Antimicrobial Pharmacology Flashcards
(97 cards)
What bugs does amoxicillin / ampicillin cover?
HELPS
-> remember we have extended gram negative and anaerobe coverage (especially with beta lactam inhibitors paired)
Hemophilus, H. pylori E. coli / Enterococcus Listeria Proteus mirabilis - UTI's Salmonella / Shigella
+ Lyme disease (robin of Ixodes)
How do nafcillin and ampicillin differ with regards to resistance?
Ampicillin - still penicillinase sensitive, just wider spectrum. Needs to be combined with a Beta-lactamase inhibitor to retain activity
Nafcillin - Penicillinase resistant, narrower spectrum. Works by having a bulky R group which is not cleaved by penicillinases, but MRSA is still resistant due to altered penicillin-binding protein.
What drug is used for prophylaxis in patients at high risk for endocarditis undergoing surgical (i.e. cystoscopy) or dental procedures?
Amoxicillin - think of the guy’s teeth getting punched out in sketchy.
Are piperacillin / ticarcillin susceptible to beta-lactamases? What are they good for?
YES! They are in the amoxicillin / ampicillin sketch.
However, they are the pipers in the tiger suit charming mona lisa, in gas masks.
They are good against P. aeruginosa and anaerobes, but they MUST be paired with a Beta-lactam inhibitor (i.e. tazobactam / sulbactam)
What is the main use for 1st generation cephalosporins? And name a few.
Surgical prophylaxis + PEK UTIs -> proteus, E. coli, Klebsiella. More gram + coverage than other cephalosporins.
Think of General “Lex” flexing and his fez
Cephalexin, Cefazolin
What is the main use for 2nd generation cephalosporins? And name a few.
Cefotetan (tea), Cefoxitin (general fox), cefuroxime (furious)
HENS - Hemophilus, Enterobacter, Neisseria, Serratia
Pretty low yield overall
What is the main use for 3rd generation cephalosporins and name a few.
Great CNS penetration -> Ceftriaxone, cefotaxime (used in neonates so no biliary sludging), cefpodixime
Used for treatment of common meningitis, and better gram negative coverage than 1st two generations: Neisseria, Hemophilus, and Streptococcus pneumoniae.
What 3rd generation cephalosporin is most useful for nosocomial pneumonia?
If you have to cover for Pseudomonas -> Ceftazidime - general Taz’s wife is Mona Lisa.
Ceph TAZ for pseudomone-AZZ
What is usage of the 4th generation cephalosporin and what is it called?
Called Cefepime (general prime) -> know that it is broad spectrum and also next to the Mona Lisa poster -> covers Pseudomonas
Also wearing meningitis helmet -> good coverage for meningitis.
What is the usage of the 5th generation cephalosporin and what is it called? Does it have Pseudomonas coverage?
Think of General Tara knocking over the emperor -> only cephalosporin to have MRSA coverage
NO Pseudomonas coverage -> not next to the poster.
What are the mechanisms of resistance to cephalosporins?
- Altered PBPs
2. Extended spectrum beta lactamases - (they are generally resistant to normal beta lactamases due to side changes)
What is the only monobactam and what is its spectrum of activity? Why is it notably useful?
Aerobic gram negatives only -> think of the bellows. Mona Lisa stands by and is covered by this drug.
Notably useful because it has no side chain -> no cross-reactivity with penicillin. Think of the penicillin pencil sticking out of the robot, who is still being treated.
What is imipenem always administered with and why?
Also given with cilastin, an inhibitor of dehydropeptidase 1, which is a renal tubular enzyme which normally breaks down imipenem.
What is the primary clinical use of carbapenems in general and what is the side effect of concern?
Used broad spectrum for all types of infections, especially against organsms making extended-spectrum beta-lactamases (think of rainbow beta-lactamase guys crawling over the wall). -> ESBLs
Side effect of concern - seizures, especially imipenem. Also cause Rash and GI distress (think of robot getting covered in poop / poopy rash)
What is the mechanism of Vancomycin / why is does it work where beta-lactams don’t?
Does not bind to PBPs, instead binds directly to what PBPs are binding, the D-ala-D-ala motif.
-> beta-lactamases and altered PBPs will have NO effect, since vancomycin doesn’t interact with this.
Resistance mechanism is just switching to D-ala-D-lac
Why is vancomycin added to meningitis regimens?
To cover penicillin-resistant Strept pneumo. (i.e. altered PBPs).
What are the side effects of vancomycin?
Nephrotoxicity - renally excreted so be careful
Ototoxicity - broken ear
Thrombophlebitis - vines coming up
Red man syndrome
DRESS syndrome may also occur
What is the mechanism of resistance to tetracycles?
Think of the efflux bike pump. Can also modify the 30S ribosome
How are tetracyclines eliminated, and why are expired ones an issue?
Eliminated fecally, so safe to use in renal failure -> think of the colonic poop tube in the back.
Expired ones are hella problematic cuz they can cause Fanconi syndrome (proximal absorption defect, including a Type II RTA).
What are the side effects of macrolides?
Increased GI motility
Prolonged QT
Cholestatic hepatitis (failure to excrete bowel, think of the Gi soldier’s yellow face)
CYP inhibition
What is the most commonly tested indication for Clindamycin?
Aspiration pneumonia -> since it has good coverage against gram positives of the mouth, as well as anaerobes
What is a common treatment regimen for severe polymicrobial infections of the female genital tract (i.e. endometritis)?
Clindamycin + gentamicin -> think of the karate lady doing Pec fly’s with the ovaries while having psi’s in her pockets
Give four other indications for clindamycin than aspiration pneumonia and female GU infections.
Trainer with MRSA tattoo holding pie:
- MRSA
- Group A strept
Guy who has falling and perforated his pants:
3. Clostridium perfringens
Plants all around the front:
4. Gardnerella vaginosis (Metronidazole can also be used)
What are the indications for chloramphenicol?
Used to treat meningitis in developing countries (kid with helmet hitting ball)
Also used to treat Rickettsia ricketsii infection of pregnant mothers (doxycycline contraindicated in pregnancy)