产ESBLs大肠埃希菌77株耐药性分析

目的 探讨郑州地区产超广谱β-内酰胺酶(ESBLs)大肠埃希菌的耐药状况,以期指导临床用药.方法 收集临床分离的大肠埃希菌77株,采用纸片扩散法(K-B法)进行14种抗菌药物敏感性测定及产ESBLs耐药菌株的初步筛选,再通过双纸片协同试验(DDST)法确认产酶菌株.结果 77株大肠埃希菌对氨苄西林、哌拉西林、萘定酸、环丙沙星、左氧氟沙星、庆大霉素的耐药率较高,而对阿米卡星、头孢吡肟的耐药率较低.我院临床分离大肠埃希菌产ESBLs率为36.36%,产:ESBLs大肠埃希菌对头孢噻肟、头孢曲松和氨曲南的耐药率明显较非产酶菌株增高,对氨苄西林、萘定酸全部耐药,而碳青霉烯类的亚胺培南敏感率100%.结论 郑州地区产ESBLs大肠埃希菌对临床常用抗生素耐药严重,亚胺培南是治疗产ESBLs菌感染的最有效抗生素.     

156例泌尿道感染患者病原菌的分布及其对不同氟喹诺酮类药物的耐药率分析

目的:比较和分析泌尿道感染患者病原菌的分布及其对不同氟喹诺酮类药物的耐药率,为临床合理使用氟喹诺酮类药物提供参考。方法:选取2014年1月—2018年1月间收治的泌尿道感染患者156例资料,分析资料中采集的尿液标本进行细菌培养、分离、鉴定及其药敏试验结果,以及致病菌对不同氟喹诺酮类药物的耐药率。结果:156例泌尿系统感染患者的尿液标本中,分离出174株致病菌株,其主要以大肠埃希菌、肠球菌、表皮葡萄球菌为主;大肠埃希菌产超广谱β-内酰胺酶(ESBLs)对左氧氟沙星、氧氟沙星、诺氟沙星、环丙沙星的耐药率高于非ESBLs,对肠球菌高水平庆大霉素耐药率(HLGR)高于非HLGR(P<0.05);而表皮葡萄球菌MRSE对氧氟沙星、环丙沙星的耐药率高于非MRSE(P<0.05);采用不同氟喹诺酮类药物治疗后细菌的消除率为91.67%。结论:泌尿道感染患者病原菌以大肠埃希菌为主,大肠埃希菌应明确ESBLs、MRSE、HLGR菌株,根据其多重耐药情况合理使用不同氟喹诺酮类药物治疗,有效清除致病菌。     

产超广谱β-内酰胺酶(ESBLs)大肠埃希菌对喹诺酮类药物的耐药性观察

目的探讨产超广谱β-内酰胺酶(ESBLs)大肠埃希菌对喹诺酮类药物的耐药情况。方法选择南阳市中心医院2008年9月至2010年9月从分类标本中分类的大肠埃希菌共200株,经超广谱β-内酰胺酶酶确证试验,其中105株产生ESBLs。观察105株超广谱β-内酰胺酶大肠埃希菌对环丙沙星、左氧沙星、莫西沙星的耐药情况。结果 200株大肠埃希菌中,产超广谱β-内酰胺酶酶菌株的检出率为52.5%;产超广谱β-内酰胺酶大肠埃希菌对左氧氟沙星的耐药率显著高于非超广谱β-内酰胺酶大肠埃希菌耐药率,差异有统计学意义(P<0.05);105株产超广谱β-内酰胺酶大肠埃希菌对喹诺酮类药物耐药的最低抑菌浓度检测结果,89.5%对环丙沙星最低抑菌浓度值>4μg/mL;87.6%对左氧氟沙星最低抑菌浓度值>8μg/mL,89.5%对莫西沙星最低抑菌浓度值>2μg/mL。尿标本产超广谱β-内酰胺酶大肠埃希菌均对3种喹诺酮类药物耐药,耐药率达82.9%;痰标本大肠埃希菌,耐药率为92.3%。结论产β-内酰胺酶大肠埃希菌所占检出大肠埃希菌中的比例较大,且对喹诺酮类药物耐药率高,临床应用中要调整喹诺酮类使用频率,减少耐药菌株出现。     

