Adjunctive betamethasone treatment of hypoxaemic adults hospitalised with Mycoplasma pneumoniae community-acquired pneumonia: an open-label, multicentre, randomised, controlled trial

Karl Hagman; Magnus Hedenstierna; Elina Andersson Norlén; Karin Biasoletto; Maria Eklund Josephson; Carl-Johan Fraenkel; Elin Hedman; Johan Ljungberg; Oskar Ljungquist; Viktor Månsson; David Nygren; Milena de Oliveira E Costa; Cecilia Rydén; Jørgen Skov Jensen; Göran Stenlund; Jonas Tverring; Lisa Wasserstrom; Anna C Nilsson; Johan Ursing

doi:10.1016/j.lanepe.2026.101610

Adjunctive betamethasone treatment of hypoxaemic adults hospitalised with Mycoplasma pneumoniae community-acquired pneumonia: an open-label, multicentre, randomised, controlled trial

Lancet Reg Health Eur. 2026 Apr 19:64:101610. doi: 10.1016/j.lanepe.2026.101610. eCollection 2026 May.

Authors

Karl Hagman^{1

2}, Magnus Hedenstierna³, Elina Andersson Norlén^{4

5}, Karin Biasoletto⁴, Maria Eklund Josephson⁶, Carl-Johan Fraenkel^{7

8}, Elin Hedman⁴, Johan Ljungberg⁹, Oskar Ljungquist^{8

10}, Viktor Månsson^{6

11}, David Nygren^{6

8}, Milena de Oliveira E Costa¹², Cecilia Rydén¹⁰, Jørgen Skov Jensen¹³, Göran Stenlund¹⁴, Jonas Tverring^{8

10}, Lisa Wasserstrom^{15

16}, Anna C Nilsson^{6

11}, Johan Ursing^{3

17}

Affiliations

¹ Department of Infectious Diseases, Sahlgrenska University Hospital, Gothenburg, Region Västra Götaland, Sweden.
² Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
³ Department of Infectious Diseases, Danderyd Hospital, Stockholm, Sweden.
⁴ Department of Infectious Diseases, Östersund Hospital, Östersund, Sweden.
⁵ Department of Clinical Microbiology, Umeå University, Umeå, Sweden.
⁶ Department of Infectious Diseases, Skåne University Hospital, Malmö, Sweden.
⁷ Department of Infectious Diseases, Skåne University Hospital, Lund, Sweden.
⁸ Division of Infection Medicine, Department of Clinical Sciences, Lund University, Sweden.
⁹ Department of Infectious Diseases, Hospital of Halland, Halmstad, Sweden.
¹⁰ Department of Infectious Diseases, Helsingborg Hospital, Helsingborg, Sweden.
¹¹ Clinical Infection Medicine, Department of Translational Medicine, Lund University, Malmö, Sweden.
¹² Department of Medicine, Capio S:t Göran Hospital, Stockholm, Sweden.
¹³ Department of Bacteria, Parasites, and Fungi, Statens Serum Institut, Denmark.
¹⁴ Department of Infectious Diseases, Malarhospital, Eskilstuna, Sweden.
¹⁵ Clinical Microbiology, Department of Translational Medicine, Faculty of Medicine, Lund University, Malmö, Sweden.
¹⁶ Clinical Microbiology, Infection Control and Prevention, Skåne University Hospital, Lund, Sweden.
¹⁷ Department of Clinical Sciences, Danderyd Hospital, Karolinska Institutet, Stockholm, Sweden.

Abstract

Background: Adjunctive corticosteroid therapy appears to be beneficial for adults with severe community-acquired pneumonia (CAP), but data on Mycoplasma pneumoniae CAP are limited. This study aimed to evaluate if adjunctive betamethasone reduced time to resolution of hypoxaemia in adults hospitalised with M. pneumoniae CAP.

Methods: An open-label, multicentre, randomised, controlled trial was conducted at eight Swedish hospitals. Adults admitted with M. pneumoniae CAP and hypoxaemia (SpO₂ <93% and respiratory rate >20 breaths/min) were eligible. Exclusion criteria included asthma and diabetes mellitus. Participants were randomised (1:1) to either standard care without corticosteroids or adjunctive oral betamethasone (3 mg daily on days 1-2, and 2 mg daily on days 3-5). Antibiotic treatment was standardised to 200 mg doxycycline once daily for 10 days. The primary outcome was time to resolution of hypoxaemia in an intention-to-treat analysis. Safety was assessed in participants receiving at least one betamethasone dose. The study was registered with the EU Clinical Trials Register (EudraCT 2016-002585-32) and is completed.

Findings: Between March 1, 2018, and November 14, 2024, 70 participants were enrolled: 36 in the betamethasone group and 34 in the control group. The median age was 42 years (IQR 28-49) including 40 (57%) male and 30 (43%) female participants. All participants achieved resolution of hypoxaemia except two who withdrew consent. Time to resolution of hypoxaemia was shorter in the betamethasone group (HR 1.82 [95% CI 1.10-3.02], p = 0.020) compared to the standard of care group, with an estimated median of 2.3 (95% CI 1.8-2.7) and 3.6 (95% CI 1.9-5.3) days, respectively. Adverse events were similar between study groups. Severe adverse events were rare, and none were attributed to betamethasone treatment.

Interpretation: Adjunctive betamethasone was well tolerated and significantly shortened the duration of hypoxaemia in adults hospitalised with M. pneumoniae CAP in this open-label trial.

Funding: The Swedish Society of Medicine.

Keywords: Antibiotics; Atypical pneumonia; Corticosteroids; Doxycycline; Oxygen.