Efficacy of cefmetazole in the treatment of active syphilis in the rabbit model

Abstract

Cefmetazole, a cephamycin-type antibiotic, was shown to be as effective as standard benzathine penicillin for therapy of active syphilis in the rabbit model. Four groups of six adult male rabbits were inoculated intradermally with 106 Treponema pallidum per site, producing primary syphilitic lesions. One week following infection, groups of rabbits were treated with benzathine penicillin (200,000 U intramuscularly weekly for 2 weeks) or cefmetazole (20 or 40 mg/kg per day intramuscularly in four divided doses for 15 days); one group was untreated. Daily dark-field microscopic examination of lesion aspirates demonstrated that the mean times to dark-field negativity were the same for benzathine penicillin-and two cefmetazole-treated groups (1.0. 1.0, and 1.17 days, respectively), while all untreated animals remained dark-field positive for >15 days. Mean maximum lesion diameters in cefmetazole-treated animals (8.7 ± 1.3 and 8.1 ± 1.3 mm) were equivalent to those in penicillin-treated animals (8.6 + 1.6 mm) and were smaller than observed in untreated animals (12.4 -2.2 mm; P < 0.01); fewer lesions ulcerated in penicillin-or cefmetazole-treated rabbits than in untreated rabbits (P < 0.001). Persistent infection was documented in lymph nodes of untreated rabbits; no evidence of latent infection was found in penicillin-or cefmetazole-treated animals.

Are nontreponemal tests suitable for monitoring syphilis treatment efficacy? Evidence from rabbit infection models

“…At the different time points post infection (30, 60 and 180 days) in both the Nichols and the Amoy BPG treatment subgroups, the lesions had disappeared, and no testicular or serological evidence of infection was observed in any of the recipients of lymph node material extracted from the BPG treatment donor rabbits. Thus, the donor rabbits in these subgroups at the three time points were adequately treated [19], particularly at 30 days post infection, at which point the RPR titres of almost all rabbits had not decreased fourfold. However, almost all rabbits in the no BPG treatment subgroup were obviously still infected at 30, 60 and 180 days post infection, although the RPR titres in almost all the donor rabbits had decreased fourfold, and one rabbit was RPR seronegative.…”

“…Then, the Nichols and Amoy groups were divided into the BPG treatment (n ¼ 15) and no BPG treatment (n ¼ 15) subgroups. The rabbits in the Nichols and Amoy BPG treatment subgroups received two intramuscular administrations of 200 000 U of BPG at 14 days and 21 days post infection [18,19]. The remaining 15 rabbits in each strain group not treated with BPG were defined as the Nichols and Amoy no BPG treatment subgroups (Fig.…”

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).…”

Efficacy of linezolid on Treponema pallidum, the syphilis agent: A preclinical study

“…Studies to support the use of alternatives for treating syphilis are overall limited. In the preclinical setting, cephalosporins, [14] , [15] , [16] aztreonam, [17] and macrolides [ 18 , 19 ] have shown anti-syphilis activity. However, only three randomized clinical trials have compared penicillin to other antibiotics (i.e., ceftriaxone and azithromycin) [20] , [21] , [22] .…”