ANTIMICROBIAL AGENTS AND CHEMOTHERAPY, Sept. 1992, p. 1894-1901 Vol. 36, No. 9 0066-4804/92/091894-08$02.00/0 Copyright © 1992, American Society for Microbiology In Vitro and In Vivo Antibacterial Activities of E1077, a Novel Parenteral with a Broad Antibacterial Spectrum KATSURA HATA,* MASAKO OTSUKI, AND TAKESHI NISHINO Department ofMicrobiology, Kyoto Pharnaceutical University, 5-Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607, Japan Received 3 February 1992/Accepted 3 July 1992

E1077 is a new iijectable cephalosporin with a broad spectrum ofantibacterial activity against gram-positive and gram-negative bacteria, including staphylococci and . The in vitro activities of E1077 against clinical isolates of -susceptible Staphylococcus aureus (MIC of E1077 for 90%o of the strains tested [MIC,0], 0.78 ;g/ml) and methicillin-resistant S. aureus (MIC90, 50 pLg/ml) were similar to those of and . Against Enterococcusfaecalis (MIC,0, 6.25 ;ag/ml), E1077 was the most active of the drugs tested and four times more active than cefpirome. The MIC90s of E1077 for streptococci, Haemophilus influenzae, and Neisseria gonorrhoeae ranged from 0.05 to 0.78 ,ug/ml; E1077 was similar in activity to cefpirome. E1077 inhibited 90% of most species of the family Enterobacteriaceae at concentrations of <1.56 iLg/ml, with the exception of Serratia marcescens and Proteus vulgaris (12.5 ,ug/ml). The activity of E1077 against P. aeruginosa (MIC90, 6.25 ;Lg/ml) was comparable to that of . In vivo activity was evaluated with systemic infections in mice. E1077 showed a protective effect against systemic infections by gram-positive or gram-negative bacteria, as reflected by its in vitro activity. The protective effects of E1077 were higher than those of cefpirome against S. aureus and P. aeruginosa infections and similar to those of cefpirome against other bacterial infections. Morphological studies using differential interference and phase-contrast microscopy showed that low concentrations of E1077 caused swelling of S. aureus and spheroplast and bulge formation in P. aeruginosa. In general, the antibacterial profile of E1077 is similar to that of cefpirome.

The newer cephalosporin used in the treatment cefuzonam (Takeda Chemical Industries, Osaka, Japan), of bacterial infections, such as ceftazidime, cefuzonam, and (Chugai Pharmaceutical Co., Tokyo, Japan), and flomoxef, possess broad antibacterial spectra. However, flomoxef (Shionogi Pharmaceutical Co., Osaka, Japan). infections caused by methicillin-resistant Staphylococcus Organisms. The bacterial strains used in this study were aureus (MRSA) and Pseudomonas aeruginosa still cause distinct clinical isolates obtained from various hospitals in major clinical problems. Accordingly, there has been con- Japan between 1985 and 1990. All isolates were maintained tinued interest