The MICs of antibiotics against Prevotella intermedia which were predominantly isolated from closed abscesses or cellulitis, and β-lactamase activity were measured to determine the role of β-lactamase in β-lactam resistant bacteria originating in odontogenic infections. 169 strains of P. intermedia (case A, 52strains, case B, 35strains and case C, 82strains) which were isolated from closed abscesses of endodontic origin were used in this experiment after identification of the microdilution plate hybridization method.In the cases of A and C, the MIC₉₀ of cefaclor was the largest among the drugs used, and their values became smaller in the order latamoxef, ceftizoxime and cefteram.The MIC₉₀s of cefmetazole and imipenem were as small as those of other antibiotics except for Plactams.The MIC₉₀ in case B was lower than that in cases A and C.β-Lactamase activity dffers with the case.Hydrolysis to substrates ampicillin (ABPC) and cefazolin (CEZ) was high in case A, and low in case B.However, in case C the ability of β-lactamase to hydrolyze substrate CEZ was high, but it was low for substrate ABPC.β-Lactamase chiefly hydrolyzed only substrate CEZ or both substrates ABPC and CEZ. Most of the isolates for which a drug had a higher MIC also had high β-lactamase activity, but in some isolates these was no relationship between the MIC and β-lactamase acitivity.These results suggest that β-lactamases which strongly hydrolyzed CEZ are closely related to the mechanism of β-lactam resistance in P.intermedia isolated from odontogenic infections, but we must also study mechanisms of β-lactam resistance other than that of β-lactamase.

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Cefditoren (CDTR), the active form of an oral cephalosporin cefditoren pivoxil (CDTR-PI) was tested for in vitro antibacterial and bactericidal activity against 158 strains of Streptococcus pneumoniae isolated from clinical materials from 1990 to 1993 in Japan in comparison with that of other oral antibacterial agents. These 158 strains consist of 90 penicillin G (PCG) sensitive strains (<0.1μg/ml) and 68 PCG-resistant (≥0.1μg/ml) strains. The MIC₈₀ values of CDTR were 0.05/0.20μg/ml against PCG-sensitive strains/PCG-resistant strains and those of cefdinir (CFDN), cefteram (CFTM), cefpodoxime (CPDX), cefaclor (CCL) and ofloxacin (OFLX) were 0.20/3.13, 0.05/0.39, 0.10/0.78, 0.39/12.5 and 1.56/1.56 μg/ml respectively. The antibacterial activity of CDTR was almost the same as that of CFTM but superior to that of CFDN, CPDX, CCL and OFLX. The bactericidal activity of CDTR in vitro was examined and compared with that of CFDN, CFTM, CPDX, CCL and OFLX at concentrations simulating the human serum level against PCG-sensitive and PCG-resistant S. pneumoniae strains. CDTR showed potent in vitro bactericidal activity against both PCG-sensitive and PCG-resistant S. pneumoniae.

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The incidence of adverse reactions, especially photosensitivity reactions, and the clinical efficacy to lomeflfoxacin hydrochloride (LFLX) were investigated. Four thousand two hundred and eighty-four patients from 100 hospitals throughout Japan were enrolled in the study over a period of 2 years from October 1991. The clinical efficacy rate of LFLX was 73.3% in 4, 276 of the evaluable cases. The incidence of adverse reactions was 2.36% in 4, 276 of the evaluable cases. Eight patients stopped visiting the hospitals. Photosensitivity reactions were observed in 44 patients (1.03%), but the degree of reaction was mild or moderate in most of them and they improved or recovered after withdrawal of LFLX. Regarding the manifestation of photosensitivity reaction induceds by LFLX, the effects of patients' factors (sex, age, underlying disease, complication. anamnesis, occupation and circumstances of residence, etc.) and therapeutic factors (daily dose and number of administrations administration period, total dose, concomitant drugs, and history of use of other drugs, etc.) were investigated by multivariate analysis. There was a higher incidence of photosensitivity reactions in patients aged 60 years or more or in patients having underlying diseases and complications. Daily dose and number of administrations did not affect the manifestation of the reaction, while an administration period of 30 days or more, a total dose of 20g or higher and previous treatment with new quinolones caused a higher incidence of photosensitiviy reactions. All new quinolones have more or less risk of inducing photosensitivity reactions. Also for LFLX as for other new quinolones, physicians need to instruct patients to protect themselves from excessive sunshine during administration of the drug and they should avoid long-term administration of the drug.

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A multicenter clinical study on pazufloxacin (PZFX), a new oral quinolone antimicrobial agent, was performed to examine its clinical efficacy in the treatment of skin infections. PZFX was administered to 19 patients. Group I consisted of 6 patients, 3 with folliculitis and 3 with acne pustulosa, group II contained 5 patients, 3 with furuncle and 2 with furunculosis and group VI had 8 patients, 5 with secondary infection of burn wounds and 3 with other secondary infections. Dosages were 100 mg or 200 mg of PZFX b. i. d. or t. i. d. for 3-8 days. The clinical efficacy was excellent in 13 cases, and good in 3. The overall efficacy rate was 82.4%. No side effects or abnormal laboratory findings were observed.

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We studied the therapeutic activity of an oral cephem antibiotic, cefetamet pivoxil (CEMT-PI) against an experimental intrauterine infection in mice, and compared it with that of cefteram pivoxil (CFTM-PI). At 20 hours after injection of on Escherichia coli suspension with 3.5 × 10³ cfu/uterus into a uterine horn, the number of viable cells reached approx. 4 × 10⁷ cfu/uterus, in the control mice. In mice to which CEMT-PI and CFTM-PI had been administered, the number of viable cells decreased in a dose dependent manner. The in vitro antibacterial activity of CEMT against E. coli RC 4 with a MIC of 0.2 μg/ml was similar to that of CFTM (0.39 μg/ml). The viable cell counts in the uterus of mice, to which CEMT-PI had been orally administered at 0.5, 2 and 8 mg/mouse were approx. 10-, 20-and 1, 300-fold lower than those obtained with CFTM-PI at the same doses, respectively. The therapeutic effect of CEMT-PI on this experimental intrauterine infection was superior to that of CFTM-PI, statistically (p<0.001).

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