Introduction to the major groups of antimicrobials Flashcards
What are examples of beta-lactams?
penicillins, cephalosporins, carbapenems
What is an example of a quinolone?
ciprofloxacin
What is an example of a macrolide?
erythromycin
What is an example of an aminoglycoside?
gentamicin
What is an example of a glycopeptide?
vancomycin
What is an example of a tetracycline?
oxytetracycline
What are examples of folate antagonist?
trimethoprim / sulphonamide
What is an example of an imidazole?
metronidazole
What are the different types of penicillins?
natural = penicillin G/V=> s pnuemoniae
semi-synthetics
- flucloxacillin => staph aureus (not MRSA)
- Piperacillin + tazobactam (tazocin) => pseudomonas, enterobacteriaceae, s. aureus, anaerobes
- ampicillin, amoxicillin (non-beta lactamase producing enterobacteriaceae, h.influenzae)
- amoxicillin + clavulanic acid (co-amoxiclav) => beta-lactamase producing haemophilus influenzae, s.pneumoniae, s.aureus anaerobes
What are the different types of cephalosporins?
1st gen = cefalexin, cefradine
2nd gen = cefuroxime
3rd gen = cefotaxime, ceftazidine
4th gen = cefpirome
What organisms are resistant to cephalosporins?
ESBL producing organisms
What are some examples of carbapenems and what are they good against?
imipenem
meropenem
ertapenem
generally stable to most GNB beta-lactamases - rare resistance but it is increasing particularly against hospital acinetobacter/pseudomonas and carbapenemase producing klebsiella/e.coli
What are carbepenems not effective against?
no against against MRSA/VRE but covers lots of other common pathogens e.g. s pneumoniae and group A strept
What is avibactam ?
broader spectrum of activity than currently available beta lactamase inhibitors
What is class A of the ambler DNA sequence classification of beta-lactamases?
active site = serine selected examples: - staphylococcal penicillinase - broad spectrum penicilinaes - serine carbapenemases
What is class B of the ambler DNA sequence classification of beta-lactamases?
active site: zinc
selected examples:
- metallo-carbapenemases
What is class C of the ambler DNA sequence classification of beta-lactamases?
active site serine
selected examples:
- chromosomal cephalosporinases AmpC plasmidic
What is class D of the ambler DNA sequence classification of beta-lactamases?
active site = serine
selected examples:
- oxacillinases broad spectrum not inhibited by clav/taz
- OXA-48 carbapenemase
What is penicillin hypersensitivity?
true life threatening is v. rare but dramatic - angioneurotic oedema
10% patients of patients ask will say they are allergic - mainly due to skin rash
skin testing can be used to identify these patients
patients on ampicillin/amoxicillin can get a maculopapular rash ++++glandular fever
can use carbapenems/aztreonam
What are the different types of allergic reaction people could have against penicillin?
immunoglobulin E mediated reaction (immediate) = urticaria, angioedema, wheezing, SOB, anaphylaxis
Non-IgE reaction (delayed) = . exfoliative dermatitis, steven johnsons syndrome, serum sickness, haemolytic anaemia, maculopapular rash etc
What are glycopeptides important for treating?
vancomycin and teicoplanin
- important for MRSA and resistant enterococci
- c diff diarrhoea - used for severe disease orally 125mg QDS as not absorbed
- potentially nephrotoxic (IV only)
What are quinolones important against?
ciprofloxacin, levofloxacin, moxifloxacin
active against gram ve and -ve but NOT MRSA streptococci
useful for UTIs(resistant bacteria)
resistance is rising
pseudomonas - resistance can emerge by mutation, safe but c.diff issues
How do aminoglycosides work?
bind to 30S subunit of mRNA
How do macrolides work?
prevent binding of the 50S subunit to mRNA