in producing with increased as stock cultures in our laboratory. activity against MRSA or P. aeruginosa, such as cefpirome Determination ofMICs. MICs were determined by the agar (12), (5), and E1040 (14). E1077 {7,B-[2-(5-amino- dilution method recommended by the Japan Society of 1,2,4-thiadiazol-3-yl)-(Z)-2-fluoromethoxyiminoacetamido]- Chemotherapy (1). Sensitivity test agar (Eiken) was used for 3 - [(E) - 3 - (carbamoylmethyl) ethylmethylammonio - 1 - pro- all organisms except the following: streptococci (sensitivity penyl] - 3 - - 4 - carboxylate} is a new parenteral test agar supplemented with 10% defibrinated horse blood), cephalosporin synthesized by Eisai Co., Ltd., Tokyo, Japan. Haemophilus influenzae (sensitivity test agar supplemented It contains a unique side chain, a propenylammonium moiety with 5% Fildes enrichment), Branhamella catarrhalis (choc- at the 3 position, and a monofluoromethoxyimino group in olate sensitivity test agar supplemented with 5% defibrinated the 71 side chain of the cephalosporin nucleus and has a horse blood), and Neisseria gonorrhoeae (chocolate sensi- broad antibacterial spectrum (4). In this study, we compared tivity test agar supplemented with 10% defibrinated horse the in vitro and in vivo antibacterial activities of E1077 with blood). Fresh cultures of the bacterial strains were diluted, those of cefpirome (12), ceftazidime (15), cefuzonam (2), and 5 pl of each bacterial suspension, corresponding to cefotaxime (9), and flomoxef (8) and examined the morpho- about 104 CFU, was spotted (Microplanter; Sakuma Sei- logical changes in S. aureus and P. aeruginosa induced by sakusho, Tokyo, Japan) onto agar plates that contained E1077. twofold serial dilutions of antibiotics. The MIC was the lowest concentration of an that completely inhib- MATERIALS AND METHODS ited visible growth on agar plates after incubation for 18 h at 37°C. For N. gonorrhoeae, incubation was carried out in a Antibiotics. E1077 was provided by Eisai Co., Ltd. Cef- candle jar. The MIC50 and MIC90 were the concentrations of pirome was provided by Hoechst Japan, Tokyo, Japan. The a drug required to inhibit 50% and 90% of the strains, following other antibiotics were obtained commercially: respectively. ceftazidime (Tanabe Pharmaceutical Co., Osaka, Japan), Differential interference and phase-contrast microscopy. S. aureus Smith and P. aeruginosa E-2 were incubated in sensitivity test broth for 3 h at 37°C and then incubated on * Corresponding author. sensitivity test agar plates containing different concentra- 1894 VOL. 36, 1992 IN VITRO AND IN VIVO ACTIVITIES OF E1077 1895

