The Dual Threat: Phenotypic Characterization and Virulence Factor Detection of Staphylococci Across Various Clinical Samples

Abstract

Background and aim: Coagulase-negative staphylococci (CoNS), apart from Staphylococcus aureus are major causative agents of nosocomial infections, as evident from their increasing incidence in recent years. Aim: To phenotypically characterize staphylococcal isolates from various clinical samples, detect different virulence factors and evaluate their antibiotic resistance pattern.

Materials and Methods: A total of 130 clinical specimens were analysed in a tertiary care hospital. The isolates were identified, speciated using standard methods, biofilm formation as well as antibiotic susceptibility using the Kirby Bauer disc diffusion method were determined in the department of Microbiology. Statistical analysis was done by counts and percentages using MS Excel version 2010.

Results: CoNS constituted the majority (67.5%) of isolates, while S. aureus accounted for 32.4%. A significant proportion of staphylococci (75.6%) were strong biofilm producers, with an additional 16.2% being moderate biofilm producers, highlighting the widespread nature of this virulence factor. High resistance was observed among biofilm-producing strains to conventional antibiotics with methicillin resistance of 91.6% in S. aureus and 84% in CoNS, although all isolates remained sensitive to vancomycin and linezolid. Staphylococcus schleiferi (20%) was the most common CoNS species identified, followed by S. hemolyticus (16%) and S. simulans (16%), a finding that differs from some other regional studies.

Conclusion: The multiple antibiotic resistance and pathogenic potential of biofilm producers emphasize the importance of developing simple, reliable, and inexpensive methods to identify virulence factors, determine the antibiotic sensitivity of CoNS and the critical need for rigorous infection control measures to mitigate the burden of these infections.