin assays as not all cases of C. difficile have pseudomembranes and isolated right-sided disease can be missed (11,12).
Pathogenicity and Virulence
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
Diphtheria toxin, an example of an A-B toxin, is produced by C. diphtheriae. The toxin is a single-chain polypeptide which catalyzes the transfer of adenine diphosphate dinucleotide from nicotinamide dinucleotide to elongation factor 2, resulting in inhibition of protein synthesis. Diphtheria formerly caused very high morbidity and mortality among young children, but since the incorporation of diphtheria toxoid into the Diphtheria-Pertussis-Tetanus (DPT) vaccine the incidence of this disease has been drastically reduced. Other A-B toxins include Shiga toxin of S. dysenteriae, exotoxin A of P. aeruginosa, tetanus toxin of C. tetani, and botulinum toxin of C. botulinum.
Recent advances in antibacterial applications of metal nanoparticles (MNPs) and metal nanocomposites (MNCs) against multidrug-resistant (MDR) bacteria
Published in Expert Review of Anti-infective Therapy, 2019
Some serotypes of E. coli can be pathogen by production of Shiga toxin. Urinary tract infections, gastroenteritis, hemorrhagic colitis, Crohn’s disease, and neonatal meningitis are associated with virulent strains of E. coli such as O157:H7 and O104:H4. Antibiotics involving rifaximin, fluoroquinolones, and azithromycin are effective agents against nonresistant strains of E. coli. Extended spectrum β-lactamases (ESBLs) can be synthesized by MDR E. coli containing plasmids of antibiotic resistance (CTX-M). These strains have developed resistance against monobactams, cephalosporins, quinolones, and aminoglycosides [19]. In addition, modification of porins (OmpF, OmpC, and PhoE) in outer membrane of E. coli is another resistance mechanism. In this case, there is a lack of porin function, and expression also changes in the type of porins. AcrAB-TolC system is another approach of resistance in which E. coli uses efflux pump to expel fluoroquinolones, chloramphenicol, fusidic acid, tetracyclines, β-lactams, and novobiocin [1].
Eyedrop vaccination: an immunization route with promises for effective responses to pandemics
Published in Expert Review of Vaccines, 2022
Jihei Sara Lee, Sangchul Yoon, Soo Jung Han, Eun-Do Kim, Jiyeon Kim, Hae-Sol Shin, Kyoung Yul Seo
Enterohemorrhagic E. coli (EHEC) is another bacterial pathogen that causes severe diarrhea. EHEC is also known to cause hemorrhagic colitis and hemolytic uremic syndrome [84]. So far, vaccines against EHEC have not been reported in either animals or humans. However, our study in 2015 showed that vaccination with eye drops might offer protective immunity against EHEC starting at the point of entry [62]. In mice, an eyedrop vaccine was developed against the outer membrane vesicle (OMV) shed from the bacteria [85]. They are thought to contain the Shiga toxin, a key mediator of pathogenesis of EHEC infection [86]. Administering Shiga toxin-deficient OMV to the eye mucosa increased serum IgG antibody and mucosal IgA antibody levels. A lethal dose of unmodified (i.e. Shiga toxin-containing) OMV was administered into the peritoneum, and only a slight body weight loss was noted in immunized mice. The level of blood urea nitrogen and creatinine remained within a normal range. Histological examinations of renal tissues of challenged mice were unremarkable.
Catastrophic antiphospholipid syndrome in a patient with systemic sclerosis and hereditary angioedema: case report and literature review
Published in Modern Rheumatology Case Reports, 2018
Jean Liew, Marcia Friedman, Sima Desai, Lindsay Taute, Nastaran Neishaboori, Peter Stenzel, Ajay Wanchu
Given the patient’s anaemia, thrombocytopenia, and purpura, an evaluation for causes of thrombotic microangiopathy was initiated. Laboratory findings were not consistent with haemolysis (normal total bilirubin 0.5 mg/dL [normal range 0.3–1.2 mg/dL] and haptoglobin 146 mg/dL [normal range 30–200 mg/dL], though LDH non-specifically elevated, 996 U/L [normal range <250 U/L]), or heparin-induced thrombocytopenia (platelet factor 4 antibody negative). Disseminated intravascular coagulation remained in the differential with low platelets and elevated PT; however, fibrinogen was not decreased (535 mg/dL, normal range 200–450 mg/dL). A peripheral smear demonstrated only rare schistocytes and the ADAMTS13 activity was 60%, which was not consistent with TTP. Shiga toxin was not evaluated. There was an initial concern for scleroderma renal crisis with the patient’s acute kidney injury, hypertension, and possible microangiopathic haemolytic anaemia, but given the improvement of renal function and blood pressure without pharmacologic intervention, this was felt to be unlikely. The findings on the CT were thought to be most likely caused by a typical exacerbation of her HAE, perhaps made worse by the recent pre-hospital administration of lisinopril.
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