TABLE 1. Antibacterial activities of E1077 and reference compounds against clinical isolates Organism Antibacterial MIC (ILg/ml) (no. of strains) agent Range 50% 90% Methicillin-susceptible Staphylococcus E1077 0.20-6.25 0.39 0.78 aureus (91) Cefpirome 0.20-25 0.78 1.56 Ceftazidime 3.13-100 12.5 12.5 Cefuzonam 0.10-25 0.39 0.78 Cefotaxime 0.39-50 1.56 3.13 Flomoxef 0.10-12.5 0.39 1.56 MRSA (132) E1077 0.39->100 6.25 50 Cefpirome 0.39->100 50 100 Ceftazidime 6.25->100 >100 >100 Cefuzonam 0.20->100 50 100 Cefotaxime 3.13-> 100 >100 >100 Flomoxef 0.20-> 100 12.5 100 Staphylococcus epidermidis (67) E1077 0.39-100 0.78 6.25 Cefpirome 0.20-100 0.78 3.13 Ceftazidime 0.20-> 100 6.25 25 Cefuzonam 0.10-> 100 0.78 3.13 Cefotaxime 0.20-> 100 3.13 12.5 Flomoxef 0.20-100 1.56 12.5 Streptococcus pneumoniae (33) E1077 <0.006-1.56 0.025 0.10 Cefpirome <0.006-0.78 0.025 0.10 Ceftazidime 0.05-50 0.39 1.56 Cefuzonam !0.006-1.56 0.025 0.10 Cefotaxime :0.006-6.25 0.05 0.20 Flomoxef 0.025-12.5 0.20 3.13 Streptococcus pyogenes (52) E1077 0.025-0.05 0.025 0.05 Cefpirome 0.012-0.025 0.012 0.05 Ceftazidime 0.10-0.39 0.20 0.20 Cefuzonam 50.006-0.025 0.012 0.012 Cefotaxime 0,012-0.05 0.025 0.025 Flomoxef 0.20-0.39 0.20 0.39 Enterococcus faecalis (40) E1077 0.20-12.5 3.13 6.25 Cefpirome 0.78-50 6.25 25 Ceftazidime 6.25->100 >100 >100 Cefuzonam 0.39->100 25 >100 Cefotaxime 0.39-100 >100 >100 Flomoxef 6.25->100 >100 >100 Neisseria gonorrhoeae (31) E1077 <0.006-0.10 0.012 0.05 Cefpirome <0.006-0.20 0.025 0.10 Ceftazidime 0.012-0.20 0.10 0.20 Cefuzonam f0.006-0.10 0.025 0.10 Cefotaxime : 0.006-0.10 0.012 0.05 Flomoxef 0.10-1.56 0.39 0.78 Haemophilus influenzae (52) E1077 0.05-1.56 0.10 0.20 Cefpirome 0.05-3.13 0.10 0.20 Ceftazidime 0.10-1.56 0.20 0.39 Cefuzonam 0.012-3.13 0.025 0.10 Cefotaxime 0.012-1.56 0.025 0.10 Flomoxef 0.39-3.13 0.78 0.78 Branhamella catarrhalis (52) E1077 0.025-1.56 0.39 0.78 Cefpirome 0.05-3.13 0.78 3.13 Ceftazidime 0.05-0.39 0.10 0.10 Cefuzonam 0.20-3.13 0.78 1.56 Cefotaxime 0.10-1.56 0.39 0.78 Flomoxef 0.025-0.39 0.20 0.39 Continued on followingpage 1896 HATA ET AL. ANTIMICROB. AGENTS CHEMOTHER.

TABLE 1-Continued

Organism Antibacterial MIC (,Lg/ml) (no. of strains) agent Range 50% 90% Escherichia coli (40) E1077 0.012-0.20 0.025 0.05 Cefpirome 0.025-0.78 0.05 0.20 Ceftazidime 0.05-0.78 0.20 0.39 Cefuzonam 0.05-0.39 0.10 0.20 Cefotaxime 0.05-0.39 0.10 0.20 Flomoxef 0.05-0.20 0.05 0.10 Kiebsiella pneumoniae (40) E1077 0.012-0.78 0.05 0.20 Cefpirome 0.025-0.78 0.10 0.39 Ceftazidime 0.10-1.56 0.20 0.78 Cefuzonam '0.006-3.13 0.10 0.78 Cefotaxime 0.012-1.56 0.10 0.39 Flomoxef 0.05-3.13 0.10 0.39 Enterobacter cloacae (39) E1077 0.025-6.25 0.05 1.56 Cefpirome 0.05-25 0.20 3.13 Ceftazidime 0.10->100 0.39 100 Cefuzonam 0.20->100 0.39 100 Cefotaxime 0.10->100 0.39 >100 Flomoxef 0.20->100 25 >100 Enterobacter aerogenes (39) E1077 0.05-0.39 0.05 0.20 Cefpirome 0.10-0.78 0.10 0.78 Ceftazidime 0.10-50 0.20 25 Cefuzonam 0.20-50 0.39 25 Cefotaxime 0.10-50 0.20 25 Flomoxef 1.56-100 25 100 Citrobacterfreundii (34) E1077 0.012-3.13 0.05 0.78 Cefpirome 