Short-term versus prolonged systemic antibiotic prophylaxis in patients treated with indwelling catheters

Newly hospitalized patients with stroke treated by indwelling catheters were assigned randomly to 3 treatment groups. Group 1 (24 patients) received 3 gm. ampicillin intramuscularly in divided doses 1 hour before, at the time of and 6 hours after insertion of the catheter. Group 2 (28 patients) received daily 1 gm. ampicillin intramuscularly every 8 hours. Group 3 (26 patients) was not subjected to any antimicrobial prophylaxis. Within 1 week after catheter insertion significant bacteriuria developed in 12.5 per cent of the patients in group 1, 42.8 per cent in group 2 and 45.1 per cent in group 3. The difference in the incidence between group 1 and either group 2 or 3 was statistically significant (p less than 0.02 and p less than 0.01, respectively). The mean number of strains (plus or minus standard error of mean) isolated per case of bacteriuria in group 3 (1.25 plus or minus 0.18) was significantly lower (p less than 0.05) and antimicrobial resistant strains were fewer (4 of 15) than in group 2 (1.75 plus or minus 0.13 and 12 of 21, respectively).