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Microbiology

Chemotherapy 1998;44:153–156

In vitro and in vivo AntibacterialActivities of S-1090, a New OralCephalosporin, in the Fields ofObstetrics and Gynecology

Hiroshige MikamoKyoko KawazoeYasumasa SatoKoji IzumiTeruhiko Tamaya

Department of Obstetrics andGynecology, School of Medicine,Gifu University, Gifu, Japan

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Key WordsS-1090Minimal inhibitory

concentrationEndometritis, uterine

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AbstractS-1090 is a new synthetic, nonesterified, oral cephalosporinwith a broad spectrum of antibacterial activity. The activitiesof S-1090 against the causative organisms in the fields ofobstetrics and gynecology are superior to those of the currentlyprescribed oral cephems, cefdinir, cefpodoxime, and cefaclor.The in vivo efficacy of S-1090 was evaluated using uterineendometritis of model rats. The accumulation of neutrophilsin the uterus in the S-1090-treated group was milder than thatin the nontreated group, and the same was true for the bacte-riological response. S-1090 is a promising oral cephalosporinantibiotic for the treatment of infections in the fields of obstet-rics and gynecology.OOOOOOOOOOOOOOOOO

Introduction

Many oral cephalosporins have been de-veloped and are now widely used for clinicaltreatment. S-1090 is a new oral cephalosporinwith the chemical structure (–)-(6R,7R)-[(Z)-2-(2-amino-4-thiazolyl)-2-hydroxyiminoacet-amido]-8-oxo-3-(1H-1,2,3-triazol-4-yl)thio-methylthio-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid monohydrochloridemonohydrate, which was primarily synthe-sized by Shionogi Pharmaceutical Co., Osaka,Japan [1, 2]. S-1090 can display relatively

potent in vitro activities among related cepha-losporins [3, 4]. We evaluated in vitro and invivo antibacterial activities of S-1090 in thefields of obstetrics and gynecology.

Materials and Methods

In vitro StudyAntimicrobial Agents. S-1090 and cefaclor were

provided by Shionogi Pharmaceutical Co., Osaka, Ja-pan. The other antimicrobial agents were provided asfollows: cefdinir, Fujisawa Pharmaceutical Co., Osaka,Japan, and cefpodoxime, Sankyo, Tokyo, Japan.

ABCFax + 41 61 306 12 34E-Mail karger@karger.chwww.karger.com

© 1998 S. Karger AG, Basel0009–3157/98/0443–0153$15.00/0

This article is also accessible online at:http://BioMedNet.com/karger

Hiroshige Mikamo, MD, PhDDepartment of Obstetrics and GynecologySchool of Medicine, Gifu University40, Tsukasa-machi, Gifu-city, Gifu 500-8705 (Japan)Tel. +81 58 267 2631, Fax +81 58 265 9006

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154 Chemotherapy 1998;44:153–156 Mikamo/Kawazoe/Sato/Izumi/Tamaya

Strains Tested. A total 100 recent clinical isolates(40 strains of aerobes and 60 strains of anaerobes) werecollected from patients in the Department of Obstet-rics and Gynecology, School of Medicine, Gifu Uni-versity during the period between January 1995 andDecember 1995. The organisms were identified withthe API STREP identification system (API System,Montalieu-Vercieu, France) and the Enterotube IIidentification system (Becton Dickinson, Cockeysville,Md., USA) for aerobic bacteria, and with the RAP IDANA system II (Innovative Diagnosis System, Atlanta,Ga., USA) for anaerobic bacteria. Organisms testedwere as follows: 20 strains of Streptococcus agalactiae,20 strains of Escherichia coli, 20 strains of Peptostrep-tococcus magnus, 20 strains of Bacteroides fragilis, and20 strains of Prevotella bivia.

Susceptibility Tests. Minimal inhibitory concentra-tions (MICs) were determined by an agar dilutionmethod [5, 6]. Aerobic and anaerobic organisms grownon agar plates were suspended in Mueller-Hintonbroth (Difco Laboratories, Detroit, Mich., USA) andGAM (Gifu Anaerobic Medium) broth (Nissui Phar-maceutical Co., Tokyo, Japan), respectively, to obtainabout 5 ! 108 CFU/ml. After a 200-fold dilution of thesuspension, the bacteria were inoculated onto agarplates containing each antimicrobial agent with a mul-tipoint inoculant (Microplanter, Sakuma Seikusho,Tokyo, Japan) at a cell density of about 2.5 ! 104

CFU/spot. Mueller-Hinton agar (Difco) was used foraerobes, Brucella HK agar (Kyokuto PharmaceuticalCo., Tokyo, Japan) supplemented with 5% laked sheepblood for anaerobes. All aerobic cultures were incu-bated at 37°C for 24 h and all anaerobic cultures at37°C for 48 h in the AnaeroPak system (MitsubishiGas Chemical Co., Tokyo, Japan). MICs were definedas the lowest concentrations of antimicrobial agentsthat prevented the visible growth of organisms.

