Gram Positive Bacteria Flashcards
List 3 examples of staphylococci.
Are they coagulase positive or negative?
COAGULASE +VE:
Staph. aureus
COAGULASE -VE:
Staph. epidermidis
Staph. saprophyticus
What conditions can staph. aureus cause? (5)
Pneumonia Cellulitis Septic arthritis Infective endocarditis Line associated infection
Describe the pathophysiology of staph. aureus infection.
Staph. aureus releases exotoxins, e.g.
TSST-1 - toxic shock syndrome
Exfoliatin - scalded skin syndrome
Enterotoxin - food poisoning
Which 2 conditions are usually related to coagulase negative staphylococci (CoNS) instead of staph. aureus?
Prosthetic valve endocarditis
Infection of medical devices
How are streptococci classified? (3)
What are the subdivisions?
List some examples.
Alpha haemolytic
- Strep pneumoniae
- Strep viridans
- Strep milleri
Beta haemolytic
- Group A (strep pyogenes)
- Group B (strep agalactiae)
- Group C
- Group G
Gamma haemolytic
-Enterococci
What can be caused by strep. pneumoniae:
a) in children? (1)
b) in adults? (2)
CHILDREN:
Otitis media
ADULTS:
Pneumonia
Bacterial meningitis
What can be caused by strep. viridans? (1)
What is a common origin of this bacteria?
Bacterial endocarditis
Often comes from dental caries
What does strep. milleri cause? (3)
Abdominal abscess
Chest abscess
Brain abscess
How would group A beta haemolytic streptococci be treated?
What is the disadvantage to this?
Penicillin (ALL group A streps are sensitive to penicillin)
BUT, 10% are resistant to erythromycin and other drugs, so difficult to treat when patient has a penicillin allergy
Which 6 conditions can be caused by group A streptococci?
Give an example of a causative organism.
Pharyngitis Scarlet fever Skin/soft tissue infections (e.g. erysipelas, myositis) Toxic shock syndrome Necrotising fasciitis Bacteraemia
E.g. strep. pyogenes
List 3 long-term complications of group A streptococci infections.
Delayed antibody-mediated disease
Rheumatic fever
Acute post-strep glomerulonephritis
Which conditions can be caused by group B streptococci in:
a) neonates? (4)
b) adults? (6)
NEONATES: Cellulitis Meningitis Neurological damage Endocarditis
ADULTS: Pneumonia Cellulitis Bone infection UTI Bacteraemia Endocarditis
Which conditions can be caused by enterococci? (4)
UTI
Infective endocarditis
Biliary tract infections
Abdominal infections
How are gram positive bacilli classified? (2)
List 2 types of bacteria found in each category.
Spore-forming gram positive bacilli
- Bacillus
- Clostridium
Non-spore-forming gram positive bacilli
- Listeria
- Corynebacterium
List 2 examples of bacillus bacteria (the species, not the shape).
Bacillus anthracis
Bacillus cereus
Which conditions can be caused by bacillus anthracis?
Anthrax
Cutaneous infection
Respiratory infection
GI infection
Describe the pathophysiology of bacillus anthracis. (4)
Produces (central) spores
Releases exotoxins, e.g.
- Oedema factor
- Protective antigen
- Lethal factor
Which 5 conditions can be caused by clostridium bacteria?
List the types of clostridium which are commonly associated with these diseases.
Botulism (C. botulinum)
Tetanus (C. tetani)
Gas gangrene (C. perfingens, C. novyi, C. septicum)
Pseudomembranous colitis (C. difficile)
Antibiotic associated diarrhoea (C. difficile)
Describe the pathophysiology of C. botulinum infection. (2)
- Releases toxins which bind to presynaptic nerve endings
2. This blocks ACh release, causing descending flaccid paralysis
Describe the pathophysiology of C. tetani infection. (2)
- Releases toxin which inhibits release of inhibitory neurotransmitters
- This causes sustained tetanic contraction
Give an example of a corynebacterium, and the disease that it causes.
Corynebacterium diphteriae
Causes: diphtheria
List 2 clinical features of diphtheria.
Bull neck swelling
Pseudomembrane formation in throat
Give an example of a listeria bacteria, and the disease that it causes.
Listeria monocytogenes
Causes: food poisoning
Which conditions can be caused by listeria monocytogenes in:
a) Pregnancy? (2)
b) Neonates? (1)
PREGNANCY:
Foetal infection
Miscarriage
NEONATES:
Maculopapular rash