In vitro effects of the combination of nitrofurantoin and trimethoprim against sensitive and nitrofurantoin and trimethoprim-resistant Escherichia coli K12.
The combination of subinhibitory concentrations of trimethoprim (Tp) and nitrofurantoin (NT) seemed additively inhibitory against sensitive Escherichia coli K12, chromosomally mediated NT, R-plasmid mediated Tp and NT-resistant E. coli strains, respectively. The minimal inhibitory concentrations of 6 micrograms/NT/ml and 2 micrograms Tp/ml against the sensitive strain were respectively reduced 5-fold by a minimum inhibitory combination of Tp + NT. The 30-fold chromosomally mediated and 15-fold R-plasmid NT resistance were 3- and 5-fold respectively reduced by a minimum inhibitory combination of Tp + NT. The minimum inhibitory combination of Tp + NT also reduced more than 20-fold the at least 1,000-fold resistance level of the R-plasmid mediated Tp resistance. This in vitro activity of NT and Tp could be of clinical relevance in the therapy of urinary tract infections due to multiple antibiotic-resistant strains.
D004338:Drug Combinations; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D009582:Nitrofurantoin / Q000494:pharmacology*; D011815:R Factors; D014295:Trimethoprim / Q000494:pharmacology*
D004338:Drug Combinations; D009582:Nitrofurantoin; D014295:Trimethoprim