In vitro activity of trimethoprim alone compared with trimethoprim-sulfamethoxazole and other antimicrobials against bacterial species associated with upper respiratory tract infections.
Trimethoprim-sulfamethoxazole has been used to treat various respiratory tract infections. Nevertheless, for many patients, intolerance of the sulfonamide component precludes use of this combination. This study examined the activity of trimethoprim alone in comparison to that of trimethoprim-sulfamethoxazole and other antimicrobials against bacterial species implicated in respiratory tract infections. For Haemophilus influenzae, minimal inhibitory concentrations of trimethoprim were equal to or one dilution greater than those of trimethoprim-sulfamethoxazole, with 56 of 58 strains inhibited by the former at < or = 0.25 microgram/ml. All oxacillin-susceptible Staphylococcus aureus and 96.7% of Streptococcus pyogenes were inhibited by trimethoprim < or = 2 micrograms/ml. In contrast, only 50% of Streptococcus pneumoniae were inhibited by this concentration of trimethoprim, whereas 93.3% were susceptible to the combination at < or = 2/38 micrograms/ml. All oxacillin-resistant S. aureus and all Moraxella catarrhalis were resistant to trimethoprim, although many of the former and all of the latter were susceptible to trimethoprim-sulfamethoxazole.
Eliopoulos
G M
GM
Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
Wennersten
C B
CB
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D006801:Humans; D008826:Microbial Sensitivity Tests; D012141:Respiratory Tract Infections / Q000382:microbiology*; D014295:Trimethoprim / Q000494:pharmacology*; D015662:Trimethoprim, Sulfamethoxazole Drug Combination
D000900:Anti-Bacterial Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014295:Trimethoprim