Antibiotics Flashcards
Which penicillin is oral? IV/IM?
oral: pen V. IV/IM: pen G.
Penicillin mech
1) bind PBPs (transpeptidases) 2) block transpeptidase cross-linking of peptidoglycan. 3) Activate autolytic enzymes.
Clinical use of Penicillin
Gram + organisms (S. pneumoniase, S. pyogenes, Actinomyces). Also used for N. Meningitidis and T. Pallidum. Bactericidal for gram positive cocci, gram positive rods, gram negative cocci, and spirochetes. Penicillinase sensitive.
Penicillin Toxicity
Hypersensitivity reactions. Hemolytic anemia
Penicilin Resistance
Penicillinase in bacteria (a type of beta lactamase) cleaves beta lactam ring
Ampicillin, amoxicillin (aminopenicillins, penicillinase sensitive penicillins) Mechanism?
Same as penicillin but wider spectrum; penicillinase sensitive. Also combine with clavulonic acid to protect against beta lactamase.
Which has better oral bioavailability, ampicillin or amoxicillin?
amOxicillin (O for oral)
What is the clinical use of Ampicillin, amoxicillin (aminopenicillins, penicillinase sensitive penicillins)?
Extended-spectrum penicillin : HELPSS kill enterococci: Haemophilus influenzae, E. Coli, Listeria monocytogenes (meningitis in the elderly) Proteus mirabilis, Salmonella, Shigella, enterococci
Ampicillin, amoxicillin (aminopenicillins, penicillinase sensitive penicillins) SE?
Hypersensitivity reactions; rash; pseudomembranous colits
Ampicillin, amoxicillin (aminopenicillins, penicillinase sensitive penicillins) Mechanism of resistance?
Penicillinase in bacteria (a type of beta lactamase) cleaves beta lactam ring
Oxacillin, nafcillin, dicloxacillin (penicillinase resistance penicillins) mechanism?
same as penicillin. Narrow spectrum; penicillinase resistant because bulky R group blocks access of beta lactamase to beta lactam ring
Oxacillin, nafcillin, dicloxacillin (penicillinase resistance penicillins) clinical use?
S. aureus ( except MRSA; resistant because of altered PBP target site). Use naf (naficillin for staph)
Oxacillin, nafcillin, dicloxacillin (penicillinase resistance penicillins) toxicity?
hypersensitivity reactions, interstitial nephritis
Ticarcillin, piperacillin mech?
Same as penicillin. Extended spectrum.
Ticarcillin, piperacillin clinical use?
Pseudomonas spp. and gram-negative rods; susceptible to penicillinase; use with beta lactamase inhibitors.
Ticarcillin, piperacillin toxicity?
hypersensitivty reactions
What are the beta lactamase inhibitors?
Clavulanic Acid, Sulbactam, Tazobactam. Often added to penicillin antibiotics to protect the antibiotic from destruction by beta lactamase (penicillinase).
what are cephalosporins
beta lactam drugs that inhibit cell wall synthesis but are less susceptible to penisillinases
What organisms are typically not covered by cephalosporins?
they are LAME: Listeria, Atypicals (chlamydia, mycoplasma), MRSA, and Enterococci.
What Cephalosporin will cover MRSA?
Ceftaroline
What is the clinical use of 1st generation Cephalosporins?
gram positive cocci: PEcK : Proteus mirabilis, E. Coli, Klebsiella pneumoniae.
What are the 1st generation Cephalosporins?
cefazolin, cephalexin
which 1st generation cephalosporin is used prior to surgery to prevent S. aureus wound infections?
Cefazolin
What are the 2nd generation cephalosporin drugs/indications?
cefoxitin, cefaxcor, cefuroxime (gram positive cocci): HEN PEcKS: Haemophilius influenzae, Enterobacter aerogenes, Neisseria spp., Proteus mirabilis, E. coli, Klebsiella pneumoniae, Serratia
What are the 3rd generation cephalosporin drugs/indications?
