RCSI Enteric (GI) Infections 2024 Undergraduate Medicine PDF

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Enteric (GI) infections Class Year 2, Semester 2 Course Undergraduate Medicine Lecturer Dr Rachel Grainger Date 10th September 2024  2. ENTEROTOXIGENIC E. COLI (T...

RCSI Royal College of Surgeons in Ireland Coláiste Ríoga na Máinleá in Éirinn Enteric (GI) infections Class Year 2, Semester 2 Course Undergraduate Medicine Lecturer Dr Rachel Grainger Date 10th September 2024  2. ENTEROTOXIGENIC E. COLI (TRAVELLERS’ DIARRHOEA) Underdeveloped countries/ regions of poor sanitation Short incubation period 1-3 days Symptoms: – Watery (non-bloody) diarrhoea, fever and nausea – Minor discomfort to severe cholera-like syndrome Self-limiting 1-5 days  2. ENTEROTOXIGENIC E. COLI (TRAVELLERS’ DIARRHOEA) Site of infection: small intestine Adherence Does not invade Enterotoxins = secretion of fluid and electrolytes resulting in diarrhoea 1. LT (heat-labile): similar to cholera toxin 2. ST (heat-stable) 3. ENTEROPATHOGENIC E.COLI: Major cause of Infantile gastroenteritis – < 6 moa – Developing countries High mortality rate (severe dehydration) Person-person spread May cause outbreaks Site of infection: small intestine – Attach to intestinal mucosa – Loss of villi – Invasion of host cells and interference with normal cellular signal transduction = symptoms Watery diarrhoea, vomiting, fever  LISTERIA MONOCYTOGENES Grows in a wide range of temperatures (2-370C) Infection peaks in warmer months Transmission: – Contaminated milk, certain soft cheeses, pate, etc. – Vertical transmission (mother → foetus) – Animal contact Pathogenesis: – Crosses mucosal barrier & disseminates – Survives within macrophages – Need a T-cell response to activate infected cells and produce intracellular killing LISTERIA MONOCYTOGENES Clinical features Healthy adults: – Mostly asymptomatic or mild influenza-like illness / diarrhoea Occupational risk: farmers / vets / butchers At-risk groups (ie opportunistic pathogen): – Pregnant women – Neonates – Immunosuppressed patients: Pneumonia Meningoencephalitis LISTERIA & Neonatal infection: Early onset (1st 2 days of life) PREGNANCY – Acquired in utero BSI +/- pneumonia or cardiopulm Perinatal listeriosis: distress “Influenza-like illness” Hepatosplenomegaly Abscesses Usually 3rd trimester CNS involvement Complications: – High mortality (40-50%) – Miscarriage Late onset (typically >5 days of – Intrauterine death life) – Acquired from maternal genital – Premature labour tract – Neonatal listeriosis – More common than early onset – Meningitis / meningo-encephalitis > BSI – Mortality ~ 12% LISTERIA MONOCYTOGENES Diagnosis: – Blood cultures / CSF Mother: high vaginal swab / placenta – Microscopy: gram-positive bacillus, tumbling motility at 250C Treatment: – High dose ampicillin / amoxicillin with an aminoglycoside (e.g. Gentamicin) – Resistant to cephalosporins Prevention: – People at high-risk should avoid raw / partially-cooked foods of animal origin  CRYPTOSPORIDIUM Clinical presentation: C. parvum & C. hominis – Incubation: 2-10 days Transmission: – Watery diarrhoea (most – Faecal-oral common) – Contaminated food or – Last 1-2 wks water-source (immunocompetent hosts) – Oocysts allow survival – Refractory diarrhoea with outside the body for long malabsorption periods (immunosuppressed) Makes it resistant to chlorine-based Diagnosis: disinfectants – Faeces Microscopy (modified acid- fast or auramine stain) PCR CASE SCENARIO A 20yo attends Emergency Department: 48hr history of abdominal pain and diarrhoea – Became bloody on day 2 of the illness Attended summer barbeque 2 days prior to the onset of symptoms Remembers eating barbequed chicken No medical history or significant family history 1. What is the most likely cause & source? 2. How would this diagnosis be confirmed? 3. What is the treatment? 4. What else should happen?