Le secnidazole : activité antibactérienne sur les anaérobies stricts

Abstract

Secnidazole is a 5-nitro-imidazole mainly used in gynecological infections due to Trichomonas or anaerobes (vaginosis). The in vitro activities of secnidazole and comparators (amoxycillin, amoxycillin + clavulanic acid, clindamycin, and metronidazole) were determined against 372 recent clinical anaerobic isolates using the NCCLS agar dilution method (M11A5,2001) with supplemented Brucella agar and an inoculum of 10 5 cfu/ml. The major groups tested included B. fragilis group species (123), Prevotella species (24), Fusobacterium species (51), Clostridium species (45) and Peptostreptococcus species (62). The following data are secnidazole MIC ranges (mg/L), MIC 90 for representative species : B. fragilis 0.125-16, 8; other Bacteroides of the fragilis group 0.125-8, 1; Prevotella ≤0.06-64, 1; Fusobacterium ≤0.06-16, 1; C. difficile 0.25-4, 4; other clostridia ≤ 0.06-2, 2; non sporulated Gram-positive bacilli ≤0.06->64, > 64; Gram-positive cocci ≤0.06->64, 2. Within the B. fragilis group, resistance rates to co-amoxiclav, clindamycin were 4.1 and 28.4% respectively, meanwhile 6 strains had decreased susceptibility to metronidazole. Resistance to either secnidazole or metronidazole could not be detected among the B. fragilis group. Strains of Porphyromonas and Fusobacterium were all inhibited by 16 mg/L of secnidazole whereas all isolates of clostridia were inhibited by 4 mg/L or less of secnidazole. Considering the B. fragilis group, clostridia and Gram-positive cocci, the MIC 50 and 90% values for metronidazole and secnidazole were identical. Resistance to secnidazole was observed mainly among non sporulated Gram-positive bacilli (including all strains of Propionibacterium), and some anaerobic cocci. The two imidazoles had similar activities against the other anaerobic species. Secnidazole appears to have good in vitro activity against a wide range of anaerobic bacteria by inhibiting respectively 99% and 100% of the Gram-negative anaerobes and clostridia. Further clinical investigation is needed.