A Test for the Rapid Detection of the Cefazolin Inoculum Effect in Methicillin-Susceptible Staphylococcus aureus
Sandra Rincón, Lina P Carvajal, Sara I Gómez-Villegas, Aura M Echeverri, Rafael Ríos, An Q Dinh, Claudia Pedroza, Karen Ordóñez, Esteban C. Nannini, Zhizeng Sun, Vance G. Fowler, Barbara E. Murray, William R. Miller, Timothy Palzkill, Lorena Díaz, César A. Arias, Jinnethe Reyes
Abstract
The overall negative predictive value ranged from 81.4% to 95.6% in Latin American countries using published prevalence rates of the CzIE. MSSA isolates from the United States were genetically diverse, with no distinguishing genomic differences from Latin American MSSA, distributed among 18 sequence types. A novel test can readily identify most MSSA isolates exhibiting the CzIE, particularly those carrying type A BlaZ. In contrast to the MIC determination using high inoculum, the rapid test is inexpensive, feasible, and easy to perform. After minor validation steps, it could be incorporated into the routine clinical laboratory workflow.