Biofilm Production and Antibiotic Resistance of Staphylococcus Epidermidis in Catheter Related Bloodstream Infections

Abstract

Background: Most Staphylococcus epidermidis -related infections are acquired in hospitals and are associated with the use of medical devices. Objectives: The aim of this study was to detect biofilm producing S. epidermidis from patients with catheter-related bloodstream infections (CRBSI) and determine their antibiotic resistance pattern. Methodology: Blood and catheter tip specimens were collected from 150 patients with CRBSI. Isolated S. epidermidis strains were tested for biofilm production by the modified tissue culture plate (MTCP) method, Congo red agar (CRA) method, and icaA and icaD genes detection by PCR. Antibiotic resistance pattern of both biofilm producing and biofilm non-producing isolates was tested using the disc diffusion method. Results: The prevalence of S. epidermidis in CRBSIs was 13.3%. Biofilm production was detected in 55% and 45% of isolates by the MTCP method and CRA method respectively. IcaA and icaD genes were detected in 20% and 30% of the isolates respectively. The sensitivities of CRA method, icaA and icaD were 81.8%, 36.4%, and 54.5% respectively. All of them showed specificity 100%. Biofilm producing isolates were more resistant to cefotaxime, erythromycin, rifampin, tetracycline, gentamycin, ciprofloxacin and ampicillin than biofilm non-producing isolates. All the isolates were sensitive to linezolid and vancomycin. Conclusion: The MTCP remains the best method for screening of biofilm production. IcaD gene detection is more sensitive for detection of biofilm production in S. epidermidis than icaA gene, however, their presence does not always correlate with phenotypic biofilm production. Biofilm producing S. epidermidis isolates showed more antibiotic resistance than biofilm non-producing isolates