Intrinsic resistance of Mycobacterium tuberculosis to clarithromycin is effectively reversed by subinhibitory concentrations of cell wall inhibitors.

Subinhibitory concentrations of bacitracin, vancomycin and other inhibitors of cell wall synthesis reversed to varying extents the intrinsic resistance of Mycobacterium tuberculosis to clarithromycin. Ethambutol reversed clarithromycin resistance in all of the M. tuberculosis strains studied regardless of their susceptibility to this drug.

Comparative in vitro activity of phenothiazines against multidrug-resistant Mycobacterium tuberculosis.

The comparative activity of five phenothiazines against multidrug-resistant strains of Mycobacterium tuberculosis (MDRTB) was studied using the Bactec 460 system. The order of antimycobacterial activity of the phenothiazines was: chlorpromazine = thioridazine > promethazine > promazine = desipramine. However, the levels required for an MIC 50 exceeded 1 mg/l and are beyond those that are clinically achievable. As phenothiazines are concentrated by macrophages that phagocytose and have in situ activity against mycobacteria, these agents may be considered for use as adjuvants for the management of freshly diagnosed tuberculosis in patients from populations with a high prevalence of MDRTB.

Evaluation of growth promotion and inhibition from mycobactins and nonmycobacterial siderophores (Desferrioxamine and FR160) in Mycobacterium aurum.

Heterologous mycobactins and the synthetic FR160 [N4-nonyl,N1,N8-bis(2,3-dihydroxybenzoyl) spermidine hydrobromide (C3 0H4 6N3, O6 Br)] promoted growth in Mycobacterium aurum in low concentrations. They were otherwise highly inhibitory, as opposed to homologous mycobactin, which was strictly growth promoting. Desferrioxamine B (Desferal) had no significant effect on growth.