Microbiology Flashcards
Eukaryote vs prokaryote ribosomes?
80S vs 70S
Prokaryote equivalent to the nucleus?
Nuceloid
Gram -ve summary?
- Stains pink
- Single-layered peptidoglycan wall
- Outer membrane
- High number of lipids, lipoproteins and lipopolysaccharides
- Produces endotoxins
Gram +ve summary?
- Stains purple
- Multi-layered peptidoglycan wall
- No outer cell wall
- Low/no lipids, lipoproteins and lipopolysaccharides
- Produces exotoxins
4 phases of bacterial growth?
Lag + exponential + stationary + death/decline
What is the peptidoglycan wall made of?
Sugars and amino acids
2 gram -ve cocci?
Neisseria meningitidis and gonorrhoeae
2 gram -ve coccibacilli?
H. influenza and B. pertussis
3 gram -ve bacilli?
Legionella, Klebsiella, Pseudomonas
Gram +ve bacilli?
Clostridium e.g. C. diff
Gram +ve cocci and test summary?
- Staph (+ve) and strep (-ve) via catalase test
- S. aureus (+ve) and s. epidermidis (-ve) via coagulase test
- Haemolysis for group A strep
- Alpha (green) = partial haemolysis via strep p. and viridans
- Beta (yellow) = full haemolysis via strep pyogenes
- Gamma (none) = staph
Gram +ve cocci cluster?
Staphylococcus
Gram +ve cocci chains?
Streptococcus
Selective media function + example?
Allows organisms to be isolated e.g. mannitol salt agar isolates staph
Differencial media function?
Chemicals produce visible changes in colonies via promoting differenciation
Bacteriostatic vs baceriocidal action?
Target protein/DNA synthesis which resume after removal vs target cell wall and cause cell death
Can you combine bacteriostatic/cidal abx?
No
Beta lactam abx?
Penicillins and cephalasporins
What is a beta lactam?
Chemical group that allows targeting of the bacterial cell wall
Abx that target cell wall?
Penicillins + cephalasporins + glycopeptides
Beta lactam resistant cillin?
Temocillin
Beta lactamase targeted cillin and how this is overcome?
Amoxicillin and combined with clavaunic acid to make co-amoxiclav (beta lactam resistant)
Penicillin action?
Targets PBPs on bacteria which cross links wall peptidoglycan chains causing cell death
Glycopeptides gram cover?
Only gram +ve
Glycopeptides?
Vancomycin and teicoplanin
Abx that target protein/DNA synthesis?
Tetracyclines + aminoglycosides + macrolides
Aminoglycoside?
Gentamicin
Macrolides?
Erythromycin, clarithromycin and azithromycin
What one out of TAM is bacteriostatic instead or cidal?
Aminoglycosides (gentamicin)
Abx affecting nucleic acids?
Metronidazole + fluoro/quinolones
Abx inhibiting folic acid synthesis?
Trimethoprim + sulphonamides
5 bacterial adaptations to overcome abx?
- Forming biofilms
- Persistor cells killing cidal abx
- Mutation of PBP that created MRSA which is penicillin resistant
- Increased efflux of abx via channels
- Horizontal gene transfer
4 factors causing abx resistance?
- Prior abx exposure
- Over-under prescribing
- Prescribing incorrectly
- Prescribing when not needed
Feature of mycoplasma pneumonia that makes it hard to treat?
Lacks a cell wall so is bacteriocidal resisitant
2 streptococci that cause alpha haemolysis?
Pneumoniae and viridans
4 antibiotics commonly used for empirical treatment for gram +ves?
Penicillins, vancomycin, teicoplanin and gentamicin
Treatment for MRSA and C. Diff?
Vancomycin/teicoplanin/gentamicin
Treatment for pseudomonas (s sound)?
Ciprofloxacin + cephalosporin
Treatment for mycoplasma?
Tetracycline + macrolide
Treatment for legionella?
Quinolone + macrolide
Is mycobacterium tuberculosis gram +ve or -ve?
Gram +ve
Antibiotic for coliform of gram -ve aerobe + anaerobes?
Gentamicin + metronidazole
Antibiotic thats is unsafe during pregnancy and is excreted rapidly via the urine?
Gentamicin
Is flucloxacillin narrow or wide spectrum?
Narrow gram +ve cover
Name of the E. Coli 0157 toxin?
Veratoxin (VTEC)
2 strict aerobes + strict anaerobe?
Pseudomonas and legionella + clostridium
4 C antibiotics that cause C. diff?
Ciprofloxacin, Co-amoixclav, Clindamycin and Cephalasporins