Microbiology 20: Antimicrobials 1 Flashcards
What coverage do Glycopeptides antibiotics have ?
Gram +ve
When would Glycopeptide antibiotics be indicated ?
Gram +ve bacteria resistant to Beta lactams
E.g MRSA
Why are beta lactams considered bactericidal ?
They dont kill existing bacteria, they inhibit cell wall synthesis so stop new bacteria from forming their cell walls and hence causing lysis.
Give 3 examples of classes of beta lactams ?
Penicillins
Cephalosporins
Carbapenems
Give an example of a drug that is a beta lactamase inhibitor ?
Clavulanic acid
tazobactam
As you go up the generations of cephalosporins what happens to their activity against gram +ve and -ve bacteria ?
As you go up the generations the activity against gram -ve goes up and +ve goes down.
What complications can glycopeptides cause ?
Nephrotoxicity
Give 2 examples of Glycopeptides ?
Vancomycin
Teicoplanin
Which Glycopeptide is often used to treat C.difficile infection ?
Vancomycin
Which antibiotic is commonly used to treat meningitis ?
Ceftriaxone (cephalosporin)
Can’t normally penetrate blood brain barrier but does so when there is inflammation ie in meningitis
List 5 classes of Protein synthase inhibitors ?
Aminoglycosides Tetracyclines Macrolides Chloramphenicol Oxazolidinones (Linezolid)
Why are Proteinase inhibitors selective for bacteria and not hum an cells ?
They bind to the ribosomal subunit which is a different size in bacteria (30S) compared to human cells
What antibiotic coverage do Aminoglycosides (gentamicin) have ?
Good gram -ve activity
Poor gram +ve and anaerobe activity
what antibiotic coverage do Tetracyclines (doxycycline) have ?
Mostly gram +ve
Very good for intracellular pathogens e.g chlamydia and mycoplasma
Which class of Protein synthesis inhibitors are contraindicated in children and pregnant women ?
Tetracyclines
Deposit in bone and also cause discolouration of teeth
Chloramphenicol is contraindicated in the 3rd trimester as it can cause “grey baby syndrome”
What is a dangerous complication of giving babies chloramphenicol ?
Grey baby syndrome
Aplastic anaemia
What is the antibiotic coverage of Linezolid ?
Very active against gram +ve bacteria
Poor activity against gram -ve bacteria
In which infection is Linezolid particularly useful ?
MRSA
Give 2 side complications you can get with Linezolid ?
Optic neuritis
Thrombocytopenia
Give 2 classes of DNA synthesis inhibitors ?
Quinolones
Nitroimidazoles
What antibiotic coverage do quinolones (ciprofloxacin) have ?
very active against gram -ves
New quinolones: moxifloxicin and levofloxacin have more gram +ve cover than gram -ve
Give one example of a Nitroimidazole ?
Metronidazole
Which bacteria is Metronidazole particularly effective against ?
Anaerobes (C.Difficile)
Give one example of a class of RNA synthesis inhibitors ?
Rifampicins
Which antibiotic turns your secretions (urine, tears etc) an Orange colour ?
Rifampicin
What is the antibiotic treatment for Pneumocystis jirovecii pneumonia ?
Septrin (Sulphonamides + Trimethoprim) (co-trimoxazole)
Which antibiotic is commonly used to treat skin infections such as cellulitis or impetigo ?
Flucloxacillin
List 2 serious side effects of gentamicin ?
- Ototoxic
- Nephrotoxic
Which antibiotic is often given in the case of penicillin allergy ?
Erythromycin (macrolide)
List 2 mechanisms of resistance that MRSA uses against Beta lactams ?
- Beta lactamses (inactivation)
- PBP2a (altered target) - Normally beta lactams bind to penicillin binding proteins in the cell wall to cause their effect. Binding To PBP2a means the cell wall is not affected.
