Biofilm producing and antibiotic resistant coagulase negative staphylococci in clinical samples isolated from tertiary care hospital of Nepal

This study investigated the phenotypic and genotypic characteristics of biofilm-producing coagulase negative staphylococci (CNS) isolated from clinical samples of a tertiary care hospital in Nepal. A total of 69 non duplicate CNS isolates were collected between August 2022 to February 2023. Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method. Biofilm formation was quantified by Tissue culture plate method (TCP) and the presence of icaA and mecA genes was detected by polymerase chain reaction (PCR). Among 69 CNS isolates, majority were resistant to penicillin (92.8%) and cefixime (89.9%). Methicillin resistance was observed among 63.8% isolates phenotypically while mecA gene was detected only in 75% isolates. Multidrug resistance was identified in 73.9% isolates and 91.3% demonstrated a MAR index of > 0.2. Majority of CNS (91.3%) were biofilm producers. TCP method revealed 31.9%, 17.4% and 42% CNS as strong, moderate and weak biofilm producers respectively. However, only 18.8% isolates showed the presence of icaA gene. No significant association was found between biofilm production, methicillin resistance and multidrug resistance. The combined phenotypic/molecular approach highlights the clinical relevance of multidrug resistant, biofilm forming CNS in clinical samples, underscoring the need for strengthened infection control and antimicrobial stewardship strategies.