Thesis (M.Sc.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Staphylococcus epidermidis is a commensal bacterium that colonizes the skin immediately after birth protecting us from invading harmful bacteria. However, in the past decades, it was found that S. epidermidis became an opportunistic organism in patients with indwelling medical devices especially immunocompromised ones. It was noted that it is one of the most common causes of sepsis caused by biofilms in catheters. It also contributes in neonatal morbidity and mortality in the neonatal intensive care units (NICUs). Diagnosis of S. epidermidis infection takes several days by blood culturing so health-care providers use broad-spectrum antibiotics aiming to treatment but unfortunately, this might lead to the development of multiple drug resistant strains. So, we planned to find a rapid and accurate diagnostic marker for S. epidermidis. Bioinformatics analyses of the S. epidermidis proteome revealed that the N-terminal fragment of the SesK protein was found to be highly conserved and species-specific candidate. Recombinant DNA technology was used to clone, express and purify the SesK-NT polypeptide for animal immunization and hence, antibodies production. The current study utilized, for the first time, SesK-NT polypeptide to produce antibodies that could be used as a diagnostic probe for S. epidermidis. The produced antibodies could differentially distinguish between S. epidermidis and another coagulase-negative staphylococcus (S. simulans).In conclusion, this study provides preliminary evidence for the potential use of the SesK-NT protein fragment as a target for the specific detection of S. epidermidis and further optimization is required to enhance the specificity against other coagulase-negative staphylococci

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