Infection Flashcards
Describe S.Aureus
Gram positive cocci
Coagulase positive
Pus forming infections, blood-stream infections, toxin illness
Describe coagulase negative Staph (S. epidermis, S. capitis)
Gram positive cocci
Coagulase-negative
Pathogenic with foreign body
Describe Group A Streptococcus (strep pyogenes)
Beta-haemolytic strep
Tonsillitis, cellulitis, soft tissue infection, puerperal sepsis
Describe group B strep (strep agalactiae)
Gram positive cocci
Normal rectal/vaginal flora
Causes neonatal meningitis, bacteraemia and pneumonia
Pathogenic in immunocompromised adults
Describe viridians strep
Gram positive cocci
Mucosal flora, sticks to teeth and gums
Can stick to heart valves and cause endocarditis
Describe enterococci
Gram positive cocci
Found in the gut - involved in intra-abdominal sepsis, UTI and bacteraemia
More resistant to antibiotics
Describe Bacillus anthracis
Gram positive bacilli
Disease of herbivores, human is incidental host
Infected by cutaneous inoculation or inhalation
Multiple toxins and virulence factors
Describe bacillus cereus
Gram positive bacilli
Cause of food poisoning
Occasional pathogen if injected into sterile site
Describe Listeria monocytogenes
Gram positive bacilli
Cause of intra-uterine or neonatal sepsis/meningitis
Can multiply at 4oc - risk in pregnancy of certain foods
Describe Corynebacteria diptheriae
Gram positive bacilli
Lots of other species are normal skin flora
Diphtheria toxin is produced in the throat via the bloodstream and inhibits protein synthesis in hearts and peripheral nerve
Transmitted person-person by respiratory droplets. Prevented by vaccine
What antibiotics would you give to provide anaerobic cover?
Metronidazole
Describe clostridium tetani
Gram positive anaerobes
Transmitted via spores in soils which contaminates wounds
Neurotoxin blocks release of GABA - causes spasm/rigidity, hyper-sympathetic state
Prevented with a vaccine
Describe clostridium botulinum
Gram positive anaerobe
Usually food-bourne - spores germinate in food in anaerobic conditions
Neurotoxin prevents release of ACh - causes symmetrical flaccid paralysis
Describe C.perfringens
Gram positive anaerobes
Spores in the soil and human gut.
Alpha toxin damages cell membranes
Causes gas gangrene and other soft tissue infection
Describe Neisseria
Aerobic gram negative cocci
Describe moraxella
Aerobic gram negative cocci
Describe E.Coli
Non-fastidious
Sugar fermentor
Normal gut flora - some strains cause diarrhoea
Most strains cause UTI
Common cause of bacteraemia secondary to UTI or gut perforation
Describe Klebsiella
Non-fastidious
Sugar fermentor
2nd commonest coliform causing UTI/bacteraemia
Often antibiotic resistant, spreads easily between patients
Describe Shigella
Non-fastidious
Sugar fermentor
Gastroenteritis
Human reservoir only - causes colitis
Describe salmonella
Non-fastidious
Sugar fermentor
Gastroenteritis
Multiple species - only human one is S. typhi which causes typhoid
Describe enterobacter
Non-fastidious
Sugar fermentor
Opportunistic pathogen
Describe pseudomonas
Non-fastidious
Non-sugar fermentors
Non-curved
Reservoir: environment, espiecally warm water
Human respiratory pathogen, forms biofilms. Bacteraemia in immunocompromised.
Describe Burkholderia
Non-fastidious Non-sugar fermentors Non-curved Plant pathogen, reservoir: soil, plants Pathogen in CF - reduces survival, difficult to treat
Describe Vibrio
Non-fastidious
Non-sugar fermentors
Curved
Reservoir: warm salt water
Toxin increases cAMP, decreased Na uptake and increased Cl secretion causing rice water stool
Death from dehydration and electrolyte imbalance
Treat with oral rehydration
Describe campylobacter
Non-fastidious Non-sugar fermentors Curved Commonest bacterial cause of gastroenteritis Natural host: birds
Describe haemophilus influenzae
Fastidious
Unencapsulated strains are common
Causes respiratory tract infections and meningitis in young children
Describe legionella
Causes severe pneumonia
Lives in water systems inside amoebae
Describe helicobacter
Produces ureas, breaks down urea to ammonia and buffers stomach acid, causing inflammation and ulcers
