We studied the therapeutic efficacy of cefditoren pivoxil (CDTR-PI) and amoxicillin (AMPC) against a mixed pneumonia model of penicillin-susceptible Streptococcus pneumoniae (PSSP) and β-lactamase negative ampicillin resistant Haemophilus influenzae (BLNAR) in mice. The efficacy of CDTR-PI against PSSP was observed at doses of 30mg/kg/day or higher, and of AMPC at doses of 7.5mg/kg/day or higher. CDTR-PI treatment against BLNAR also showed therapeutic efficacy at doses of 18.8mg/kg/day or higher, unlike AMPC. Moreover, the efficacy of atherapy switchingfrom AMPC to CDTR-PI was superior tothat of AMPC monotherapy against BLNAR. The effect of switching from AMPC to CFPN-PI and CFDN was approximately equal to that of AMPC monotherapy. This suggests that CDTR-PI is likely to become the drug of choice due to its balanced activity against mixed infection caused by S. pneumoniae and H. influenzae. CDTR-PI is likely to become the drug of second choice in failure of AMPC therapy as the first choice.

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The susceptibilities of Pseudarnonas aeruginosa isolated from lower respiratory tract infections (2, 067 strains) and urinary tract infections (1, 454 strains) against various antibacterial agents were examined. The strains were clinically isolated between 1996 and 2003 at Toho University Omori Hospital. Susceptibility rates (SR) were calculated according to break point of National Committee for Clinical Laboratory Standards document. Against strains isolated from lower respiratory tract infections, the SR of amikacin was superior to other drugs and was more than 88%. The SR of ceftazidime was 57% in 1996, but it recently increased and reached 92% in 2003. The SR of imipenem gradually decreased and was 54% in 2003. The SR of ciprofloxacin trended to recover after 1997, but it dropped by 67% in 2003. Against strains isolated from urinary tract infections, the trends of SR were similar to those of lower respiratory tract infections.

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Cefdinir (CFDN) concentrations in human serum, gingiva, mandibular bone, and dental follicle following a single oral administration of CFDN (200mg) were studied. The mean concentrations in serum, gingiva, mandibular bone, and dental follicle peaked at identical times, 3.5h after administration, and were 1.39μg/mL, 0.60, 0.25, and 0.51μg/g. The mean concentration ratios of gingiva/serum, mandibular bone/serum, and dental follicle/serum at the peak were 0.42, 0.18, and 0.35. Most of the CFDN concentrations in gingiva, mandibular bone, and dental follicle exceed the MIC for 80% of clinically isolated strains of oral streptococci. CFDN may thus be a valuable antimicrobial agent for the treatment of odontogenic infection.

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In this study, in vitro combination effects of teicoplanin and beta-lactams was investigated. MRSA strains (50) were isolated from a variety of clinical specimens at Kurume University Hospital during the period from May 2003 through August 2003. TEIC plus meropenem (MEPM), plus panipenem/betamipron (PAPM/BP), plus biapenem (BIPM), plus cefozopran (CZOP), plus cefepime (CFPM), plus sulbactam/ampicillin (SBT/ABPC), plus ciprofloxacin (CPFX), plus, pazufloxacin (PZFX) were revealed by microbroth dilution method, and compared their fraction inhibitory concentration (FIC) index. The mean value of FIC indices obtained from each of the combinations was 0.293 as to TEIC+MEPM, 0.482 as to TEIC+PAPM, 0.488 as to TEIC+BIPM, 0.593 as to TEIC+CZOP, and 0.387 as to TEIC+CFPM, and 1.066 as to TEIC+SBT/ABPC, and 0.839 as to TEIC+CPFX, in other words, the combination of TEIC+MEPM showed the lowest value of all the combinations. While MIC90 was 2.0 micrograms/mL when TEIC was used alone, it was<or=0.25 microgram/mL when used together with MEPM. The present results suggested that simultaneous use of TEIC and MEPM could yield an enhancement of both bacteriological and clinical efficacies in treatment of the patients with MRSA infection.

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