Effects of cefetamet (Ro 15-8074) on Treponema pallidum and experimental syphilis

Abstract

Cefetamet pivoxil (Ro 15-8075) is a newly developed, expanded-spectrum cephalosporin that is orally active.In vitro, the active form, cefetamet (Ro 15-8074),-at a concentration of 0.05 ;Lg/ml killed and lysed Treponema paUlidum. Rabbit serum did not diminish its effectiveness. The antibiotic rapidly entered the circulation following intramuscular inection into rabbits, attaining its highest levels of 24 to 37 ,ug/ml within 10 to 30 min.Animals were infected intradermally with T. paUlidum and then treated with different doses of cefetamet.Accelerated healing was detected following treatment with 15 and 30 mg/kg of body weight. The antibiotic was also effective in killing organisms that had disseminated to distant tissues. In three separate sets of experiments, rabbits were infected with treponemes and then treated with cefetamet intramuscularly at 1, 15, or 30 mg/kg as follows: (i) after lesions had just become clinically apparent, (ii) after lesions were enlarged and well developed, or (iii) prior to the appearance of clinical lesions. Antibiotic effectiveness was determined by sacrificing the animals 1 week after antibiotic treatment and exawining splenic tissue for residual, disseminated treponemes. Cefetamet was treponemicidal in all three situations. Maximum effects occurred when the antibiotic was injected before lesions had become clinically apparent (incubation period). These results suggest that cefetamet pivoxil might be useful for treating syphilitic infections.

Syphilis: Review with Emphasis on Clinical, Epidemiologic, and Some Biologic Features

“…Time to resolution of clinical signs was also shorter in the azithromycin group than in the penicillin and erythromycin groups. The newer cephalosporins, i.e., cefmetazole, ceftizoxime, and cefetamet (Ro 15-8074), also show promise in animal models (14,92,188). Although useful in the treatment of other sexually transmitted diseases, quinolones have shown poor efficacy in animal models of syphilis (6,327,344).…”

Immune Transformations in Primary and Secondary Syphilis Patients before and after Treatment and its Clinical Significance

“…Penicillin remains the first choice for the treatment of syphilis till today. [7] The highest treponemicidal serum concentration of penicillin is 0.36 µg/ml which can eliminate the organism in 6-9 h. [8] Human infections with TP elicit dynamic immune reactions causing damage to the body. Several researchers have shown that T cells, B lymphocytes, NK cells, and IL-2 may participate in the pathogenesis of the spirochete.…”