583. Auramine-Rhodamine Staining in Comparison to Modern Liquid Culture Systems for the Detection of Mycobacterium spp
Session: Poster Abstract Session: Mycobacterial Diagnostics
Friday, October 21, 2011
Room: Poster Hall B1
Background:

Auramine-Rhodamine (AR) positive (+) staining of tissue samples can be very helpful for the diagnosis of tuberculosis (TB). However, with new liquid culture methods, the expectation is that a smear (+) specimen should grow a mycobacterium. The objective of this study was to compare the culture results and histology of AR (+) tissue specimens.

Methods:  

Tissue samples collected from patients that were submitted for mycobacterial culture and had AR (+) staining were retrospectively analyzed with respect to mycobacterial culture result, histology and/or Ziehl-Neelsen (ZN) method.

Results:  

Of 54 AR (+) specimens 17 samples revealed a (+) culture result for M. tuberculosis (MTB), 6 were (+) for M. avium complex (MAC), 2 were (+) for M.gordonae, 1 specimen was (+) for MTB and MAC, and 28 specimens were culture negative (-). Necrotizing granulomas were present in 38 of the samples (14 grew mycobacteria), 14 specimens contained non-necrotizing granulomas (1 grew mycobacteria) and no granulomas could be found in 2 samples (both grew MTB). Of 54 AR (+) specimens ZN was (+) in 18 samples of which 9 grew mycobacteria.

Conclusion: 

As previously described AR staining may generate many false (+) AR results (Gruft 1978). In a study of sputum specimens Roland hypothesized that false (+) AR results might be related to contamination of the sample with blood (Roland 1975). Another explanation might be that some of the TB cultures failed to grow. Specimens from non-sterile sites undergo a decontamination process which could destroy mycobacteria and lead to false (-) culture results. Furthermore, discordant results may occur if the sample contains other fastidious acid fast organisms and if the AR stain was done on a different section of the tissue than what was used for culture.

 Our study is the first to evaluate AR staining in comparison to modern liquid culture systems.

 


Subject Category: D. Diagnostic microbiology

Petra Smyczek, MD1, Robert Verity, MD2, Surinder Kanwal, MD3, Lakshmi Puttagunta, MD3 and Dennis Kunimoto, MD1, (1)Medicine, University of Alberta, Edmonton, AB, Canada, (2)DynaLIFEDx, Edmonton, AB, Canada, (3)Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada

Disclosures:

P. Smyczek, None

R. Verity, None

S. Kanwal, None

L. Puttagunta, None

D. Kunimoto, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.