Biofilm detection in staphylococcal strains by two phenotypic methods

Various infections in the hospital are caused by bacterial strains of Staphylococcus aureus. Some strains of this species have the capacity to produce biofilm, causing infections related to the contamination of various materials or surgical devices due to their difficult eradication of the infected site. The purpose of this study was to determine the expression of slime or biofilm in strains of Staphylococcus aureus carriers of the icaA and icaD genes by means of two different phenotypic methods to identify the sensitivity of each of them. In the present study, 76 strains from different clinical isolates were evaluated, being found by the gold standard test of detection of biofilm producing strains used by the PCR method by the detection of the icaA and icaD genes, which was applied to all staphylococcal strains tested. Regarding the gold standard test, the results indicated that the sensitivity by the CRA method with 800 mg/L, was the lowest with 64.0%, but that by increasing the concentration of the dye to 1200 mg/L in the CRA modified, the sensitivity increased to 86%, being almost the same as the highest sensitivity obtained by the detection of biofilm in polystyrene plates by crystal violet as a developer, with a sensitivity of 89%.