MICRO Infections of the GIT - Week 5/6 Flashcards
Transmission of H. pylori gastric ulcers
Person-to-person, ingestion of contaminated food/water.
Symptoms of gastric ulcers
o Symptoms: dyspepsia, upper abdo pain, nausea, frequent burping, bloating
NB: infections are, however, commonly asymptomatic.
Complications of H. pylori gastric ulcers
Gastric & duodenal ulcers, acute & chronic gastritis, gastric adenocarcinoma, mucosa-associated lymphoid tissue (MALT) lymphoma.
Diagnosis of H. pylori gastric ulcers
Urea breath tests, faecal H. pylori antigen testing, endoscopy w biopsy specimens, histopathology, rapid urease test of biopsy, PCR.
Transmission of non-typhoidal salmonella
o Transmission/sources: large animal reservoirs (transferred to humans via contaminated food)
Diagnosis of non-typhoidal salmonella
o Diagnosis: Culture on selective media, rapid molecular methods, blood cultures.
Treatment of non-typhoidal salmonella
o Treatment : usually self-limiting & resolves without treatment, fluid & electrolyte replacement.
Complications of non-typhoidal salmonella
Invasive infection, septicaemia
Causative agents of typhoid & paratyphoid salmonella/enteric fever
Salmonella typhi & salmonella paratyphi
Transmission of typhoid & paratyphoid salmonella/enteric fever
o Transmission: person-to-person via contaminated food/water
Diagnosis of typhoid & paratyphoid salmonella/enteric fever
o Diagnosis: stool, blood culture or culture from another body fluid/tissue
Symptoms of typhoid & paratyphoid salmonella/enteric fever
o Symptoms: fever, malaise, aches, diarrhoea & constipation, rose spots
Treatment & prevention of typhoid & paratyphoid salmonella
Antibiotics
Vaccine developed.
Causative agents of shigellosis
o Causative agents: Shigella sonnei , S. flexneri, S. boydii , S. dysenteriae.
Transmission of shigellosis
o Transmission: person-to-person via faecal-oral route (highly infectious).
Symptoms of shigellosis
o Symptoms: mild-severe gastroenteritis, initial watery diarrhoea which later worsens to contain mucous & blood , lower abdominal cramps.
Diagnosis of shigellosis
Culture or rapid molecular tests.
Treatment of shigellosis
Antibiotics for severe cases, rehydration.
Causative agents of campylobacter
Campylobacter jejuni.
Transmission of campylobacter
o Transmission: large animal reservoir via contaminated food consumption (highly infectious).
Treatment of camylobacter
Antibiotics for invasive infections.
Causative agents of cholera
V. cholerae.
Transmission of cholera
Contaminated food/water.
Symptoms of cholera
o Symptoms: severe watery non-bloody diarrhoea (rice water stools), massive fluid loss & electrolyte imbalance.
Diagnosis of cholera
o Diagnosis: culture, PCR tests.
Treatment & prevention of cholera
o Treatment: oral or IV fluids, antibiotics.
Vaccine developed.
Causative agent of C. difficile antibiotic-associated diarrhoea.
o Causative agent: C. difficile (antibiotic disruption of normal gut flora -> C. difficile multiplication).
C. difficile symptoms
o Symptoms: diarrhoea, abdominal pain, fever after antibiotic treatment.
Complications of C. difficile infection.
Toxic megacolon.
Diagnosis of C. difficile
C. difficile toxin in stools.
Treatment of C. difficile
FMT, anti-anaerobic (e.g., metronidazole) or vancomycin.
Causative agents of E. Coli
o Causative agents: enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohaemorrhagic (EHEC), enteroinvasive (EIEC), enteroaggregative (EAEC).
Causative agents of staphylococcal food poisoning
S. aureus.
Transmission of staphylococcal food poisoning
Contaminated food.
Symptoms of staphylococcal food poisoning.
Vomiting or diarrhoea 1-6hrs post consumption.
Treatment of staphylococcal food poisoning
Usually self-limiting.
Bacillus cereus causative agent.
B. cereus.
Transmission of B. cereus
o Transmission: spores (present in soil/food ) survive cooking, germinate upon cooling.
Symptoms of 2 x types of bacillus cereus.
o Symptoms:
Emetic form: vomiting 15min-4hrs post consumption (due to ingestion of enterotoxin).
Diarrhoeal form: watery diarrhoea within 8-12hrs post consumption (due to production of enterotoxin in the gut).
Causative agent botulism.
C. botulinum.
Transmission of botulism.
Toxins in food (often canned food) ingested.
Symptoms of botulism.
Descending paralysis.
Complications of botulism.
Death.
Clostridium gastroenteritis causative agents.
C. perfringens.
Clostridium gastroenteritis transmission.
o Transmission: ingestion of spore-containing or inadequately cooked food.
Clostridium gastroenteritis symptoms.
Abdominal pain, diarrhoea.
Clostridium gastroenteritis complications.
Necrosis of the small bowel.
