Patients With acute PID are usually treated in hospital, and antibiotics are used intravenously to get the result as soon as possible. Chlamydia trachomatis is a major PID-causing pathogen, and azithromycin is one of the most active antibiotics against this microorganism.

Aim of the study To evaluate azithromycin concentrations after intravenous infusions in tubal tissues from women with and without PID.

Patients and Methods To prevent possible complications after future surgery azithromycin was infused intravenously (500 mg twice with 24-hours interval prior surgery, total dose 1.0 g) into 70 patients with PID (before surgery to prepare them for IVF), and into 28 patients without PID (before surgical sterilisation). Azithromycin pharmacokinetics was studied in tubal tissues incised at surgery 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 16 and 18 days after the second infusion.

Results In patients without PID maximal azithromycin concentration (4.30 ± 0.30 µg/g) was achieved 24 hours after infusion and remained constant for 24 hours more, with a steady drop thereafter. In women with PID maximal azithromycin concentration was achieved in tubal tissues 72 hours after the second infusion, and was lower than in women without PID (3.38 ± 0.10 µg/g). But on 6th day after infusion azithromycin concentration in inflamed tissues from women with PID was significantly higher than in non-inflamed tissues from women without PID (1.50 ± 0.10 µg/g and 0.95 ± 0.15 µg/g, respectively). In both groups azithromycin tissue concentration exceeded C. trachomatis MIC (0.125 µg/g) even 18 days after the second infusion.

Conclusion Azithromycin tubal tissue concentration even 18 days after infusion of 1 g (500 mg twice with 24 hours interval) exceeds MIC to C.trachomatis both in inflamed and non-inflamed tubes. Maximal azithromycin concentration is higher and achieved faster in women without PID, but it is higher in women with PID one week after infusion.