• Older patient with multiple myeloma (monoclonal spike on SPEP and bone marrow biopsy showing >50% plasma cells), which leads to impaired production of normal immunoglobulins, leading to increased risk for sinopulmonary infections (due to impaired IgA production) and encapsulated infections (due to impaired IgG –> impaired opsonization –> increased risk of encapsulated infections such as Strep pneumo, H. influenzae and Neisseria)

https://step-prep.org/tutoring/

Idk but I thought of this like the B cell immunodeficiencies, most of which cause susceptibility to encapsulated organisms like S. pneumoniae.

According to wiki:

Most common infections in multiple myeloma are Pneumonia and Pyelonephritis. Pneumonia is caused by strep, staph, and klebsiella. Pyelonephritis is caused by E. Coli and other gram negatives