Antibiotics Flashcards
Mechanism of Penicillin ABx
Bind Penicillin binding proteins (transpeptidases)
Block transpeptidase cross linking of peptidoglycan cell wall
Activate autolytic enzymes
Clinical use of Penicillin G (IV) and V (oral)
Gram positives
Syphilis (spirochetes)
S/E of Penicillin G and V
Hypersensitivity
Mechanism of resistance to Penicillin G/V
Penicillinase in bacteria (B lactamase that cleaves B lactam ring)
Which penicillin ABx is used for the following?
a. Syphilis
b. UTI
c. Pseudomonas
d. Neonatal infection
a. Penicillin G
b. Amoxicillin
c. Ticarcillin, Piperacillin
d. Ampicillin (plus Gentamicin)
Patient with mononucleosis is given a drug and develops full body rash. What were they given?
Amoxicillin
Which has greater oral bioavailability; Amoxicillin or Ampicillin?
Amoxicillin has greater oral bioavailability
Penicillinase-resistant Penicillins
Nafcillin, Oxacillin, Dicloxacillin
Clinical use for Penicillinase-resistant Penicillins
Staph aureus
Anti-pseudomonal Penicillins
Piperacillin, Ticarcillin
Beta lactamase inhibitors
Clavulonic acid
Tazobactam
Sulbactam
Organisms NOT covered by Cephalosporins (LAME)
Listeria
Atypicals (Chlamydia, Mycoplasma)
MRSA
Enterococci
Clinical use of:
a. 1st generation Cephalosporins
b. 2nd gen Cephalosporins
c. 3rd gen Cephalosporins
d. 4th gen Cephalosporins
a. Gram positives, Proteus, E. coli, Klebsiella (UTI, URI, Prophylaxis for Viridans strep endocarditis, prior to surgery)
b. Gram positives, PEcK plus H. influenzae, Enterobacter, Neisseria, Serratia
c. Serious gram negative infections; Ceftriaxone - meningitis, gonorrhea, Lyme disease; Ceftazidime - Pseudomonas
d. Cefepime - Pseudmonas, broad coverage
S/E of Cephalosporins
Disulfiram like reaction
Vit K deficiency
Cross reactivity with Penicillins = Hypersensitivity
Increased nephrotoxicity with Aminoglycosides
ABx to avoid in pregnancy
Tetracyclines - discolored teeth and inhibits bone growth Fluoroquinolones - cartilage rupture Aminoglycosides - nephro/oto toxicity Clarithromycin - Embryotoxic Sulfonamides - Kernicterus Metronidazole - Mutagenesis Ribavirin - Teratogenic Griseofulvin - Teratogenic
Why is Imipenem administered with Cilastatin?
Cilastatin inhibits renal dehydropeptidase I to decrease the inactivation of Imipenem in renal tubules
Use of Carbapenems
WIDE spectrum
Does NOT cover MRSA
S/E of Carbapenems
Significant side effects
Seizures and CNS toxicity at high levels
Use of Aztreonam
Gram negative rods ONLY; for Penicillin allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides
Mechanism of Vancomycin
Binds D-ala-D-ala portion of cell wall precursors and inhibits cell wall peptidoglycan formation
Use of Vancomycin
MRSA, C. difficile (oral)
S/E of Vancomycin
Nephrotoxic, Ototoxic, Thrombophlebitis, Red man syndrome
Cause of Red Man Syndrome
When taking Vancomycin there is nonspecific mast cell degranulation causing widespread release of histamine and diffuse flushing
Protein synthesis inhibitor Abx
Buy AT 30, CCEL at 50
Aminoglycosides
Tetracycline
Chloramphenicol
Clindamycin
Erythromycin - Macrolides
Linezolid
Mechanism of Aminoglycosides
Binds 30s subunit and causes misreading of RNA
REQUIRES 02 FOR UPTAKE
Use of Aminoglycosides
Gram negative rods (Neonatal infections)
Neomycin for bowel surgery
Why are Aminoglycosides not effective against anaerobes?
They require O2 for uptake
S/E of Aminoglycosides
Nephrotoxicity (worse with Cephalosporins), Ototoxicity, Teratogen
Mechanism of Tetracyclines
Binds 30s subunit and prevents attachment of amino-acyl tRNA
What should you avoid while taking Tetracyclines?
Milk (Calcium) , Antacids (Calcium or Mg), Iron - they disrupt absorption of the drug
Clinical use of Tetracyclines (VACUUM The BedRoom)
Vibro cholera Acne Chlamydia Ureaplasma Tularemia Mycobacterium pneumoniae Borrelia Rickettsia
Why are Tetracyclines effective against Rickettsie and Chlamydia?
They can accumulate intracellularly.
S/E of Tetracycline
Discoloration of teeth
Inhibition of bone growth
Photosensitivity
S/E of Chloramphenicol (and cause of this)
Gray baby syndrome - they lack UDP glucuronyl transferase
S/E of Clindamycin
Pseudomembranous colitis
Use of Linezolids
MRSA
VRE
Mechanism of Macrolides
Erythromycin, Clarithromycin, Azithromycin - they bind 23sRNA of 50s subunit and block translocation
Use of Macrolides
Atypical pneumonias (Mycoplasma, Legionella, Chlamydia)
STIs (Chlamydia)
URIs
B. pertussis
Toxicity of Macrolides
Motility issues, Arrhythmia caused by long QT, acute Cholestatic hepatitis, Rash, Eosinophilia
Increases serum concentration of theophylline and anticoagulants
Clarithryomycin and Erythromycin inhibits p450 enzymes
Mechanism of Trimethoprim
Inhibits dihydrofolate reductase
Use of Trimethoprim
Used in combo with Sulfonamides for UTIs, Shigella, Salmonella, PCP prophylaxis and treatment, Toxoplasmosis prophylaxis
Sulfonamides mechanism
Inhibits folate synthesis (PABA antimetabolites inhibit dihydropteroate synthase)
Sulfa drugs (Sulfa Pills Frequently Cause Terrible Acute Symptoms)
Sulfasalazine Probenecid Furosemide Celecoxib Thiazides/TMP-SMX Acetazolamide Sulfonylureas
Mechanism of Nitrofurantoin
Reduced by bacterial proteins to a reactive intermediate that inactivates bacterial ribosomes
Use for Nitrofurantoin
UTI cystitis by E. coli or Staph saprophyticus
Safe in pregnancy
Mechanism of Fluoroquinolones
Inhibits prokaryotic enzymes topoisomerase II (DNA gyrase) and IV
What can you not take while taking Fluoroquinolones?
Antacids - inhibits absorption
S/E of Daptomycin
Myopathy, Rhabdomyolysis
Why is Daptomycin NOT used for pneumonia?
It avidly binds and is inactivated by Surfactant
Mechanism of Daptomycin
Disrupts cell membrane
Mechanism of Metronidazole
Forms toxic free radical metabolites in bacterial cell that damage DNA - ANTIprotozoal
Use of Metronidazole
Giardia Entamoeba Trichomonas Gardnerella vaginalis Anaerobes H. pylori
S/E of Metronidazole
Disulfiram like reaction (flushing, tachycardia, hypotension) with alcohol