0.025-3.13 0.10 3.13 Ceftazidime 0.05->100 0.78 >100 Cefuzonam 0.012-50 0.39 50 Cefotaxime 0.012-100 0.39 50 Flomoxef 0.10-100 6.25 >100 Serratia marcescens (39) E1077 0.10-50 1.56 12.5 Cefpirome 0.10-100 1.56 25 Ceftazidime 0.20-100 1.56 100 Cefuzonam 0.39->100 3.13 100 Cefotaxime 0.20->100 3.13 >100 Flomoxef 0.39->100 25 >100 Proteus mirabilis (38) E1077 0.05-0.78 0.05 0.20 Cefpirome 0.05-1.56 0.10 0.39 Ceftazidime 0.05-1.56 0.10 0.20 Cefuzonam 0.05-1.56 0.20 0.78 Cefotaxime 0.05-0.20 0.05 0.20 Flomoxef 0.20-3.13 0.39 3.13 Proteus vulgaris (40) E1077 0.05-50 0.78 12.5 Cefpirome 0.05-25 0.39 3.13 Ceftazidime 0.05-3.13 0.10 0.39 Cefuzonam 0.025-12.5 0.20 0.78 Cefotaxime 0.025-25 0.20 1.56 Flomoxef 0.20-0.78 0.39 0.78 Morganella morganii (40) E1077 0.025-3.13 0.05 0.39 Cefpirome 0.025-6.25 0.05 0.78 Ceftazidime 0.10-100 0.20 25 Cefuzonam 0.05-25 0.20 6.25 Cefotaxime 0.025-50 0.20 12.5 Flomoxef 0.39->100 1.56 100 Continued on followingpage VOL. 36, 1992 IN VITRO AND IN VIVO ACTIVITIES OF E1077 1897

TABLE 1-Continued

Organism Antibacterial MIC (,ug/ml) (no. of strains) agent Range 50% 90% Providencia rettgeri (36) E1077 0.012-1.56 0.025 0.39 Cefpirome 0.012-6.25 0.10 1.56 Ceftazidime 0.10-12.5 0.39 3.13 Cefuzonam 0.012-3.13 0.20 1.56 Cefotaxime '0.006-0.78 0.20 0.78 Flomoxef 0.05-50 0.20 12.5 Pseudomonas aeruginosa (50) E1077 0.78-25 1.56 6.25 Cefpirome 1.56-25 6.25 12.5 Ceftazidime 0.78-25 3.13 6.25 Cefuzonam 12.5-> 100 25 100 Cefotaxime 12.5-> 100 25 50 Flomoxef >100-> 100 > 100 > 100 Acinetobacter calcoaceticus (32) E1077 0.39-25 1.56 12.5 Cefpirome 0.78-50 3.13 12.5 Ceftazidime 1.56-50 6.25 25 Cefuzonam 3.13-100 25 100 Cefotaxime 1.56-100 12.5 50 Flomoxef 3.13->100 50 >100 tions of E1077. After 3 h of incubation, morphological cuspneumoniae type III, were cultured overnight at 37°C in changes of cells were examined by differential interference nutrient broth (Nissui). For S. pneumoniae, broth was microscopy for S. aureus and by phase-contrast microscopy supplemented with 10% horse serum. Challenge organisms for P. aeruginosa. were prepared in nutrient broth and 3% hog mucin (Orthana Systemic infection in mice. The protective effect of E1077 Kemisk Fabrik A/S) in sterile water. The mice were injected against systemic infections in mice was determined as de- intraperitoneally with 0.5 ml of the bacterial suspension. The scribed previously (3). Male ddY strain mice weighing 18 to challenge inoculum was sufficient to kill 100% of untreated 20 g were used. The bacterial strains, except for Streptococ- control mice within 48 h postinfection, with the exception of

FIG. 1. Differential interference micrographs of S. aureus Smith exposed to E1077 for 3 h. Panels: A, untreated control; B, 0.025 ,ug/ml; C, 0.1 pLg/ml; D, 0.39 pg/ml; E, 1.56 .g/ml; F, 6.25 ,g/ml. 1898 HATA ET AL. ANTIMICROB. AGENTS CHEMOTHER.

