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Indian Journal of Microbiology Research

Comparison of Phenotypic and molecular profile of Coagulase negative Staphylococci from clinical isolates and commensals along with Biofilm detection

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Author Details: Faiza Samreen, Anjana Gopi, Prachee Bele Kenge, Swati Jain

Volume : 4

Issue : 2

Online ISSN : 2394-5478

Print ISSN : 2394-546X

Article First Page : 194

Article End Page : 198


Background: Coagulase-Negative Staphylococci (CoNS) are commensals of the human skin and mucosa. However, Staphylococcus epidermidis (S. epidermidis) and other CoNS have emerged as nosocomial pathogens. This study aims to identify and characterize clinical and commensal isolates of CoNS, to compare their association with potential virulence factors and to determine their antimicrobial resistance pattern.
Materials and Method: This study was conducted in Department of Microbiology of a tertiary care centre in Bangalore. A total of 100 samples were processed (50 samples isolated from clinical samples were treated as cases and 50 from skin of healthy volunteers were considered as controls).Identification and speciation of CoNS was done by conventional biochemical tests. Antimicrobial susceptibility was tested by Kirby Bauer disc diffusion method. Detection of biofilm by Tissue culture plate method. Detection of icaAB, atlE genes which code for polysaccharide intracellular adhesin (PIA) that is fundamental for biofilm formation and mecA gene which encodes an altered Penicillin binding protein (PBP2a) mediating oxacillin resistance was done by multiplex PCR.
Results: Out of the 50 cases from clinical samples, 21/50 (42%) of the isolates were from blood, 18/50 (36%) from pus, 9/50 (18%) from urine and 2/50 (4%) were from CSF. S. epidermidis was the most common species isolated among clinical and commensal isolates. Biofilm was detected in 16/50 (32%) clinical isolates and 05/50 (10%) of controls. 37/50 (74%) cases and 27/50 (54%) controls were tested positive for mecA gene. 17/50 (34%) cases and 15/50 (30%) controls were found to express atlE gene. 20/50 (40%) cases and 12/50 (24%) controls possessed icaAB gene.
Conclusion: Species identification, antimicrobial susceptibility testing and understanding the genetic components involved in pathogenesis are important aids in the diagnosis and management of serious CoNS infections.

atlE gene, biofilm, Coagulase-Negative Staphylococci (CoNS), icaAB gene, mecA gene