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Table 1 Results of positive Bactec 12B vials (n = 21).

From: Viability testing of material derived from Mycobacterium tuberculosisprior to removal from a Containment Level-III Laboratory as part of a Laboratory Risk Assessment Program

Description of material Growth on TSA + 5% SBA @ 48 hrs Growth on Middlebrook 7H11 Kinyoun Stain direct from positive 12B Probe Conclusion
RFLP lysate – before CTAB addition (2 vials) - +, MTB morphology AFB+ (4+), serpentine cording ND Viable MTB 1
RFLP lysate from frozen storage #1 - +, KS of growth AFB - 4 AFB/slide, morph not consistent with TB MTB- contaminant present – ubiquitous mycobacteria
RFLP lysate from frozen storage #2 - +, KS of growth AFB - 15 AFB/slide, morph not consistent with TB MTB- contamination present – ubiquitous mycobacteria
RFLP lysate from frozen storage #3 & #4 - +, KS of growth AFB - No AFB   contamination present
Boiled lysate - +, Smooth colonies not consistent with MTB AFB+ 5–10/field, clumping, no obvious serpentine cording MTB- ubiquitous mycobacteria
Smear, 1 h at 95°C & Smear, 2 h at 95°C2 - +, MTB morphology AFB+ (4+), serpentine cording MTB+ Viable MTB
Protein extracts (2) - +, MTB morphology AFB+ (4+), serpentine cording MTB+ Viable MTB
  1. 1 Accuprobe was not performed on these isolates, as MTB was expected due to morphology observed in addition to data from prior studies [7].
  2. 2 All 12Bs from smears (n = 12) were positive, only 2 were chosen as representative for further testing Definitions: KS = Kinyoun stain, AFB = acid-fast bacilli, MTB = M. tuberculosis