In vivo StudyAnimals. Female Sprague-Dawley rats (specific

pathogen-free, 12 weeks old, weighing 220–260 g) wereused.

Organisms. Organisms were clinically isolatedfrom patients with uterine endometritis. MICs ofS-1090 and cefdinir for E. coli GOG 0020 were 0.025and 0.10 mg/l, respectively. The MICs were deter-mined by a standard agar dilution method with Muel-ler-Hinton agar (Becton Dickinson) for E. coli. TheMIC was defined as the lowest drug concentration,which was preventable for any visible growth of bacte-ria. Aerobic organisms grown on agar plates were sus-pended in Mueller-Hinton broth (Difco), to obtain

about 5 ! 108 CFU/ml. After a 200-fold dilution of thesuspension, bacteria at the density of about 2.5 ! 104

CFU per spot were inoculated onto agar plates con-taining each antimicrobial agent with a multipoint ino-culant (Microplanter, Sakuma Seisakusho, Tokyo, Ja-pan). All aerobic cultures were incubated at 37°C for24 h.

Twenty-four-hour cultivation of E. coli was per-formed on Mueller-Hinton agar (Becton Dickinson,Cockeysville, Md.). Mueller-Hinton broth (BectonDickinson) was used for inoculating medium into theuterine cavity.

Procedures of the Model of Rat Uterine Endometri-tis. Rats were intraperitoneally anesthetized with sodi-um pentobarbital at a dosage of 25 mg/kg. The abdom-inal and flank hair was shaved, and then the abdomi-nal wall was thoroughly swabbed with povidone-iodine. A small vertical incision was made at theabdominal wall, and uterus and adnexa were exposed.An intrauterine sterile foreign body, 3 ! 7 ! 1 mm ofa part of the injured intrauterine device FD-1 (FujiLatex, Tokyo, Japan) was placed into the uterine cavi-ty. The uterus was repaired by vicryl 5-0 (Johnson &Johnson, Somerville, N.J., USA). Using a disposablesterile tuberculin syringe with a 27-gauge needle,0.05 ml of the bacterial suspension containing 1.1 !106 CFU/rat of E. coli was injected into the right sideof uterine cavity. The abdominal wall was closed with1-0 silk suture. After operation, the abdominal woundwas disinfected with povidone-iodine every day.

Therapeutic Study. Within 16 h after intrauterineinoculation of 1.1 ! 106 CFU/rat of E. coli, S-1090,20 mg/kg p.o. b.i.d. for 3 days or cefdinir, 20 mg/kgp.o. t.i.d. for 3 days was given to the rats. The adminis-tered dose and frequency were determined by anotherstudy for pharmacokinetics. Within 88 h after the bac-terial inoculation, under anesthesia with sodium pen-tobarbital, the peritoneal cavity was opened aseptical-ly, and the right uterine corpus was resected [3, 7]. Partof it was submitted to histological examinations, andthe major part of the uterine corpus was homogenizedand subjected to quantitative bacterial examinations[8]. Quantitative bacterial cultures were performedwith BTB agar (Eiken Chemical Co., Tokyo, Japan) forE. coli.

Statistical AnalysisValues are reported as mean B standard deviation.

All results were analyzed using the Bonferroni/Dunntest and significance was assigned at p ! 0.05.

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In vitro and in vivo AntibacterialActivities of S-1090

Chemotherapy 1998;44:153–156 155

Fig. 1. Histological analysis for the uterine corpus in S-1090-treated, cefdinir-treated anduntreated groups of rats.

Table 1. In vitro antimicrobialactivity of S-1090, cefdinir, cefpo-doxime and cefaclor against clini-cal isolates in the fields of obstet-rics and gynecology

Organism Compound MIC, Ìg/ml

range 50% 90%

S. agalactiae S-1090cefdinircefpodoximecefaclor

0.025–1.560.05–1.56

0.025–3.130.0125–0.78

0.0250.100.101.56

0.050.200.203.13

E. coli S-1090cefdinircefpodoximecefaclor

!0.0125–0.78!0.0125–1.56!0.0125–3.13!0.0125–6.25

0.050.100.101.56

0.200.390.393.13

P. magnus S-1090cefdinircefpodoximecefaclor

0.025–6.250.0125–12.50.0125–250.0125–50

0.200.200.200.78

6.2512.52550

B. fragilis S-1090cefdinircefpodoximecefaclor

0.20–11000.39–11001.56–11006.25–1100

1.563.136.25

12.5

100110011001100

P. bivia S-1090cefdinircefpodoximecefaclor

0.78–11000.78–11001.56–11006.25–1100

1.566.256.25

1100

100110011001100

There were 20 strains of each organism. Inoculum size: 106 CFU/ml.

