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Published on: May 5, 2016
Modification of the Congo red agar method to detect biofilm production by Staphylococcus epidermidis
Thaís Dias Lemos Kaiser1, Eliezer Menezes Pereira, Kátia Regina Netto Dos Santos
1Laboratório de Resistência Bacteriana, RESBAC, Departamento de Patologia e Programa de Pós-Graduação em Doenças Infecciosas, Universidade Federal do Espírito Santo, Brazil.
Abstract:
Staphylococcus epidermidis in immunocompromised patients can cause bacteremia related to the use of catheter due to biofilm production. There are different phenotypic methods to detect biofilm formation. One method is based on culture in brain heart infusion agar (BHIA) containing sucrose and red Congo dye (original Congo red agar). Our group created a new CRA formula and we have confirmed its capacity to detect biofilm production in 210 S. epidermidis strains, including 76 (36.2%) icaAB gene-positive strains. Other parameters were also evaluated. The new CRA formula that gave the best results was BHIA with sucrose (5%), Congo red (0.08%), NaCl (1.5%), glucose (2%), and vancomycin (0.5 mg/mL) (vancomycin-modified CRA-CRAmod). The CRAmod plus vancomycin may be a promising tool and can help to determine the real participation of S. epidermidis in the infectious process.