FIG. 2. Phase-contrast micrographs of P. aeruginosa E-2 exposed to E1077 for 3 h. Panels: A, untreated control; B, 0.39 1Lg/ml; C, 1.56 ,ug/ml; D, 6.25 ,ug/ml; E, 25 ,ug/ml; F, 100 ,ug/ml. miCe infected with Klebsiellapneumoniae KC-1 or P. aerug- was four times more active than cefpirome. The other inosa 15846, which died within 3 days after challenge. The reference compounds did not inhibit most strains of E. antibiotic doses were administered subcutaneously in a faecalis at a concentration of 100 ,ug/ml or less. The MIC90s volume of 0.2 ml of normal saline 2 h after infection. At least of E1077 for N. gonorrhoeae and H. influenzae were 0.05 five levels (serial twofold doses) of the test compounds were and 0.20 ,ug/ml, respectively. E1077 was 4 to 16 times more employed with 10 mice at each level, and the 7-day survival active against these species than was flomoxef and was ratios were determined. The 50% effective dose (ED50) was comparable to the other compounds tested. Against B. calculated by the Litchfield-Wilcoxon method (7). catarrhalis, E1077, with an MIC90 of 0.78 ,ug/ml, was four times more active than cefpirome but eight times less active than ceftazidime. RESULTS In general, E1077 and cefpirome were more active against most members of the family Enterobacteriaceae than were Antibacterial activity. The antibacterial activities of E1077, the other compounds tested. The MIC90s of E1077 for cefpirome, ceftazidime, cefuzonam, flomoxef, and cefotax- Escherichia coli and K pneumoniae were 0.05 and 0.20 ime against clinical isolates are shown in Table 1. E1077 was ,ug/ml, respectively. E1077 was equal to or four times more active against staphylococci. The MIC90 of E1077 for methi- active than cefpirome against these species. The MIC90s of cillin-susceptible S. aureus strains was 0.78 ,ug/ml, which E1077 for Enterobacter cloacae, Enterobacter aerogenes, was similar to those of cefpirome, cefuzonam, and flomoxef and Citrobacter freundii were 1.56, 0.20, and 0.78 jig/ml, and 1/16 to 1/4 times those of cefotaxime and ceftazidime. respectively, and E1077 was equal to or four times more The MIC50 and MIC90 of E1077 for MRSA strains were 6.25 active than cefpirome and 64 to > 128 times more active than and 50 ,ug/ml, respectively. Its MIC50 was similar to that of ceftazidime, cefuzonam, cefotaxime, and flomoxef against flomoxef and eight times lower than those of cefuzonam and these species. Against Serratia marcescens, E1077 was cefpirome, and its MIC-w was similar to those of cefpirome, comparable to cefpirome and eight or more times more cefuzonam, and flomoxef. Ceftazidime and cefotaxime were active than the other reference compounds, with an MIC90 of inactive against MRSA, with MIC50s of >100 ,ug/ml. The 12.5 ,ug/ml. Against Morganella morganii and Providencia activity of E1077 was comparable to that of cefpirome and rettgeri, E1077 was equal to or 4 times more active than cefuzonam against Staphylococcus epidermidis. Against cefpirome and 4 to 64 times more active than ceftazidime and streptococci, E1077 was comparable to cefpirome and cefo- cefuzonam, with MIC90s of 0.39 and 0.39 ,g/ml, respec- taxime and 4 to 16 times more active than ceftazidime and tively. E1077 was similar in activity to cefpirome, ceftazi- flomoxef. However, E1077 was four times less active than dime, and cefotaxime and four times more active than cefuzonam against S. pneumoniae. cefuzonam against Proteus mirabilis. E1077 was four or E1077, with an MIC90 of 6.25 ,ug/ml for Enterococcus more times less active than these reference compounds faecalis, was the most potent of the compounds tested. It against Proteus vulgaris. VOL. 36, 1992 IN VITRO AND IN VIVO ACTIVITIES OF E1077 1899

