Bactericidal action of oleic acid for tubercle bacilli. I. Quantitative and analytical survey of the action

A Protein Complex from Human Milk Enhances the Activity of Antibiotics and Drugs against Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of human tuberculosis (TB), has surpassed HIV/AIDS as the leading cause of death from a single infectious agent. The increasing occurrence of drug-resistant strains has become a major challenge for health care systems and, in some cases, has rendered TB untreatable. However, the development of new TB drugs has been plagued with high failure rates and costs. Alternative strategies to increase the efficacy of current TB treatment regimens include host-directed therapies or agents that make M. tuberculosis more susceptible to existing TB drugs. In this study, we show that HAMLET, an α-lactalbumin-oleic acid complex derived from human milk, has bactericidal activity against M. tuberculosis HAMLET consists of a micellar oleic acid core surrounded by a shell of partially denatured α-lactalbumin molecules and unloads oleic acid into cells upon contact with lipid membranes. At sublethal concentrations, HAMLET potentiated a remarkably broad array of TB drugs and antibiotics against M. tuberculosis For example, the minimal inhibitory concentrations of rifampin, bedaquiline, delamanid, and clarithromycin were decreased by 8- to 16-fold. HAMLET also killed M. tuberculosis and enhanced the efficacy of TB drugs inside macrophages, a natural habitat of M. tuberculosis Previous studies showed that HAMLET is stable after oral delivery in mice and nontoxic in humans and that it is possible to package hydrophobic compounds in the oleic acid core of HAMLET to increase their solubility and metabolic stability. The potential of HAMLET and other liprotides as drug delivery and sensitization agents in TB chemotherapy is discussed here.

EFFECT OF TWEEN 80 ON THE GROWTH OF TUBERCLE BACILLI IN AERATED CULTURES

Lyon, Richard H. (Veterans Administration Hospital, Minneapolis, Minn.), Herman C. Lichstein, and Wendell H. Hall. Effect of Tween 80 on the growth of tubercle bacilli in aerated cultures. J. Bacteriol. 86:280-284. 1963.-The effect of Tween 80 (polyoxyethylene sorbitan monooleate), glucose, and glycerol on aerated and stationary growth of Mycobacterium tuberculosis strain H(37)Ra was examined in Dubos liquid medium. Previous studies established that aeration (rotation) of liquid cultures of M. tuberculosis strains H(37)Ra and H(37)Rv caused an inhibition of growth in a medium containing glucose as a source of carbohydrate. The present studies show that Tween 80 exerts a toxic effect on the growth of tubercle bacilli in aerated cultures when glucose is present in the medium as the sole source of carbohydrate, but not when glycerol is included. The role of hydrolytic products of Tween 80, viz. oleic acid and the polyoxyethylene derivative of sorbitol, is discussed. The hypothesis is submitted that glycerol protects against the growth suppression by aeration because it reduces the concentration of free fatty acids in the medium to subinhibitory levels.

Microthrix parvicella, a filamentous bacterium isolated from activated sludge: cultivation in a chemically defined medium

A large number of media have been tested for cultivating Microthris parvicella, a filamentous microorganism often present in the activated sludge of oxidation ditches. The bacterium was found to utilize oleic acid (preferably as Tween 80) as the sole source of carbon and energy. Sulfur is required in the reduced form. The tested media vary from a complex to a chemically defined medium. Growth yields of 1.3 to 1.5 g/liter were obtained on media containing Tween 80 (4 g/liter), reduced nitrogen and reduced sulfur compounds, calcium and magnesium salts, phosphate buffer, trace elements, thiamin, and cyanocobalamin. The optimum temperature for growing the organism is approximately 25 degrees C, and the pH of the nutrient medium should be above 7.

Bactericidal action of oleic acid for tubercle bacilli. II. Morphological response

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