Prevalence of virulence genes of biofilm producing strains of Staphylococcus epidermidis isolated from clinical samples in Iran

  • Solati S
  • Tajbakhsh E
  • Khamesipour F
 et al. 
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Coagulase negative staphylococci are recognized as opportunistic pathogens and are widespread in the environment. It is possible to prevent and control infections due to these bacteria if their virulence factors are recognized. Eighty isolates of Staphylococcus epidermidis (S. epidermidis) including 42 from urine (52.5%), 23 from blood (28.75%), 15 from dialysis bags (18.75%) were studied for biofilm production on Congo red agar (CRA). The virulence genes in S. aureus were investigated using polymerase chain reaction (PCR) with primers. Out of 80 isolates studied, 40 isolated (50%) formed black colonies (biofilm-forming strains) on CRA. In 22 of these isolates (25%) reaction was strongly positive; in 12 isolates (15%) reaction was moderately positive, and in the remaining 6 isolates, reaction was weakly positive. In the 22 isolates that had strong positive reaction and produced black colonies on biofilm, all virulent genes (icaC, icaD, icaA icaB, icaR) were expressed. In the 12 isolates that had moderate positive reaction, 8 expressed all genes (icaC, icaD, icaA icaB, icaR) expressed while the remaining 4 expressed only ica A, and ica D genes. Of the 6 isolated which had weak positive reaction, only 1 isolate (2.5%) expressed all the genes, in the other 5 isolates no gene was observed. Urinary isolates more frequently form biofilms than the isolates from other clinical samples. Statistical analysis using Chi square test showed that there was a significant correlation between the type of sample and the biofilm production (P 

Author-supplied keywords

  • Biofilm
  • Clinical isolates
  • Microtiter assay plate
  • Staphylococcus epidermidis
  • Virulence genes

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