Keita Takeda1, Yoshiro Murase2, Masahiro Kawashima3, Maho Suzukawa4, Junko Suzuki5, Akira Yamane6, Yuriko Igarashi7, Kinuyo Chikamatsu8, Yuta Morishige9, Akio Aono10, Hiroyuki Yamada11, Akiko Takaki12, Atsuhisa Tamura13, Hideaki Nagai14, Hirotoshi Matsui15, Shigeto Tohma16, Satoshi Mitarai17. 1. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan; Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan; Department of Basic Mycobacteriology, Graduate School of Biomedical Science, Nagasaki University, Japan. Electronic address: takedak@tokyo-hosp.jp. 2. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: ymurase@jata.or.jp. 3. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: mkawashima-in@tokyo-hosp.jp. 4. Clinical Research Center, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: suzukawam@tokyo-hosp.jp. 5. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: junkosz-in@tokyo-hosp.jp. 6. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: yamanea@tokyo-hosp.jp. 7. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: igarashi@jata.or.jp. 8. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: chikamatsu@jata.or.jp. 9. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: ymorishige@jata.or.jp. 10. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: a.aono1967@gmail.com. 11. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: hyamada@jata.or.jp. 12. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan. Electronic address: takaki@jata.or.jp. 13. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: tamura-in@tokyo-hosp.jp. 14. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: hnagai-tokyohosp@umin.ac.jp. 15. Center for Pulmonary Diseases, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: matsui.hirotoshi.sa@mail.hosp.go.jp. 16. Asthma, Allergy and Rheumatology Center, National Hospital Organization Tokyo National Hospital, Japan. Electronic address: touma-shigeto@tokyo-hosp.jp. 17. Department of Mycobacterium Reference and Research, The Research Institute of Tuberculosis, Japan; Department of Basic Mycobacteriology, Graduate School of Biomedical Science, Nagasaki University, Japan. Electronic address: mitarai@jata.or.jp.
Abstract
SETTING: A laboratory cross-contamination event was suspected because Mycobacterium tuberculosis was unexpectedly detected at a high incidence in the cultures of several clinical specimens at the National Hospital Organization, Tokyo National Hospital, Japan. OBJECTIVE: To describe a case of Mycobacterium tuberculosis laboratory cross-contamination. DESIGN: We reviewed the medical records of 20 patients whose clinical specimens were suspected to have been contaminated by Mycobacterium tuberculosis. Variable number of tandem repeat analysis with 15 loci, the Japan Anti-Tuberculosis Association-12, and three additional hyper-variable loci, was performed to identify the cross-contamination event. RESULTS: The clinical, laboratory, and variable number of tandem repeat data revealed that the cross-contamination had possibly originated from one strongly positive specimen, resulting in false-positive results in 11 other specimens, including a case treated with anti-tuberculosis drugs. CONCLUSION: Clinical and laboratory data must be re-evaluated when cross-contamination is suspected and variable number of tandem repeat analysis should be used to confirm cross-contamination. Furthermore, original isolates should be stored appropriately, without sub-culturing and genotyping should be performed at the earliest possible for better utilization of variable number of tandem repeat for the identification of cross-contamination.
SETTING: A laboratory cross-contamination event was suspected because Mycobacterium tuberculosis was unexpectedly detected at a high incidence in the cultures of several clinical specimens at the National Hospital Organization, Tokyo National Hospital, Japan. OBJECTIVE: To describe a case of Mycobacterium tuberculosis laboratory cross-contamination. DESIGN: We reviewed the medical records of 20 patients whose clinical specimens were suspected to have been contaminated by Mycobacterium tuberculosis. Variable number of tandem repeat analysis with 15 loci, the Japan Anti-Tuberculosis Association-12, and three additional hyper-variable loci, was performed to identify the cross-contamination event. RESULTS: The clinical, laboratory, and variable number of tandem repeat data revealed that the cross-contamination had possibly originated from one strongly positive specimen, resulting in false-positive results in 11 other specimens, including a case treated with anti-tuberculosis drugs. CONCLUSION: Clinical and laboratory data must be re-evaluated when cross-contamination is suspected and variable number of tandem repeat analysis should be used to confirm cross-contamination. Furthermore, original isolates should be stored appropriately, without sub-culturing and genotyping should be performed at the earliest possible for better utilization of variable number of tandem repeat for the identification of cross-contamination.