Antibiotics 2 Flashcards
What is amoxycillin good for?
Gram negative bacteria
What is the problem with using amoxycillin?
It is susceptible to beta lactamases
How is amoxycillin’s weakness to beta lactamases countered?
By combining it with clavulanic acid in augmentin
Why is cephalexin prescribed for S. aureus?
Because it is good against gram positive
Can cephalexin function adequately in gram negatives?
Yes, unless they produce beta lactamases cephalosporinases
What is nitrofuran?
An antibiotic used against UTIs.
Why is nitrofuran only used for UTIs?
It has almost no tissue penetration but passes through urine if renal function is normal
Why is nitrofurantoin avoided in elderly?
Their kidneys are often not good at concentrating the antibiotic enough.
If people are on it it can cause pulmonary fibrosis
When is trimethoprim used alone?
Only in the cause of treating UTIs
What is trimethoprim commonly used with?
Sulphamethoxazole
What are the only oral antibiotics that can treat pseudomonas aeruginosa?
Norfloxacin and ciprofloxacin
What is norflaxacin?
A quinolone antibiotic
Why is norfloxacin not used to treat the UTI in the old lady’s case study?
It is of the few drugs that can treat pseudomonas so it would be a waste if it was used against E.coli
How is pseudomonas aeruginosa so good at resisting antibiotics?
It has active efflux mechanisms for beta lactams
It has reduced ingress of antibiotics like imipenem and aminoglycosides
It destroys antibiotic beta lactamases
PBPs and DNA gyrases with low affinity for beta lactams and quinolones
Which beta lactam antibiotic is effective against pseudomonas?
Piperacillin (Found and used as tazocin)
What cephalosporins are used to treat pseudomonas aeruginosa infections?
Cefepime
Ceftazidime
What carbapenems are used against pseudomonas aeruginosa and when?
They are last resort drugs. The ones typically used for pseudomonas are:
imipenem
meropenem
What carbapenems are commonly used but not effective against pseudomonas aeruginosa?
Ertepenem (No activity against pseudomonas aeruginosa)
Which monobactams work against pseudomonas?
Aztreonam
Which aminoglycosides work against pseudomonas aeruginosa?
Gentamicin
Tobramicin
Which quinolones work against pseudomonas bacteria?
Norfloxacin
Ciprofloxacin
Moxifloxacin
Why must damage be taken when using aminoglycosides?
They can damage kidneys
Can damage hearing
Will anti-pseudomonas drugs always be effective?
No some strains develop resistance