Azithromycin

Materials The following 47 compounds were purchased from Wako Pure Chemical Industries, Ltd., Osaka, Japan for use in this study: acetylsalicylic acid, acyclovir, allopurinol, amitriptyline, amoxicillin, azathioprine, azithromycin, budesonide, caffeine, carbamazepine, chloramphenicol, chlorpheniramine maleate salt, chlorpromazine, diethylcarbamazine, digoxin, diphenhydramine hydrochloride, doxycycline, erythromycin, ethosuximide, fluconazole, folic acid, furosemide, haloperidol, hydrochlorothiazide, hydrocortisone, ibuprofen, isoniazid, loratadine, metformin, metoclopramide, metronidazole, nitrofurantoin, ondansetron, oseltamivir, paracetamol, phenytoin, potassium iodide, prednisolone, primaquine, propranolol, propylthiouracil, quinine hydrochloride, salbutamol, spironolactone, sulfamethoxazole, valproic acid and vancomycin.

The following antimicrobial agents were used: cefmetazole (sodium salt, Sigma-Aldrich Japan); clindamycin phosphate (MP Bio Japan, Tokyo, Japan); ofloxacin (LKT Laboratories, St. Paul, MN, USA); and amoxicillin trihydrate, azithromycin, clarithromycin, ciprofloxacin hydrochloride monohydrate, and cefcapene pivoxil hydrochloride hydrate (all from Wako Pure Chemical Industries, Osaka, Japan). Stock solutions were made by dissolving each antibiotic in purified water or ethanol; 4-fold serial dilutions of each stock were prepared, and each solution was filter-sterilized (pore size, 0.22 μm; Millipore, Bedford, MA, USA). Solutions were added to blood agar to yield final antibiotic concentrations of from 32 to 0.0019 μg/ml.