Successful combination therapy by meropenem and colistin for multi-drug-resistant Pseudomonas aeruginosa infection after allogeneic bone marrow transplantation

A 66-year-old male with acute type adult T-cell leukemia that was refractory to chemotherapy underwent unrelated allogeneic bone marrow transplantation after non-myeloablative conditioning with fludarabine, busulfan and total body irradiation. During an episode of neutropenia on day 12 after transplantation, pneumonia and sepsis due to multi-drug resistant Pseudomonas aeruginosa developed. Drug susceptibility tests demonstrated resistance to all kinds of intravenous antibiotics available for P. aeruginosa in Japan. Multi-drug susceptibility tests by the breakpoint-checkerboard plate method were then performed and combination therapy with meropenem hydrate and colistin was started based on the test results. After starting treatment, clinical symptoms and laboratory data immediately improved and engraftment of neutrophils was achieved on day 18. Infections with multi-drug-resistant P. aeruginosa are often critical for patients after hematopoietic stem cell transplantation and are difficult to control. In this paper, we report a case of severe multi-drug-resistant P. aeruginosa infection that was successfully treated by combination therapy selected using the breakpoint-checkerboard plate method.