The study evaluated the course and outcome of erythema migrans in patients receiving tumour necrosis factor-alpha (TNF-α) inhibitors. Among 4157 adults diagnosed with erythema migrans in the period 2009-2018, 16 (2.6%) patients were receiving TNF-α inhibitors (adalimumab, infliximab, etarnecept, golimumab), often in combination with other immunosuppressants, for rheumatic (13 patients) or inflammatory bowel (three patients) disease. Findings in this group were compared with those in 32 sex- and age-matched immunocompetent patients diagnosed with erythema migrans in the same years. In comparison with the control group, the immunocompromised patients had a shorter incubation period (7 vs. 14 days; p = 0.0153), smaller diameter of erythema migrans (10.5 vs. 15.5 cm; p = 0.0014), and more frequent comorbidities other than immune-mediated diseases (62.5% vs. 25%, p = 0.0269), symptoms/signs of disseminated Lyme borreliosis (18.8% vs. 0%, p = 0.0324), and treatment failure (25% vs. 0%, p = 0.0094). After retreatment with an antibiotic, the clinical course of Lyme borreliosis resolved. Continuing TNF inhibitor treatment during concomitant borrelial infection while using identical approaches for antibiotic treatment as in immunocompetent patients resulted in more frequent failure of erythema migrans treatment in patients receiving TNF inhibitors. However, the majority of treatment failures were mild, and the course and outcome of Lyme borreliosis after retreatment with antibiotics was favourable.
Keywords: Lyme borreliosis; TNF-α inhibitors; erythema migrans; immunocompromised host; outcome; treatment.