Study on biofilm-forming properties of clinical isolates of Staphylococcus aureus

  • Yasmeen Taj Dow Medical College Karachi, Karachi, Pakistan
  • Farhan Essa Dow Medical College Karachi, Karachi, Pakistan
  • Faisal Aziz University of Karachi, Karachi, Pakistan
  • Shahana Urooj Kazmi University of Karachi, Karachi, Pakistan
Keywords: Staphylococcus aureus, biofilm production, electron microscopy

Abstract

Introduction: The purpose of this study was to observe the formation of biofilm, an important virulence factor, by isolates of Staphylococcus aureus (S. aureus) in Pakistan by different conventional methods and through electron microscopy.

Methodology: We screened 115 strains of S. aureus isolated from different clinical specimens by tube method (TM), air-liquid interface coverslip assay method, Congo red agar (CRA) method, and scanning electron microscopy (SEM).

Results: Out of 115 S. aureus isolates, 63 (54.78%) showed biofilm formation by tube method. Biofilm forming bacteria were further categorized as high producers (n = 23, 20%) and moderate producers (n = 40, 34.78%). TM coordinated well with the coverslip assay for strong biofilm-producing strains in 19 (16.5%) isolates. By coverslip method, weak producers were difficult to differentiate from biofilm negative isolates. Screening on CRA showed biofilm formation only in four (3.47%) strains. Scanning electron micrographs showed the biofilm-forming strains of S. aureus arranged in a matrix on the propylene surface and correlated well with the TM.

Conclusion: Biofilm production is a marker of virulence for clinically relevant staphylococcal infections. It can be studied by various methods but screening on CRA is not recommended for investigation of biofilm formation in Staphylococcus aureus. Electron micrograph images correlate well with the biofilm production as observed by TM. 

Author Biographies

Yasmeen Taj, Dow Medical College Karachi, Karachi, Pakistan
Dow Medical College Karachi , Associate Professor
Farhan Essa, Dow Medical College Karachi, Karachi, Pakistan
Dow Medical College Karachi , Assistant Professor
Faisal Aziz, University of Karachi, Karachi, Pakistan

Immunology & Infectious Diseases Research Laboratory (IIDRL) , University of Karachi, Research Associate

Shahana Urooj Kazmi, University of Karachi, Karachi, Pakistan
University of Karachi, Pro Vice Chancellor
Published
2011-12-13
How to Cite
1.
Taj Y, Essa F, Aziz F, Kazmi SU (2011) Study on biofilm-forming properties of clinical isolates of Staphylococcus aureus. J Infect Dev Ctries 6:403-409. doi: 10.3855/jidc.1743
Section
Original Articles