Comparison of MB-Check and Löwenstein-Jensen media for recovery of mycobacteria

• Published in: Microscopy research and technique Vol. 38; no. 5; pp. 512 - 518
• Main Authors: Palacios, Juan J., García, José M., Ferro, José, Rodríguez, Javier, Sánchez, Andrés, Villar, Henar, Muñiz, Manuel M., Marrón, Manuel G., Ozores, María, Calvo, Carmen, Prendes, Pilar
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.1997
• Subjects: Bacterial Typing Techniques; Culture Media; diagnosis; DNA probes; Mycobacterium tuberculosis; Mycobacterium tuberculosis - classification; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Septi-Chek AFB; tuberculosis
• ISSN: 1059-910X; 1097-0029
• DOI: 10.1002/(SICI)1097-0029(19970901)38:5<512::AID-JEMT8>3.0.CO;2-J

We have compared the rate of recovery of mycobacteria with the MB‐Check culture system (liquid phase) and the Löwenstein‐Jensen (LJ) medium in 2,907 clinical specimens obtained from 830 patients submitted for mycobacterial culture during 1‐year period. Direct smear examination was carried out by auramine‐rhodamine staining. All primary isolates from the culture media were confirmed by Ziehl‐Neelsen staining and identified by acridinium‐ester‐labeled DNA probes specific for Mycobaterium tuberculosis complex. A total of 214 isolates were of the M. tuberculosis complex (88 patients) and 54 of “potentially pathogenic environmental mycobacteria” (45 patients). A total of 117 (54.7%) samples were smear‐positive and the remaining 97 (45.3%) were smear‐negative. There was a significant difference in the percentage of positive cultures obtained by the MB‐Check method (99.1%) as compared with the LJ medium (73.8%) (P < 0.05). This difference, however, occurred almost exclusively at the expense of the 97 smear‐negative samples (positive cultures 97.95% by the MB‐Check method vs. 42.3% by the LJ culture, P < 0.05). The number of patients diagnosed of tuberculosis by the MB‐Check was significantly higher as compared with LJ medium (88 [100%] vs. 77 [87.5%], P < 0.05). In 11 (12.5%) patients, the diagnosis was only established by the MB‐Check system. In smear‐positive samples, the mean (± SD) detection time for M. tuberculosis complex was 14.8 ± 8 days with MB‐Check and 19.9 ± 7 days with LJ medium. The corresponding figures in smear‐negative samples were 22.8 ± 3 days and 27.8 ± 6 days, respectively. DNA probes directly applied to MB‐Check liquid medium showed a sensitivity of 98.8% and specificity of 100%. These results indicate that the MB‐Check system is more efficient for the recovery of mycobacteria than LJ medium. Microsc. Res. Tech. 38:512–518, 1997. © 1997 Wiley‐Liss, Inc.