Mycobacterium tusciae, sp. nov.

1
Mycobacterium tusciae, sp. nov.

• Enrico Tortoli

19 ESM, Lisbon, July 22-25, 1998
2
Case report

• 7-year old boy suffering from nephrotic syndrome
  from the age of 3
• steroid treatment in the last 4 years
• cervical lymphadenitis
• surgical removal
• no relapse so far

3
Cultural features

• growth slow (4 weeks)
• growth temperature 25-32C
• pigmentation scotochromogenic
• colonies rough

4
Biochemical features

• positive reactions
• nitrate reduction
• thermostable catalase
• urease
• Tween 80 hydrolysis
• 14-day arylsulfatase
• acid phosphatase

5
Antimicrobial susceptibility
Drug MIC Ciprofloxacin ? 1 Clarithromycin ?
2 Ethambutol 8 Rifabutin ?
0.5 Rifampin ? 0.5 Sparfloxacin ?
0.5 Streptomycin ? 2
6
Lipidic analysis

• TLC
• ?-mycolates
• keto-mycolates
• wax esters
• pattern shared by M. scrofulaceum, M.
  interjectum, M. xenopi
• Gas-chromatography
• 160 30
• 181 cis 9 21
• 180 alcohol 11
• 180 10-methyl 10
• pattern shared by M. scrofulaceum

7
HPLC
8
16S rDNA sequence

• unique sequence both in hypervariable region A
  and B
• short helix 18
• phylogenetic position among rapid growers, close
  to M. flavescens and M. smegmatis

9
M. tusciae sp. nov.

• Features of the type strain
• acid fast rod
• G C content 66.4 mol
• distinguishable from other scotochromogenic
  mycobacteria by means of biochemical tests
• unique HPLC profile
• not identifiable by TLC and GC alone
• susceptible to all antimycobacterial drugs
• unique sequence within 16S rDNA

10
Conclusions

• M. scrofulaceum is classically considered a major
  responsible of cervical lymphadenitis
• M. tusciae adds to the scotochromogenic
  mycobacteria recently described as cause of
  pediatric lymphadenitis
• part of pathologies attributed to M. scrofulaceum
  are probably due to misidentified novel
  mycobacteria