Flashcards in Microbiology 1 (Dr Orange) Deck (90)
What host factors affect your risk of gastrointestinal infection? (5)
Age (very young and elderly)
Decreased gastric acid secretion
Decreased gut motility
Influence of colonic microflora
What bacterias seen in the UK cause Gastrointestinal infections? (8)
Campylobacter coli/ jejuni
E coli O157
Staph aureus/ Clostridium perfingens/ Bacillus cereus
What viruses seen in the UK cause gastrointestinal infections? (2)
What parasites seen in the UK cause gastrointestinal infections? (2)
What bacterias, usually imported from abroad, case gastrointestinal infections?
Vibrio cholerae/ parahaemolyticus
Salmonella typhi/ paratyphi
Shigella dysenteriae/ flexneri/ boydii
What parasite, usually imported from abroad, can cause GI infections?
What is diarrhoea?
3 or more loose stools in 24 hours
What is the source/ reservoir of infection?
The original source of the infection e.g. animal gut, another human's gut, etc.
What is the vehicle of infection?
The means by which the infection is transmitted from one person to another (e.g. contaminated food/ water)
What is the source and vehicle of infection of E. coli O157
Source = cattle GI tract
Vehicle of infection = undercooked hamburger
What shape is camplobacter (C. jejune, C. coli)?
Curved gram negative bacilus
What is the commonest cause bacterial GI infection in the UK?
Incubation period of campylobacter?
How does campylobacter make you unwell?
Causes inflammation of the colon and rectum leading to bloody diarrhoea
Can invade and occasionally get into bloodstream (patients get systemically unwell with flu like symptoms)
What is the main source/ vehicle of infection of campylobacter?
Undercooked poultry + other farm animals, water and unpasteurised milk (person to person spread is rare - outbreaks usually because consumed the same chicken)
Symptoms of campylobacter?
Diarrhoea =/- blood
Management of campylobacter?
Usually self limiting but give ERYTHROMYCIN or CIPROFLOXACIN for 5 days if patient develops systemic illness
What does "enteric" in Salmonella enterica mean?
It is the agreed species name for all food poisoning i.e. non-typhoidal salmonella (often still called by species name e.g. S. enteritiditis, S. typhimurium, etc.
What is the incubation period for Salmonella enterica?
12 - 48 hours
What is the mechanism of action of Salmonella enterica?
Causes inflammation of the ileum and colon - multiply in gut and cause mucosal damage, decreased mucosal damage and increased fluid excretion
Can invade and occasionally get into bloodstream
What is the source/ vehicle of infection of salmonella enterica?
Undercooked poultry + other farm animals (much less common since immunisation of poultry against Salmonella spp.)
Symptoms of salmonella enterica?
Diarrhoea (occasionally bloody)
Management of salmonella?
Usually ciprofloxacin for 5 days if patient at risk of or develops systemic illness
What type of Shigella is seen in the UK?
Shigella sonnei (most benign type) - outbreaks occur every few years amongst cohorts of vulnerable children
Incubation period for Shigella sonnei?
Mechanism of action of Shigella sonnei?
Invades intestinal mucosa causing severe inflammation, but does not invade further (never seen in blood cultures)
What is seen in the stools of a patient with Shigella?
Blood and pus cells
Source/ vehicle of infection of Shigella?
Human only infection
Often spread person- person amongst young children in schools, etc.
Symptoms of shigella Sonnei?
Diarrhoea (occasionally blood)