Trends in bacterial infections in febrile neutropenic patients: 1986-1992

Bacterial infection is a major cause of morbidity and mortality in neutropenic patients.

(1) To review patterns and trends in bacterial infections in three cohorts of febrile neutropenic patients managed by a single unit over a seven year period. (2) To relate any changes to the use of central venous (Hickman's) catheters and high-dose cytosine arabinoside chemotherapy.

Retrospective review of the results of initial bacteriological work-up performed on 344 episodes of febrile neutropenia. The three cohorts were 1986-87 (n = 102), 1989-90 (n = 92) and 1991-92 (n = 150).

(1) The ratio of gram-negative to gram-positive bacteraemias fell from 1.36 in the first cohort to 1.05 in the second and 0.40 in the third (p = 0.03). There was a fall in both percentage and number of gram-negative isolates coupled with a rise in the frequency of gram-positive isolates. (2) Coincidentally there was a rise in the frequency of positive cultures from Hickman catheter entry wounds and an increasing frequency of simultaneous isolation of the same organism from the catheter entry site and the blood. The types of organisms isolated from catheter entry wounds showed a trend towards fewer gram-negative and more gram-positive. (3) A relationship was observed between the use of high-dose cytosine arabinoside chemotherapy and the incidence of bacteraemia (p = 0.025) but not with the change in types of organisms.

Over seven years we have documented a major change in the types of infections, particularly bacteraemias, seen in febrile neutropenic patients. In our institution the more widespread use of intravenous catheters and high-dose cytosine arabinoside chemotherapy have been identified as two possible contributing factors.