Biologic compounds are being used more frequently to treat a multitude of systemic inflammatory conditions. These novel compounds are composed of antibodies or other peptides that act through one of three mechanisms: inhibiting inflammatory cytokine signaling (typically tumor necrosis factor or TNF), inhibiting T-cell activation, or depleting B-cells. The increase in use and ever expanding list of new immune modulating therapies make knowledge of the infectious complications associated with immune modulation even more important. Of particular concern is the risk for developing atypical and opportunistic infections including tuberculosis, herpes zoster, Legionella pneumophila, and Listeria monocytogenes.
The risk of infection is always a concern with any immunosuppressive treatment, and such infections are documented with all biologic therapies. Of the TNF inhibitors, inﬂiximab seems to carry the highest risk of infection. In comparison to inﬂiximab, use of etanercept (HR: 0.64, 95% CI: 0.49-0.84), abatacept (HR:
0.68, 95% CI: 0.48-0.96), rituximab (HR: 0.81, 95% CI: 0.55-1.20), and adalimumab (HR: 0.52, 95% CI: 0.39-0.72) was associated with lower rates of hospitalized infections, although the authors attributed variability in patients’ risk of infection to factors other than treatment with biologics. 26 Additionally, a 3-year national French registry (RATIO) study comparing incidence of nontuberculosis opportunistic infections (45 cases in 43 patients) between TNF-α inhibitors found that risk factors were inﬂiximab (OR: 17.6 [95% CI: 4.3-72.9]; p<0.0001) or adalimumab (OR:10.0 [95% CI: 2.3 to 44.4]; p=0.002) versus etanercept.