(7) Antimicrobials: Inhib Bacterial Protein Synth (2.1-2.6) Flashcards
MOA: Tetracyclines
Inhibit 30s ribosome ⇒ Blocks A-site tRNA binding
Are Tetracyclines active against MRSA?
Yes
Which class of antibiotics is particularly effective against bacteria transmitted by ticks?
Tetracyclines
Name 3 zoonotic infections Tetracyclines are used to treat
(1) Coxiella
(2) Brucella
(3) Yersinia
Name 2 atypical (non-zoonotic) infections Tetracyclines are used to treat
(1) Chlamydia
(2) Mycoplasma
What notoriously reduces the GI absorption of Tetracyclines?
Divalent cations
Contraindications (2) : Tetracyclines
(1) Children
(2) Pregnant
Adverse Effects (2) : Tetracyclines
(1) GI distress
(2) Photosensitivity
What has been associated with the use of expired Tetracyclines?
Fanconi syndrome (Type 2 RTA)
Resistance: Tetracyclines
Efflux pumps
How are Tetracyclines eliminated?
Fecally
MOA: Macrolides
Inhibit 50s ribosome ⇒ Inhibition of translocation
What class of antibiotic is used for pertussis?
Macrolide
(Treatment and prophylaxis)
What class of antibiotic is indicated for community-acquired pneumonia in a patient with a history of penicillin allergy?
Macrolide
(Or respiratory fluoroquinolone?)
Name 3 atypical pathogens macrolides are used to treat
(1) Mycoplasma
(2) Legionella
(3) Chlamydia
What antibiotic is used to treat neonatal conjunctivitis due to Chlamydia trachomatis?
Erythromycin
(Er-redcrow-mycin)
What is the treatment for babesiosis?
Clindamycin + Atovaquone
What’s the antibiotic used for diphtheria?
Erythromycin
Which antibiotic is used to treat Bartonella henselae?
Azithromycin
(SketchyMicro also shows doxycycline)
What antibiotic is given as prophylaxis for Mycobacterium intracellulare when CD4 < 50?
Azithromycin
Adverse Effects (3) : Macrolides
(1) Diarrhea
(2) Jaundice
(3) Torsades
* (All macrolides except Erythromycin also inhibit CYP450 system)*
What macrolide most notably inhibits the CYP450 system?
Clarithromycin
(Erythromycin inhibits CYP450 system as well. However, AZITHROMYCIN does not!!)
What protein synthesis inhibitor is used in H. pylori triple therapy?
Clarithromycin
MOA: Clindamycin
Inhibits 50s ribosome ⇒ Blocks translocation
Is Clindamycin bacteriostatic or bacteriocidal?
Bacteriostatic
What is the spectrum of activity of Clindamycin?
(1) Gram (+)
(2) Anaerobes
* (Occasionally used for plasmodium)*
What type of Strep. pyogenes infections is Clindamycin indicated for?
Soft tissue
Does Clindamycin or Azithromycin have activity against MRSA?
Clindamycin
What type of anaerobic infection is Clindamycin particularly effective against?
Lung abscesses
(Accumulates in MΦs)
What antibiotic is indicated in the treatment of pneumonia due to Bacteroides fragilis?
Clindamycin
What is an example of an anaerobe BELOW the diaphragm treated with Clindamycin
Clostridium perfringens ⇒ Gas gangrene
(Clindamycin above diaphragm, metronidazole below)
Treatment: Polymicrobial infections of female genital tract
Clindamycin + Gentimicin
Which protein synthesis inhibitor is used for Gardnerella vaginalis?
Clindamycin
Adverse Effect: Clindamycin
Diarrhea
What antibiotic is most frequently implicated in causing pseudomembranous colitis?
Clindamycin
MOA: Chloramphenicol
Inhibits 50s ribosome ⇒ Inhibits peptidyl transferase
Is Chloramphenicol bacteriostatic or bacteriocidal?
Bacteriostatic
Indications (2) : Chloramphenicol
As an ALTERNATIVE treatment, it has been used for:
(1) Meningitis
(2) Rocky Mountain spotted fever
* (Meningitis in developing countries)*
Adverse Effects (3) : Chloramphenicol
(1) Reversible RBC suppression
(2) Aplastic anemia
(3) Grey baby syndrome
What is the mechanism of grey baby syndrome?
Accumulation of the drug in newborns (due to ineffective glucuronic acid conjugation system);
causes flaccidity, hypothermia, & shock
MOA: Linezolid
Inhibits 50s ribosome ⇒ Blocks initiation complex
What is Linezolid’s spectrum of activity?
Gram (+) Cocci
MOA: Linezolid
Inhibits 50s ribosome ⇒ Blocks initiation complex
What is Linezolid’s spectrum of activity?
Gram (+) Cocci
Which inhibitor of protein synthesis is effective against both MRSA and VRSA?
Linezolid
Adverse Effects (4) : Linezolid
(1) Thrombocytopenia
(2) Optic neuropathy
(3) Peripheral neuropathy
(4) Serotonin syndrome
MOA: Aminoglycosides
(1) Inhibit 30s ribosome ⇒ Inhibits initiation complex
(2) Induce misreading of mRNA
Are aminoglycosides bacteriostatic or bacteriocidal?
Bacteriocidal
Which class of antibiotics induces misreading of the mRNA?
Aminoglycosides
What type of organisms are aminoglycosides most effective against?
Aerobic gram (-) bacilli
What type of antibiotics are aminoglycosides synergistic with?
Call wall active drugs
(β-lactams, vancomycin, etc.)
Can aminoglycosides be used to treat Clostridium perfringens?
No – requires AEROBE
ROA: Aminoglycosides
IV
What antibiotic is used to sterilize the bowel before colorectal surgery?
Neomycin
Which aminoglycoside is active against GI luminal parasites?
Paromycin
Which aminoglycoside is used to treat Francisella?
Streptomycin
(Also treats Yersinia)
Indication: Gentamicin
Resistant gram (-) organisms
Name 3 aminoglycosides that are active against Pseudomonas
(1) Gentamicin
(2) Tobramycin
(3) Amikacin
Name a gram (+) organism aminoglycosides are effective against
Enterococcus (when paired with cell wall active agent)
What is Enterococcus’ mechanism of resistance to aminoglycosides?
Acetylation
Adverse Effects (5) : Aminoglycosides
(1) Teratogen
(2) Ototoxicity
(3) Nephrotoxicity
(4) Acute tubular necrosis
(5) Neuromuscular blockade
* (MC cause of acute tubular necrosis)*
Contraindication - Autoimmune: Aminoglycosides
Myasthenia gravis
(Lambert-Eaton too?)
What developmental defect is associated with aminoglycoside use during pregnancy?
Deafness
