TABLE 2.
Phenotypic characteristics of the M. elephantis cluster in comparison with the type strain of the species and closely related speciesa
| Test | Result for strain(s):
|
|||||||
|---|---|---|---|---|---|---|---|---|
| Clinical strains | M. elephantis DSM 44368b (our laboratory) | M. elephantis DSM 44368b (Shojaei et al. [16]) | MCRO 17c | MCRO 20d | M. flavescens | M. scrofulaceum | M. pulveris | |
| Growth ratee | M | M | R | M | S | M | ||
| Growth temp (°C) | ||||||||
| 25 | + | + | + | + | ||||
| 31 | + | + | + (28°C) | |||||
| 37 | + | + | + | + | + | + | ||
| 42 | + (best) | + (best) | + | Vi | − | + | ||
| 52 | − | − | − | − | ||||
| Pigmentationf | Sg | Sg | N | S | S | N | ||
| Morphologyh | S, Y | S, Y | S, Y | S, Y | S | |||
| Niacin | − | − | − | − | − | |||
| Nitrate reductase | + | + | + | + | + | + | − | + |
| Semiquantitative catalase (mm) | >45 | >45 | >45 | >45 | >45 | >45 | >45 | |
| 68°C catalase | + | + | + | + | ||||
| Tween 80 hydrolysis | + | + | + | + | + | + | − | 88% (7 days) |
| Tellurite reduction | − | − | − (5 days) | + | − | −/+ (44%) | +/− (64%) | |
| 5% NaCl tolerance | + | + | − | − | − | + (62%) | − | + |
| Iron uptake | − | − | − | − | ||||
| Arylsulfatase activity | ||||||||
| 3 days | − | − | − (84%) | − (99%) | − | |||
| 14 days | − | − | − | + (78%) | − (64%) | + | ||
| Growth on MACj | − | − | − | − | ||||
| Urease activity | + | + | + | + | + | + (72%) | + | 25% |
| Pyrazinamidase | + | + | + | V | + | |||
| Acetamidase | − | − | − | − | ||||
| Benzamidase | − | − | − | |||||
| Nicotinamidase | + | + | + | + | ||||
| Succinamidase | − | − | − | |||||
| Acid phosphatase | + | + | + | − | + | |||
| β-Glucosidase | + | + | ||||||
| Sodium citrate | − | − | ||||||
| Acid production | ||||||||
| Fructose | − | − | ||||||
| Mannitol | − | − | V | |||||
| Sorbitol | − | − | V | |||||
| Inositol | − | − | ||||||
Species closely related to the M. elephantis cluster on the basis of the 16S rRNA gene were Mycobacterium sp. strains MCRO 17 (18) and MCRO 20 (18), M. elephantis (16), and M. pulveris (22). Those closely related to the cluster on the basis of phenotypic characteristics were M. flavescens and M. scrofulaceum (7, 13). Seven of the 11 strains (00-160, 00-253, 00-254, 01-17, 01-19, 01-81, and 01-101) were tested by biochemical methods, and results were identical for all strains.
Testing was performed in our laboratory for each colony type (1 and 2). Results were identical, with the exception of the morphology.
Previously identified as M. scrofulaceum.
Previously identified as M. flavescens.
M, moderate; S, slow; R, rapid.
S, scotochromogen; N, nonchromogen.
Pigmentation was difficult to establish, as isolates were generally a pale yellow, intensifying to a bright yellow within a few days.
S, smooth; Y, yellow.
V, variable.
MAC, MacConkey agar without crystal violet.