[Evaluation of cefoxitin and cefotaxime screening plates for the detection of methicillin-resistance in Staphylococcus aureus]. / Evaluación de placas de screening de cefoxitina y cefotaxima para la detección de resistencia a meticilina en Staphylococcus aureus.

ABSTRACT

Detection of methicillin-resistant Staphylococcus aureus (MRSA) isolates represents a serious problem to low and media level microbiology labs. In this work cefoxitin (FOX) and cefotaxime (CTX) screen plates (AS) (8-16 microg/ml) with and without 4% of NaCl were evaluated to detect MRSA. Sensitivity, specificity, positive and negative predictive values were determined. The AS oxacillin and the agglutination test MRSA-Screen Latex for the detection of PLP2a were used as reference methods for the evaluation of the different studied screening plates. The 100% (94 strains) PLP2a positive were detected as MRSA with FOX (8 microg/ml), and CTX (8 microg/ml with 4% NaCl) AS. The advantage of FOX AS (8 microg/ml) is that it does not need the addition of NaCl, and CTX AS (8 microg/ml with 4% NaCl) is that cefotaxime is an antimicrobial easily accessible in our country.