Classes and mechanisms of action Flashcards
What is a cell wall synthesis inhibitor?
Beta-lactam antibiotics - penicillins, cephalosporins, carbapenems
- inactivate enzymes involved in terminal stages of cell wall synthesis = bactericidal
Glycopeptides - vancomycin and teicoplanin
Gram stains and the colour?
Positive = Purple Negative = magenta (pink)
atypical - legionella, mycoplasma, chlamydia
Key features of beta-lactams?
non-toxic renally excreted short half life not cross the blood-brain barrier cross-allerginic
identify some beta-lactams?
Penicillin - Amoxicillin, - Flucloxacillin - Piperacilllin
Cephalosporins: cephalexin - cefuroxime - ceftriaxone
Carbapenems - stable to extended. spectrum b-lactamase enzymes - meropenem - imipenem - ertapenem
Features of glycopeptides
Only active against Gram Positive
can’t penetrate Gram Negative outer cell wall
inhibits cell wall synthesis
treats MRSA infections
slow bactericidal
nephrotoxic
Inhibitors of protein synthesis?
Aminoglycosides - gentamicin, amikacin, tobramycin
Tetracylcine
Macrolides - erythromycin, Lincosamides - clindamycin
Streptogramins - synercid
Chloramphenicol
Oxazolidinones
Features of aminoglycosides?
Features of Tetracyclines?
Features of macrolides?
ototoxic and nephrotoxic
bactericidal
broad-spectrum
bacteriostatic
not for kids or pregnant women
bacteriostatic
good for mild staph or strep
Which antibiotics inhibit DNA synthesis?
Quinolones - ciprofloxacin, levofloxacin, moxifloxacin
Nitroimidazoles - metronidazole + tinidazole
Features of fluoroquinolone?
Act on DNA gyrase
broad antibacterials - gram negative
UTIs, pneumonia, bacterial gastroenteritis
Features of nitroimidazoles?
rapidly bactericidal
active against anaerobic bacteria
which antibiotics inhibit RNA synthesis?
Rifamycins - rifampicin +. rifabutin
binds to RNA polymerase preventing initiation
bactericidal
can interact with other drugs in liver
Orange WEE
What are some mechanisms of antibiotic resistance?
Chemical modification or inactivation of the antibiotic - beta lactase, chloramphenicol
- Modification or replacement of target - b-lactams, macrolides, quinolones, rifampicin
- Reduced antibiotic accumulation - tetracycline, b lactase, aminoglycosides, quinolone
1) Impaired uptake
2) Enhanced efflux
• Bypass antibiotic sensitive step
How do bacteria bypass beta lactams?
beta lactamases
MRSA is resistant by altering its target - low affinity for binding beta lactams.
What are ESBLs?
Extended Spectrum ß Lactamases (ESBL)
- break down cephalosporins - cefotaxime, ceftazidime, cefuroxime
more common in E. coli and Kelbsiella
How to reduce the spread of antibiotic resistance in hospital?
Control antibiotic usage
improve standard fo hospital hygiene
