Immunology/Infection Flashcards
How many bacteria are there in the stomach, small intestine and large intestine respectively?
Stomach - should be sterile
Small intestine - Low bacterial numbers
Large intestine - Lots of bacteria
Most bacteria in the stomach are commensals or symbiotes, what is a commensal and a symbiote?
Commensal - One organism benefits and the other is unaffected
Symbiosis - Both organisms benefit
Two types of Gi infections?
Intra-luminal: ingestion of exogenous pathogen
Extra-luminal: Spillage of endogenous bacteria (so commensals)
Common pathogens that cause oesophagitis?
Candida
CMV
HSV (herpes simplex)
Symptoms of community acquired infantile diarrhoea, and most common causative organism?
Poor feeding, irritable
Watery stool
Failure to thrive
E.coli, rotavirus, adenovirus
What is cryptosporidium parvum, what symptoms does it cause, who is at risk?
Protozoa
Watery diarrhoea
Normally self-limiting but in immunocompromised can lead to severe condition/death
What is Bacillus cereus, two main causes?
Bacterium, the toxin causes food poisoning
Re-heated cooked rice
Enetrotoxins from variety of foods
Two different types of salmonella infections?
Non-typhoidal, rarely systemic, antibiotics sometimes required
Typhoidal: always systemic, always need antibiotic
Two strains of typhoidal salmonella that can cause invasive gastroenteritis?
Salmonella Typhi
Salmonella Paratyphi
Actions in hospital acquired diarrhoea?
Isolate immediately
Acute diarrhoea definition?
Diarrhoea for less than 4 weeks
Factors that mean you should investigate diarrhoea further?
Recent hospitalisation > a week Travel Blood in stool Dehydration/weight loss High inflammatory markers
Microscopic examination techniques for stool samples?
- Saline wet mount: Worm eggs/larvae, protozoa and cysts
2. Iodine wet Mount: Used to stain nuclei/glycogen of cysts
Other lab techniques used for diagnosis of stool samples?
PCR
ELISA
What percentage of infective diarrhoea’s are caused by viruses?
90%
Viruses commonly associated with causing gastroenteritis?
Rotaviruses Norovirus Adenovirus Sapovirus Astrovirus
Features of Rotaviruses?
RNA genome
Infects apical cells of small intestine
How do rotaviruses lead to diarrhoea?
Necrosis of apical cell villi leading to malabsorption
Features of adenovirus?
Contains DNA
Most people have been infected by three
Diagnosed by ELISA or electron microscopy
Features of astroviruses?
Small RNA virus (like a star)
Diagnosed by electron microscopy only
Features of Sapovirus?
Small RNA virus
Vomiting is prominent feature
Electron microscopic diagnosis only
Features of norovirus?
Self-limiting
Vomiting and/or diarrhoea
Small RNA
Highly infectious
Entamoeba histolytica features?
Normally infects caecum, or sigmoid colon
Can spread to peritoneum, and liver
Diagnosed with stool sample, colonoscopy
Treated with metronidazole and diloxanide
Adult worm treatments?
Piperazine or Mebendazole
What are geohelminths? Types?
soil-transmitted helminths
Ascaris
Whipworm
Hookworm
Ascaris helminth symptoms?
Treatment?
Nausea, vomiting, anorexia, abdominal discomfort
Mebendazole, Piperazine, Levamisole
Hookworms diagnosis? treatment?
Stool sample
Mebendazole; Albendazole
What is cysticercosis, treatment?
Pork tapeworm
Anticonvulsants, corticosteroids (symptomatic treatment)
Surgery or Cestocidal tretment (albendazole)
