Brain abscess caused by Nocardia cyriacigeorgica in two patients with multiple myeloma: novel agents, new spectrum of infections.

OBJECTIVE AND IMPORTANCE

Introduction of high-dose chemotherapy and the novel agents including bortezomib, Lenalidomide, and Thalidomide has provided a significant progress in the treatment of multiple myeloma (MM) with an increase in median overall survival up to 6-8 years. However, the advances in myeloma treatment comes at a price with new spectrum of treatment-related infectious complications which should be taken into consideration while treating these patients.

CLINICAL PRESENTATION

We report here two patients with Ig G λ MM presenting with intracerebral mass lesions in the abscence of constitutional symptoms that would suggest an infectious etiology. Both patients had severe hypogammaglobulinemia and lymphopenia, which was attributed to treatment regimens including bortezomib. Intervention The surgical intervention-revealed abscess in both cases caused by Nocardia cyriacigeorgica, a relatively new pathogen which rarely causes infections in humans and also an unexpected pathogen in myeloma patients.

CONCLUSION

Although every aspect of immune system is known to be affected in MM, humoral immune deficiency is the hallmark of the inherent immune defect in this disease. Introduction of the novel agents, bortezomib in particular seems to have changed the characteristics of the immune dysfunction and the spectrum of the opportunistic infections by causing qualitative and quantitative changes in cellular immunity. The new spectrum of infectious agents might not be limited to hepatitis B and herpes zoster. Monitoring lymphopenia and administration of prophylactic antimicrobial agents accordingly could be considered in patients treated with bortezomib.