Department of Obstetrics and Gynaecology, School of Medicine, Gifu University, Tsukasa-machi, Gifu City, Gifu 500-8705, Japan
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Abstract |
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Introduction |
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Materials and methods |
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Antimicrobial agents.
S-4661 was provided by Shionogi Co. Ltd, Osaka, Japan; imipenem by Banyu Pharmaceutical Co. Ltd, Tokyo, Japan; panipenem by Sankyo Co. Ltd, Tokyo, Japan; meropenem by Sumitomo Pharmaceutical Co. Ltd, Tokyo, Japan; and ceftazidime by Nippon Glaxo Co. Ltd, Tokyo, Japan.
Strains tested.
A total of 135 recent clinical isolates (64 strains of aerobes and 71 of anaerobes) was collected from patients in the Department of Obstetrics and Gynaecology, School of Medicine, Gifu University between January 1997 and December 1998. The organisms were identified with the API STREP identification system (bioMérieux SA, Marçy l'Etoile, France), the Enterotube II identification system (Becton Dickinson, Cockeysville, MD, USA) and the Oxi/Ferm Tube II system (Becton Dickinson) for aerobic bacteria, and with the RAP ID ANA system II (Innovative Diagnosis System, Norcross, GA, USA) for anaerobic bacteria. Organisms tested were as follows: 33 isolates of Streptococcus agalactiae, 31 of Escherichia coli, 21 of Peptostreptococcus magnus, 22 of Bacteroides fragilis and 28 of Prevotella bivia.
Susceptibility tests.
MICs were determined by an agar dilution method.5,6 E. coli were grown on MuellerHinton agar (Difco Laboratories, Detroit, MI, USA); S. agalactiae on MuellerHinton agar (Difco) supplemented with 5% sheep serum (Irvine Scientific, Santa Ana, CA, USA); P. magnus and B. fragilis on modified Gifu anaerobic medium (GAM) agar (Nissui Pharmaceutical Co., Tokyo, Japan); and P. bivia on Brucella HK agar (Kyokuto Pharmaceutical Co., Tokyo, Japan) supplemented with 5% laked sheep blood. They were then suspended in Mueller Hinton broth (Difco) or GAM broth at c. 5 x 108 cfu/mL. After 200-fold dilution of the suspension, the bacteria were inoculated on to appropriate agar plates containing each antimicrobial agent (at concentrations ranging from 0.0020 to 256 mg/L) with a multipoint inoculator (Microplanter, Sakuma Seisakusho, Tokyo, Japan) providing an inoculum of c. 2.5 x 106 cfu/spot. All aerobic cultures were incubated at 37°C for 24 h and all anaerobic cultures at 37°C for 48 h in an Anaero Pack (Mitsubishi Gas Chemical Co., Tokyo, Japan). MICs were defined as the lowest concentrations of antimicrobial agents that prevented visible growth of organisms.
In vivo study
Animals.
Female SpragueDawley rats (specific pathogen free, 6 weeks old, weighing 155170 g) (Nippon Bio-Supply Centre, Tokyo, Japan) were used.
Organisms.
Organisms were clinical isolates from patients with uterine endometritis. The MICs of S-4661 and imipenem for E. coli GOG 0020 were both 0.0125 mg/L, while those for B. fragilis GOG 3102 were both 0.10 mg/L.
Experimental animal model.7,8
Rats were anaesthetized with sodium pentobarbital 25 mg/kg ip. Abdominal and flank hair was shaved, then the abdominal wall was thoroughly swabbed with povidoneiodine. A small vertical incision was made in the prepared abdominal wall and the uterus and adnexa were exposed. The uterine cervix was ligated with 1-0 silk. A 24 h culture of E. coli and 48 h culture of B. fragilis on MuellerHinton agar and modified GAM agar, respectively, and GAM broth as an inoculating medium, were used for inoculation. With a disposable sterile tuberculin syringe and a 27-gauge needle, 0.05 mL of bacterial suspension (4.3 x 105 cfu/rat of E. coli and 4.1 x 105 cfu/rat of B. fragilis) was injected into the right side of the uterine cavity. The abdominal wall was closed with 1-0 silk suture. After the operation, the abdominal wound was disinfected daily with povidoneiodine.
Therapeutic study.
Sixteen hours after bacterial inoculation, the rats were treated with S-4661 10 mg/kg iv tds for 5 days or with imipenem 10 mg/kg supplemented with cilastatin 10 mg/kg iv tds for 5 days; they were then compared with an untreated control group (six rats in each group). At 136 h after bacterial inoculation, the rats were anaesthetized with sodium pentobarbital, the peritoneal cavity was opened aseptically and bacterial counts of the uterine contents were performed using BTB agar (Eiken Chemical Co. Ltd,Tokyo, Japan) for E. coli and modified GAM agar for B. fragilis.
Statistical analysis.
Values are reported as mean ± s.d. All results were analysed using Fisher's protected least significance difference test and P values of <0.05 were considered significant.
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Results and discussion |
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Notes |
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References |
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Received 1 December 1999; returned 3 March 2000; revised 20 April 2000; accepted 19 May 2000