Rheumatic fever and acute glomerulonephritis are known to occur secondary to infection with Streptococcus pyogenes, and early elimination of the Streptococcus pyogenes by treatment with an appropriate antibiotic is required. Treatment with penicillins for 10 days has been recommended for Streptococcus pyogenes infections, but cephems are also now being used, and cefditoren pivoxil (CDTR-PI) is listed as one of the recommended drugs in the Guidelines for the Management of Respiratory Infectious Disease in Children in Japan 2007. We therefore conducted this study in order to collect appropriate use information in the clinical setting of CDTR-PI to treat Streptococcus pyogenes infections. In this study, 790 patients were enrolled in 147 institutions. Of them, 734 and 718 patients were chosen for safety and efficacy analysis, respectively.

There were 11 adverse drug reactions in 11 patients, and the incidence of adverse drug reactions was 1.50% (11/734 patients). The most common adverse drug reactions were diarrhea and hematuria, and there were 3 events of each, but a positive urinalysis after administration were only obserbed without the clinical symptoms. With the exception of the 3 patients in which the patient did not return to the hospital and the outcome is unknown, the patients either recovered from all of the adverse drug reactions or they were relieved. No serious adverse drug reactions were reported in this study.

The response rate was 98.5% for laryngopharyngitis (457/464 patients) and 98.4% (250/254 patients) for tonsillitis. Examination of the response rates according to patient background showed that they were high, 95% or more, in every group. The Streptococcus pyogenes eradication rate was 94.6% for laryngopharyngitis (194/205 patients) and 92.4% (110/119 patients) for tonsillitis.

In summary, CDTR-PI exhibited excellent safety and efficacy in laryngopharyngitis and tonsillitis caused by Streptococcus pyogenes, and CDTR-PI was reconfirmed as a useful drug.

The minimum inhibitory concentrations (MICs) and the mutant prevention concentrations (MPCs) of garenoxacin (GRNX), were compared to those of levofloxacin (LVFX), and moxifloxacin (MFLX) against 78 Streptococcus pneumoniae isolates from otorhinolaryngological infections in Japan during the period January 2007 to June 2007.

The MIC and MPC for 90% of the isolates (MIC₉₀ and MPC₉₀) of GRNX were 0.06 and 0.12𝜇g/mL, respectively, and were the lower values than LVFX and MFLX MIC₉₀s and MPC₉₀s. The ratios of MPC/MIC of GRNX were the lower values than those of LVFX and MFLX.

We calculated achievement rates of target attainment of AUC/MIC using Monte Carlo simulation (MCS). Two doses of pazufloxacin mesilate (PZFX) between q.d. and b.i.d. were compared for each species of bacterium. Concentrations for AUC of PZFX of 8 patients were measured at this hospital, and those from a phase I clinical study (phase I, 6 healthy volunteers) were used. MICs of PZFX were determined for each species of bacterium of respiratory organ origin (Pseudomonas aeruginosa, Haemophilus influenzae, Streptococcus pneumoniae, and Klebsiella pneumoniae). AUC per day of 500 mg b.i.d. used twice AUC (PZFX 500mg×2/day by patient, PZFX 500 mg×2/day by phase I). Target attainment of AUC/MIC was AUC/MIC ≥30 in S. pneumoniae and AUC/MIC ≥125 in the other species of bacteria (P. aeruginosa, H. influenzae, and K. pneumoniae). As a result, patients showed an about 3 times higher AUC than the phase I subjects (67.9/21.9µg/mL). In addition, the target attainment of AUC/MIC showed the highest rate in PZFX 500mg×2/day in patients with each type of bacteria: H. influenzae (98%), K. pneumoniae (89%), S. pneumoniae (66%), and P. aeruginosa (41%). Target attainment of AUC/MIC was H. influenzae (91%), K. pneumoniae (81%), P. aeruginosa (5%), and S. pneumoniae (0%) in phase I. Therefore, the effectiveness of PZFX was estimated to be low using the MCS method with the phase I data.