TABLE 2. Protective effects of E1077 and reference compounds against systemic infection in mice

Challenge dose, Test MIC ED50, mg/kg Organism CFU/mouse (95% confidence limits) (no. of LD50Sa) compound (F±g/ml) Staphylococcus aureus Smith 3.3 x 106 (260) E1077 0.39 0.300 (0.198-0.455) Cefpirome 0.78 0.987 (0.728-1.34) Ceftazidime 6.25 9.17 (6.86-12.3) Cefuzonam 0.39 3.07 (2.02-4.65) Flomoxef 0.39 0.613 (0.351-1.07) Streptococcus pneumoniae type III 6.6 x 10 (90) E1077 0.025 2.18 (1.23-3.86) Cefpirome 0.025 4.19 (2.75-6.38) Ceftazidime 0.20 37.0 (20.2-67.9) Cefuzonam 0.012 12.7 (10.5-15.5) Flomoxef 0.20 2.78 (1.79-4.31) Escherichia coli KC-14 1.5 x 105 (90) E1077 0.025 0.0094 (0.0071-0.0125) Cefpirome 0.05 0.0173 (0.0112-0.0267) Ceftazidime 0.20 0.0369 (0.0270-0.0504) Cefuzonam 0.10 0.0707 Flomoxef 0.05 0.102 (0.0839-0.124) Klebsiella pneumoniae KC-1 2.4 x 104 (26) E1077 0.025 0.247 (0.149-0.410) Cefpirome 0.05 0.332 (0.240-0.460) Ceftazidime 0.10 0.939 (0.595-1.48) Cefuzonam 0.10 0.852 (0.541-1.34) Flomoxef 0.05 12.3 (10.1-14.9) Citrobacterffreundii B3 1.7 x 106 (22) E1077 0.78 0.152 (0.108-0.214) Cefpirome 1.56 0.224 (0.139-0.362) Ceftazidime 100 30.6 Cefuzonam 25 22.5 (14.6-34.7) Flomoxef 100 16.3 (11.4-23.4) Serratia marcescens T-55 2.1 x 106 (80) E1077 0.78 0.187 (0.103-0.341) Cefpirome 0.39 0.131 (0.071-0.242) Ceftazidime 0.39 0.207 (0.141-0.303) Cefuzonam 0.78 0.948 (0.540-1.67) Flomoxef 6.25 3.35 (2.10-5.34) Pseudomonas aeruginosa 15846 7.5 x 104 (74) E1077 0.78 2.66 (1.85-3.83) Cefpirome 6.25 11.7 (7.26-18.9) Ceftazidime 3.13 5.70 (3.64-8.94) Cefuzonam 50 >200 Flomoxef >100 >200 Acinetobacter calcoaceticus Ac-54 2.2 x 105 (18) E1077 1.56 4.88 (3.02-7.89) Cefpirome 3.13 9.31 (5.47-15.9) Ceftazidime 6.25 8.90 (6.02-13.2) Cefuzonam 25 97.1 (52.4-179.8) Flomoxef 50 101.9 (63.0-165.1) a LD50, 50% lethal dose.

Against P. aeruginosa, the activity of E1077 was similar to mally rod-shaped cells at concentrations of one-fourth to that of ceftazidime. The MIC50 and MIC90 of E1077 for P. four times the MIC. When P. aeruginosa cells were exposed aeruginosa were 1.56 and 6.25 ,ug/ml, respectively. The to high concentrations of E1077 (25 and 100 ,ug/ml), for- MIC50 of E1077 was equal to or four times lower than those mation of spheroplasts and bulges and cell lysis were ob- of ceftazidime and cefpirome. E1077 was as active as cef- served. pirome and ceftazidime against Acinetobacter calcoace- Activity against systemic infections in mice. The in vivo ticus, with an MIC50 of 1.56 ,ug/ml and an MIC90 of 12.5 activity of E1077 against systemic infections in mice is p,g/ml. shown in Table 2. E1077 showed in vivo activity against Morphological effects. The morphological changes induced gram-positive and gram-negative bacterial infections, as by E1077 in S. aureus Smith and P. aeruginosa E-2 were reflected by its in vitro activity. The ED50 of E1077 against examined by differential interference and phase-contrast S. aureus was 0.300 mg/kg; E1077 was comparable to microscopy, respectively. In S. aureus (Fig. 1), E1077 flomoxef, 3 times more effective than cefpirome, and 10 to 30 induced a little swelling at a concentration of one-fourth of times more effective than cefuzonam and ceftazidime. the MIC and lysis above the MIC. In P. aeruginosa (Fig. 2), Against S. pneumoniae infection, the activity of E1077 was E1077 induced formation of filamentatous cells from nor- comparable to those of cefpirome and flomoxef and about 5 1900 HATA ET AL. ANTIMICROB. AGENTS CHEMOTHER. to 17 times those of ceftazidime and cefuzonam. The activ- bacterial infections. The M'C50 and MIC90 of E1077 for P. ities of E1077 against E. coli and K pneumoniae infections, aeruginosa were 1.56 and 6.25 ,ug/ml, respectively, and its with ED50s of 0.0094 and 0.247 