Comparison of Bacteriostatic and Bactericidal Activity of Isoniazid and Ethionamide against Mycobacterium avium and Mycobacterium tuberculosis 1- 3
LEONID B. HEIFETS, PAMELA J. LINDHOLM-LEVY, and MARCELLA FLORY
Introduction SUMMARY Minimal Inhibitory and bactericidal concentrations (MIC and MBC) of Isoniazid and
Isoniazid is recognized as the most imethionamide were determined In 7H12broth In experiments with 68 Mycobacterium ar/um strains portant drug in the treatment of tubercuand 14 wild drug-susceptible M. tuberculosis strains. MICs of Isoniazid for M. tuberculosis were losis. This fact influenced its wide use in from 0.025 to 0.05 Jig/ml, and for M. ar/um from 0.6 to > 10.0 Jig/mi. MICs of ethionamide for M. the chemotherapy of Mycobacterium avituberculosis werefrom 0.3to 1.25 Jig/ml, and 42.7% of M. ar/um strains were within the same range. urn disease even though the clinical outIsoniazid and ethJonamlde were highly bactericidal against M. tuberculosis, but they had very low bactericidal activity against M. ar/um. All REV RESPIR DIS 1991; 143:288-270 come of such treatment is unknown, either for patients with AIDS and disseminated disease or for patients without AIDS but with localized pulmonary disease. Ethionamide, a second-line drug in MO) was dissolved in distilled water, and that in the drug-free vial that represented 1070 the therapy of tuberculosis, is structur- ethionamide (Sigma) was dissolved in ethyl- of the bacterial population (1:100 control). ally related to isoniazid and is also used ene glycol. Appropriate working solutions The lowest concentration of drug in the presin the treatment of M. avium disease al- weremade in sterile distilled water from these ence of which the daily increase in the radiothough, once again, there is no firm evi- stock solutions and stored in aliquots at metric growth index (01) and final 01 readings were lower than those in the 1:100 con- 70 C until needed. dence of its effectiveness. trol was considered to have inhibited more Test Strains In 1952,extensivework with thiosemithan 99070 of the bacterial population, and carbazones led to the discovery of the ex- Sixty-eight strains of M avium, speciated by was therefore designated the MIC (9, 15).Our ceptional antituberculosis activity of Gen-Probe DNA-RNA hybridization, were previous studies have justified this approach isoniazid (1-3), though this substance had used in this study: 35 were isolated from pa- for both M. tuberculosis and M. avium on been synthesized 40 yr before (4). Ethion- tients with AIDS and 33 were isolated from the basis of comparison with the MIC deteramide was synthesized in 1956 (5), and patients without AIDS but with respiratory mined by sampling and plating from the same disease. Smooth transparent colonies, known its antituberculosis activity was described as SmT (14),growing on 7HI0 agar, were sub- vials and counting the number of cfu/ml (16, in 1959 (6). M. avium and M. intracel- cultivated in 7H9 broth, and aliquots of the 17). More technical details are given in these lulare are known to be resistant to isonia- broth cultures were preserved at - 70 C un- reports. Replicate radiometric testing of the zid (7, 8). Our previous studies (9) indi- til needed. To ensure having only transparent MICs in previous and current studies showed good reproducibility, with MICs the same or cated that ethionamide has greater inhibi- colonies, a fresh aliquot was thawed and used having a permissible one twofold dilution tory activity against M. avium than has for each MIC or MBC experiment. H37Rv variation. isoniazid. The bactericidal effect of iso- and 13clinical isolates of M tuberculosiswere MBC Determination niazid against M. tuberculosis was sug- subcultivated in 7H9 broth, and aliquots were gested in severalpublications (10-13), but made and frozen at - 70 C until needed. The The definition of MBC most often used in it has not been described in minimal bac- 68 strains of M avium and 14 strains of clinical microbiology designates it the lowest tericidal concentration (MBC) values or M. tuberculosis were used to determine the drug concentration that kills 99.9070 of the MICs. Previous studies on bactericidal activ- bacterial population within a limited period in MBC to minimal inhibitory concen- ity of antituberculosis drugs, particularly of of cultivation in liquid medium (18).Wehave tration (MIC) ratios. The MBCs of iso- isoniazid, have been done with one strain onniazid for M. avium have not been report- ly (10). We selected for our study the same ed, and there are no clear data in the liter- M. tuberculosis strain, H37Rv, but also in- (Received in original form May 14, 1990) ature on the MBC of ethionamide for cluded two clinical isolates of M. tuberculosis and four strains of M. avium. either M. tuberculosis or M. avium. 1 From the National Jewish Center for Immunology and Respiratory Medicine, and the DepartThe aims of this study were to deterMIC Determination ments of Microbiologyand Immunology and Medimine the MBC of isoniazid and ethionacine, Division of Pulmonary Sciences, University. The MIC was defined as the lowest concenmide against M. avium and, for compartration ofa drug that inhibited more than 99070 of Colorado Health Sciences Center, Denver, ison, against M. tuberculosis, and to of the bacterial population within 8 days of Colorado. compare the MBC/MIC ratios for both cultivation in 7H12 broth inoculated with 1
