Studies on MRSA pneumonia as a complication of hematopoietic malignancies

Abstract

Recently, the progress of chemotherapy has improved the clinical outcome of chemotherapy for hematopoietic malignancies considerably. However, the incidence of MRSA infections has increased in patients with hematopoietic malignancies, since preventive, multi-drug administration of antibiotics is frequently used in these patients. Moreover, patients with hematopoietic malignancies complicated by MRSA pneumonia have a poor prognosis. We examined lymphocyte subpopulations in bronchoalveolar lavage fluid (BALF) in MRSA pneumonia-complicated patients with hematopoietic malignancies and studied their relationship with the clinical features. We also discuss the cause of their poor prognosis. Of 223 patients with hematopoietic malignancies, 18 (8.1%) were complicated by MRSA pneumonia. Many of those patients had lymphoid malignancies. MRSA pneumonia occurred when neutrophil count was decreased. Most patients had been treated with chemotherapy containing anticancer drugs or with corticosteroid therapy. They had also been treated with third generation cefem antibiotics. We studied lymphocyte subsets in BALF in MRSA pneumonia-complicated patients with non-Hodgkin's lymphoma (NHL) and observed the local changes of the pulmonary immunological system due to NHL itself and due to anti-lymphoma chemotherapy. Our findings suggest the possibility that these immunological changes may play a role in the susceptibility to MRSA pneumonia.