BioMed Research International

Research Article

Macrocolonies (Granules) Formation as a Cause of False-Negative Results in the MGIT 960 System: Cause Analysis and Correlation with Mycobacterial Species

Table 2

The MGIT culture outcomes when inoculated with different bacterial loads in duplicate (by tubes).
Number and speciesDiluted McFarland turbidity standardCulture positiveTurn-around time (days)
(means ± SD)		Culture negative with granules formingCulture negative without granules forming
3 M. xenopi strains10−56/69.67 ± 1.030/60/6
10−62/613.5 ± 0.714/60/6
10−71/626.3 ± 0.575/60/6
10−80/6—6/60/6
3 M. intracellulare strains10−56/69.17 ± 1.470/60/6
10−64/611.75 ± 1.260/62/6
10−70/6—0/66/6
10−80/6—0/66/6
2 MTC strains 10−54/411.00 ± 0.820/40/4
10−64/415.00 ± 0.810/40/4
10−73/425.00 ± 1.000/41/4
10−81/436.000/43/4
H37Rv10−52/210.00 ± 0.000/20/2
10−62/213.50 ± 0.710/20/2
10−72/225.00 ± 1.410/20/2
10−80/2—0/22/2
SD: standard deviations.