Phenotypic and Genotypic detection of biofilm producing organisms

Abstract

newline Aims and objectives: Phenotypic and genotypic methods for biofilm detection and comparison of three different genes in Staphylococcus epidermidis among commensal, colonizer and invasive isolates. newline Materials and methods: Its a prospective study with a sample size of 1249. An initial pilot study was conducted with 449 samples which included only invasive devices to estimate the common isolate as a coloniser known to produce biofilms phenotypically as well as genotypically and to standardise the most significant phenotypic method. A total of 800 samples were considered for the main study, out of these 600 blood samples were from the patients suspected to have blood stream infections, 100 nasal and skin swabs from healthy volunteers and 100 central venous catheter tips from dialysis unit and coronary care units without associated infection.The significance of biofilm formation and its associated infections among various isolates was evaluated by tissue culture plate method and the presence of three genes (ica, aap and atlE) by uniplex PCR. newlineStatistical analysis: Mean values, P value by Pearson Chi square test. newlineResults: The P value of 0.040 was found to be significant, in relation to atlE gene among the invasive, commensals and colonizers isolates producing biofilms. A P value of 0.011 of the icaAB gene among the biofilm producers was found to be very significant in invasive and colonizers than in the commensals. newlineDiscussion and Conclusion: Staphylococcus epidermidis is known to cause nosocomial infections especially associated with invasive devices, contaminating the blood cultures and making interpretation a major challenge. Staphylococcus epidermidis showed the involvement of several genes in biofilm formation apart from ica gene, which play an important role in biofilm formation which include steps like initial adhesion, formation of complex biofilm structure, regulation and dispersion as emboli. It is very important to rule out the presence of these genes which confirms a true commensal, not involved in biofilm formation. The expression of atlE gene was stable throughout the process of implantation of biofilms, having a significant role in persistence of biofilms and can be used as targets, in prevention of biofilm related infections.