Ceftriazone (meningitis and gonorrhea), Ceftazidime (Pseudomonas), Cefotaxime: Serious gram negative infections resistant to other beta lactams
What is the 4th generation cephalosporin drug/indications?
Cefepime - increased activity against Pseudomonas (G-) and other gram positive organisms
What is a 5th generation cephalosporin, and what is the indication?
Ceftaroline: broad gram positive and gram negative organism coverage including MRSA ; does NOT cover Pseudomonas
What toxicites can cephalosporins cause?
Hypersensitivity reactions, vitamin K deficiency. Low cross reactivity with penicillins. Increased nephrotoxicity of aminoglycoside
Aztreonam mechanism
A monobactam; resistant to beta lactamases. Prevent peptidoglycan cross linking by binding to PBP 3. Synergisitc with aminoglycosides. No cross allergenicity with penicillins.
What is the clinical use of Aztreonam?
Gram negative rods only. no activity against gram positives or anaerobes. Used for penicillin allergic patients and those with renal insufficiency who cannot tolerate aminoglycosides.
What is the toxicity of Aztreonam?
generally none. occasional GI upset
What are the carbapenems?
Imipenem, meropenem, ertapenem, doripenem
What is the mechanism of carbapenems, specifically imipenem?
broad spectrum beta lactamase resistance carbapenem.
What drug is alway administered with Imipenem? Why?
Cilastin (inhibitor of renal dehydropeptidase I) to decrease inactivation of drug in renal tubules.
The kill is lastin with cilastin!
haha
What carbapenem has limited psuedomonas coverage?
ertapenem
What is the clinical use of the carbapenems?
Gram-positive cocci, gram-negative rods (enterobacter cloacae, serratia marcescens, klebsiella pneumonia) and anaerobes. Wide spectrum, but significant SE limit use to life threatening infection or after other rgus have failed.
What carbapenem has resistance to dehydropeptidase I?
Meropenem
What carbapenem has a decreased risk of seizures?
Meropenem
What are the SE/Toxicities of carbapenems?
GI distress, skin rash, and CNS toxicity (seizures) at high plasma levels.
Vancomycin mech
inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors. Bactericidal.
What is the use of Vancomycin?
Gram positive only. serious, multi-drug resistant organisms including MRSA, enterococci, and C diff - Oral dose for pesudomembrane colitis!
What are the toxicites of Vancomycin?
Well tolderated in general but NOT trouble free: Nephrotoxicity, Ototoxicity, Thrombophlebitis, diffuse flushing (RED MAN SYNDROME)
how can RED MAN syndrome be prevented?
Vanco + antihistamines and slow infusion
What is the mech of resisitance to Vancomycin?
Ocurrs in bacteria via amino acid modification of D-Ala D-ala to D-ala D-lac.
Protein synthesis inhibitors
Specifically target smaller bacterial ribosome 70S, made of 30S and 50S subunits, leaving human ribosomes 80s unaffected
buy AT 30, CCEL at 50
1) 30s inhibitors: Aminoglycosides (bactericidal), Tetracyclines (bacteriostatic)
2) 50s inhibitors: Chloramphenicol, Clindamycin (bacteriostatic), Erythromycin (macrolide, bacteriostatic), Linezolid (variable)
What are the Aminoglycosides?
Mean (aminoglycoside) GNATS caNNOT kill anaerobes. Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin mechanism
Bactericidal; inhibit formation of initiation complex and cause misreading of mRNA. Also block translocation. Require O2 for uptake; therefore ineffective against anaerobes.
Aminoglycoside mneumonic?
A INITIATES the Alphabet
What is the SE’s of Aminoglycosides?
Mean (aminoglycoside GNATS caNNOT kill anaerobes. Nephrotoxicity (especially when used with cephalosporins), Neuromuscular blockase, Ototoxicity (especially with loop diuretics). Teratogen
What is the mechanism of resistance to Aminoglycosides?
Bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, or adenylation