Determination of Inducible Clindamycin Resistance and Correlation with Vitek2 Inducible Clindamycin Resistance Test in Staphylococcus aureus Isolated from Clinical Samples.

Abstract

To compare the performance of Vitek2 with the gold standard D test in terms of inducible clindamycin resistance (ICR) detection. Descriptive study. Place and Duration of the Study: Indus Hospital and Health Network Karachi, Pakistan, from November 2021 to April 2022. Standard operating procedures of the laboratory were followed for processing of clinical samples. Methicillin-resistant Staphylococcus aureus (MRSA) isolates were included. The isolates from the same patient within two-week time period were excluded. Clinical laboratory standards institute guidelines were followed for performing and interpreting D test. The results of the D test were compared with Vitek2 results for ICR. A total of 313 isolates were MRSA, of which 93 isolates tested positive for ICR on both the D test and Vitek2. Nine isolates were positive for ICR on Vitek2 and negative on the Kirby-Bauer disk diffusion method. One isolate tested positive on the disk method and negative on Vitek2. Vitek 2 appeared to give false positive results. Reporting false susceptibility of clindamycin can cause therapeutic failure which can markedly affect the patient's outcome. This discordance needs to be investigated further with a large sample size and stringent observation of D-test results to pick laboratory error. Methicillin-resistant Staphylococcus aureus, Inducible clindamycin resistance, D zone, Vitek2.