Flurithromycin

The in vitro activity of flurithromycin, a 14-membered macrolide drug, was found to be similar to that of erythromycin against 41 strains of Mycoplasma spp. and 100 strains of Ureaplasma urealyticum. All 28 strains of Mycoplasma hominis were uniformly resistant to both macrolides with MICs > 256 mg/L, U. urealyticum showed intermediate resistance with MIC50s of 0.5 and 1 mg/L for erythromycin and flurithromycin, respectively, whereas the ten strains of Mycoplasma pneumonia were susceptible to < or = 0.03 mg/L of both macrolides.

The minimal inhibitory concentrations (MIC) of flurithromycin on 49 clinical isolates of Helicobacter pylori was investigated. The MICs were determined using an agar dilution technique. Flurithromycin inhibited the growth of H. pylori strains with MIC(50) and MIC(90) values of 0.156 and 0.625 mg/l, respectively. The postantibiotic effects (PAE) were studied on ten strains, by exposure of the bacteria to flurithromycin at five and ten times MIC for 1 or 2 h. Regrowth was determined by measuring the viable counts after drug removal by a 10(3) dilution procedure. All PAEs increased as a function of concentration and time of exposure. The mean duration of PAEs varied between 1.5 and 6 h. These data are encouraging since macrolides play a key role in the clinical treatment of H. pylori infections, and the strong PAE caused by flurithromycin may contribute to the in vivo efficacy of this drug.

The purpose of the present investigation was to evaluate, in 20 periodontal patients, the microbial and clinical effects of flurithromycin therapy plus scaling and root planning (SRP) in comparison with SRP alone. Clinical assessments of plaque, bleeding on probing and pocket depth were made prior to SRP alone and SRP plus flurithromycin therapy (375 mg twice daily for 5 days) and after both treatments. Subgingival plaque samples (n. 180) were taken prior to and after both treatments and analyzed by conventional bacteriological procedures. Differences in pocket depth and prevalence of bacterial species were analyzed pre- and post-therapies using statistical analyses. A significant decrease (p<0.001) was seen for pocket depth post SRP alone and post SRP plus flurithromycin. After two treatments, Actinobacillus actinomycetemcomitans, Bacteroides forsythus and Prevotella melaninogenica were eradicated from all tested sites. If we compare the prevalence of the species isolated after SRP alone and after SRP plus flurithromycin statistically significant differences were detected for P. gingivalis and for Fusobacterium nucleatum (p<0.05 and p<0.01, respectively). Flurithromycin can be considered a useful adjunct to mechanical periodontal treatment since it is more efficient in eliminating periodontal pathogens.