Chemotherapeutic effect of cefoxitin on experimental pyelonephritis in rats. Comparative study with cefazilin.

Ascending pyelonephritis was successfully produced in rats by means of direct inoculation with a virulent strain of Escherichia coli into the bladder enclosing a glass ball. 3-Carbamoyloxymethyl-7-alpha-methoxy-7-[2(2-thienyl)-acetamido]-3-cephem-4-carboxylic acid (cefoxitin) or cefazolin as a control drug was applied to the affected rats characterized by purulent inflammation in pelvis and medulla sometimes accompanied with abscess formation in medulla and/or coretex 3 days after challenge. The treatments were performed at an i.v. dose of 40 mg/kg 3 times a day for 5 consecutive days. The improvement of the disease, that is disappearance of the bacilli in the kidney, improvement of BUN value and of histopathological findings in cefoxitin-treated animals was approximately equal to that in cefazolin-treated ones. Both antibiotics exhibited great effectiveness against purulent pyelonephritis, however, not sufficiently effective against medullar and cortical abscesses. Chemotherapeutic effect of cefoxitin on experimental pyelonephritis was discussed with special reference to its distribution into the affected tissues.