Abstract

Abstract Coagulase-negative staphylococci (CNS) are a group of micro-organisms that are increasingly implicated as a cause of significant infection especially in patients undergoing catheter and other medical devices related infections. They are often multiresistant to antibiotics, and the ability to form biofilm is considered their main virulence determinant. In the present study, Three hundred specimens were isolated; only one hundred isolates were analyzed: 53% S. haemolyticus, 26% S. epidermidis and 21% S. hominis. The results showed that only 93% were phenotypically biofilm formation in Christensen tube and TS-Congo red agar methods. Then these isolates subjected to molecular studies using PCR we found 98% of CoNS isolates carried aap gene while 93% of isolates were expressed icaA and icaD genes. Keywords: coagulase-negative staphylococci, catheter-related infections, icaA gene, icaD gene, aap gene.