Anti microbial agents 1 and 2 Flashcards
What are the 3 targets of abx?
Cell wall synthesis
Bacterial protein synthesis
DNA gyrase and other prokaryote specific enzymes
Which abx target cell wall synthesis (peptidoglycan layer)
B lactam
Glycopeptides
What subtypes of beta lactams are there?
Penicillin
Cephalosporin
Carbapenems
What subtypes of glycopeptides are there?
Vancomycin and teicoplanin
What are beta lactams method of action?
Effective against rapidly dividing bacteria
Effective against bacteria that have peptiodoglycan cell walls
Bactiricidal
What are some examples of bacteria that do not have a peptidoglycan cell wall?
Mycoplasma and chlamydia
Which beta lactam can be used against gram positive like strep and clostridia?
Penicillin
What is amoxicillin?
Broad spectrum penicillin that extends cover to enterococci and gram negative organisms
Which abx are stable to beta lactamase produced by bacteria?
Flucloxacillin (Penicillin-like)
Penicillins and amoxacillin are broken down by beta lactamase
What beta lactam covers Pseudomonas and other gram negative organisms?
Piperacillin
But is broken down by beta lactamase
What are some beta lactamase inhibitors
Clavulanic acid
Tazobactam
What is co amoxiclav
Amoxicillin and clavulanic acid
Are cephalosporins stable to beta lactamases?
Yes
What are some first gen cephalosporins
Cephalexin
What are some second gen cephalosporins
Cefuroxime
Cefuroxime vs co amoxiclav, whats the difference?
Both are resistant to beta lactamasesm but cefuroxime is less active against anaerobes and need to add metronidazole
What can the 3rd gen cephalosporin ceftriaxone be used for?
Sepsis
Meningococcal
Pneuomococcal
But gives rise to C.difficile
What can the 3rd gen cephalosporin ceftazidime be used for?
Pseudomonas
What organisms are resistant to all cephalosporins
ESBL producing organisms
Which type of Beta lactams are resistant to ESBL?
Carbapenems
What are some examples of Carbapenems
Meropenem
Imipenem
Ertapenem
How are beta lactams excreted
Renally
Will beta lactams cross the BBB?
No, but can be used in meningitis
Are beta lactams cross reactive
Penicillins have about 10 % cross reactivity with cephalosporins and carbapenems
What are glycopeptides effective against?
Gram positive ONLY as they weaken the peptidoglycan cell wall
Which infections are glycopeptides primarily used for?
MRSA (iv only)
Which glycopeptides can be used for c difficile
Vancomycin
What do you need to note about glycopeptides?
Nephrotoxic
Which abx inhibit protein synthesis in bacteria?
Amnioglycasides
Tetracyclines
Macrolides
Chloramphenicol
Oxazolidinones
What organisms are aminogylcasides used against?
Gentamicin and tobramycin are used against Pseudomonas aeruginosa
Primarily used against gram negatives
What can aminoglycasides and beta lactams be used synergistically for?
Endocarditis
What can tetracyclines be used for?
Intracellular pathogens such as chalmydia, legionella, rickettsiae, mycoplasma
MRSA
Atypical pneumonia
Soft tissue infections
What to keep in mind for tetracyclines
Not used in preggo women or children
Light sensitive rash
What can macrolides be used in
Mild stpah or strep infections in those who have penicillin allergy
Camplylobacter sp and legionella pneumophilia
Atypical pneumonia
Name a macrolide used against salmonella
Erythromycin
Name some new macrolides
Clarithromycin and azithromycin which have higher half life so can be used in paeds and preggo women
When is chloramphenicol used?
Meningococcal and penuomococcal in penicillin allergy people
Eye preparations
What are the down sided of chloramphenicol
Grey bebe syndrome
Aplastic anaemia
What can oxazolidinones be used for and give an example of this abx
Gram +ve organisms like MRSA and VRE
Linezolid
What are some downsides of oxazolidinones?
Can cause thrombocytopaenia and optic neuritis
What abx inhibit bacterial DNA synthesis?
Quinolones
Nitroimidazoles
What can floroquinalones be used against?
Gram -ve organisms
Pseudomonas aeruginosa
UTI
Pneumonia and atypical pneumonia
Bacterial gastroenteritis
What do you need to watch out for in floroquinalones
Can cause tendonitis and seizures (especially in those using steroids)
What can nitroimidazoles be used for?
Exclusively against anaerobes and protozoa
Which abx closely related to nitroimidazoles can be used for simple UTIs
Nitrofurans like nitrofurantoin can be used as they are excreted via urine and can be used against e coli and staph and enterococci
Which abx inhibit RNA synthesis
Rifamycins such as rifampicin and rifabutin
What can rifampicin be used against?
Mycobacteria (TB) and chlamydia
What needs to be noted when using rifampicin
Interaction with oral contraceptives and warfarin
Monitor LFTs
Can turn urine orange
Why should rifampicin never be used for short term prophylaxis and what is the exception
Develop resistance really quickly due to chromosomal mutation
Can be used for meningococcal infection
What can daptomycin be used for
Gram +ve
Treat MRSA and VRE infections
What can colistin be used for?
Gram -ve - Pseudomonas, acinetobacter and klebsiella
Nephrotoxic
Not absorbed orally
What is cotrimoxazole and what is it sued for?
Sulfonamide and diaminopyrimidine (trimethoprim)
Used in HAP, soft tissue infections and pneuomocystic pmeumonia in HIV
What are some methods of abx resistance
Inactivation of abx
Modification or replacement of target
Reduced abx accumulation
Bypass abx sensitive step
Which organisms have the biggest beta lactamase method of inactivating abx
Staph auereus
Gram -ve bacilli
What is the method of resistance of penicillin in pneuomococci and MRSA
Altered penicillin binding protein
Can penicillin be used for strep penumonia
The resistance is not due to beta lactamase. So co amoxiclov will not be useful
Resistance can be overcome by giving high dosage of amoxicillin
Why can’t macrolides be used against UTIs
Metabolised by liver and not excreted via the bladder
What abx would you use for pharyngitis due to Group A Strep
Narrow spectrum penicillin
What side effects can aminoglycasides cause?
Ototoxicity
What is the minimum inhibitory concentration
The lowest concentration of an antibiotic that prevents the visible growth of bacteria
It should be below the breakpoint
How would you treat sepsis or hospital acquired pneumonia
Broad spectrum abx
What would you use for E coli UTI?
Amoxicillin
