Oct 1, 2004 - Edward Graviss, PhD, MPH1, James Musser, MD, PhD2, Larry Teeter, PhD1, Natalie Williams-Bouyer, PhD1, Thanh Bui, MD1 and L.D. Teeter ...
Abstract: Mycobacterium tuberculosis (MTB) Culture Cross-Contaminati...
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577. Mycobacterium tuberculosis (MTB) Culture Cross-Contamination Among Reported Tuberculosis Cases Session: Poster Session: Mycobacteria Friday, October 1, 2004: 12:00 AM Room: Halls A and B 0 Background: False positive MTB cultures due to laboratory cross-contamination can result in misdiagnosis and unnecessary antimicrobial therapy. We used MTB molecular characterization methods to aid in the detection of unrecognized laboratory contaminants. Methods: MTB isolates from tuberculosis (TB) cases reported in Harris County, TX between 10/1/95 and 9/30/01 were characterized by IS6110 restriction fragment length polymorphism and spoligotyping. Persons having only 1 culture positive specimen that were part of molecular clusters were identified and their specimen collection dates were compared with those of other members within their cluster. Specimens collected within 4 days of another specimen from the same cluster were evaluated as possible laboratory contaminants. Components of the evaluation included specimen AFB smear status, the laboratory that processed the specimen, and epidemiologic links to other cases. Results: Isolates from 2305 of 2523 (91%) culture positive TB cases were characterized including 1435 (62%) whose molecular profile matched at least one other case. Of 354 clustered cases with only one positive culture, 99 had specimen collection dates within 4 days of another specimen in the same cluster and were AFB smear negative. Evaluation of the 22 individuals in clusters that included fewer than 20 other cases indicated that only 2 had epidemiologic linkage to the cluster. Laboratory contamination was likely for the remaining 20 because the specimens were processed by the same laboratories as the next specimen in their cluster (including 15 that were AFB smear positive). Evaluation of persons in larger clusters was hindered by the high number and frequency of positive cultures. For example, 49 of the 99 cases were in 3 clusters, each including more than 300 positive cultures with an average of less than 7 days between specimens in the cluster. Conclusion: Laboratory contamination should be a consideration if bacteriologic evidence is limited to one AFB smear negative specimen. Molecular characterization of MTB isolates facilitates the detection of laboratory contaminants but has less utility if endemic strains are present.
Edward Graviss, PhD, MPH1, James Musser, MD, PhD2, Larry Teeter, PhD1, Natalie Williams-Bouyer, PhD1, Thanh Bui, MD1 and L.D. Teeter, None; T.T. Bui, None; N. Williams-Bouyer, None; J.M. Musser, None; E.A. Graviss, None., (1)Baylor College of Medicine, Houston, TX, (2)Methodist Hospital Research Institute, Houston, TX
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https://idsa.confex.com/idsa/2004/webprogram/Paper19774.html
3/23/2015
