Rea B, Maisel JR, Glaser L, Alby K. Identification of Clinically Relevant Mycobacterial Species After Extended Incubation Times in the BACTEC MGIT System.
Am J Clin Pathol 2019;
151:63-67. [PMID:
30169764 DOI:
10.1093/ajcp/aqy086]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Objectives
Traditionally, for mycobacterial culture both solid and broth media are used and routinely held for 6 weeks minimum to optimize yield. We retrospectively reviewed all positive mycobacterial cultures over a 12-month period to assess growth kinetics of clinically relevant isolates.
Methods
From January to December 2015, 658 positive mycobacteria cultures by solid (7H11 and 7H10 plates) and/or broth (BACTEC MGIT) media were identified and reviewed.
Results
In broth-only cultures, 21 of 153 (13.7%) from 21 patients were positive after 28 days' incubation. Subsequent chart review revealed the following species: 11 Mycobacterium avium intracellulare complex (MAI), five Mycobacterium tuberculosis (MTB), and five other non-MTB/MAI mycobacteria. Two of the cases of MTB were first-time isolates, and 11.4% of MTB-positive cultures became positive after 4 weeks' incubation.
Conclusions
These data provide strong evidence reaffirming that clinically meaningful results are frequently detected after extended incubation times by broth-only methods, including several MTB isolates.
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