Virulence Determination in Invasive and Commensal Staphylococcus Epidermidis

Abstract

Aims: The research primarily focuses on the virulence factors in Staphylococcus epidermidis isolates and their role in human disease. Methods: 15 Staphylococcus epidermidis isolates were obtained from urine, wound, and blood samples from various hospitals in Baghdad. Additionally, 15 Staphylococcus epidermidis isolates were collected from the urine and fingerprints of healthy individuals in Baghdad from July 2021 to January 2022. The resistance of the isolates to antibiotics was evaluated by conducting the disk diffusion test, which involves placing antibiotic-containing disks on a culture plate to observe the extent of bacterial growth inhibition around each disk. The antibiotics tested included Vancomycin (VA- 30µg), Cefoxitin (CFX- 30µg), Gentamicin (CN-10µg), Tetracycline (TE-10 µg), Levofloxacin (LEV- 5µg), Oxacillin (OX- 5µg), Penicillin G (P-10 µg), Rifampin (RA- 5µg), and Clindamycin (DA-10 µg). The frequency of virulence genes (fdh, mecA, clf, IgG, sesI) was determined using PCR assay. Results: A total of 30 S. epidermidis isolates were detected by traditional biochemical tests, and Viteck 2 had higher rates of resistance to cefoxitin (80%), oxacillin (90%), penicillin (86.6%), clindamycin (60%), gentamicin (76.6%), levofloxacin (80%), and tetracycline (26.6%). The most effective antibiotics are vancomycin (90%) and rifampin (86%). Moreover, the detection of 3/15 (20%), 12/15 (80%) of commensal marker fdh, and 3/15 (20%), 1/15 (6.6%) of invasive marker sesI genes, 11/15 (73.3%), 14/15 (93.3%) while other virulence genes mecA, clf, IgG were detected in 6/15 (40%), 7/15 (46.6%), 9/15 (60%), and 14/15 (93.3%) in clinical and healthy individual isolates, respectively.