Determination of MIC of Different Antibiotics against Intermediate Isolates of S. aureus at a Tertiary Care Hospital by E-test

Abstract

Background: The E-test involves using a predefined antibiotic gradient on a strip, which is then placed on an agar plate containing the bacterial culture. The point at which the antibiotic concentration on the strip causes inhibition of bacterial growth is taken as the MIC. This method allows for the rapid and accurate determination of the MIC of antibiotics against specific bacterial strains and can aid in selecting appropriate antibiotics for treatment. Objectives: The aim of this study was also to include a comparison of the results with those of previous studies and an evaluation of the study's limitations. Method: A cross-sectional microbiological study was conducted at the Department of Microbiology, and the Department of ENT Rajshahi Medical College, Bangladesh, from January to December 2019. This section will provide a detailed description of the methods used in the study, including the study design, sampling methods, and procedures for collecting and analyzing the data. The methods section will also explain the E-test method used to determine MIC, including the procedure for performing the test and the criteria for interpreting the results. Results: A total of 96 samples, among 73 isolates from 68 culture-positive cases, 37 isolates showed intermediate susceptibility towards selected antibiotics such as beta-lactams, aminoglycosides and quinolones by disc diffusion method. Regarding MIC breakpoint in terms of susceptibility, out of 21 intermediate isolates of S. aureus, 16(76.2%) were susceptible, 01(4.8%) was intermediate, and 04(19%) were resistant to different antibiotics by E-test. Conclusion: In general, the conclusion of such an article would likely summarize the study's findings, such as the MIC values for the different antibiotics tested and how they compare to established MIC breakpoints, and any significant observations or trends noted. It may also discuss the clinical relevance of the results and provide recommendations for future research.