Microbiology of bacterial, fungal and parasite infections Flashcards
What are staphylococcus bacteria?
Gram POSITIVE (purple) cocci in clusters Aerobes and faculative anaerobes.
What are the 2 important types of staphylococcus?
1) Staph aureus which is coagulase positive and shows up golden on agar
2) coagulase negative staphs e.g. epidermidis
What does coagulase positive mean?
Clots plasma
What is SSSST?
Staph. scalded skin syndrome toxin
What is PVL?
A toxin called Panton Valentine Leukocidin
What kind of infections do coag. negative staphs (e.g. S. epidermidis) cause?
Infection in artificial materials e.g. valves, catheters, joints.
What kind of infections do Staph. saprophyticus cause?
UTIs in women of child bearing age
Describe streptococcus bacteria
Gram positive cocci in chains.
Aerobic and faculative anaerobes
How are streptococci classified?
Beta haemolytic - complete
Alpha haemolytic - partial
Gamma haemolytic- none
What are examples of beta haemolytic streps (dangerous!) ?
Group A strep causes throat and skin infections
Group B causes neonatal meningitis
Give two examples of alpha haemolytic strep
Strep pneumoniae which causes pneumonia
Strep viridans which cause endocarditis
What kind of gamma strep are commensals of bowels and cause UTIs?
Enterococcus faecalis
What kind of infections can strep. pyogenes (A) cause?
Infected eczema Impetigo Cellulitis Erysipelas necrotising fasciitis
How are infections diagnosed?
A swab of the lesion is taken if the surface is broken.
If it is a deeper lesion then pus or tissue can be taken.
Blood cultures if systemic
What is the treatment for staph aureus and strep. pyogenes infections?
Flucloxacillin