Rapidly growing mycobacteria: testing of susceptibility to 34 antimicrobial agents by broth microdilution

Abstract

A total of 18 strains of Mycobacteriumfortuitum, 15 strains of M. chelonei, and 31 strains of M. chelonei-like organisms were tested by both broth microdilution and agar dilution to determine their susceptibility to 34 antimicrobial agents. All strains grew well enough in cation-supplemented Mueller-Hinton broth for endpoints to be read after 72 h of incubation. Some strains of M. chelonei did not grow on Mueller-Hinton agar. A few discrepancies were noted between the broth and agar procedures. For M. fortuitum, doxycycline, minocycline, amikacin, sulfamethoxazole, and sulfamethoxazole-trimethoprim were the most active agents. For M. chelonei, amikacin, sisomicin, tobramycin, and erythromycin were the most active agents. The M. chelonei-like organisms were most susceptible to ampicillin, doxycycline, minocycline, amikacin, erythromycin, sulfamethoxazole, and sulfamethoxazole-trimethoprim. Broth microdilution appears to be a reliable method for susceptibility testing of rapidly growing mycobacteria, although clinical studies are needed to determine how well in vitro results correlate with therapeutic in vivo outcome.

Standartization of broth microdilution method for Mycobacterium tuberculosis

“…The BMM was used for determining drug susceptibility of M. avium (Telles & Yates 1994, Collins & Franzblau 1997, of rapidly growing mycobacteria (Swenson et al 1982) and other slowly growing mycobacteria including M. tuberculosis (Wallace Jr et al 1986). To improve the mycobacterial growing reading, an association of this method with colorimetric techniques was suggested (GomesFlores et al 1995, Sato et al 1997, Franzblau et al 1998).…”

Antibacterial Activities of Ramalin, Usnic Acid and its Three Derivatives Isolated from the Antarctic Lichen Ramalina terebrata

“…The qualitative antibacterial assay was performed by the disk diffusion assay as described previously (Bhattarai et al, 2006) to measure the zone of inhibition of the target microorganism. The quantitative antibacterial assay was performed by determining the minimum inhibitory concentration (MIC) of the test sample against the target microorganism as described previously (Swenson et al, 1982).…”

Antimicrobial Activity of Extracts from Ecuadorian Lichens

“…The bacteria were incubated in Petri dished for 24 h at 28 °C (B. subtilis) or 37 °C (E. coli and S. aureus). The inhibition zones for bacteria growth were measured after 24 h. Minimal inhibitory concentration (MIC) was determined using the broth dilution method [7] with some modifications. Determination of the sensitivity of phytopathogenic bacteria to plant extracts was carried out by limiting dilution on a potato agar (PA) solid nutrient medium.…”