LEONID B. HEIFETS, PAMELA J. LINDHOLM-LEVY, and MARCELLA FLORY
Introduction SUMMARY Minimal Inhibitory and bactericidal concentrations (MIC and MBC) of Isoniazid and
Isoniazid is recognized as the most imethionamide were determined In 7H12broth In experiments with 68 Mycobacterium ar/um strains portant drug in the treatment of tubercuand 14 wild drug-susceptible M. tuberculosis strains. MICs of Isoniazid for M. tuberculosis were losis. This fact influenced its wide use in from 0.025 to 0.05 Jig/ml, and for M. ar/um from 0.6 to > 10.0 Jig/mi. MICs of ethionamide for M. the chemotherapy of Mycobacterium avituberculosis werefrom 0.3to 1.25 Jig/ml, and 42.7% of M. ar/um strains were within the same range. urn disease even though the clinical outIsoniazid and ethJonamlde were highly bactericidal against M. tuberculosis, but they had very low bactericidal activity against M. ar/um. All REV RESPIR DIS 1991; 143:288-270 come of such treatment is unknown, either for patients with AIDS and disseminated disease or for patients without AIDS but with localized pulmonary disease. Ethionamide, a second-line drug in MO) was dissolved in distilled water, and that in the drug-free vial that represented 1070 the therapy of tuberculosis, is structur- ethionamide (Sigma) was dissolved in ethyl- of the bacterial population (1:100 control). ally related to isoniazid and is also used ene glycol. Appropriate working solutions The lowest concentration of drug in the presin the treatment of M. avium disease al- weremade in sterile distilled water from these ence of which the daily increase in the radiothough, once again, there is no firm evi- stock solutions and stored in aliquots at metric growth index (01) and final 01 readings were lower than those in the 1:100 con- 70 C until needed. dence of its effectiveness. trol was considered to have inhibited more Test Strains In 1952,extensivework with thiosemithan 99070 of the bacterial population, and carbazones led to the discovery of the ex- Sixty-eight strains of M avium, speciated by was therefore designated the MIC (9, 15).Our ceptional antituberculosis activity of Gen-Probe DNA-RNA hybridization, were previous studies have justified this approach isoniazid (1-3), though this substance had used in this study: 35 were isolated from pa- for both M. tuberculosis and M. avium on been synthesized 40 yr before (4). Ethion- tients with AIDS and 33 were isolated from the basis of comparison with the MIC deteramide was synthesized in 1956 (5), and patients without AIDS but with respiratory mined by sampling and plating from the same disease. Smooth transparent colonies, known its antituberculosis activity was described as SmT (14),growing on 7HI0 agar, were sub- vials and counting the number of cfu/ml (16, in 1959 (6). M. avium and M. intracel- cultivated in 7H9 broth, and aliquots of the 17). More technical details are given in these lulare are known to be resistant to isonia- broth cultures were preserved at - 70 C un- reports. Replicate radiometric testing of the zid (7, 8). Our previous studies (9) indi- til needed. To ensure having only transparent MICs in previous and current studies showed good reproducibility, with MICs the same or cated that ethionamide has greater inhibi- colonies, a fresh aliquot was thawed and used having a permissible one twofold dilution tory activity against M. avium than has for each MIC or MBC experiment. H37Rv variation. isoniazid. The bactericidal effect of iso- and 13clinical isolates of M tuberculosiswere MBC Determination niazid against M. tuberculosis was sug- subcultivated in 7H9 broth, and aliquots were gested in severalpublications (10-13), but made and frozen at - 70 C until needed. The The definition of MBC most often used in it has not been described in minimal bac- 68 strains of M avium and 14 strains of clinical microbiology designates it the lowest tericidal concentration (MBC) values or M. tuberculosis were used to determine the drug concentration that kills 99.9070 of the MICs. Previous studies on bactericidal activ- bacterial population within a limited period in MBC to minimal inhibitory concen- ity of antituberculosis drugs, particularly of of cultivation in liquid medium (18).Wehave tration (MIC) ratios. The MBCs of iso- isoniazid, have been done with one strain onniazid for M. avium have not been report- ly (10). We selected for our study the same ed, and there are no clear data in the liter- M. tuberculosis strain, H37Rv, but also in- (Received in original form May 14, 1990) ature on the MBC of ethionamide for cluded two clinical isolates of M. tuberculosis and four strains of M. avium. either M. tuberculosis or M. avium. 1 From the National Jewish Center for Immunology and Respiratory Medicine, and the DepartThe aims of this study were to deterMIC Determination ments of Microbiologyand Immunology and Medimine the MBC of isoniazid and ethionacine, Division of Pulmonary Sciences, University. The MIC was defined as the lowest concenmide against M. avium and, for compartration ofa drug that inhibited more than 99070 of Colorado Health Sciences Center, Denver, ison, against M. tuberculosis, and to of the bacterial population within 8 days of Colorado. compare the MBC/MIC ratios for both cultivation in 7H12 broth inoculated with 1
