Antibiotics Shuffled Flashcards
How is imipenem metabolized?
it is inactivated by renal dipeptidase
How do bacteria develop resistance against fluoroquinolones?
they modify their DNA gyrases
What are the major side effects of vancomycin?
- it enhances the ototoxicity and renal toxicity of aminoglycosides
- it triggers histamine release to cause “red man” syndrome
List the four important anti-pseudomonas penicillins.
- ticarcillin
- mezlocillin
- piperacillin
- carbenicillin indanyl
What is the primary urinary tract antiseptic currently in use?
nitrofurantoin
What is the major side effect of ethambutol?
it has a dose-dependent optic neuritis that affects red-green differentiation and visual acuity
What is the mechanism of action for penicillins?
- mimic PBP ligand and irreversibly inhibit transpeptidase
- activate murein hydrolases
How is isoniazid used clinically?
- alone for TB prophylaxis
- in combination for TB treatment
Vancomycin is a preferred treatment for which two difficult to treat infections?
- MRSA
- C. diff
How does MRSA achieve beta-lactam resistance?
it altered PBP structure, so penicillin could no longer bind
In what cases does nitrofurantoin cause side effects?
cleared so quickly, it has none unless the individual has a renal insufficiency
What is the mechanism of action of fosfomycin?
it inhibits the cytoplasmic step of cell wall precursor synthesis
How is rifampin used clinically?
- in combination for active TB
- alone for TB prophylaxis if isoniazid isn’t an option
What are the major side effects of cephalosporins?
- renal toxicity (enhanced by ahminoglycosides)
- inject site reaction
- moderate cross-reactivity with PCN-sensitive patients
- disulfiram effect with bleeding disorders (mostly cefotetan and cefoperazone)
What is the clinical utility of macrolides?
they are used for gram+ infections in PCN-sensitive patients
What is the mechanism of action of oxazolidinones?
they inhibit 70s ribosomal formation
What is the mechanism of action of imipenem?
it is a beta-lactam
What are the adverse effects of sulfonamides?
- Steven-Johnson syndrome reaction
- hematuria
- hematopoietic effects
What is the mechanism of action of cephalosporins?
they are beta-lactams
What are the side effects of trimethoprim? How do we compensate for this?
- anemia, leukopenia, etc.
- administer with folinic acid
What are the limitations of polymixins?
they have systemic toxicity and are therefore restricted to topical applications or as salvage therapy for highly resistant bacteria
What is co-trimoxazole?
trimethoprim-sulfamethoxazole combination therapy
What is special about the distribution of aztreonam?
it crosses the BBB
How do we use trimethoprim clinically?
- monotherapy for UTI
- with a sulfonamide (co-trimoxazole) otherwise
What is clindamycin used for?
- mostly anaerobes
- B. fragilis
- MRSA
- endocarditis prophylaxis
List four important tetracyclines.
- tetracycline
- doxycycline
- minocycline
- tigecycline
What is amoxicillin?
an extended spectrum penicillin
What is the mechanism of action of bacitracin?
it is a ICWS
What is the mechanism of action of aztreonam?
it is a beta-lactam and ICWS
Describe the side effects of aminoglycosides.
- time and dose dependent
- nephrotoxicity likely reversible
- ototoxicity may be reversible
- causes a neuromuscular blockade at high dose
What is the mechanism of action of quinolones?
they are DNA gyrase inhibitors and target topoisomerase II and IV
What mediates the selectivity of trimethoprim?
high selectivity for bacteria dihydrofolate reductase
Sulfonamides are usually combined with what other therapy?
trimethoprim
What is colistin?
another name for polymixin E, a basic peptide that serves as a detergent to disrupt cell membranes
The primary drug used against leprosy is what?
dapsone
How is chloramphenicol metabolized?
via glucuronidation
What is special about azithromycin compared to other macrolides?
it has a 2-4 day half life
What are the advantages of chloramphenicol?
- excellent pharmacokinetics
- resistance is slow to development is minimal
What is the primary indication of oxazolidinones?
vancomycine resistant E. faecium
What is pyrazinamide?
an anti-mycobacterial of unknown mechanism
What is the mechanism of action of rifampin?
it inhibits RNA synthesis
List the important first generation cephalosporins.
- cephalothin
- cephalexin
- cefazolin
In what preparations is vancomycin available?
- IV for systemic infection
- oral for C. diff infection
What is dapsone used to treat?
- leprosy
- P. jiroveci pneumonia
What are quinupristin and dalfopristin?
they are streptogrim protein synthesis inhibitors
What are strep monosomes?
a term used to describe the way streptomycin disrupts bacterial polysomes
What are the side effects of chloramphenicol?
- GI disturbance followed by fungal superinfection
- aplastic anemia, which is often fatal
- gray baby syndrome
What is gray baby syndrome?
a side effect of chloramphenicol due to the poor glucuronidation abilities of babies
Describe the distribution of tetracyclines.
- does not reach the CNS or synovial fluid
- does cross the placenta and enter breast milk
What is the mechanism of action of aminoglycosides?
- it targets 30s ribosomal subunits
- causes mRNA misreading, disrupts initiation, and breaks up polysomes
List the four important anti-Staph penicillins.
- methicillin
- nafcillin
- oxacillin
- cloxacillin
Why does tetracycline cause bone deformities?
because it is a chelator of metal ions
What is the basis for the selectivity of tetracyclines?
bacterial uptake, not ribosomal affinity
What is the mechanism of action of sulbactam?
it is a beta-lactam