Cefazolin or Anti-Staphylococcal Beta-Lactams for MSSA?

The cefazolin inoculum effect caused a reduction of this antibiotic's efficacy in a mouse model of methicillin-susceptible Staphylococcus aureus pneumonia.

The selection of antimicrobial therapy must sometimes balance convenience and safety against therapeutic reliability. One example is management of serious methicillin-susceptible Staphylococcus aureus (MSSA) infections with either the better-tolerated and more-convenient cefazolin (CZ) or the semisynthetic anti-staphylococcal beta-lactams (ASBs), which are not subject to the CZ inoculum effect (CIE). MSSA exhibiting the CIE are not susceptible to CZ (MIC >16 mg/L) when tested at 10⁷ colony-forming units per mL instead of the standard 10⁵ cfu/mL due to overexpression of beta-lactamase, especially the type A variant.

Using a murine model of pneumonia, Lee and colleagues assessed the microbiologic efficacy of CZ versus oxacillin as treatment ag…

Reviewing Author

George Sakoulas, MD

Disclosures

Consultant/Advisory BoardParatek Pharmaceuticals; Nestle Corp.; AbbVie; Shionogi

Speaker’s BureauAllergan/AbbVie; Paratek Pharmaceuticals; Nestle Corp.

RoyaltiesUpToDate

Editorial BoardsAntimicrobial Agents and Chemotherapy; Open Forum Infectious Diseases