Antibiotic therapy for hospital infections should incorporate at least two different aspects:(1) therapeutic success in individual patients and (2) preventing the emergence of antibiotic-resistant mutants. To reduce the emergence of antibiotic-resistant hospital strains, several strategies should be employed: lowering antibiotic consumption by not treating healthy carriers; stopping treatment when an infection is cured (when cultures are negative and further infection is unlikely) or has not been diagnosed; not overusing any antibiotic class to reduce selection pressure; and using sufficient antibiotic doses to prevent the selection of first-step mutants. The trend towards increased antibiotic resistance requires a more prudent use of antimicrobial drugs in the treatment of hospital infections. Simultaneously, preventing the transmission of resistant organisms from one person to another is critical to successful preventive efforts.

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Between June 2003 and January 2004, we studied the in vitro activity of prulifloxacin (PUFX) against clinical isolates causing otorhinolaryngological infection: coagulase negative Staphylococcus (CNS), Staphylococcus aureus, α-Streptococcus, Streptococcus pneumoniae, Corynebacterium spp., Branhamella catarrhalis, and Haemophilus influenzae.
1) MIC₈₀ and MIC₉₀ for CNS were 4.0μg/ml, and susceptibility distribution showed two peaks, at 0.125μg/ml and 4.0μg/ml.
2) MIC₈₀ and MIC₉₀ for S. aureus were 0.5μg/ml and 8.0μg/ml, and susceptibility distribution showed two peaks, at 0.25μg/ml and 0.5μg/ml.
3) MIC₈₀ and MIC₉₀ for α-Streptococcus were 4.0μg/ml, and susceptibility distribution showed one peak, at 2.0μg/ml.
4) MIC₈₀ and MIC₉₀ for S. pneumoniae were 2.0μg/ml, and susceptibility distribution showed two peaks, at 1.0μg/ml and 2.0μg/ml.
5) MIC₈₀ and MIC₉₀ for Corynebacterium spp. were 8.0μg/ml and 32.0μg/ml, and susceptibility distribution showed two peaks, at 0.5μg/ml and 32.0μg/ml.
6) MICK80 and MIC₉₀ for B. catarrhalis were 0.125μg/ml, and susceptibility distribution showed one peak, at 0.125μg/ml.
7) MC80 and MIC₉₀ for H. influenzae were 0.031μg/ml, and susceptibility distribution showed one peak, at 0.031μg/ml.
Compared to other new quinolone antimicrobial agents for Gram-positive bacteria-except gatifloxacin (GFLX), which showed good activity-PUFX showed activity almost equal to that of ciprofloxacin (CPFX) and levofloxacin (LVFX). For Gram-negative bacteria, PUFX showed activity almost equal to that of GFLX, CPFX, and LVFX. We concluded that we get good results with PUFX in patients with otorhinolaryngological infection caused by the above strains.

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To demonstrate the rapid therapeutic effect of cefozopran (CZOP), an injectable cephalosporin antibacterial agent, we conducted a postmarketing comparative study in patients with lower respiratory tract infections, using ceftazidime (CAZ) as a control. Patients were given CZOP and CAZ at a dose of lg (potency) twice daily for 7 days by intravenous drip infusion. Results were as follows:
1. A total of 412 patients were enrolled in the study, and 376 were included in the full analysis set (FAS). Judgment of clinical efficacy was not possible in 3. Efficacy (proportion of patients showing good responses) was 92.0%(173/188) for the CZOP group and 91.4%(169/185) for the CAZ group, which supported the noninferiority of CZOP to CAZ both at the 90% and 95% confidence intervals (two-sided). Stratified by disease, efficacy was 90.9%(120/132) in patients with bacterial pneumonia for the CZOP group and 93.3%(126/135) for the CAZ group. In patients with chronic respiratory infection, it was 94.6%(53/56) for the CZOP group and 86.0%(43/50) forthe CAZ group, verifying the noninferiority of CZOP to CAZ both atthe 90%and 95% confidence intervals (two-sided).
2. Bacteriological effects were evaluated in 210 patients in whom causative organisms were identified and the presence or absence of bacteria followed up. Eradication (proportion of patients in whom the causative organism was eradicated or replaced with another organism) was 89.5%(94/105) for the CZOP group and 90.5%(95/105) for the CAZ group. No significant difference was seen between groups. Eradication for individual causative organisms was 91.1%(113/124) for the CZOP group and 90.8%(108/119) for the CAZ group, showing no significant difference between groups. Eradication for S. pneumoniae, the most frequently isolated organism, was 100%(42/42) for the CZOP group and 89.5%(34/38) for the CAZ group, indicating a statistically significant difference (p=0.047). Eradication on day 5 of treatment also favored the CZOP group over the CAZ group statistically significantly (p=0.049).
3. The aim of therapy was achieved in 52.4%(99/189) of the CZOP group and 50.3%(94/187) of the CAZ group at completion of the study, requiring no additional treatment with antibacterial agents. No statistically significant difference was seen between groups in achieving the aim of therapy.
4. The incidence of adverse symptoms and signs was 3.9%(8/206) in the CZOP group and 5.0%(10/202) in the CAZ group. The incidence of abnormal alterations of laboratory variables was 31.6%(65/206) in the CZOP group and 32.2%(65/202) in the CAZ group. No statistically significant differences were seen between groups.
Results indicate that CZOP is not inferior to CAZ in clinical efficacy. They also verified that CZOP has a rapid therapeutic effect in patients with lower respiratory tract infections caused by S. pneumoniae.

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