Organisms isolated from rhinopharyngeal fluid obtained from pediatric patients with upper respiratory tract bacterial infection were examined for β-lactamase production and susceptibility of anti-microbial drugs to estimate the direct pathogen as well as the β-lactamase-producing indirect pathogen, and to consider the preferable first choice antimicrobial drugs for the treatment of these patients. The predominant organisms which were estimated as the direct pathogen were Streptococcus pneumoniae and Haemophilus influenzae; 29.5% of the S. pneumoniae were penicillin-intermediate S. pneumoniae and penicillin-resistant S. pneumoniae, and 13.8% of the H. influenzae were β-lactamase-producing strains. The main organisms which were estimated as the indirect pathogen were Moraxella subgenus Branhamella catarrhalis and Staphylococcus aureus which produced β-lactamase. These organisms were often isolated concomitantly with S. pneumoniae or H. influenzae. The predominant patterns of isolated bacteria were S. pneumoniae plus M.(B.) catarrhalis and H. influenzae plus M.(B.) catarrhalis, these two patterns accounted for 32.6% of all patients. Thus it is suggested that the main indirect pathogenic factor in pediatric patients with upper respiratory tract bacterial infection is β-lactamase which is produced by M.(B.) catarrhalis. In the patients in whom an indirect pathogen is involved, the rate of elimination of S. pneumoniae and H. influenzae was significantly higher in those treated with clavulanic acid/amoxicillin than in those treated with amoxicillin.

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One hundred and seventy six pediatric patients with upper respiratory tract bacterial infection were clinically evaluated for indirect pathogenicity by β-lactamase-producing organisms to consider the selection of antimicrobial drugs used to treat this infection. The patients included 41 with monomicrobial infections (23.3%) and 135 with polymicrobial infections (76.7%). The main bacteria isolated as the direct pathogen were Haemophilus influenzae and Streptococcus pneumoniae, while those isolated as the indirect pathogen were Moraxella subgenus Branhamella catarrhalis, and Staphylococcus aureus. Of all the patients evaluated, 130 (73.9%) suggested possible involvement of either direct or indirect pathogenicity by β-lactamase-producing organism. These selected patients were randomly treated with amoxicillin (AMPC) or clavulanic acid/amoxicillin (CVA/AMPC), and the effect on eradication of the direct pathogen and the clinical effect were assessed and compared between patients caused by a β-lactamase-non-producing organism [β-negative (-) infection] and those caused by a β-lactamase-producing organism [β-positive (+) infection]. No significant difference was observed between the two treatment groups in terms of the rate of eradication of the direct pathogen both on either day 3 or 7 after treatment in the β-negative patients, while those treated with CVA/AMPC showed a significantly better eradication rate in the β-positive patients. Patients with polymicrobial infection from which M.(B.) catarrhalis was isolated showed a result similar to that in the β-positive patients. No significant difference in the clinical effect was found between the two treatment groups, while those treated with CVA/AMPC tended to show a more favorable clinical effect on patients with polymicrobial infectionfrom whom M.(B.) catarrhalis was isolated. It is clear that the indirect pathogenicity by a β-lactamase-producing organism was involved in eradication of the direct pathogen, but further studies including evaluation of long-term prognosis seem to be required to determine its clinical significance.

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Ampicillin (ABPC) treatment failed in a 4-month-old boy with Haemophilus influenzae type b meningitis. The isolate was β-lactamase-negative (B-L-N) and ABPC resistant. Subdural effusion which was one of the complications of meningitis was successfully treated by chloramphenicol. In our hospital 22%(13/59) of the H. influenzae strains were β-lactamase-positive (B-L-P) in 1993 and 10%(6/61) in 1996. The percentages of β-lactamase-negative, ABPC-resistant H. influenzae strains, of which the MICs were over 1.56μg/ml, were about 15% in 1993 and 29% in 1996. After inhibition by β-lactamase, several strains of B-L-P, H. influenzae were resistant to ABPC. The standard disk containing 30μg of ABPC for sensitivity testing could not detect ABPC resistance in B-L-N strains. Because of the prevalence of ABPC resistant H. influenzae, ABPC should not be used in the tratment of H. influenzae meningitis. While a few strains resistant to cefotaxime were recovered, cefotaxime may be preferable for treating H. influenzae meningitis.

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We compared the clinical efficacy of sulbactam/cefoperazone (SBT/CPZ) alone and SBT/CPZ in combination with clindamycin (CLDM) on respiratory infections as a complication in lung cancer patients. SBT/CPZ was administered alone to 22 patients and in combination with CLDM to 21 patients. Evaluation of clinical effects showed a response rate of 46.7% in the SBT/CPZ monotherapy group and 64.3% in the combination therapy group. The SBT/CPZ monotherapy group and the combination therapy group are not significantly defferent in their effectiveness. In patients with moderate or severe infection according to the severity grade of respiratory infection, the response rate was 37.5% in the SBT/CPZ monotherapy group and 60.0% in the combination therapy group. In patients with intractable moderate-severe infection, administration of SBT/CPZ in combination with CLDM appears to be an effective treatment.

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