![]() ![]() Caution with Unasyn for polymicrobial intraabdominal infections due to high rate of resistance of E.coli (>50% at some institutions).Used for: similar situations as for Amoxicillin/Clavulanate but where IV form is desirable also, some intraabdominal and GYN infections, aspiration pneumonia and lung abscesses, and more. Still no activity against other SPICE organisms. Spectrum: Similar to Amoxicillin/Clavulanate, except has activity vs most Acinetobacter (sulbactam component has activity). Used for: Sinusitis, respiratory infections, otitis media, some skin/soft tissue infections (including bite wounds), and more. Notable holes include NO Pseudomonal activity and other SPICE A organisms. Spectrum: Relatively broad spectrum with some gram positive (MSSA, Strep), some gram negatives, and anaerobes. Amoxicillin/Clavulanate (Augmentin) – PO.COMBINED PENICILLIN/BETA-LACTAMASE INHIBITORS:addition of beta lactamase inhibitor confers broader spectrum against common beta-lactamase producing organisms (such as MSSA, some gram negatives including H.influenza, Moraxella, and virtually all anaerobes). Usually combined with beta lactamase inhibitors (see below) which confers broader activity however, beta-lactamase component does not add activity vs Pseudomonas (so if Pseudomonas is sensitive, could use Piperacillin alone).ī. Anti-pseudomonal PCNs - Piperacillin, Ticarcillin Nafcillin tends to be better tolerated than Oxacillin (less hepatitis and rash)Ĥ.bacteremia, osteomyelitis, endocarditis), in general the entire course of therapy must be given intravenously. Dicloxacillin is a reasonable oral choice for non-severe cellulitis otherwise, for all serious MSSA infections (e.g.If >10 years ago, and/or not characteristic of IgE, give cephalosporin or carbapenem (80%). If skin testing unavailable and beta-lactam is preferred, decision depends on prior type of reaction and how recently it occurred.Rash occurs in up to 5% of patients receiving PCN, but the overall rate of anaphylaxis to PCN is 98% will tolerate PCN, but not 100% à give 10% “test” dose and observe for 1 hour prior to full dose.Cefepime and Piperacillin/Tazobactam can be used with caution as well. The SPICE-A organisms (Serratia, Pseudomonas/Providencia, Indole-positive Proteus, Citrobacter, Enterobacter, and Acinetobacter) have inducible, chromosomal beta-lactamases (AmpC) that may not be detected on initial susceptibility testing, but can lead to resistance while on therapy to all beta-lactams except carbapenems.Beta-lactams exhibit time-dependent killing, meaning that efficacy depends on the amount of time the drug concentration is above the MIC.No beta-lactam has activity vs MRSA (except Ceftaroline), and none have activity vs atypical intracellular organisms (i.e.Most oral beta-lactams have poor bioavailability and achieve low serum concentrations, making them poor choices for serious or deep seated infections (Amoxicillin has the best bioavailability).As a general rule, if pathogen is susceptible and patient non-allergic, beta-lactams are the preferred drug for most situations due to high efficacy and cidal nature.Main side effects: Hypersensitivity reactions including anaphylaxis, Rashes, Bone marrow suppression, Interstitial Nephritis, GI (nausea, diarrhea, and C.diff) interstitial nephritis, GI (nausea, diarrhea, and C.diff), seizures (mainly with high doses in renal failure).Cell wall inhibitors: bind PBPs (Penicillin-binding proteins) in cell membrane and inhibit cell wall crosslinking -> bactericidal. ![]() BETA-LACTAMS = PCNs, Cephalosporins, Carbapenems, Monobactam(Aztreonam) Last Tidbit: Very common antibiotic regimen = VANCOMYCIN / ZOSYN RIFAMYCINS – include Rifampin, Rifaximin, Rifapentine, Rifabutin. Urinary Tract Infection-Specfic Antibiotics "SUPER GRAM NEGATIVE ANTIBIOTICS" THAT COVER PSEUDOMONAS ![]()
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