Antimicrobial susceptibility testing of rapidly growing mycobacteria by microdilution - Experience of a tertiary care center

Dr Mohammed Rafiyuddin

Volume : VII, Issue : VIII, August - 2018

Antimicrobial susceptibility testing of rapidly growing mycobacteria by microdilution - Experience of a tertiary care center

Dr Mohammed Rafiyuddin

Abstract :

Purpose: The objective of the study was to perform antimicrobial susceptibility testing of rapidly growing mycobacteria(RGM) isolated from various clinically suspected cases of extrapulmonary tuberculosis, from January 2007 toApril 2008, at a tertiary care centre in Mumbai. Materials and Methods: The specimens were processed for microscopyand culture using the standard procedures. Minimum inhibitory concentrations (MIC) were determined by othmicrodilution, using Sensititre CA MHBT. Susceptibility testing was also carried out on Mueller Hinton agar by theKirby Bauer disc diffusion method. Results: Of the 1062 specimens received for mycobacterial cultures, 104 (9.79%)grew mycobacteria. Of the mycobacterial isolates, six (5.76%) were rapid growers. M. abscessusand M. chelonaeappeared to be resistant organisms, with M. chelonaeshowing intermediate resistance to amikacin and minocycline.However, all the six isolates showed sensitivity to vancomycin and gentamicin by the disc diffusion test. Also allthree isolates of M. abscessuswere sensitive to piperacillin and erythromycin. Further studies are required to test theirsensitivity to these four antimicrobials by using the microoth dilution test, before they can be prescribed to patients.

Conclusions: We wish to emphasize that reporting of rapidly growing mycobacteria from clinical settings, along withtheir sensitivity patterns, is an absolute need of the hour.