In-vitro susceptibilites to levofloxacin and various antibacterial agents of 18,639 clinical isolates obtained from 77 centers in 2004

A total of 18,639 clinical isolates in 19 species collected from 77 centers during 2004 in Japan were tested for their susceptibility to fluoroquinolones (FQs) and other selected antibiotics. The common respiratory pathogens, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae showed a high susceptible rate against FQs. The isolation rate of beta lactamase non-producing ampicillin-resistant H. influenzae was approximately three times as large as those of western countries. Most strains of Enterobacteriaceae were also susceptible to FQs. The resistance rate of Escherichia coli against FQs has however been rapidly increasing so far as we surveyed since 1994. The FQs-resistant rate in methicillin-resistant Staphylococcus aureus (MRSA) showed approximately 90% except for 36%. of sitafloxacin while FQs-resistant rate in methicillin-susceptible S. aureus (MSSA) was around 5%. The FQs-resistant rate of methicillin-resistant coagulase negative Staphylococci (MRCNS) was also higher than that of methicillin-susceptible coagulase negative Staphylococci (MSCNS), however, it was lower than that of MRSA. In Pseudomonas aeruginosa clinical isolates, 32-34% from UTI and 15-19% of from RTI was resistant to FQs. Acinetobacter spp. showed a high susceptibility to FQs. Although FQs-resistant Neisseria gonorrhoeae have not been increased in western countries, it is remarkably high in Japan. In this survey, isolates of approximately 85% was resistant to FQs.     

In vitro antibacterial activity of various cephems against clinical isolates from complicated urinary tract infections

In vitro antibacterial activity of several cephems (CEZ as the first generation (group A); CTM and CMZ as the second generation (group B); CMX, CPZ, LMOX, CTX and CZX as the third generation (group C)) against 8 species, each of 54 strains, of Gram-negative clinical isolates from complicated urinary tract infection was compared by determination of the MICs. The following results were obtained: The most sensitive drugs against each species in MIC80; CTX (MIC80 0.20 microgram/ml) against E. coli, CMX (1.56 microgram/ml) against K. pneumoniae, LMOX (0.39 microgram/ml) against P. mirabilis, LMOX (0.78 microgram/ml) against Indole (+) Proteus, CMX and CPZ (50 micrograms/ml) against E. cloacae, CMX and LMOX (50 micrograms/ml) against C. freundii, CMX (3.13 micrograms/ml) against S. marcescens and CPZ (25 micrograms/ml) against P. aeruginosa The most sensitive drugs against each species in MICS100; CMX (MIC100 3.13 micrograms/ml) against E. coli, CMX (6.25 micrograms/ml) against K. pneumoniae, CTX (0.78 microgram/ml) against P. mirabilis, LMOX (1.56 microgram/ml) against Indole (+) Proteus, CPZ (100 micrograms/ml) against E. cloacae, CMX (100 micrograms/ml) against C. freundii, CMX (12.5 microgram/ml) against S. marcescens and CPZ (50 micrograms/ml) against P. aeruginosa. In each species, the group C were most sensitive followed by those of the group B. Many isolates were highly resistant to the group A (especially in C. freundii, S. marcescens and P. aeruginosa).     

Levofloxacin体外抗菌活性研究

利用试管双倍稀释法及纸片法测定ｌｅｖｏｆｌｏｘａｃｉｎ（ＬＶＬＸ）体外抗菌活性，并与其它１０种药物比较。结果表明ＬＶＬＸ对革兰氏阴性菌具有良好抗菌作用，尤以对痢疾杆菌、伤寒杆菌、变形杆菌、肺炎杆菌、产气杆菌、大肠杆菌作用更为突出，ＭＩＣ５０≤０．０３～０．２８μｇ／ｍｌ，ＭＩＣ９０≤０．０３～１２８μｇ／ｍｌ，抑菌率６０％～１００％；其活性为氧氟沙星的１～４倍，比诺氟沙星、头孢呋辛强，与环丙沙星、庆大霉素及头孢噻肟相当。ＬＶＬＸ抗葡萄球菌活性为所测喹诺酮中最强，与头孢唑林相当，对肺炎球菌、溶血性及草绿色链球菌作用与头孢菌素相当。ＬＶＬＸ有较强抗铜绿假单胞菌活性，ＭＩＣ５０与ＭＩＣ９０分别为０．５与６４μｇ／ｍｌ，与阿米卡星及头孢哌酮相当。ＬＶＬＸ为一广谱高效抗菌药物。     

