Ampicillin (ABPC) resistant streptococci in healthy adults' saliva were screened using Mitis-Salivarius agar plates which contained 1, μg/ml ABPC, and the screen test revealed that 56 out of 74 volunteers (75.4%) retained the resistant strains. The streptococcal isolates (154 strains) were identified as Streptococcus parasanguis (80 strains; 51.9%), Streptococcus oralis (33 stains; 21.4%), and Streptococcus mitis (7 strains; 4.5%) by biochemical characteristics. The MIC values of ABPC, cefaclor (CCL), and imipenem (IPM) against the isolates ranged as follows: 1-16, μg/ml for ABPC, 2->128μg/ml for CC, L, and ≤0.06-2, μg/ml for IPM; these values did not necessarily show proportionate distribution between each other. In both S. parasanguis and S. mitis, the numbers and molecular sizes of penicillin binding proteins (PBPs) varied among strains belonging to the same species, even among strains with the same amplification patterns of the 16S-rRNA gene, when examined by polymerase chain reaction (PCR) method. Although the binding affinity for each PBP of the isolates was diverse among the three β-lactams, a correlation between the IC, value for total PBPs and the MIC value was observed for all three. The gene detection in the conserved region of PBP2b and 2x by means of PCR indicated the possibility of alteration, at least in the PBP2b gene of S. mitis resistant strains. These results suggest that the β-lactam-resitant population of streptococci may universally exist in the healthy oral cavity, and that they may be important because of their own latent pathogenicity and potential resistant gene source of Streptococcus pneumoniae.

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To evaluate the cause of the vulnerability to infections in the patients with lung cancer, the ability of polymorphonuclear leukocytes (PMN) to generate reactive oxygen species (ROS) in the patients was assessed by a luminol-dependent chemiluminescence (CL) assay after stimulation with non-opsonized zymosan, Pseudomonas aeruginosa. CL values of whole blood and isolated PMN from patients induced by zymosan tended to be lower than that in normal controls. CL values of whole blood and CL per PMN from the patients also exhibited significantly lower CL responses to the stimulation of P. aeruginosa as compared with those of normal controls. There were no significant difference in zymosan-induced CL values of whole blood correlated with type of cancer histology or stage of cancer. After anticancer chemotherapy, CL values of whole blood gradually declined as granulocytopenia progressed. Recombinant human granulocyte colony-stimulating factor (G-CSF) enhanced the CL response of PMN in vitro during phagocytosis of zymosan or P. aeruginosa in healthy adults and in lung cancer patients both before and after anticancer chemotherapy. G-CSF administration to patients treated with chemotherapy increased the PMN count in peripheral blood and enhanced their ROS generation in ex vivo studies. There results suggest that the administration of G-CSF to lung cancer patients may provide immuno-supportive therapy against bacterial infection serving to improve granulocytopenia and to enhance the usually reduced ROS production of PMN following anticancer chemotherapy.

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Clinical and bacteriological studies were carried out in infantile and chidren with acute purulent otitis media due to benzylpenicillin-insensitive or resistant Streptococcus Pneumoniae. The results are as follows:
1. Forty-three strains were isolated from 40 patients and the rate of benzylpenicillin-insensitive or resistant S. pneumoniae was 61.2%.
2. The isolation of benzylpenicillin-insensitive or resistant S. pneumoniae was frequent especially in children aged 3 Years and under. Ages ranged from 0.2 to 6 years with in average age of 1.8 years.
3. In the MIC₈₀ of oral, β-lactum antibiotics, cefditoren pivoxil demonstrated the strongest effect power (MIC80: 0.5, μg/ml) against benzylpenicillin-insensitive or resistant S. pneumoniae. In the MIC₉₀ of oral β-lactum antibiotics benzylpenicillin, cefditoren pivoxil and cefteram pivoxil all demonstrated the same effect (MIC₉₀: 1.0 iug/ml) against benzylpenicillin-insensitive or resistant S. pneumoniae.
4. In some strains of benzylpenicillin-insensitive or resistant S. pneumoniae (85.7%), clindamycin showed the strongest at MIC₈₀ (MIC₈₀: under 0.125 μg/ml), however, some strains (14.3%) showed resistance to clindamycin (MIC: over 16.0 μg/ml).
5. Effective clinical treatment was achieved in 75% of the patients by a combination of oral antibiotics and operative treatment (myringotomy with or without insertion of tympanotomy tube), however, in 20% of all patients, ear discharge recurred due to benzylpenicillin-insensitive of resistant S. pneumoniae.

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Between September 1997 and April 1998, 78 patients were diagnosed as having an infection caused by Streptococcus pneumoniae in the pediatric ward of Asahikawa Kosei Hospital. Thirty-eight of these patients had an infectious disease caused by penicillin-resistant Streptococcus pneumoniae (PRSP). The age range of the patients was from 5 months to 5 years. Their diseases were: pneumonia/bronchitis with otitis media in 17, pneumonia/bronchitis in 13, otitis media in 4, maxillary sinusitis in 2, bacteremia with otitis media in 1, and bacteremia of unknown origin in 1. Three patients were rehospitalized in our hospital for treatment of a second infection episode caused by PRSP. In 10 patients, the highest CRP value was more than 10mg/dl. Thirty-five patients in the first infection episode were treated with cephalosporins: 30 received cefotaxime and 5 flomoxef. Thirty patients showed improvement in clinical symptoms after cephalosporin therapy and in 5 cephalosporins were replaced with carbapenems because PRSP was isolated from the patients' specimens. The MICs of penicillin G against PRSP were from 0.0125 to 1μg/ml in 28 strains and 2μg/ml in 10.

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