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An evaluation of methods for the isolation of nontuberculous mycobacteria from patients with cystic fibrosis, bronchiectasis and patients assessed for lung transplantation

Lookup NU author(s): David Stephenson, Dr Daniela Lee, Jill Davison, Dr Stephen Bourke, Professor Anthony De Soyza, Dr James Lordan, Dr Alison Robb, Dr John Perry

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

BACKGROUND: RGM medium is an agar-based, selective culture medium designed for the isolation of nontuberculous mycobacteria (NTM) from the sputum of patients with cystic fibrosis (CF). We evaluated RGM medium for the detection of NTM in patients with CF (405 samples), bronchiectasis (323 samples) and other lung diseases necessitating lung transplantation (274 samples). METHODS: In total, 1002 respiratory samples from 676 patients were included in the study. Direct culture on RGM medium, with incubation at two temperatures (30 °C and 37 °C), was compared with conventional culture of decontaminated samples for acid-fast bacilli (AFB) using both a solid medium (Löwenstein-Jensen medium) and a liquid medium (the Mycobacterial Growth Indicator Tube; MGIT). RESULTS: For all three patient groups, significantly more isolates of NTM were recovered using RGM medium incubated at 30 °C than by any other method (sensitivity: 94.6% vs. 22.4% for conventional AFB culture; P < 0.0001). Significantly more isolates of Mycobacterium abscessus complex were isolated on RGM at 30 °C than by AFB culture (sensitivity: 96.1% vs. 58.8%; P < 0.0001). The recovery of Mycobacterium avium complex was also greater using RGM medium at 30 °C compared to AFB culture (sensitivity: 83% vs. 70.2%), although this difference was not statistically significant and a combination of methods was necessary for optimal recovery (P = 0.21). CONCLUSIONS: In the largest study of RGM medium to date, we reaffirm its utility for isolation of NTM from patients with CF. Furthermore; we show that it also provides an effective tool for culture of respiratory samples from patients with bronchiectasis and other lung diseases.


Publication metadata

Author(s): Stephenson D, Perry A, Appleby MR, Lee D, Davison J, Johnston A, Jones AL, Nelson A, Bourke SJ, Thomas MF, De Soyza A, Lordan JL, Lumb J, Robb AE, Samuel JR, Walton KE, Perry JD

Publication type: Article

Publication status: Published

Journal: BMC Pulmonary Medicine

Year: 2019

Volume: 19

Issue: 1

Online publication date: 21/01/2019

Acceptance date: 07/01/2019

Date deposited: 13/02/2019

ISSN (electronic): 1471-2466

Publisher: BioMed Central Ltd.

URL: https://doi.org/10.1186/s12890-019-0781-2

DOI: 10.1186/s12890-019-0781-2

PubMed id: 30665395


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