Identification of Inducible Clindamycin Resistance in Staphylococcus aureus using Automated Vitek-2 Compact System and D test

Abstract

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common pathogen causing serious and life-threatening clinical infections. Detecting inducible resistance to clindamycin (ICR) in S. aureus is challenging with routine testing methods, potentially leading to treatment failure. Hence, use of both automated systems like VITEK-2 and conventional methods for detecting ICR in routine microbiology laboratories will be helpful in accurate diagnosis. Aim and Objectives: To identify S. aureus in clinical samples and assess the reliability of VITEK-2 for detecting inducible clindamycin resistance as compared to routine D-test. Materials and methods: A total of 80 isolates of S. aureus were identified from clinical samples by routine conventional microbiological methods and antibiotic susceptibility testing was performed using both automated VITEK-2 and conventional technique. Results: The sensitivity of the Vitek-2 test for detecting ICR was 91.18% and specificity was 100% as compared to D-test. The PPV and NPV were 100% and 94.23% respectively. However, 3 isolates which showed ICR by D-test could not be detected in VITEK-2 system. Conclusion: Use of both automated systems and routine conventional techniques together in detecting ICR in Staphylococcus aureus will accurately give the diagnosis and accelerate the treatment. Keywords: VITEK-2, D-test, Resistance, Staphylococcus aureus, Inducible clindamycin resistance (ICR)