Optimized molecular resolution of cross-contamination alerts in clinical mycobacteriology laboratories

• Main Authors: de Viedma Darío, Bouza Emilio, Lirola Miguel, Fernández Rosa, Herranz Marta, Martín Ana
• Format: Article
• Language: English
• Published: BMC 2008-02-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/8/30

<p>Abstract</p> <p>Background</p> <p>The phenomenon of misdiagnosing tuberculosis (TB) by laboratory cross-contamination when culturing <it>Mycobacterium tuberculosis </it>(MTB) has been widely reported and it has an obvious clinical, therapeutic and social impact. The final confirmation of a cross-contamination event requires the molecular identification of the same MTB strain cultured from both the potential source of the contamination and from the false-positive candidate. The molecular tool usually applied in this context is IS6110-RFLP which takes a long time to provide an answer, usually longer than is acceptable for microbiologists and clinicians to make decisions. Our purpose in this study is to evaluate a novel PCR-based method, MIRU-VNTR as an alternative to assure a rapid and optimized analysis of cross-contamination alerts.</p> <p>Results</p> <p>MIRU-VNTR was prospectively compared with IS6110-RFLP for clarifying 19 alerts of false positivity from other laboratories. MIRU-VNTR highly correlated with IS6110-RFLP, reduced the response time by 27 days and clarified six alerts unresolved by RFLP. Additionally, MIRU-VNTR revealed complex situations such as contamination events involving polyclonal isolates and a false-positive case due to the simultaneous cross-contamination from two independent sources.</p> <p>Conclusion</p> <p>Unlike standard RFLP-based genotyping, MIRU-VNTR i) could help reduce the impact of a false positive diagnosis of TB, ii) increased the number of events that could be solved and iii) revealed the complexity of some cross-contamination events that could not be dissected by IS6110-RFLP.</p>