EFFECT OF DISCONTINUING PROPHYLAXIS WITH NORFLOXACIN IN PATIENTS WITHHEMATOLOGIC MALIGNANCIES AND SEVERE NEUTROPENIA - A MATCHED CASE-CONTROL STUDY OF THE EFFECT ON INFECTIOUS MORBIDITY

The use of fluorinated quinolones for prophylaxis of infections in neu tropenic cancer patients has led to a reduction of infections with gra m-negative enteric bacilli, but there is concern about the emergence o f antibiotic-resistant enterobacterial infections and a rise of gram-p ositive bacteremias. Due to these concerns, in mid-1995 the use of pro phylactic norfloxacin was discontinued in our unit. In order to evalua te the impact of this measure on the infectious morbidity in our unit, 91 severe neutropenic episodes in 58 patients with hematologic malign ancies who did not receive norfloxacin prophylaxis (NO group) were clo sely matched to 91 episodes in 60 patients who received norfloxacin pr ophylaxis (NORFLO group). There were no differences in the incidence o f febrile neutropenia, fever of unknown origin or bacteremia during th e first febrile episode. There was a trend for a higher rate of coagul ase-negative staphylococcal bacteremia in the NORFLO group (5 vs. 11 c ases in the NO and NORFLO groups, respectively, p = NS). Enterobacteri al bloodstream infections were more frequent in the NO group (13 vs. 2 cases, respectively, p = 0.01), especially Escherichia coli (9 vs. 1 case, respectively, p = 0.01). Twelve of 13 enterobacterial isolates i n the NO group were sensitive to the fluoroquinolones vs. 0/2 in the N ORFLO group (p = 0.07). We conclude that the abrupt discontinuation of norfloxacin prophylaxis in our ward led to a rapid increase in the ra te of fluoroquinolone-susceptible enterobacterial infections, with a s carce impact on infectious morbidity. This suggests that the selection of resistant flora in an inpatient ward by prophylactic antimicrobial s may be reversible following the discontinuation of the prophylactic agent(s).