Rapid detection of laboratory cross-contamination with Mycobacterium tuberculosis using multispacer sequence typing

Abstract

Background. The ability to culture Mycobacterium tuberculosis from clinical specimens serves as the gold standard for the diagnosis of tuberculosis. However, a number of false-positive diagnoses may be due to cross-contamination of such specimens. We herein investigate such episode of cross-contamination by using a technique known as multispacer sequence typing (MST). This technique was applied to six M. tuberculosis isolates prepared within the same laboratory over a two-week period of time. Results. MST analysis indicated a unique and common sequence profile between a strain isolated from a patient with proven pulmonary tuberculosis and a strain isolated from a patient diagnosed with lung carcinoma. Using this approach, we were able to provide a clear demonstration of laboratory cross-contamination within just four working days. Further epidemiological investigations revealed that the two isolates were processed for culture on the same day. Conclusion. The application of MST has been demonstrated to serve as a rapid and efficient method to investigate cases of possible cross-contamination with M. tuberculosis.