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Results for “M. tuberculosis”

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At least 37 records · Page 2Linked to original sources
PubMed1975

Reappraisal of the activity of morphazinamide against M. tuberculosis.

Morphazinamide was shown to have an in vitro activity similar to an equimolar concentration of pyrazinamide. This activity was not due, as had been previously assumed, to pyrazinamide formed by hydrolysis from morphazinamide, since it was demonstrated in slide cultures containing tubercle bacilli which were incubated with freshly prepared dilutions of morphazinamide in acid medium for several successive periods of only 1 hour, during which time little hydrolysis occurred. A new method was used for measuring morphazinamide and pyrazinamide separately in plasma. In man, the estimated in vitro antibacterial activity was similar after approximately equimolar oral doses of morphazinamide or pyrazinamide. However, it is uncertain whether the in vivo activity of morphazinamide is the same as its in vitro activity.

Animals↗
PubMed1978

Comparison of various measures of sensitivity of M. tuberculosis to ethambutol.

A sensitivity test for ethambutol was standardised, and performed on cultures isolated from patients before and after the start of chemotherapy with ethambutol and isoniazid. A discrimination type of approach was employed and three criteria of resistance were evolved: (a) growth of 20 colonies or more on ethambutol 4 microgram/ml, using a standard inoculum; (b) a proportion of 25% or more on ethambutol 1.4 microgram/ml; (c) a proportion of 5% or more on ethambutol 2 microgram/ml. The MIC definition appears to be the best in view of its simplicity and insensitivity of the classification (as sensitive or resistant) to variations in inoculum size.

Drug Resistance, Microbial↗
PubMed1977

Cross-resistance in M. tuberculosis to kanamycin, capreomycin and viomycin.

Drug resistant mutants to streptomycin, kanamycin, viomycin, capreomycin, and rifampicin were isolated from four strains of Mycobacterium tuberculosis. The mutants isolated from each parent were then tested for evidence of development of cross-resistance to other drugs. There was no cross-resistance between either streptomycin or rifampicin and any of the other drugs. Complete cross-resistance between viomycin and capreomycin was found. Cross-resistance between kanamycin and capreomycin, and kanamycin and viomycin was variable. A review of the medical histories of 27 patients with kanamycin-resistant tubercle bacilli indicated that cross-resistance with capreomycin and viomycin occurs, but is unpredictable. Because of this variability in cross-resistance and the fact that kanamycin is a more toxic drug than capreomycin, it is suggested that capreomycin be used in the first retreatment regimen for tuberculosis when streptomycin resistance has been demonstrated.

Capreomycin↗
PubMed2025

Active- and Allosteric-Site Cyclic Peptide Inhibitors of Secreted M. tuberculosis Chorismate Mutase.

The secreted Chorismate mutase enzyme of Mycobacterium tuberculosis (*MtbCM) is an underexplored potential target for the development of new antitubercular agents that are increasingly needed as antibiotic resistance rises in prevalence. As an enzyme suspected to be involved in virulence and host-pathogen interactions, disruption of its function could circumvent the difficulty of treating tuberculosis-infected granulomas. Drug development, however, is limited by novel ligand discovery. Currently, *MtbCM activity is measured by using a low throughput acid/base-mediated product derivatization absorbance assay. Here, we utilized an RNA-display affinity selection approach enabled by the Random Peptides Integrated Discovery (RaPID) system to screen a vast library of macrocyclic peptides (MCP) for novel *MtbCM ligands. Peptides identified from the RaPID selection, and analogs thereof identified by analyzing the selection population dynamics, produced a new class of *MtbCM inhibiting MCPs. Among these were two noteworthy "chorismides", whose binding modes were elucidated by X-ray crystallography. Both were potent inhibitors of the CM enzyme activity. One was identified as an allosteric binding peptide revealing a novel inhibition approach, while the other is an active-site binding peptide that when conjugated to a fluorescent probe allowed for the development of a series of alternative fluorescence-based ligand-displacement assays that can be utilized for the assessment of potential *MtbCM inhibitors.

Mycobacterium tuberculosis↗