The use of immunosuppressive agents is a major risk factor for infections in patients with rheumatic diseases.
Signs of infection may be masked in these patients by the underlying disease and its treatment.
Biological agents targeted against TNF-alpha (etanercept, infliximab, adalimumab), B lymphocyte depleting agents (rituximab), or anti-IL-6R monoclonal antibodies (tocilizumab) are associated with an increased risk of infection.
Specific infections associated with TNF blockade:
Mycobacterium tuberculosis (especially with infliximab).
Streptococcus pneumoniae.
Listeria monocytogenes.
Aspergillus fumigatus.
Histoplasma capsulatum.
Cryptococcus.
Pneumocystis pneumonia.
Assessment of patients on biological agents:
Have a high index of suspicion for sepsis in the unwell patient on biological agents.
Patients should be investigated thoroughly for underlying organism; initial investigations should include CBC + diff, Na, K, creatinine, bili, ALP, AST, ALT, blood cultures, urinalysis, sputum culture, CXR.
Other diagnostic imaging may be required to determine the source of infection.
Empiric treatment:
Immunosuppressive therapy should be minimized and no further biological agent should be given until the sepsis has been adequately treated.
Broad spectrum antibiotics may be required until the organism is isolated.
The on-call Rheumatologist/Immunologist should be consulted if suspected infection in any patient known to our service on anti-TNF or other biological therapy.