In vitro antibacterial activities of carbapenems against clinical isolates

Antibacterial activities of four carbapenems, imipenem, panipenem, meropenem, and biapenem, were determined using 353 strains belonging to 18 bacterial species which were isolated from clinical materials at Ehime University Hospital. The MIC values of these carbapenems against MRSA were widely distributed between 0.1 and 100 micrograms/ml, and MIC90 values of these 4 carbapenems were 25-50 micrograms/ml. Any of these carbapenems prevented the bacterial growth of enterobacteriaceae of 8 bacterial species excluding S. macrescens at concentrations of 1 microgram/ml or less. The MIC values against P. aeruginosa showed relatively wide distribution, being 0.39-25 micrograms/ml for imipenem, 0.2-25 micrograms/ml for panipenem, 0.1-12.5 micrograms/ml for meropenem, and 0.2-12.5 micrograms/ml for biapenem. From those results, it was confirmed that any of the carbapenems tested had a wide antibacterial spectrum and strong antibacterial activities.     

帕珠沙星对临床分离致病菌的体外抗菌活性研究

目的评价帕珠沙星的体外抗菌活性。方法采用琼脂二倍稀释法，测定帕珠沙星与左氧氟沙星对342株临床分离菌株的最低抑菌浓度（MIC）。结果帕珠沙星对革兰阴性菌和革兰阳性菌的MIC90分别为0．06～4和1～16μg／ml。对大肠埃希菌、阴沟肠杆菌、变形菌、铜绿假单胞菌、不动杆菌和链球菌的MIC90为0．06～4μg／ml，是左氧氟沙星的1／2～1／8;对肺炎克雷伯菌、金葡菌和表葡菌与左氧氟沙星抗菌作用相当，MIC90分别为0．5、1、1μg／ml；对流感嗜血杆菌、黏膜炎莫拉菌和粪肠球菌的MIC90为0．5、1、16μg／ml，高于左氧氟沙星（0．25、0．5、8μg／ml）。结论帕珠沙星对革兰阴性菌和革兰阳性菌均具有广谱的抗菌作用，对革兰阴性菌的抗菌活性优于革兰阳性菌。     

乳酸左氧氟沙星体外抗菌作用研究

乳酸左氧氟沙星（ｌｅｖｏｆｌｏｘａｃｉｎ ｌａｃｔａｅ）具有对革兰氏阳性菌,阴性菌抗菌作用强的特点。从临床分离的３０２株细菌敏感试验结果显示,该药对金葡萄球菌甚为敏感,其ＭＩＣ５０为０．０６ｍｇ／ＬＭ,ＭＩＣ９０为０．２５ｍｇ／Ｌ,ＭＢＣ５０为０．０６ｍｇ／Ｌ,ＭＢＣ９０为０．５ｍｇ／Ｌ,与日产左氧氟沙星基本一致,较氟沙星强。     

In vitro activities of levofloxacin and other antibiotics against fresh clinical isolates

In this study, the in vitro activity of levofloxacin (LVFX) against 1,020 fresh bacterial clinical isolates was compared with the activities of a range of ofloxacin, ciprofloxacin (CPFX), ampicillin (ABPC), cefaclor, cefpodoxime, methicillin and benzylpenicillin. The clinical isolates except Vibrio cholerae were collected in Japan during 1998 from patients with infectious diseases. MICs were determined using the agar dilution method according to the recommendations by the Japan Society of Chemotherapy. Some isolates of methicillin resistant Staphylococcus aureus (MRSA) and coagulase negative Staphylococcus were resistant to fluoroquinolones, but the MIC50 of LVFX against MRSA was 6.25 micrograms/ml. LVFX was the most active against MRSA among the antibiotics tested. Most of Staphylococcus epidermidis strains were susceptible to the fluoroquinolones. LVFX showed greater activity against all streptococci strains compared with fluoroquinolones tested. In particular, all Streptococcus pneumoniae strains including PRSP were susceptible to LVFX at < or = 1.56 micrograms/ml. Among Enterococcus, ABPC showed superior activity against Enterococcus faecalis but many isolates of Enterococcus species were resistant to ABPC. LVFX was more active against to these Enterococcus species compared with other fluoroquinolones. On the other hand, LVFX and CPFX showed similar activity against isolates of Enterobacteriaceae. CPFX had an MIC50/90 of 0.20, 0.39 microgram/ml and LVFX showed an MIC50/90 of 0.78, 1.56 micrograms/ml against Pseudomonas aeruginosa. LVFX (MIC50/90 0.10, 0.20 microgram/ml) was more active against Acinetobacter species than CPFX (MIC50/90 0.10, 0.39 microgram/ml). Haemophilus influenzae, Branhamella (Moraxella) catarrhalis and V. cholerae were inhibited by low concentration of the fluoroquinolones tested. The MIC90 of LVFX and CPFX were < or = 0.10 microgram/ml against above three species. Some isolates of Neisseria gonorrhoeae and Campylobacter species were moderately resistant to the fluoroquinolones tested but the MIC50 of LVFX and CPFX were < or = 0.39 microgram/ml. Among anaerobes, Propionibacterium acnes was more susceptible than Peptostreptococcus species, and the MIC90 of beta-lactams and fluoroquinolones tested were < or = 0.78 microgram/ml. In conclusion, this study, performed on large number of strains, confirmed an excellent and wide spectrum antibacterial activity of LVFX compared with the fluoroquinolones and beta-lactams tested. And our results suggest that LVFX may be useful in the treatment of various bacterial infections.     

