sodium-dodecyl-sulfate and Mycobacterium-Infections

Mycobacterium tuberculosis infects one-third of the world's population and causes two million deaths annually. The unusually low permeability of its cell wall contributes to the ability of M. tuberculosis to grow within host macrophages, a property required for pathogenesis of infection. Mycobacterium marinum is an established model for discovering genes involved in mycobacterial infection. Mycobacterium marinum mutants with transposon insertions in the beta-ketoacyl-acyl carrier protein synthase B gene (kasB) grew poorly in macrophages, although growth in vitro was unaffected. Detailed analyses by thin-layer chromatography, nuclear magnetic resonance (NMR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, infrared spectroscopy, and chemical degradations showed that the kasB mutants synthesize mycolic acids that are 2-4 carbons shorter than wild type; the defect was localized to the proximal portion of the meromycolate chain. In addition, these mutants showed a significant (approximately 30%) reduction in the abundance of keto-mycolates, with a slight compensatory increase of both alpha- and methoxy-mycolates. Despite these small changes in mycolate length and composition, the kasB mutants exhibited strikingly altered cell wall permeability, leading to a marked increase in susceptibility to lipophilic antibiotics and the host antimicrobial molecules defensin and lysozyme. The abnormalities of the kasB mutants were fully complemented by expressing M. tuberculosis kasB, but not by the closely related gene kasA. These studies identify kasB as a novel target for therapeutic intervention in mycobacterial diseases.

Topics: Animals; Anti-Bacterial Agents; Cell Line; Cell Wall; Cerulenin; Chromatography, Gas; Chromatography, Thin Layer; Colony Count, Microbial; Defensins; DNA Transposable Elements; Drug Resistance, Bacterial; Genetic Complementation Test; Macrophages; Magnetic Resonance Spectroscopy; Mice; Muramidase; Mutagenesis, Insertional; Mycobacterium Infections; Mycobacterium marinum; Mycolic Acids; Permeability; Phagosomes; Rifampin; Sodium Dodecyl Sulfate; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrophotometry, Infrared

A total of 52 mycobacterial isolates were recovered from 1,197 clinical specimens decontaminated by a sodium dodecyl (lauryl) sulfate (SDS)-NaOH protocol. Of these, 94% were recovered with the BacT/Alert 3D system (Organon Teknika, Durham, N.C.) and 79% were recovered on Löwenstein-Jensen (LJ) medium. Mean times to detection of organisms of the Mycobacterium tuberculosis complex (n = 47) were 22.8 days with LJ medium and 16.2 days with the system. The BacT/Alert 3D system is a rapid and efficient detection system which can be used with an SDS-NaOH decontamination procedure.

Topics: Bacteriological Techniques; Culture Media; Disinfection; Humans; Mycobacterium; Mycobacterium Infections; Mycobacterium tuberculosis; Sodium Dodecyl Sulfate; Sodium Hydroxide; Tuberculosis