Clostridium gastroenteritis treatment.
Usually self-limiting.
Norovirus causative agent.
Norovirus virus.
Norovirus transmission.
Food/water-borne (highly infectious - w short 24h incubation period).
Norovirus symptoms.
Nausea, abdo pain, vomiting (projectile), diarrhoea.
Norovirus diagnosis.
PCR, electron microscopy, ELISA.
Norovirus treatment.
Usually self-limiting.
Rotavirus causative agents.
Rotavirus virus.
Rotavirus transmission.
Faecal-oral route or contaminated food/water.
Rotavirus symptoms.
o Symptoms: vomiting, diarrhoea , respiratory symptoms (e.g., cough, coryza).
Rotavirus treatment.
o Treatment: fluid & electrolyte replacement (particularly for at risk populations).
Rotavirus diagnosis.
PCR, ELISA.
Rotavirus prevention.
Vaccine.
Hep A symptoms
Usually asymptomatic.
Hep B symptoms
Usually asymptomatic.
Hep C symptoms.
Usually asymptomatic.
Hep D symptoms.
Usually asymptomatic.
Hep E symptoms.
Usually asymptomatic.
Hep A treatment.
Usually self-limiting.
Hep A complications.
Serious or fatal fulminant hepatitis.
Hep B treatment.
Usually self-limiting.
Hep B complications.
Cirrhosis, liver failure, liver cancer.
Hep C treatment.
Usually self-limiting.
Hep C complications.
Cirrhosis, liver failure, liver cancer.
Hep D treatment.
Usually self-limiting.
Hep E treatment.
Usually self-limiting.
Hep A transmission.
Contaminated food, water, objects, person-to-person.
Hep B transmission.
Contact w infected body fluids.
Hep C transmission.
Contact w infected body fluids.
Hep D transmission.
Contact w infected blood.
Hep E transmission.
Faecal-oral route (often via contaminated water or undercooked meat).
+ve HBsAg indicates
Infection/recent vaccination.
+ve HBeAg indicates
Acute phase infection.
+ve HBsAb
Infection/previous vaccination.
HBeAb +ve, but HBeAg -ve indicates
Been through active phase - immune response.
When does the the HBeAg escape?
During infection.
A higher HBeAg level indicates:
Higher infectivity level.
IgM high titre indicates… IgM low titre indicates…
Acute infection. Chronic infection.
IgG +ve, but HBsAg -ve indicates
Past infection.
H. pylori microscopy
Gram -ve spiral bacterium.
Campylobacter jejuni microscopy
Curved/S-shaped gram -ve.
C. difficile toxin A and B.
Toxin A (enterotoxin) -> increased intestinal permeability & fluid secretion.
Toxin B (cytotoxin) -> colonic inflammation, haemostasis & tissue necrosis in the colon.
C. perfringens microscopy
Anaerobic gram +ve, spore-forming rod.
Which Hep viruses are transmitted via faecal-oral route?
Hepatitis A and E are transmitted via faecal-oral route (often food-borne infections e.g., shellfish).
(Non-enveloped/naked viruses tend to be very hardy and tough and can survive through acid of the stomach -> GIT infectious agents).
Amoebiasis mode of transmission.
Contaminated food/water or person-to-person via faecal-oral route. NB: also involves cyst formation.
Giardiasis mode of transmission.
Contaminated food/water or person-to-person.
Amoebiasis signs, symptoms & complications.
Asymptomatic
OR diarrhoea, dysentery, abdominal distension, fever.
Complications – liver abscess (symptoms incl. fever, nausea, liver, intermittent diarrhoea, mucous, pain, flatulence, weight loss).
Giardiasis signs & symptoms.
Asymptomatic
OR weight loss, GI symptoms incl. diarrhoea, nausea, stomach cramps, gas, greasy stools, dehydration, malnutrition.
Amoebiasis diagnosis.
Stool ova & parasite exam, immunoassay, serology, biopsy, molecular & antibody tests. MRI can be used to detect liver abscesses.
Giardiasis diagnosis.
Stool ova & parasite exam, immunoassay, ELISA.
Ascariasis/roundworm mode of transmission.
Eggs of worms are transmitted via contaminated food/water.
Hookworm mode of transmission.
Eggs develop into larvae in soil contaminated by dog or cat faeces -> penetrate the skin -> reside in lumen of small/large intestine.
Roundworm signs, symptoms, complications.
Shortness of breath, cough, nausea, diarrhoea, blood in the stools, abdominal pain, weight loss, fatigue.
Complications – children w substantial infections may experience intestinal blockage.
Hookworm signs, symptoms, complications.
Cough, itchy rash, loss of appetite, abdominal pain, diarrhoea., cutaneous larva migrans.
Prevention of helminth infections.
Clean water, improving sanitation, improving hygiene, not walking barefoot, deworming.
Roundworm diagnosis.
Eggs can be ID via microscopy. Worms via XRT, MRI, USS.
Hookworm diagnosis.
Stool microscopy.
