Speciation of Clinically Significant Coagulase Negative Staphylococci Isolates from Clinical Samples and their Susceptibility Pattern: A Cross-sectional Study from Western Uttar Pradesh, India

Introduction: Coagulase-negative Staphylococci (CoNS) have emerged as predominant organisms associated with a variety of infections, particularly Bloodstream Infections (BSIs). As CoNS isolates become increasingly resistant to antimicrobials, this presents a potentially concerning emerging characteristic. There is a need to identify the species and resistance profile of CoNS. These organisms are increasingly recognised as nosocomial pathogens and are associated with multiple antimicrobial resistance mechanisms, particularly methicillin resistance. Rapid and reliable identification at the species level is essential to predict the potential pathogenicity or antibiotic susceptibility of each clinical isolate. Aim: To isolate and assess the speciation of CoNS from various clinical specimens and to determine the antibiotic susceptibility profile, with special reference to linezolid and vancomycin. Materials and Methods: This was a hospital-based crosssectional study carried out in the Department of Microbiology at Subharti Medical College, a tertiary care teaching hospital in Western Uttar Pradesh (UP), India. The duration of the study was one year, from January 2019 to December 2019. A total of 1,061 clinically significant isolates of CoNS were presumptively identified by standard bacteriological techniques, which were further confirmed at the species level by an automated Vitek-2 Compact system. Antimicrobial Susceptibility Testing (AST) was conducted using the Kirby-Bauer disc diffusion method, and the Minimum Inhibitory Concentration (MIC) for vancomycin was assessed using the automated Vitek-2 Compact system. The data were analysed using the Statistical Package for the Social Sciences (SPSS) version 20.0. Statistical analysis included the Chi-square test. Results: A total of 1,061 CoNS were isolated. CoNS were predominantly isolated from Inpatient Department (IPD) samples, with 993/1,061 (93.60%) coming from these sources, and the majority from blood (928/1,061; 87.46%), followed by pus (69/1,061; 6.50%) and urine (31/1,061; 2.92%). There was male predominance, with 606/1,061 (57%), and isolation rates were higher among the extremes of age. Staphylococcus epidermidis (472/1,061; 44.48%) was the predominant species isolated, followed by Staphylococcus haemolyticus (360/1,061; 33.93%). The majority of the isolates were resistant to penicillin (995/1,061; 93.77%), followed by erythromycin (896/1,061; 84.45%) and cotrimoxazole (798/1,061; 75.2%). The prevalence of methicillin resistance among CoNS was 964/1,061 (90.9%). The emergence of resistance to linezolid in 27/1,061 (2.54%) was concerning; however, all isolates were sensitive to vancomycin. Conclusion: Multidrug-resistant CoNS are an emerging therapeutic problem in hospital settings because their prevalence not only limits treatment options but also acts as a reservoir for drug-resistant genes. Speciation and susceptibility testing of these isolates are essential for better clinical outcomes.