Microbiology Flashcards
What samples are sent to microbiology?
- blood cultures
- urine
- CSF
- fluids (joint, abscess)
- tissues
- swabs
- line tips
What are the components of the Gram stain?
- crystal violet
- iodine
- alcohol
- safranin
Why do Gm+ bacteria appear purple?
Retain crystal violet bc thick peptidoglycan wall
Why do Gm- bacteria appear pink?
Thin peptidoglycan wall allows crystal violet to wash out, counter-stained with pink safranin
How do staph infections appear on microbiology?
Gm+ cocci in clusters
Coagulase: (+ aureus, - epidermidis)
How do strep infections appear on microbiology?
Gm+ cocci in chains
- Optochin (pneum)
- ß-haemolytic : Groups ABCG
- viridans
How do enterococcus infections appear on microbiology?
Gm+ cocci in chains : Group D
- faecium = amox resistant
Which bacteria are particularly sensitive to metronidazole?
Anaerobes
Common infections caused by staph
Skin & soft tissue infections
Common infections caused by strep
- pneumonia
- skin & soft tissue
- endocarditis
- abscesses (liver, dental)
Common infections caused by entococcus
- endocarditis
- intra-abdominal
Common infections caused by Gm+ bacilli
Listeria
Common infections caused by Gm-ve cocci
- meningitis
- gonorrhoea (genitourinary infections)
- pneumonia
Common infections caused by Gm -ve bacilli
- urosepsis
- GI infections
- intra-abdominal abscesses
What is the Ziehl-Nielsen stain?
For acid-fast bacilli (mycobacteria)
- TB!
- or infection in immunsuppressed, bronchiectasis, prosthetic materials
