Antibiotic classes Flashcards
Penicillins belong to which AB class?
What part of the bacteris do they target?
Beta-lactams
Target cell wall synthesis
What ABx class does ciprofloxacin belong? How does it work?
(Flouro)quinolone class.
Acts by inhibiting DNA replication (acts on toboisomerases)
Which ABx class (and examples) should never be used with statins? Why?
Macrolides - erythromycin, clarithromycin, azithromycin
They r both metabolised by the same liver enzyme resulting in increased statin bioavailability resulting in risk of myopathy/rhabdo
What ABx class do cephalosporins belong?
Beta-lactams.
Eg ceftriaxone, cephalexin,
What bad adverse reaction can you have to Vancomycin? What is the mechanism of this reaction?
Red man syndrome.
Driven by vancomycin directly activating mast cells to release histamine and cause skin reaction. Other Sx include Hypotension, Flushing and rarely Ototoxicity
What class of ABx does vancomycin belong and how dies it kill bacteria?
Glycopeptide class.
Acts on the cell wall synthesis
What class does erythromycin/azithromycin belong? How do they work?
Macrolides. Target the 50s subunit on ribosomes to prevent protein synthesis
How does gentamicin work? What class idoes it belong to?
Inhibits 30s subunit of ribosomes preventing protein synthesis. Aminoglycosides
How does Trimethoprim work?
DHFR inhibitor - interferes with folic acid synthesis in bacterial cells
Name two ABx classes that act via inhibiting the 30s subunit of ribosomes
Tetracyclines (Doxycycline, Tetracycline) + Aminoglycosides (Gentamycin, Neomycin, Tobramycin)
Daptomycin method of action
Loss of cell wall selective permeability
Note: binds to surfactant & cannot be used in lung infections
Pt with MRSA pneumonia - what ABx can NOT be used and why?
Daptomycin. It binds to surfactant so cannot be used in lung infections
Gold standard method for identifying osteomyelitis?
MRI
Blood cultures are positive in __% of cases of osteomyelitis.
How frequently do swabs of wound correlate with bacteria at bone in osteomyelitis?
50%
superficial swabs rarely correlate with bacteria at bone in osteomyelitis therefore no need to do.
No ABx therapy is recommended in persons with travellers diarrhoea unless..
Severe disease
Immunocomromised (HIV, … )
IBD
Have comorbidities that would be adversely affected by dehydration
Treatment of travellers diarhhoea with ABx in A) normal, B) immunosuppressed Pt’s, reduces the duration of illness by how long?
A) nothing
B) 1-2days
What complication can occur if Pt’s with uncomplicated gastro are treated with ABx?
Prolonged bacterial shedding = prolonged duration of bacteria in gut/stool ?prolonged contagious?
What are the beta lactic antibiotics?
penicillins cephalosporins monobactams Carbapenams - meropenem, ertapenem Clavulinic acid tazocin
what drugs block folic acid synthesis?
trimethoprim
sulphonamides
What are the 4 main mechanisms of antibiotic resistance
antibiotic inactivation
alteration of antibiotic target sites
decreased antibiotic permeability of cell wall
active antibiotic efflux
what are the escappm bacteria, and how do you treat them?
Gram negatives with inducible chromosomal mediated beta lactase production, inactive 3rd gen cephalosporins
Need meropenum
enterobacter serratia citrobacter acientobacter pseudomonas proteus morganella
How does flagyl / metronidazole work?
DNA damage
What is the gene that encodes MRSA
MEC A gene
alters PBP therefore penicillin can’t bind
ICU patient with resistant GNB on meropenum - what is it and how to treat?
Likely strentophonomonous maltophilia
Treat with bactrim
