Detection of icaA, icaD genes and biofilm production by Staphylococcus aureus and Staphylococcus epidermidis isolated from urinary tract catheterized patients

Gamal Fadl Mahmoud Gad, Mohamed Ali El-Feky, Mostafa Said El-Rehewy, Mona Amin Hassan, Hassan Abolella, Rehab Mahmoud Abd El-Baky
Journal of Infection in Developing Countries 2009, 3 (5): 342-51

BACKGROUND: Staphylococci are a common cause of catheter-associated urinary tract infections. The present study evaluated biofilm forming capacity and the presence of both icaA and icaD genes among staphylococci strains isolated from patients undergoing ureteral catheterization.

METHODOLOGY: Different bacterial strains were isolated from urine and stents segments collected from 100 patients. Strains were identified by traditional microbiological methods. Stents were examined for biofilm using a scanning electron microscope (SEM). Staphylococcal isolates were tested for their ability to produce biofilm using the tissue culture plate assay method (TCP). The presence of icaA and icaD genes was determined by PCR technique.

RESULTS: Fifty-three staphylococcal strains were isolated and identified from 284 samples (18.7%). Forty-six staphylococcal strains were isolated from stent segment cultures while only seven strains were isolated from urine samples at the day of stent removal. S. aureus represented 6.3%, and S. epidermidis represented 12.3%. Out of the 18 S. aureus strains, 15 (83.3%) were biofilm producers and out of 35 S. epidermidis strains, 31 (88.6%) were biofilm producers. Staphylococcal strains were further classified as high (56.6%), moderate (30.2%) and non biofilm producers (13.2%). All biofilm producing strains were positive for icaA and icaD genes, and all biofilm negative strains were negative for both genes.

CONCLUSION: Staphylococci isolated from catheter segments showed a higher extent of biofilm production than that isolated from urine samples. All biofilm producing staphylococci were positive for icaA and icaD genes, which indicates the important role of ica genes as virulence markers in staphylococcal infections associated with urinary catheterization.

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