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156 Chemotherapy 1998;44:153–156 Mikamo/Kawazoe/Sato/Izumi/Tamaya

Results and Discussion

Table 1 shows MIC ranges, MICs for 50%of the strains tested and MICs for 90% of thestrains tested of S-1090, cefdinir, cefpodox-ime and cefaclor. This compound showed abroad and well-balanced spectrum of antibac-terial activities against clinical isolates ofgram-positive and gram-negative organisms.The activities of S-1090 against the causativeorganisms in the fields of obstetrics and gyne-cology are superior to those of the currentlyprescribed oral cephems, cefdinir, cefpodox-ime, and cefaclor.

Bacteriological effects of S-1090 and cef-dinir against infections caused by E. coli inthe uterine endometritis model are as follows:mean B SD, unit: log CFU/g (actual data,unit: log CFU/g): S-1090-treated group: 1.95B 0.17 (1.78, 1.95, 2.12), cefdinir-treatedgroup: 2.13 B 0.09 (2.05, 2.12, 2.22), anduntreated group: 4.29 B 0.06 (4.36, 4.25,

4.25). The viable cell counts of E. coli in theS-1090- and cefdinir-treated groups were sig-nificantly lower than those in the untreatedgroup. Bacteriological effects of S-1090,20 mg/kg p.o. b.i.d. were almost equal to thoseof cefdinir 20 mg/kg p.o. t.i.d.

Figure 1 shows the histological effects ofS-1090 and cefdinir on the rat uterine corpusin S-1090-treated, cefdinir-treated and un-treated groups. The accumulation of neutro-phils in the uterus in the S-1090- or cefdinir-treated group was milder than that in theuntreated group, and the same was true forthe bacteriological response.

The findings in this study together withpotent and balanced antibacterial activity andexcellent oral absorbability revealed in phar-macokinetic studies suggest that S-1090 is apromising oral cephalosporin antibiotic forthe treatment of infections in the fields ofobstetrics and gynecology.

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References

1 Kume M, Kubota T, Kimura Y, Na-kashimizu H, Motokawa K, NakanoM: Orally active cephalosporins. II.Synthesis and structure-activity re-lationships of new 7 ß-[(Z)-2-(2-ami-nothiazol-4-yl)-2-hydroxyiminoacet-amido]-cephalosporins with 1,2,3-triazole in C-3 side chain. J Antibiot1993;46:177–192.

2 Kume M, Kubota T, Kimura Y, Na-kashimizu H, Motokawa K: Orallyactive cephalosporins. III. Synthesisand structure-activity relationshipsof new 3-heterocyclicthiomethyl-thio-7ß-[(Z)-2-(aminothiazol-4-yl)-2 - hydroxyiminoacetamido ] - 3 - ce -phem-4-carboxylic acids. J Antibiot1993;46:316–330.

3 Tsuji M, Ishii Y, Ohno A, MiyazakiS, Yamaguchi K: In vitro and invivo antibacterial activities of S-1090, a new oral cephalosporin. An-timicrob Agents Chemother 1995;39:2544–2551.

4 Komatsu Y, Murakami K, NagataH, Motokawa K, Doi M, Higashiya-ma I, Sasaki S, Yoshida T, Kuwaha-ra S: In vitro antibacterial activity ofa new oral cephalosporin, S-1090. JInfect Chemother 1997;3:38–48.

5 National Committee for ClinicalLaboratory Standards: Methods forDilution Antimicrobial Susceptibili-ty Testing for Bacteria that GrowAerobically, ed 2. Villanova, Na-tional Committee for Clinical Labo-ratory Standards, 1990, NCCLSDocument M7-A2, vol 10, No 8.

6 National Committee for ClinicalLaboratory Standards: Methods forDilution Antimicrobial Susceptibili-ty Testing of Anaerobic Bacteria,ed 2. Villanova, National Commit-tee for Clinical Laboratory Stan-dards, 1990, NCCLS DocumentM11-A2, vol 10, No 15.

7 Nakashima M, Oguma T, KimuraY, Sasaki S, Sendo Y, Imoto H:Phase I clinical studies of S-1090:Safety and pharmacokinetics. J In-fect Chemother 1996;2:271–279.

8 Mikamo H, Ito K, Tamaya T: Stud-ies on the clinical implication ofanaerobes, especially Prevotella bi-via in obstetrics and gynecology.Acta Sch Med Univ Gifu 1994;42:230–248.