Speciation and Antibiotic Susceptibility Pattern of Coagulase Negative Staphylococci in a Tertiary Care Hospital of Manipur, India

Introduction: Coagulase Negative Staphylococci (CoNS) are common opportunistic pathogens. They are increasingly being recognised as nosocomial pathogens and are associated with multiple antimicrobial resistance mechanisms particularly methicillin resistance. Therefore, rapid and reliable identification upto the species level is necessary to predict the potential pathogenicity or antibiotic susceptibility of each clinical isolate.

Aim: The aim of the present study was isolation and speciation of CoNS from various clinical samples, and to determine their antibiotic susceptibility pattern.

Materials and Methods: This study was a hospital-based cross-sectional study carried out in the Department of Microbiology, Jawaharlal Nehru Institute of Medical Sciences (JNIMS), Imphal, Manipur, India, during the period from September 2017-August 2019. Total 135 CoNS isolates were identified using conventional microbiological procedures and speciation was done following the scheme of Kloos and Schleifer. Antibiotic susceptibility was determined by using the Kirby Bauer’s disk diffusion method. Detection of methicillin resistance among CoNS was performed using cefoxitin disk (30 μg) diffusion method. Data analysis was done using descriptive statistics.

Results: CoNS isolates were identified from different clinical specimens, which included 88 (65.2%) from urine, 37 (27.5%) from blood, 3 (2.2%) from pus, 2 (1.5%) from catheter tip, 2 (1.5%) from wound swab, 1 (0.7%) each from aural swab, sputum and ascitic fluid. Predominant isolates were Staphylococcus epidermidis (40.7%) followed by Staphylococcus haemolyticus (19.3%), Staphylococcus hominis (11.9%), Staphylococcus xylosus (7.4%), Staphylococcus saprophyticus (6.0%), Staphylococcus schleiferi (5.2%), Staphylococcus simulans (4.4%), Staphylococcus warneri (3.0%), Staphylococcus lugdunensis (0.7%), Staphylococcus capitis (0.7%) and Staphylococcus cohnii (0.7%). Most isolates were resistant to penicillin (84.5%) and erythromycin (59.3%), and least to tigecycline (2.2%). No resistance to vancomycin and linezolid was seen. Methicillin sensitive CoNS (MSCoNS) was detected in 79 (58.5%) isolates and methicillin resistant CoNS (MRCoNS) in 56 (41.5%) isolates.

Conclusion: This study demonstrated the occurrence of various species of CoNS in our healthcare set up with varying antimicrobial susceptibility pattern. Therefore, there is a need for accurate identification to species level by simple, inexpensive methodology and their antibiogram.