The use of variable-number tandem-repeat mycobacterial interspersed repetitive unit typing to identify laboratory cross-contamination with Mycobacterium tuberculosis.
A retrospective study including 515 Mycobacterium tuberculosis isolates from 215 patients was conducted to investigate possible laboratory contamination with M. tuberculosis over a 1-year period in a university hospital. All cultures underwent variable-number tandem-repeat (VNTR) typing. Cultures suspected of being contaminated in the VNTR analysis and possible sources of contamination underwent mycobacterial interspersed repetitive unit (MIRU) typing further. Overall, 8 (3.7%) cases of 215 patients were considered possible false-positives. Five (2.3%) cultures might be contaminated during initial batching processing, and 1 (0.5%) and 4 (1.9%) cultures of them were further classified as presumed and possible cases, respectively, of cross-contamination on clinical grounds. Three (1.4%) cultures might be contaminated by cultures that had been processed in species identification procedures in the same laminar-flow hood. The 2-step strategy using VNTR and MIRU analyses in combination in this study appears to be a valuable means for the study of false-positive cultures.
Yan
Jing-Jou
JJ
Department of Pathology, National Cheng Kung University Hospital, Tainan 70428, Taiwan. jingjou@mail.ncku.edu.tw
Jou
Ruwen
R
Ko
Wen-Chien
WC
Wu
Jiunn-Jong
JJ
Yang
Mei-Lin
ML
Chen
Hung-Mo
HM
D015373:Bacterial Typing Techniques; D003470:Culture Media; D004269:DNA, Bacterial / Q000032:analysis; D004866:Equipment Contamination; D005189:False Positive Reactions; D006785:Hospitals, University; D006801:Humans; D007753:Laboratories; D018598:Minisatellite Repeats; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D012091:Repetitive Sequences, Nucleic Acid; D014376:Tuberculosis / Q000175:diagnosis / Q000382:microbiology; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000382:microbiology
D003470:Culture Media; D004269:DNA, Bacterial