Radiometric method for testing susceptibility of mycobacteria to pyrazinamide in 7H12 broth

Journal Article · Fri Feb 01 00:00:00 EST 1985 · J. Clin. Microbiol.; (United States)

OSTI ID:5676150

Heifets, L B; Iseman, M D

The test of susceptibility to pyrazinamide requires an acid environment (pH less than or equal to 5.5). This, however, is not favorable to the growth of Mycobacterium tuberculosis, especially in solid agar media. To obviate this difficulty, we developed a testing method with 7H12 broth medium and based on radiometric readings of the growth. The radiometric method employed in this study (BACTEC system) provides an opportunity to detect the dynamics of growth by daily recording of the growth index, which reflects the metabolic activity of the multiplying bacteria. In our technique, M. tuberculosis isolates were initially cultivated at pH 6.8. After logarithmic growth had begun, phosphoric acid solution was added to obtain pH 5.5. When pyrazinamide was added simultaneously with the acid, the growth index of susceptible cultures decreased, whereas it continued to increase in pH 5.5 control vials and in tests with pyrazinamide-resistant strains.

• Research Organization: National Jewish Hospital and Research Center/National Asthma Center, Denver, CO
• OSTI ID: 5676150
• Journal Information: J. Clin. Microbiol.; (United States), Vol. 21:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
MYCOBACTERIUM TUBERCULOSIS
GROWTH
AMIDASES
CARBON 14 COMPOUNDS
CULTURE MEDIA
INHIBITION
PH VALUE
PYRAZINES
SENSITIVITY
AZINES
BACTERIA
ENZYMES
HETEROCYCLIC COMPOUNDS
HYDROLASES
LABELLED COMPOUNDS
MICROORGANISMS
MYCOBACTERIUM
NON-PEPTIDE C-N HYDROLASES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
550701* - Microbiology- Tracer Techniques