不同配比的头孢呋辛/三唑巴坦对临床分离革兰阴性菌的体外药效学研究

目的比较不同配比头孢呋辛／三唑巴坦（cefuroxime／tazobactam，1：1、2：1、4：1）对临床分离致病菌的体外抗菌活性，为新药研发提供实验依据。方法以平皿二倍稀释法测定MIC值，nitrocefin纸片法测定产酶株，双纸片法筛选ESBLs菌株。结果对本次研究收集的2004年1月～2006年1月共482株致病菌进行MIC测定，其中84．85％的菌株产β-内酰胺酶，36．31％产生ESBLs。不同配比的头孢呋辛／三唑巴坦联合制剂对革兰阴性菌的抗菌作用较强，尤其对大肠埃希菌与克雷伯菌属，头孢呋辛／三唑巴坦（1：1）的MIC90值分别从〉256和〉256μg／ml下降至32和64μg／ml，部分细菌，尤其是产ESBLs菌株的耐药率明显下降。头孢呋辛／三唑巴坦3个配比中以1：1配比的抗菌作用最强。头孢哌酮／舒巴坦和哌拉西林／三唑巴坦对革兰阴性菌具有较好的抗菌活性。结论头孢呋辛／三唑巴坦（1：1）为一强效广谱杀菌药物，对产ESBLs菌具有较好的抗菌活性。本次研究中孢呋辛／三唑巴坦1：1配比的MIC50与MIC90值都低于2：1和4：1两个配比，对产超广谱β-内酰胺酶的大肠埃希菌和肺炎克雷伯菌的抗菌活性最强。     

Susceptibility of clinical isolates from primary care clinics to oral antibacterial agents

The antimicrobial susceptibility of clinical isolates from specimens of patients in primary care clinics in 2005 was investigated by determining the minimum inhibitory concentrations of oral antibacterial agents. The numbers of test strains were 550 for Gram-positive aerobes, 700 for Gram-negative aerobes, and 150 for anaerobes. Cefcapene (CFPN), cefditoren (CDTR), and cefteram (CFTM) showed the most potent activities against Staphylococcus spp. and Streptococcus spp. among the cephems tested and moxifloxacin (MFLX) and tosufloxacin among the new quinolones. Although the new quinolones generally showed potent activities against these species, resistant strains were frequently detected in methicillin-resistant Staphylococcus aureus. In addition, 70% or more of Streptococcus pneumoniae isolates were intermediate or resistant to macrolides. Cephems showed good activities against aerobic Gram-negative bacteria except for Proteus spp. Specifically, CFPN, CDTR, and CFTM showed the most potent activity against Haemophilus influenzae among the cephems tested. The new quinolones showed potent activities against Gram-negative bacteria, especially H. influenzae and Moraxella catarrhalis, but not against Proteus mirabilis and Providencia spp. When compared with the susceptibilities of clinical isolates from tertiary care hospitals, found in other research, differences were noted, for example, there was a lower frequency of quinolone-resistant strains of methicillin-susceptible S. aureus but a higher frequency of macrolide-resistant strains of Streptococcus pyogenes. Therefore, to accurately grasp susceptibility trends, well-focused surveillance studies are necessary.     

