In vitro activity of A-56268 (TE-031) and four other antimicrobial agents against Chlamydia trachomatis

Abstract

The in vitro activity of A-56268 (TE-031), a new macrolide antibiotic, against 11 strains of Chiamydia trachomatis was determined and compared with that of four other antibiotics. A-56268 was the most active drug tested. Doxycycline, trimethoprim-sulfamethoxazole, and erythromycin had good activity but were less active in vitro than A-56268.A-56268 (TE-031) is a new macrolide antibiotic which is structurally related to erythromycin. Since erythromycin has both in vitro and in vivo activities against Chlamydia trachomatis (2, 6, 7, 9-12), we tested the activity of A-56268 against 11 strains of C. trachomatis (2 laboratory and 9 clinical strains). The susceptibilities of these strains to doxycycline, erythromycin, trimethoprim-sulfamethoxazole, and ciprofloxacin were also determined.A-56268 and erythromycin base (Abbott Laboratories, North Chicago. Ill.), trimethoprim-sulfamethoxazole (Burroughs Wellcome Co., Research Triangle Park, N.C.), ciprofloxacin (Miles Pharmaceuticals, West Haven, Conn.), and doxycycline hydrochloride (Sigma Chemical Co., St. Louis, Mo.) were prepared as stock solutions at concentrations of 1,280 ,ug/ml according to their stated potency, except for sulfamethoxazole, which was prepared at a concentration of 25,600 ,ug/ml. Stock solutions were stored at -70°C for a maximum of 2 weeks. On the day of use, the drugs were diluted to the appropriate concentration with medium containing Hanks balanced salt solution, amino acids, vitamins, 1% glutamine, 10% inactivated fetal calf serum, 5.4 g of glucose per liter, and 1 ,ug of cycloheximide per ml. Trimethoprim-sulfamethoxazole was prepared at a ratio of 1:20. The 11 strains of C. trachomatis tested included strains D (ATCC VR-885) and LGV-II (ATCC V9-902-B), and 9 clinical strains (conjunctival or genital origin). The clinical strains had been passed fewer than 10 times in the laboratory. All isolates were passed an additional two times in antibiotic-free medium before susceptibility testing and were stored at -70°C until the time of use.In vitro susceptibility studies were performed with McCoy cells which had been serially passed at least six times in antibiotic-free medium. McCoy cell monolayers were treated with trypsin and suspended with antibiotic-free medium to a concentration of about 2 x 106 cells per ml. Cell suspensions (100-,u portions) were seeded into 96-well microtiter plates and incubated at 37°C in 5% CO2 for 24 h. * Corresponding author.Duplicate plates were prepared for each drug. The monolayers were inoculated with 0.05 ml of a dilution of the C. trachomatis test strain known to yield 100 to 1,000 inclusions per well. The plates were centrifuged at 1,000 x g at 25°C for 60 min and then overlaid with 0.1 ml of each drug to yield appropriate twofold dilutions. Each dilution was tested three times. Appropriate antibiotic-free controls were included on each plate. Cultures were incubated for 48 h at 37°C in 5% C02, then fixed with absolute ethanol, and stained with 0.02 ml of fluorescein-conjugated mouse monoclonal antibody to C. tr...

In Vitro Antibacterial Potency and Spectrum of ABT-492, a New Fluoroquinolone

“…are obligate intracellular bacteria, and the susceptibility test methods require the use of infected mammalian cells (32). The MICs of ABT-492 for two strains of C. trachomatis in this study were 0.03 and 0.06 g/ml, respectively, which were comparable to the MICs of trovafloxacin, while levofloxacin and ciprofloxacin were less active.…”

“…The susceptibility of Chlamydia trachomatis was determined by broth microdilution with infected McCoy cells incubated at 37°C in an atmosphere containing 5% CO 2 for 48 h; intracellular C. trachomatis was visualized by fluorescentantibody staining (Merifluor Chlamydia; Meridian Diagnostics, Inc., Cincinnati, Ohio) (32).…”

In vitro activities of T-3262, NY-198, fleroxacin (AM-833; RO 23-6240), and other new quinolone agents against clinically isolated Chlamydia trachomatis strains

“…The MICs of pipemidic acid, norfloxacin, and enoxacin were comparable to those found by other investigators (1,10). The MICs of minocycline were as favorable as those previously reported for doxycycline and tetracycline (2,10,16,18). This study also showed that T-3262 is very effective against C. trachomatis in vitro.…”

“…Also, infertility resulting from salpingial obstruction is considered to be frequently caused by C. trachomatis (6). Several studies have shown that some kinds of quinolone, macrolide, and tetracycline drugs are effective against C. trachomatis in vitro (1,2,7,10,(15)(16)(17)(18). We evaluated the in vitro activities of three newly developed quinolone agents, T-3262, NY-198, and fleroxacin (AM-833, RO 23-6240), against 10 clinically isolated C. trachomatis strains and compared them with those of other quinolones and minocycline.…”

New directions for macrolide antibiotics: structural modifications and in vitro activity

“…Activity of clarithromycin was increased two-to fourfold against Legionella species (35,45), B. catarrhalis (20), and P. multocida (31); in contrast, activity against H. influenzae and H. parainfluenzae was approximately half that of erythromycin (7,9,34,51). Clarithromycin was more than 10-fold more active against C. trachomatis (11,73) while comparable to erythromycin against N. gonorrhoeae (11, 31) and H. ducreyi (24). Activity was equivalent to that of erythromycin against various species of Campylobacter (8,9).…”