Factors related to poor outcome in drug-resistant bacterial infection treatment were analyzed based on surveys at 54 National Hospital Organization facilities. Results showed common etiological causes of Methicillin-resistant Staphylococcus aureus (MRSA) and Penicillin-resistant Streptococcus pneumoniae (PRSP). Specifically, the odds ratio in the elderly, aged 75 years and older, was 1.473 (p=0.006) for MRSA and 6.401 (p=0.0001) for PRSP. Among those undergoing tracheal intubation, the odds ratio was 1.767 (p=0.021) for MRSA and 4.185 (p=0.0001) for PRSP, showing that advanced age and tracheal intubation tended to aggravate disease. MRSA-specific causes were pneumonia with an odds ratio of 2.426 (p=0.0001) and sepsis with one of 1.417 (p=0.013). Causes specific to Multi-drug resistant Pseudomonas aeruginosa (MDRP) were Intravenous hyperalimentation (IVH) with an odds ratio of 2.078 (p=0.0001) and urinary-tract infection with one of 0.566 (p=0.027). The individual roles of these factors in poor outcomes must thus be clarified to develop preventive measures against them.