The in vitro activity of amifloxacin (WIN 49375), a new fluoroquinolone, was compared with the activities of antimicrobial agents that are commonly used for the treatment of urinary tract infection (cinoxacin, cephalexin, gentamicin, amoxicillin, trimethoprim, and trimethoprim-sulfamethoxazole) against 25 strains of Staphylococcus saprophyticus and 28 strains of Escherichia coli. Bacterial strains were isolated from urine specimens of college women with acute urinary tract infections. Bacterial isolates were more susceptible to trimethoprim-sulfamethoxazole, trimethoprim, and amifloxacin than to the other drugs tested. The in vitro activity of amifloxacin against S. saprophyticus had an inverse relation to increases in the pH of the test medium. Changes in the type of culture medium had no effect on the in vitro activity of amifloxacin. There was a direct relationship between increases in inoculum size and the MICs of amifloxacin.Amifloxacin (WIN 49375) is a new synthetic fluoroquinolone agent structurally related to nalidixic acid and cinoxacin. Staphylococcus saprophyticus, which causes 10 to 13% of urinary tract infections in young women, is usually resistant to nalidixic acid and cinoxacin (5-7). The purposes of this study were as follows: (i) to compare the in vitro activities of amifloxacin against S. saprophyticus and Escherichia coli isolated from urine specimens of college women with acute urinary tract infections; (ii) to compare the in vitro activity of this agent with that of antimicrobial agents that are commonly used in the treatment of urinary tract infections, i.e., cinoxacin, trimethoprim-sulfamethoxazole (TMP-SMZ), trimethoprim, amoxicillin, cephalexin, and gentamicin; and (iii) to determine the influence of changes in the pH of the culture medium, the type of culture medium, and the inoculum size on the activity of amifloxacin.MATERIALS AND METHODS Bacterial strains. The organisms studied were 25 strains of randomly selected S. saprophyticus and 28 strains of E. coli recently isolated from urine samples from college women with urinary tract infections at the University of Florida Student Health Services Kidney Clinic.Bacteriological methods. Urine specimens were plated on blood and MacConkey agar. Gram-negative organisms were identified on API 20E (Analytab Products, Plainview, N.Y.) (3, 9). S. saprophyticus was identified by the method previously reported (7) and tested for susceptibility to novobiocin by the diffusion method with a 5-,ug disk (1).Antimicrobial agents. The powder of the following antimicrobial agents was either purchased or supplied by the manufacturers: amifloxacin (Winthrop Laboratories, Div. Sterling Drugs Inc., New York, N.Y.); sulfamethoxazole, gentamicin, amoxicillin, and cephalexin (Sigma Chemical Co., St. Louis, Mo.); trimethoprim (Hoffman-La Roche, Inc., Nutley, N. J.); and cinoxacin (Eli Lilly & Co., Indianapolis, Ind.). * Corresponding author. Stock antibiotic solutions. Stock solutions of antimicrobial agents (2 mg/ml) were prepared from powder of known potency in...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.