Microbiology Flashcards
Pathogenic infection sequence (6)
Exposure => Adhesion => Invasion => Colonization => Toxicity => Tissue damage and disease
Enterobacteriaceae characteristics (4)
Gram negative
Non spore forming
Grows on variety of solid media
Ferments sugars producing acid - Facultative anaerobes
Anaerobes in GI tract (3)
Clostridium sp
Bacteroides sp
Anaerobic cocci
Normal flora in mouth (5)
Strep viridans Neisseria sp Anaerobes Candida sp - Few Staphylococci
Normal flora in stomach/duodenum (2)
Usually sterile
Few Candida sp and Staphylococci
Normal flora in jejunum (2)
Coliforms and Anaerobes - Few
Normal flora in colon (3)
Coliforms
Anaerobes
Enterococcus faecalis
Normal flora in bile ducts
Usually sterile
Clostridium difficile features (4)
Gram positive bacillus
Common cause of healthcare-associated diarrhoea
Carried as part of normal bacterial flora in elderly and infants
Produces 2 toxins; toxin A (Enterotoxin) and toxin B (Cytotoxin)
Clostridium difficile source (2)
When antibiotics are prescribed bowel flora is killed off allowing C diff overgrow
C diff produces spores that survive in environment that are more resistant to disinfectants - Can be transmitted from one patient to another
Clostridium difficile symptoms (4)
Diarrhoea +/- blood
Abdominal pain
Severe case - Pseudomembranous colitis, perforation
Clostridium difficile management (2)
Less severe - Oral metronidazole
More severe - Oral vancomycin
Clostridium difficile prevention (4)
Use narrow spectrum antibiotics
Avoid 4C’s as much as possible
Patient isolation
Hand washing
Clostridium difficile investigations (3)
Screen for glutamate dehydrogenase (GDH)
If GDH positive then test for toxin A and B
Culture to type strain
Rotavirus features (7)
Most common cause of diarrhoea and vomiting in children (Less than 3)
Person to person spread - Faecal -oral route
More common in winter months
Mild to severe diarrhoea but NO blood
Self limiting - 1 week duration
Decrease fluid absorption, increasing bowel secretion - Dehydration
Children may develop post-infection malabsorption causing more diarrhoea