Changing patterns of infections in patients with multiple myeloma.

A total of 59 infections were encountered in 29/46 patients with multiple myeloma (MM). Most infections arose in the urinary tract (31%), respiratory tract (29%), followed by blood (12%), oropharynx (12%), skin and soft tissue (7%). Gram-negative bacilli were identified in 51% of infections, most common being Enterobacteriaceae and Haemophilus influenzae. Gram-positive organisms were responsible for 7% of infections. 24% of patients with urinary tract infections had signs of cord compression Absolute lymphopenia was common, and was seen in 65% of patients with urinary infections, 75% of respiratory infections, and 86% of septicemic patients. In contrast, granulocytopenia was mainly observed in patients with septicemia (71%), followed by those with respiratory infections (31%). All patients were on cytotoxic chemotherapy, and most were hypoglobulinemic. About one third of septicemias, and one half of urinary and respiratory infections, respectively, were hospital-acquired. Results indicate that the current pattern of infections in MM seems to favor gram-negative organisms. The role of predisposing factors in the pathogenesis of infections in these patients is discussed.