Dedicated decontamination: A necessity to prevent cross contamination in high throughput mycobacteriology laboratories.

UNLABELLED Unrecognized cross-contamination has been known to occur in laboratories frequently, especially with sensitive recovery system like BACTEC 460 TB. In March 2001, we investigated a pseudo-outbreak of Mycobacterium tuberculosis isolates in three smear negative clinical specimens and would like to present our experience in this communication. METHODS All suspected cases were confirmed by checking the drug susceptibility and DNA fingerprints using spoligotyping as well as restriction fragment length polymorphism. RESULTS On investigation, the most likely cause was found to be the use of common decontamination reagents and phosphate buffer. CONCLUSIONS To avoid erroneous diagnosis, we have devised a dedicated decontamination procedure, which includes separate aliquoting of phosphate buffer and decontamination reagents per patient. Timely molecular analysis and appropriate changes to specimen processing have been identified as useful measures for limiting laboratory cross contamination.