Journal of Clinical Microbiology, March 1999, p. 748-752, Vol. 37, No. 3
0095-1137/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
New York University School of Medicine,
Received 12 October 1998/Returned for modification 11 November
1998/Accepted 27 November 1998
We evaluated the BACTEC MGIT 960 system, which is a fully
automated, noninvasive system for the growth and detection of
mycobacteria with a capacity to incubate and continuously monitor 960 7-ml culture tubes. We studied 3,330 specimens, 2,210 respiratory and 1,120 nonrespiratory specimens, collected from 2,346 patients treated
at six sites. Processed specimens were inoculated into the BACTEC MGIT
960 and BACTEC 460 TB systems, as well as onto Lowenstein-Jensen slants
and Middlebrook 7H11/7H11 selective plates. From all culture systems, a
total of 362 isolates of mycobacteria were recovered; these were
recovered from 353 specimens collected from 247 patients. The greatest
number of isolates of mycobacteria (289, or 80% of the 362 isolates)
was recovered with the BACTEC MGIT 960, followed by the BACTEC 460 TB
(271, or 75%) and solid media (250, or 69%). From all culture systems
a total of 132 isolates of Mycobacterium tuberculosis
complex were recovered. The greatest number of isolates of M. tuberculosis complex was recovered when liquid medium was
combined with conventional solid media; the number recovered with
BACTEC 460 TB plus solid media was 128 (97%), that recovered with
BACTEC MGIT 960 plus solid media was 121 (92%), that recovered with
BACTEC 460 TB was 119 (90%) and that recovered with all solid media
combined was 105 (79%). The recovery with BACTEC MGIT 960 alone was
102 (77%). The mean times to detection (TTD) for M. tuberculosis complex were 14.4 days for BACTEC MGIT, 15.2 days
for BACTEC 460 TB, and 24.1 days for solid media. The numbers of
isolates of Mycobacterium avium complex (MAC) recovered were 172 (100%) for all systems, 147 (85%) for BACTEC MGIT 960, 123 (72%) for BACTEC 460 TB, and 106 (62%) for all solid media combined.
The TTD for MAC in each system were 10.0 days for BACTEC MGIT 960, 10.4 days for BACTEC 460 TB, and 25.9 days for solid media. Breakthrough
contamination rates (percentages of isolates) for each of the systems
were 8.1% for BACTEC MGIT 960, 4.9% for BACTEC 460 TB, and 21.1% for
all solid media combined.
*
Corresponding author. Mailing address: Department of
Pathology, New York University School of Medicine, Bellevue 4W1, New York, NY 10016. Phone: (212) 263-6444. Fax: (212) 263-8284. E-mail: bah2{at}is2.nyu.edu.
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