The annual multicenter studies on isolated bacteria from infections in general surgery and their antimicro bial susceptibility have been conducted in Japan since July 1982. This paper describes the results obtained in fiscal 1998 (from April 1998 to March 1999).
The number of cases investigated as objectives was 225 for one year. A total of 429 strains (121 strains fromprimary infections and 308 strains from postoperative infections) were isolated from 183 cases (81.3% of total cases). In primary infections, the isolation rates of anaerobes and Escherichia coli were higher than in postoperative infections, while in postoperative infections, those of Gram-positive aerobes and Pseudomonas aeruginosa were higher than in primary infections.
On the whole, among Gram-positive aerobes, the isolation rate of Enterococcus faecalis was the highest, followed by Staphylococcus aureus with high frequency in isolation from postoperative infections. Among Grampositiveanaerobes, Peptostreptococcus spp. and Streptococcus spp. were predominantly isolated. Among Gramnegative aerobes, E. coli, P. aeruginosa, Klebsiella pneumoniae and Enterobacter cloacae were frequently isolated. Among Gram-negative anaerobes, Bacteroides fragilis group was the majority of isolates.
In primary infections, the percentage of Gram-negative aerobes has gradually increased since fiscal 1995 or 1996 with these years as the turning point, while those of Gram-positive and Gram-negative anaerobes have gradually declined. In postoperative infections, the percentage of Gram-negative anaerobes has increased continuously since the mid-1980s.
The percentage of MRSA among S. aureus rose to 89.7%, which was the highest level scince the beginning of this study.
The susceptibilities of B. fragilis, which did not show apparent changes, were recognized to have decreased against cephems in fiscal 1998. Among other bacteria in B. fragilis group, development of resistance to ontinued on a long-term basis since the mid-1980s. E. coli and K. pneuminiae have obviously not changed in susceptibilities, however, the susceptibilities of isolated strains in fiscal 1998 against high-generation cephems, oxacephems and monobactams have declined.
We found neither vancomycin-resistant nor teicoplanin-resistant strains of S. aureus and Enterococcus spp.

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Clinical studies of ceftriaxone (CTRX) were performed at a dose of 40mg/kg once daily to evaluate its pharmacokinetics, and clinical and bacteriological efficacies in pediatric patients with respiratory tract infections. The following results were obtained.
1. Of 45 patients, clinical responses to CTRX were excellent in 34 (75.6%), good in 9 (20.0%) and poor in 2 (4.4%), indicating the overall efficacy rate of 95.6%.
2. Haemophilus influenzae (23 strains), Streptococcus pneumoniae (20 strains) and Moraxella catarrhalis (17 strains) were isolated from the patients as the main causative organisms. MIC₉₀ of CTRX against these detected bacteria was≤0.06μg/ml with H. influenzae [β-lactamase (-)/ABPC (S)], 0.25 μg/ml with H. influenzae (BLNAR), 0.05μg/ml with PSSP, 1.0 μg/ml with PISP/PRSP and 2.0 μg/ml with M. catarrhalis, respectively.
3. The eradication rate of causative organisms was 90.0% (27/30).
4. Serum levels of CTRX after administration of a 1-hour intravenous drip infusion of 40mg/kg were investigated in 12 patients. Mean serum level at 24 hours after the administration was 9.4±2.8μg/ml, which covered the level of MIC₉₀ throughout the 24 hours.
5. No adverse reactions related to CTRX were observed.
As the approved dosage of CTRX in pediatric patients is twice daily, while it is once daily in adults, there have been few reports on the efficacy of once-daily CTRX in pediatrics.
According to the results of the study, it is suggested that once-daily CTRX for the pediatric patients with respiratory tract infections is useful. Further studies might be required to establish outpatient parenteral antibiotic therapy (OPAT) in pediatric infections.

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