mg/kg, respectively, were activity was comparable to that of ceftazidime and four times similar to those of cefpirome and higher than those of the higher than that of cefpirome. Watanabe et al. have reported other reference compounds. The ED50 of E1077 against C. that introduction of the aminothiadiazolyl group in the 71 freundii was 0.152 mg/kg; E1077 was similar in efficacy to side chain of the cephem nucleus enhances antibacterial cefpirome and 10 to 20 times as effective as the other activity against P. aeruginosa (14). The in vivo activity of reference compounds. Against S. marcescens infection, the E1077 in systemic infection clearly reflected its in vitro activity of E1077 (ED50, 0.187 mg/kg) was comparable to activity against P. aeruginosa. those of cefpirome and ceftazidime and about 5 to 20 times Thus, E1077 has a broad antibacterial spectrum covering those of cefuzonam and flomoxef. E1077 was also effective gram-positive bacteria, including staphylococci and E. against P. aeruginosa infection. The activity of E1077, with faecalis, and gram-negative bacteria, including P. aerugi- an ED50 of 2.66 mg/kg, was similar to that of ceftazidime and nosa. The in vitro study results were generally consistent four times that of cefpirome, while cefuzonam and flomoxef with those of Watanabe et al. (13). E1077 also showed were ineffective against P. aeruginosa infection. Against A. efficacy in systemic infections with various bacteria, and calcoaceticus infection, the activity of E1077 (ED50, 4.88 this was clearly reflected by its in vitro activity. Overall, mg/kg) was comparable to those of cefpirome and ceftazi- E1077 is a very promising antibacterial agent for the treat- dime and about 20 times higher than those of cefuzonam and ment of various bacterial infections. Further studies on flomoxef. pharmacokinetic and toxicological behaviors are therefore warranted.

DISCUSSION ACKNOWLEDGMENT E1077 is a new injectable cephalosporin, which has been This study was financially assisted by Eisai Co., Ltd. described by Watanabe et al. (13), with a broad antibacterial spectrum and potent antibacterial activity. One of the anti- bacterial characteristics of E1077 is its activity against S. REFERENCES aureus and E. faecalis. The activity of E1077 against methi- 1. Committee for Revision of MIC Determination Method. 1981. cillin-susceptible S. aureus was comparable to those of Revision of minimal inhibitory concentration (MIC) determina- cefpirome, cefuzonam, and flomoxef. E1077 also inhibited tion method. Chemotherapy (Tokyo) 29:76-79. 50% and 90% of MRSA strains at concentrations of 6.25 and 2. Hikida, M., M. Inoue, and S. Mitsuhashi. 1986. In vitro antibac- 50 ,ug/ml, respectively. Its activity was similar to that of terial activity of L-105, a new cephalosporin. J. Antimicrob. flomoxef, which has been reported to be more active in vitro Chemother. 18:585-591. 3. Hiruma, R., M. Otsuki, M. Tashima, Y. Obana, and T. Nishino. than other cephalosporins against MRSA (8). However, its 1990. In-vitro and in-vivo antibacterial activities of E1040, a activity, with an MIC90 of 50 ,ug/ml, is probably inadequate new cephalosporin with potent antipseudomonal activity. J. for clinical use for MRSA infections. In addition, E1077 was Antimicrob. Chemother. 26:769-781. active against E. faecalis, which was resistant or less sus- 4. Kamiya, T., T. Naito, Y. Kai, Y. Komatsu, M. Sasho, N. Sato, T. ceptible to most of the existing cephalosporins. The MIC90 Nakamura, S. Negi, Y. Machida, and Y. Yamauchi. 1990. of E1077 for E. faecalis was 6.25 ,ug/ml, and its activity was Program Abstr. 30th Intersci. Conf. Antimicrob. Agents Che- four times that of cefpirome. The other reference com- mother., abstr. 