16种抗菌药物对来源于免疫功能低下患者的革兰氏阴性杆菌的体外抗菌活性比较

对从武汉地区免疫功能低下患者分离的１０６３株革兰氏阴性杆菌，用琼脂平皿稀释法测定１６种抗菌药物的最小抑菌浓度（ＭＩＣ）。用ＷＨＯＮＥＴ－３计算机软件完成数据分析。主要革兰氏阴性杆菌是铜绿假单胞菌（３２．５％）、大肠杆菌（２２．９％）、克雷伯氏菌属（１４．３％）、肠杆菌属（７．９％）、不动杆菌属（６．１％）和柠檬酸菌属（４．９％）。通过ＭＩＣ测定显示大部分菌株对１６种抗菌药物有不同程度的耐药性。４７．２％的菌株同时对５种以上抗菌药物耐药。１０６３株革兰氏阴性杆菌对亚胺培南／西司他丁最敏感，其次是对阿米卡星和头孢他啶，敏感率分别为９５％、８８％和８６％。亚胺培南／西司他丁的体外抗菌活性最高，ＭＩＣ５０和ＭＩＣ９０为０．５和２μｇ／ｍｌ，阿米卡星（ＭＩＣ５０和ＭＩＣ９０为２和６４μｇ／ｍｌ）及头孢他啶（ＭＩＣ５０和ＭＩＣ９０为２和３２μｇ／ｍｌ）次之。根据对１６种药物抗菌活性的比较，为正确合理使用抗菌药物治疗免疫功能低下者革兰氏阴性杆菌急危重症感染提供了依据     

国产甲磺酸左氧氟沙星体外抗菌活性研究

测定国产甲磺酸左氧氟沙星体外抗菌活性,并与进口左氧氟沙星作比较,以临床常用的氧氟沙星和环丙沙星为对照。结果表明,国产甲磺酸左氧氟沙星与进口左氧氟沙星体外抗菌活性无差异。甲磺酸左氧氟沙星抗菌谱广抗菌活性强,对革兰氏阴性肠道杆菌、肺炎克雷伯氏菌、肠杆菌属细菌、变形杆菌及嗜血杆菌和不动杆菌ＭＩＣ５０值是氧氟沙星的１／２,与环丙沙星一致,分别为＜０．０３、＜０．０３、＜０．０３、０．１２５和０．０３ｍｇ／Ｌ;它对大肠埃希氏菌、金葡球菌、肺炎链球菌、肠球菌、厌氧菌的ＭＩＣ５０值是氧氟沙星和环丙沙星的１／２～１／４;对铜绿假单胞菌ＭＩＣ５０为１ｍｇ／Ｌ,是氧氟沙星的１／２,但稍高于环丙沙星。该产品体外抗菌活性受细菌接种量、血清含量和ｐＨ值影响不明显。研究还表明该产品为一杀菌剂,对临床常见致病菌如大肠埃希氏菌、肺炎克雷伯氏菌、变形杆菌、铜绿假单胞菌、不动杆菌、葡萄球菌、肠球菌、肺炎链球菌、厌氧菌均有良好的杀菌作用。     

In vitro antibacterial activities of telithromycin against clinical isolates of Neisseria gonorrhoeae

In vitro antibacterial activity of telithromycin (TEL) against the isolates of Neisseria gonorrhoeae (212 isolates) derived from urine or genital secretion in 2002 (April to December) was examined in comparison with those of macrolides (erythromycin [EM], clarithromycin [CAM]), penicillins (penicillin G [PCG]), cephems (cefodizime [CDZM], cefixime [CFIX]), quinolones (levofloxacin [LVFX]), tetracyclines (minocycline [MINO]), and aminoglycosides (spectinomycin [SPCM]). The MIC of TEL was ranged from < or = 0.039 to 0.25 microg/mL and the MIC50 and MIC90 of TEL were respectively 0.125 and 0.25 microg/mL, which were the lowest values compared with those of other oral antibacterial agents measured. When compared TEL with other agents in the order of the MIC50 and MIC90, TEL was more superior to EM and CAM (both eight times), MINO (four times and twice), and LVFX (16 and 64 times). The MIC90 of TEL was superior in twice though the MIC50 was the same in comparison with CFIX. The CDZM resistant strain did not exist and SPCM also inhibit growth with 32 microg/mL or less that was the breakpoint MIC excluding one stock though the PCG sensitive strain was only 1.4% in the injection drug. However, clinical breakpoint MIC is not established, but the efficacy of TEL is prospective because of its high antibacterial activity to inhibit growth of all stocks for gonococcus with 0.25 microg/mL. It is expected that TEL can become an oral antibiotic recommended for treatment of gonococcus if dosage and administration are considered.     

