The causative agent of Johne's disease is Mycobacterium avium subsp. paratuberculosis. This is a chronic, debilitating gastrointestinal disorder that affects ruminants and is responsible for significant economic loss. The specimen processing method that combines C(18)-carboxypropylbetaine (CB-18) treatment and lytic enzyme decontamination has been shown to improve the diagnosis of mycobacterios...

A radiometric method for testing the susceptibility of Mycobacterium tuberculosis to pyrazinamide in egg-yolk-enriched 12A medium (pH 5.5) is described. We obtained 100% agreement between the 7H10 agar method with 25 microgram of pyrazinamide per ml and the modified radiometric method with a drug concentration of 50 microgram/ml in tests of 90 clinical isolates.

Nocardia farcinica infections are rare and potentially life threatening. Identification is based on growth at 45 degreesC, opacification of Middlebrook 7H10 agar, and resistance to antibiotics. We describe a case of fatal pulmonary N. farcinica infection in a patient with pneumoconiosis that was diagnosed by culture of sputum onto selective media.

Thirty strains of mycobacteria, consisting of 17 species, were inhibited by various concentrations of garlic extract incorporated in Middlebrook 7H10 agar. The concentration required ranged from a low of 1.34 mg/ml to a high of 3.35 mg/ml of media. When there were multiple strains of a species, a mean inhibitory concentration was determined for that species. Six strains of Mycobacterium tubercu...

Among 58 aerobic actinomycetes isolated from different sources and geographical locations, none of 23 Nocardia asteroides isolates, at 18 N. farcinica isolates, 1 of 5 N. otitidiscaviarum isolates, and 1 of 4 Rhodococcus species isolates opacified Middlebrook 7H10 medium. Within the N. asteroides complex, this characteristic, together with growth at 45 degrees C and resistance to each of erythr...

Two novel systems were evaluated for performing indirect kanamycin susceptibility tests on 72 strains of Mycobacterium tuberculosis. The microplate Alamar blue colorimetric method (breakpoint, 2.5 microg/ml) and the Mycobacterium Growth Indicator Tube (MGIT) system (breakpoint, 5.0 microg/ml) both produced 98.6% agreement when compared with the conventional proportion method performed on 7H10 a...