LETTER TO EDITOR
Year : 2011 | Volume
: 54 | Issue : 2 | Page : 418--419
When molecular diagnosis went wrong
KV Jayashree1, B Appalaraju1, J Jayalakshmi1, N Sowmya1, K Jayachandran2, TS Balashanmugam3, R. M. P. L. Ramanathan4,
1 Department of Microbiology, PSG Institute of Medical Sciences, Peelamedu, Coimbatore - 641 004, Tamil Nadu, India
2 Department of Medicine, PSG Institute of Medical Sciences, Peelamedu, Coimbatore - 641 004, Tamil Nadu, India
3 Department of Surgery, PSG Institute of Medical Sciences, Peelamedu, Coimbatore - 641 004, Tamil Nadu, India
4 Department of Pulmonology, PSG Institute of Medical Sciences, Peelamedu, Coimbatore - 641 004, Tamil Nadu, India, India
K V Jayashree
Department of Microbiology, PSG Institute of Medical Sciences, Peelamedu, Coimbatore - 641 004, Tamil Nadu
|How to cite this article:|
Jayashree K V, Appalaraju B, Jayalakshmi J, Sowmya N, Jayachandran K, Balashanmugam T S, Ramanathan R. When molecular diagnosis went wrong.Indian J Pathol Microbiol 2011;54:418-419
|How to cite this URL:|
Jayashree K V, Appalaraju B, Jayalakshmi J, Sowmya N, Jayachandran K, Balashanmugam T S, Ramanathan R. When molecular diagnosis went wrong. Indian J Pathol Microbiol [serial online] 2011 [cited 2020 Jan 24 ];54:418-419
Available from: http://www.ijpmonline.org/text.asp?2011/54/2/418/81605
Liposuction is a common cosmetic procedure in the West and is becoming popular in India. A rare complication is infection with rapidly growing mycobacteria such as Mycobacterium fortuitum, M. chelonae, and M. abscessus.  The clues for diagnosis are persistent discharge, multiple abscesses, and failure to grow any organism on routine culture. Presumptive diagnosis can be done with clinical history but demonstrating acid fast bacilli (AFB) and/or a positive culture for mycobacteria is required to make a definitive diagnosis.  Acid fast staining, though rapid, lacks sensitivity and Mycobacterial culture results take 2-3 weeks or longer. Hence, the diagnosis of these infections is delayed in most cases. However, with the availability of nucleic acid amplification test (NAA), these tests are increasingly being requested in the need for more rapid and specific diagnosis.
We describe a case of a 37-year-old lady who presented with painful swellings on the right thigh 4 weeks after a liposuction procedure. She had received antibiotics like linezolid, piperacillin, and clindamycin with no improvement in symptoms. Zeihl- Neelsen stain was positive for AFB on two occasions. Hence, a clinical diagnosis of post-liposuction wound infection with atypical mycobacteria was done and the patient was started on clarithromycin and amikacin. The serous discharge was also sent for DNA-PCR for tuberculosis which was reported positive for M. tuberculosis. The patient was started on anti-tuberculous treatment (ATT) but was stopped due to intolerance. The patient was treated with clarithromycin and ciprofloxacin for 6 months. The patient responded well to this treatment and is doing well. Interestingly, the mycobacterial culture grew M. abscessus, 3 weeks later, confirming the diagnosis of post-liposuction wound infection with atypical mycobacteria.
The advantages of NAA tests have been widely publicized and there is a misconception among clinicians and microbiologists that these tests are sensitive and specific. NAA tests for tuberculosis mostly target specific DNA genes.  In an article by Rattan,  who compared several in-house PCR tests and commercially available amplification tests, the sensitivity of PCR for tuberculosis was found to be ranging from 80 to 92% and false positive results varied from 0 to 20%. None of the methods convincingly demonstrated the superiority of one over the other. Despite the fact that the NAA are approved for respiratory specimen, many investigators have used them to test specimen from other sites.  However, Honoré -Bouakline et al. reported high false positive PCR for extra pulmonary specimen when using DNA-PCR and suggested the use of RNA-PCR. Post-liposuction infections with M. tuberculosis have not been reported earlier.
Clinicians and microbiologists should be aware of false positive PCR results. A therapy like the one against tuberculosis, which is long and not exempt from side effects should not be undertaken only on the basis of a positive result of a single amplification test. 
|1||Meyers H, Brown-Elliott BA, Moore D, Curry J, Truong C, Zhang Y, et al. An Outbreak of Mycobacterium chelonae Infection Following Liposuction. Clin Infect Dis 2002;34:1500-7.|
|2||Rattan A. PCR For diagnosis of tuberculosis. Where are we now? Ind J Tub 2000;47:79-81.|
|3||Tortoli E, Palomino JC. New Diagnostic Methods. In: Palomino JC, Leao CS, Ritacco V, editors. TUBERCULOSIS 2007. From basic science to patient care. Available from: http://www.tuberculosistextbook.com.[Last accessed on 2007].|
|4||Honoré-Bouakline S, Vincensini JP, Giacuzzo V, Lagrange PH, Herrmann JL. Rapid Diagnosis of Extrapulmonary Tuberculosis by PCR: Impact of Sample Preparation and DNA Extraction. J Clin Microbiol 2003;41:2323-9.|