不同配比头孢呋辛与他唑巴坦的体外抗菌活性

目的评价不同配比头孢呋辛／他唑巴坦及单剂对临床分离致病菌的体外抗菌活性。方法以平皿二倍稀释法对22种661株致病菌测定MIC值；以试管二倍稀释法测定MBC值；以活菌计数法绘制杀菌曲线。结果661株致病菌中，72．01％产β内酰胺酶；联合制剂明显增强了对革兰阴性菌的抗菌作用；酶抑制剂他唑巴坦可明显提高头孢呋辛对耐药菌的抗菌作用，MIC90值下降到单药的1／8～1／30，耐药率减少了12％～80％。在碱性条件下，使联合制剂抗菌作用增强；而酸性环境，可减弱其抗菌作用；4个配比中，1：1配比抗菌作用最强。结论头孢呋辛／他唑巴坦（1：1）为一强效广谱杀菌药。     

4种β-内酰胺类抗生素对临床分离致病菌的体外抗菌活性

目的 对比研究头孢呋辛、头孢克洛、头孢噻肟和阿莫西林等4种β-内酰胺类抗生素对随机选取的临床分离致病菌的体外抗菌活性。方法 随机收集2006-2007年解放军总医院微生物科和空军总医院感染控制科分离的部分临床致病菌，采用琼脂平板稀释法测定最低抑菌浓度（MIC）。结果 头孢呋辛对金葡菌、表葡菌的敏感率分别为45％和83．33％，抗菌活性显著强于头孢克洛，对肺炎克雷伯菌、大肠埃希菌、阴沟肠杆菌及不动杆菌的敏感率分别为38．10％、30．77％、0、0，高于阿莫西林，弱于头孢噻肟。结论 第二代头孢菌素目前对大部分革兰阳性菌仍具有较强的抗菌活性，但对革兰阴性菌的抗菌活性明显弱于第三代头孢菌素。     

甲磺酸左氧氟沙星对耐青霉素肺炎链球菌的体外抗菌活性

目的 观察甲磺酸左氧氮沙星对耐青霉素肺炎链球菌(PRSP)的药敏及疗效。方法 对6株临床分离的耐青霉素肺炎链球菌，采用E—test方法，测定甲磺酸左氧氮沙星等6种抗生素的抗菌活性。同时观察甲磺酸左氧氮沙星单药治疗取SP临床疗效及不良反应。结果6株取SP均为低耐药菌株，对甲磺酸左氧氮沙星敏感。6例患者经治疗后，5例痊愈，l例显效，无明显副反应发生。结论 甲磺酸左氧氮沙星可有效治疗耐青霉素肺炎链球菌性肺炎。     

In vitro activities of carbapenem antibiotics against the various clinical isolates

The annual changes of antibacterial activities of beta-lactam antibiotics, mainly carbapenem antibiotics, were investigated against 5 bacterial species, S. aureus (MSSA), methicillin-resistant S. aureus (MRSA), Klebsiella pneumoniae, Serratia marcescens, Pseudomonas aeruginosa, which had been isolated from the clinical materials at Toho University Omori Hospital during the period of 1995 to 1997. In addition, antibacterial activities against other main bacterial strains isolated from the clinical materials during 1997 were also determined. The five bacterial species on which annual changes of the sensitivity were investigated did not show any remarkable trend to increase in resistance to the carbapenem antibiotics tested. The antibacterial activities of the carbapenem antibiotics against MRSA were weak, and MIC90 values were between 25 and 50 micrograms/ml. In S. marcescens and P. aeruginosa on which high resistance by the production of metallo-beta-lactamase has become a problem in recent years, there were no remarkable changes in annual changes of sensitivities. Especially, MIC90 valuses of the carbapenem antibiotics against P. aeruginosa were between 12.5 and 25 micrograms/ml, 4 to 8 times better than that of PIPC, like the case of CAZ. Furthermore, the carbapenem antibiotics showed strong antibacterial activities against clinically important 16 bacterial species, from Gram-positive to Gram-negative bacteria.     

