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Multicenter Study
. 2023 Mar 28;227(6):820-827.
doi: 10.1093/infdis/jiad007.

A Rough Colony Morphology of Mycobacterium abscessus Is Associated With Cavitary Pulmonary Disease and Poor Clinical Outcome

Wilhelm Hedin  1 , Gabrielle Fröberg  1   2 , Kalle Fredman  3 , Erja Chryssanthou  1 , Ingrid Selmeryd  4 , Anna Gillman  5 , Letizia Orsini  6 , Michael Runold  7 , Bodil Jönsson  8 , Thomas Schön  3   9 , Lina Davies Forsman  2   10
Affiliations
Multicenter Study

A Rough Colony Morphology of Mycobacterium abscessus Is Associated With Cavitary Pulmonary Disease and Poor Clinical Outcome

Wilhelm Hedin et al. J Infect Dis. .

Abstract

Background: The Mycobacterium abscessus complex (MABC) is a difficult to treat mycobacterium with two distinct morphologies: smooth and rough. As the clinical implications are unclear, we explored the morphology of MABC in relation to disease and outcome.

Methods: We performed a retrospective multicenter cohort study including patients with confirmed MABC in Sweden, 2009-2020, with treatment outcome as the primary outcome. MABC colony morphology was determined by light microscopy on Middlebrook 7H10 agar plates.

Results: Of the 71 MABC isolates, a defined morphology could be determined for 63 isolates, of which 40 were smooth (56%) and 23 were rough (32%). Immunosuppression, pulmonary disease, and cavitary lesion on chest radiographs were significantly associated with a rough isolate morphology. Participants with smooth isolates had more favorable treatment outcomes (12/14, 86%) compared to those with rough isolates (3/10, 30%). In an age-adjusted logistic regression, rough morphology of MABC was associated to lower odds of clinical cure compared to smooth morphology (adjusted odds ratio, 0.12; P = .049).

Conclusions: Study participants with rough MABC colony morphology of isolates had a worse clinical outcome compared to those with smooth isolates. The biological mechanisms should be further characterized and colony morphology of MABC taken into account during clinical management.

Keywords: Mycobacterium abscessus complex; colony morphology; nontuberculous mycobacteria; subspecies; treatment outcome.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Mycobacterium abscessus complex colony morphology determined by light microscopy with 50 × magnification of cultures grown on Middlebrook 7H10/oleic albumin dextrose catalase agar plates (Merck). Morphology was categorized as (A) smooth, (B) rough, or (C) mixed. (Photograph, Gabrielle Fröberg.)
Figure 2.
Figure 2.
Flow chart of study participants regarding treatment and treatment outcome. * Missing outcome since treatment was ongoing by the end of the study period 31 May 2021.
See this image and copyright information in PMC

References

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