Clinical and laboratory study of tobramycin in the treatment of infections due to gram-negative organisms.

Tobramycin, an aminoglycoside antibiotic, was used to treat 52 infections due to gram-negative organisms in 51 patients. Complicated urinary tract infections, bacteremia and pyelonephritis accounted for 80% of the infections. The rate of immediate satisfactory response was 79%. During therapy with tobramycin, resistant organisms emerged in four patients--two Pseudomonas aeruginosa and two Escherichia coli strains. There were four superinfections with tobramycin-resistant Providencia sp. In four seriously ill patients the serum creatinine concentration increased 1 mg/dL or more; in three the increase was transient. No auditory toxicity was noted in the 19 patients in whom serial audiograms were made. In vitro testing of isolates from these patients showed that tobramycin and gentamicin had equal activity against Enterobacteriaceae. Tobramycin was two to four times more active against susceptible P. aeruginosa.

Amoxicillin therapy of acute urinary infections in adults.

Fifty-two patients, 48 females and 4 males, with suspected urinary infection were treated with amoxicillin. Twenty-two females with presumed bladder infection were treated with amoxicillin, 250 mg three times a day for 7 days; 26 females and 4 males with presumed renal infection were treated with amoxicillin, 500 mg three times a day for 14 days. Five patients were immediate treatment failures, with positive urine cultures during therapy. All five patients had been infected with amoxicillin-resistant urinary pathogens. Three patients, treated as for bladder infections, reinfected during 6 weeks of follow-up, and only one relapsed. Two patients, treated as for renal infections, reinfected, whereas four relapsed. During therapy, amoxicillin-susceptible gram-negative rods were eradicated from the periurethral area in all but one patient. Of 28 patients studied, 19 acquired a predominant growth of either resistant aerobic gram-negative rods or Candida albicans from periurethral cultures. Our findings suggest that these two regimens of amoxicillin achieve satisfactory cure rates in urinary infection, but both regimens significantly alter the normal periurethral flora.

Clinical evaluation of amikacin in treatment of infections due to gram-negative aerobic bacilli.

The efficacy and safety of amikacin were evaluated in 42 patients with infections presumed to be due to gram-negative rods. The dosage of 7.5 mg of amikacin/kg every 12 hr was administered intramuscularly to 32 patients and intravenously to seven patients; three patients with renal impairment were given a modified regimen. The duration of treatment was three to 51 days (mean, 9.6 days). Of 19 patients with acute pyelonephritis, five had positive blood culture results. Ten patients had chronic urinary infection, and isolates of Pseudomonas aeruginosa from four of these patients acquired resistance to amikacin during therapy. Of seven patients with gram-negative bacteremia from sources other than the urinary tract, four showed satisfactory and three had less than optimal responses to therapy with amikacin. Two patients with chronic osteomyelitis or soft tissue infection improved but subsequently relapsed. Two patients with acute febrile illness, in whom the etiologic agent was unidentified, recovered. Serial audiograms revealed no change in 26 of 27 patients; one had a significant deterioration in hearing. A transient rise in the level of serum creatinine was noted in three patients. Serial tests of liver function revealed no abnormalities.