Case of sepsis caused by multidrug-resistant neutropenic-phase Pseudomonas aeruginosa treated successfully with antibiotic combination therapy

Multidrug-resistant Pseudomonas aeruginosa (MDRP), defined as Pseudomonas aeruginosa resistant to aminoglycosides, carbapenems, and fluoroquinolones, has emerged as an increasingly problematic cause of hospital-acquired infection. With parenteral colistin unavailable in Japan, effective antimicrobial options are severely limited. We report a case of MDRP bacteremia successfully treated with antibiotic combination therapy screened by a 'Break-point Checkerboard Plate'. A 54-year-old man with malignant lymphoma who became febrile 9 days after a recent course of chemotherapy had a neutrophil count of 176/microL. Treatment with meropenem and vancomycin was ineffective and high fever persisted. Methicillin-resistant Staphylococcus aureus (MRSA) and MDRP were isolated from blood culture and combination therapy with aztreonam and amikacin was selected for MDRP based on 'Break-point Checkerboard Plate' results. Linezolid was used for MRSA. The patient recovered successfully from MDRP and MRSA sepsis.