In vitro study of the antibacterial activity of ofloxacin against recent clinical isolates

The in vitro activity of ofloxacin, a new broad-spectrum antimicrobial agent, was studied by a standardized single disc method. A total of 990 clinical isolates were tested, including 20 strains of anaerobic bacteria. Ofloxacin was highly active against 683 strains (70.41%), had intermediate activity against 109 (11.23%) and had no activity against 178 (18.35%). Ofloxacin was highly active against E. coli, Klebsiella sp., Citrobacter sp., Proteus mirabilis, Proteus morganii, Salmonella sp., Campylobacter jejuni, Haemophilus influenzae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Eubacterium sp., Propionibacterium acnes and Streptococcus sp. Pseudomonas sp., Serratia sp. and Proteus vulgaris had percentages of resistance to ofloxacin of 37.11%, 32% and 33.33% respectively. High percentages of resistance to ofloxacin were found only for Providencia sp., Proteus rettgeri and Bacteroides fragilis. With regard to Streptococcus faecalis, the results obtained with the disc procedure were not reliable and MIC determination was necessary to assess the behaviour of the drug.     

In vitro antibacterial activity of irloxacin (E-3432) on clinical isolates

Irloxacin (E-3432) is a new quinolone derivative. In this study, the activity of irloxacin was compared with that of nalidixic acid, norfloxacin and ciprofloxacin against strains of clinical isolates. Irloxacin showed greater in vitro activity than nalidixic acid, similar activity to norfloxacin and lower activity than ciprofloxacin. Against Staphylococcus, the MIC range of E-3432 was 0.06-1 mg/l, better than the other compounds studied.     

In vitro interactions of antifungal agents against clinical isolates of Fusarium spp

The in vitro activities of amphotericin B (AMB), itraconazole (ITC), voriconazole (VCZ) and terbinafine (TBF) alone and in the combinations AMB+VCZ, TBF+ITC and TBF+VCZ were evaluated against 29 clinical isolates of Fusarium spp. (15 Fusarium solani, 7 Fusarium oxysporum, 2 Fusarium decemcellulare, 2 Fusarium dimerum and 3 other Fusarium spp.). Minimum inhibitory concentrations were determined using the method of the Clinical and Laboratory Standards Institute and the interaction activity was calculated using the fractional inhibitory concentration index. The four antifungal drugs tested alone showed very limited activity against most of the isolates. In contrast, the combination TBF+VCZ showed synergy for 21 isolates. The combination AMB+VCZ showed synergism for only five strains. No interaction or antagonism was observed among the remaining strains. TBF+ITC showed no interaction for 18 strains. The in vitro antifungal activity of the drugs alone and in combination varied for different species. These results corroborate previous in vitro studies in which the combination TBF+VCZ showed synergy against Fusarium spp., although further studies are needed to elucidate its potential usefulness for therapy.     

In vitro activity of antimicrobial agents against clinical isolates of Pseudomonas aeruginosa

Two hundred and seven clinical isolates of Pseudomonas aeruginosa were collected at Tenri Hospital between April 2003 and March 2004. We determined the minimum inhibitory concentration (MIC) of 16 antimicrobial agents, including prulifloxacin, pazufloxacin and biapenem which were recently published in Japan, against these isolates according to the guidelines of the Clinical and Laboratory Standards Institute. For the fluoroquinolones, the rank order of activity was prulifloxacin (MIC50, 0.5 microg/ml)>ciprofloxacin (1 microg/ml)> pazufloxacin (2 microg/ml)=levofloxacin (2 microg/ml)>gatifloxacin (4 microg/ml). For the carbapenems, the rank order of activity was meropenem (MIC50, 1 microg/ml)=biapenem (1 microg/ml)>imipenem (2 microg/m)>panipenem (8 microg/ml). For the cephalosporins and monobactam, the overall rank order of activity was cefozopran (MIC50, 4 microg/ml)= ceftazidime (4 microg/ml)>cefepime (8 microg/ml)=piperacillin/tazobactam (8 microg/ml)>aztreonam (16 microg/ml)= cefoperazone/sulbactam (16 microg/ml)=cefpirome (16 microg/ml). The rates of susceptibility to antimicrobial agents as per the criteria of the Japanese Society of Antimicrobial Chemotherapy were especially high for cefozopran (63%), biapenem and meropenem (61%), and pazufloxacin (53%) and ciprofloxacin (53%). These findings suggest that prulifloxacin, pazufloxacin and biapenem, which are newly introduced, are clinically effective in the treatment of infection caused with P. aeruginosa.