The prognosis of patients with rheumatic diseases has improved considerably following the use of biological therapies. However, an increase in the frequency of bacterial infections has been observed in patients receiving these therapies. In the present study we aimed to assess the frequency of Listeria monocytogenes infection in a large series of patients with rheumatic diseases on treatment with tumor necrosis factor (TNF)-alpha blockers because of active disease refractory to conventional therapy, included in the Spanish Registry of Adverse Events of Biological Therapies in Rheumatic Diseases (BIOBADASER) of the Spanish Society for Rheumatology.
Assessment of the incidence of infection due to Listeria monocytogenes in the Spanish Registry Study (BIOBADASER) per 1000 patient-years and 95% confidence intervals (95% CIs) was performed. Rate from this registry was compared with that from the general population in Europe and with the rate found in patients with rheumatoid arthritis (RA) from the Spanish Rheumatoid Arthritis Registry Cohort Study (EMECAR) that assessed morbidity and clinical expression of RA and included patients treated in most cases with conventional therapies.
Six patients on treatment with TNF-alpha antagonists were diagnosed as having Listeria monocytogenes infection. The incidence of this infection per 1000 patient-year (95% CI) was 0.256 (95% CI: 0.115-0.570). This was greater than the incidence observed in the general population from Europe and in the EMECAR study.
Despite the benefits associated to the use of TNF-alpha antagonists, a high level of surveillance is required to reduce the potential risk of infections related to the use of these drugs.