447. pounds were inactive (MIC50s, >100 ,ug/ml). Kamiya et al. 5. Kessler, R. E., M. Bies, R. E. Buck, D. R. Chisholm, T. A. have suggested that the high activity of E1077 against S. Pursiano, Y. H. Tsai, M. Misiek, K. E. Price, and F. Leitner. 1985. Comparison of a new cephalosporin, BMY 28142, with aureus and E. faecalis is provided by the introduction of a other broad-spectrum ,3-lactam antibiotics. Antimicrob. Agents quatemary ammoniopropenyl substituent at the 3 position of Chemother. 27:207-216. the cephem nucleus (4). 6. Kobayashi, S., S. Arai, S. Hayashi, and K. Fujimoto. 1986. A second characteristic of E1077 is that E1077 is very P-Lactamase stability of cefpirome (HR810), a new cephalospo- effective against most members of the family Enterobac- rin with a broad antibacterial spectrum. Antimicrob. Agents teriaceae. In general, the activity of E1077 was comparable Chemother. 30:713-718. to that of cefpirome and higher than those of the other 7. Litchfield, J. T., Jr., and F. Wilcoxon. 1949. A simplified method reference compounds against these species. In particular, of evaluating dose-effect experiments. J. Pharmacol. Exp. Ther. the activity of E1077 was much higher (.64 times) than 96:99-113. of 8. Murakami, K., K. Nomura, M. Doi, and T. Yoshida. 1987. those ceftazidime, cefuzonam, cefotaxime, and flomoxef Production of low-affinity -binding protein by low- and against Enterobacter and Citrobacter species, which pro- high-resistance groups of methicillin-resistant Staphylococcus duce high levels of chromosomal ,-lactamase (11). Cef- aureus. Antimicrob. Agents Chemother. 31:1307-1311. pirome (6) and cefepime (10) have been reported to be active 9. Neu, H. C., N. Aswapokee, P. Aswapokee, and K. P. Fu. 1979. against these species. In this study, E1077 was four times HR756, a new cephalosporin active against gram-positive and more active than cefpirome against E. aerogenes and C. gram-negative aerobic and anaerobic bacteria. Antimicrob. freundii. E1077 also showed higher in vivo activity against Agents Chemother. 15:273-281. systemic infection caused by a strain of C. freundii that was 10. Phelps, D. J., D. D. Carlton, C. A. Farrell, and R. E. Kessler. resistant to the other extended-spectrum cephalosporins 1986. Affinity of cephalosporins for P-lactamases as a factor in than did ceftazidime and seems to antibacterial efficacy. Antimicrob. Agents Chemother. 29:845- cefuzonam. This activity 848. be due to the resistance of E1077 to enzymatic hydrolysis 11. Sanders, C. C. 1987. Chromosomal cephalosporinases respon- and the low affinity of the compound for 1-lactamases (13). sible for multiple resistance to newer 3-lactam antibiotics. E1077 possessed potency comparable to that of ceftazi- Annu. Rev. Microbiol. 41:573-593. dime against P. aeruginosa, an opportunistic pathogen that 12. Seibert, G., M. Limbert, I. Winkler, and T. Dick. 1983. Anti- is one of the major causes of life-threatening nosocomial bacterial activity in vitro and P-lactamase stability of the new VOL. 36, 1992 IN VITRO AND IN VIVO ACTIVITIES OF E1077 1901

cephalosporin HR810 in comparison with five other cephalospo- vitro evaluation of E1040, a new cephalosporin with potent anti- rins and two aminoglycosides. Infection 11:275-279. pseudomonal activity. Antimicrob. Agents Chemother. 32:693-701. 13. Watanabe, N., R. Hiruma, and K. Katsu. 1992. In vitro evalu- 15. Wise, R., J. H. Andrews, and K. A. Bedford. 1980. Comparison ation of E1077, a new cephalosporin with a broad antibacterial of in vitro activity of GR20263, a novel cephalosporin deriva- spectrum. Antimicrob. Agents Chemother. 36:589-597. tive, with activities of other beta-lactam compounds. Antimi- 14. Watanabe, N., K. Katsu, M. Moryama, and K. Kitoh. 1988. In crob. Agents Chemother. 17:884-889.