Bacteremia Due to Gram-negative Bacilli

Abstract

This report concerns 113 cases of bacteremia due to gram-negative bacilli observed at the Mayo Clinic for the period 1955 through 1959. Almost 60% of patients were more than 60 years old. Underlying diseases or treatment capable of predisposing to infection included malignant disease in 17% of cases, hematologic disease in 13%, diabetes mellitus in 11%, hepatic cirrhosis in 5%, prior treatment with antibiotic agents in 19%, administration of pharmacologic doses of adrenal steroids in 14%, and use of antimetabolites in 5%. In 46% there was an apparent precipitating surgical or instrumental procedure, or roentgen therapy. In only 5% were such predisposing or precipitating factors not identified. Members of the coli-aerogenes group of organisms remain the most common cause of bacteremia due to gram-negative bacilli. However, the relative incidence of Pseudomonas bacteremia has increased, apparently because of the propensity of Pseudomonas to invade the blood of victims of terminal neoplastic, hemopoietic and renal diseases. The mortality rate from bacteremia due to Pseudomonas is considerably in excess of that due to other gram-negative bacilli, apparently because of this agonal association. Polymyxin B remains an effective agent, although a newer one, colistin sulfate, may have potential application. As a generalization, treatment of bacteremia due to gram-negative bacilli of enteric origin, other than Pseudomonas with streptomycin and a tetracycline continues to be successful. The recovery rate, uncorrected for such factors as underlying disease which probably made a considerable number of fatalities inevitable, approximated 70% in this series.