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

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.

Staphylococcus aureus bacteremia and cardiac implantable electronic devices in a county hospital setting: a population-based retrospective cohort study.

BACKGROUND: Due to a high incidence of cardiac implantable electronic device-associated infective endocarditis (CIED-IE) in cases of Staphylococcus aureus bacteremia (SAB) and high mortality with conservative management, guidelines advocate device removal in all subjects with SAB. We aimed to investigate the clinical course of SAB in patients with a CIED (SAB+CIED) in a Swedish county hospital setting and relate it to guideline recommendations. METHODS: All CIED carriers with SAB, excluding clinical pocket infections, in the County of Västmanland during 2010-2017 were reviewed retrospectively. RESULTS: There were 61 cases of SAB+CIED during the study period, and CIED-IE was diagnosed in 13/61 (21%) cases. In-hospital death occurred in 19/61 (31%) cases, 34/61 (56%) cases were discharged with CIED device retained, and 8/61 (13%) cases were discharged after device removal. Subjects dying during hospitalization were elderly and diseased. No events was seen if the CIED was removed. Among four discharged cases with conservatively managed CIED-IE one relapse occured. Among 30 cases discharged with retained CIED and no evidence of IE, 22/30 (73%) cases had an uneventful follow-up, whereas adverse events secondary to overlooked CIED-IE were likely in 1/30 (3%) cases and could not be definitely excluded in additionally 4/30 (13%) cases. CONCLUSIONS: During the study period, management became more active and prognosis improved. The heterogeneity within the population of SAB+CIED suggests that a management strategy based on an individual risk/benefit analysis could be an alternative to mandatory device removal.