Micro - Antimicrobials 1 + 2 Flashcards
Name 2 antimicrobials causing renal dysfunction
Vacnomycin (glycopeptide) + gentamicin (amino glycoside)
3 patterns of Abx activity
type 1 : concentration dependent killing
type 2 : time dependent killing
type 3: both
Concentration-dependent Abx?
Aminoglycosides e.g. gentamicin, amikacin
time dependent Abx
penicillin
time + concentration dependent Abx
VANCOMYCIN
Length of abx course for bacterial endocarditis? for acute osteomyelitis?
IE 4-6 weeks
Osteomyelitis 6 weeks
Group A strep pharyngitis length of treatmnet
10 days
Typical Abx for pharyngitis? how long for?
BenPen 10 days
mx of CAP mlid and severe
mild: amoxicillin
severe: Co-amoxiclav + clarithromycin
mx of HAP
Amoxicillin + gent or taz
management of Neisseria meningitidis
Benpen or ceftriaxone +/- amoxicillin (old or neonate)
typical Abx for UTI - community? hospital?
community - trimethoprim/nitro
nosocomial = cefalexin or co-amox
Typical Abx for Sepsis - severe?
tazocin/ceftriaxone, metro +/- gentamicin
typical abx for neutropaenic
tazocin + gentamicin
6 main MOA of antibiotics
- inhibit cell wall synthesis
- inhibit protein synthesis
- inhibit DNA syntehsis
- Inhibit RNA synthesis
- Cell membrane toxine
- Inhibit folate synthesis
3 types of beta lactam
penicillins
cephalosporins
carbapenems
How do the cephalosporins change from 1st –> 3rd gen?
increased gram -ve activity
name 3 cephalosporins
cefuroxime, cefotaxime, ceftriaxone
Why were carbapenems developed?
bacteria developed extended spectrum beta lactamases, therefore resistant to cephalosporins but nOT carbapenems e.g. meropenem
Which cell wall synthesis inhibitors cannot be used against Gram-ves?
glycopeptides e.g. vancomycin and teicoplanin as they cannot cross the gram -ve cell wall
What type of Abx is gentamicin?
MOA?
Aminoglycoside
Inhibits protein synthesis by binding to 30S ribosome subunit
What are aminoglycosides particularly useful vs?
neutropenic gram -ve sepsis, particularly pseudomonas
Doxycycline - which Abx class is it in? What is it useful against?
tetracycline - intracellular organisms e.g. chlamydia
doxy MOA
Targets 30S subunit of ribosome/ protein synthesis inhibitor
considerations with doxy
do not give to pregnant women or children
SE: photosensitivity rash
Name 3 macrolides.
azithromycin, clindamycin, erythromycin
MOA of macrolides
bind to 50S ribosomal subunit
Usefulness of macrolides vs?
Against staph or strep in penicillin allergy, atypical pneumonia
Chloramphenicol - why isn’t it used much?
MOA
Binds to 50S subunit
Risk of aplastic anaemia and grey baby syndrome in neonates
linezolid class of antibiotic and MOA?
Inhibits protein synthesis (oxazolidinone) - prevents formation of 70s complex by binding to 23S component of 50S subunit
Linezolid - USE?
Gram +VE ONLY - MRSA, VRE
Quinolone - eg? MOA?
Ciprofloxacin, moxifloxacin (new)
Bind to alpha unit of DNA gyrase and inhibit DNA synthesis
Eg of nitroimidazoles?
metronidazole
2 useful groups which metronidazole is used against? give eg of each?
Anaerobes e.g. C.diff and protozoa e.g. Giardia
Name an RNA synthesis inhibitor?
Rifampicin
Orange secretions, impaired LFTs, DDI with COCP
Rifampicin
name 2 cell membrane toxins
Daptomycin and colistin
lipopeptide
daptomycin
polymyxin
colistin
When is colistin used? SE?
Last resort in MDR gram -ve bacteria
last resort as highly nephrotoxic
when is daptomycin used?
GRAM +VES ONLY, WHEN RESISTANT
4 mechanisms of Abx resistance (beat)
Bypass antibiotic sensitive step
Enzyme chemical modification/ inactivation of antibiotic
Accumulation reduced of antibiotic
Target altered or replaced
2 main modes of resistance against beta lactams?
Enzyme mediated inactivation - beta lactamases
Altered target - MecA gene in MRSA encodes novel Penicillin binding proteins, PBP mutations in S.pneumonia
2 main SEs of aminoglycosides
ototoxicity and nephrotoxicity