临床分离产超广谱β-内酰胺酶大肠埃希菌及其耐药性检测

目的了解临床分离大肠埃希菌中产超广谱β-内酰胺酶(ESBLs)菌株的分布及耐药性。方法采用纸片法增强法进行产ESBLs菌株的检测,琼脂稀释法测定大肠埃希菌对10种抗菌药物的敏感性。结果产ESBLs菌株的检出率为45.45%(35/77);产ESBLs大肠埃希菌对美罗培南、头孢美唑、头孢他啶的耐药率均为0%、对氨苄西林、头孢唑林、头孢呋辛、头孢噻肟、头孢吡肟、环丙沙星、左氧氟沙星、阿米卡星、舒普深的耐药率分别为100%、100%、100%、80%、65.71%、97.14%、94.28%、28.57%、25.71%。产ESBLs组的耐药率明显高于非产ESBLs组(P<0.05)。结论产ESBLs大肠埃希菌的发生率较高,对大多数抗菌药物耐药显著。     

我院儿科产ESBLs大肠埃希菌和肺炎克雷伯菌的临床分布与耐药性分析

目的：分析我院儿科产ESBLs大肠埃希菌和产ESBLs肺炎克雷伯菌的临床分布特征及耐药性,为临床合理用药提供参考。方法：对2012年12月至2015年12月在我院儿科住院的感染性疾病患儿送检的标本进行培养,采用VITEK细菌鉴定与药敏分析系统对菌落进行菌种鉴定及药敏分析。结果：临床共分离大肠埃希菌86株,其中产ESBLs菌60株（69.77%）,83.33%（50/60）来源于痰液标本;肺炎克雷伯菌62株,其中产ESBLs菌57株（91.94%）,92.98%（53/57）来源于痰液标本。产ESBLs大肠埃希菌对美罗培南、环丙沙星、阿米卡星、左氧氟沙星的耐药率分别为0%、1.67%、3.33%、3.33%,对其他抗菌药物的耐药率为5.00%~96.66%;产ESBLs肺炎克雷伯菌对美罗培南、环丙沙星、左氧氟沙星的耐药率均为0%,对其他抗菌药物的耐药率为3.51%~92.98%。结论：产ESBLs大肠埃希菌和产ESBLs肺炎克雷伯菌主要来源于痰液标本,对常用抗菌药物的耐药情况基本一致（β-内酰胺酶抑制剂复方制剂除外）。二者对大部分头孢菌素耐药率较高（头孢替坦除外）,对碳青霉烯类（美罗培南、亚安培南）、氨基糖苷类（阿米卡星、庆大霉素、妥布霉素）、喹诺酮类（左氧氟沙星、环丙沙星）的耐药率较低。临床医师应结合药敏试验结果,合理选用抗菌药物,避免滥用,以减少细菌耐药。     

产超广谱β-内酰胺酶细菌的耐药性监测

目的研究2001—2003年大肠埃希菌、克雷伯菌产超广谱β-内酰胺酶(ESBLs)的检出率及对常用抗生素的耐药情况。方法对2001—2003年分离的837株大肠埃希菌、216株克雷伯菌用标准纸片扩散确证法(K-B法)检测其ESBLs产生率。采用K-B法进行药敏检测。结果2001、2002、2003年大肠埃希菌产ESBLs分离率分别为12.3%、15.9%、30.9%,克雷伯菌属产ESBLs分离率分别为23.9%、28.8%、30.0%;产ESBLs株对头胞菌素类、氨基糖苷类、氟喹诺酮类耐药率均高于非产ESBLs菌株,未发现对亚胺培南耐药的菌株。结论大肠埃希菌、克雷伯菌产ESBLs菌株逐年升高,应引起足够的重视。     

357株大肠埃希菌耐药性监测

目的 对本院近3年大肠埃希菌进行常用抗生素的耐药监测及产ESBLs检出率进行比较分析.方法 药敏实验和双纸片协同试验对我院 2004年～2006年临床分离的357株大肠埃希菌进行监测分析.结果 大肠埃希菌对氨苄西林、环丙沙星、左氧氟沙星的耐药率都在50%以上,对头孢呋辛、头孢噻肟、头孢曲松、头孢他啶、氨曲南、庆大霉素、阿米卡星的耐药率都在40%左右,对哌拉西林/他唑巴坦、头孢西丁、头孢吡肟耐药率为20%左右,对碳青霉烯类抗菌药物亚胺培南/西司他丁、美罗培南全部敏感.大肠埃希菌ESBLs检出率 2004～2006年分别为 36.5%、38.7%、41.6%.结论 大肠埃希菌对绝大部分抗菌药物的耐药率均逐年增加,大肠埃希菌产ESBLs率呈逐年上升的趋势,积极加强耐药监测,合理、规范选用抗菌药物,才能控制耐药菌株的出现和传播.     

295株大肠埃希菌的耐药性分析

目的 探讨大肠埃希菌的耐药性.方法 采用头孢西丁、头孢噻肟、头孢他啶、头孢呋辛、头孢吡肟、哌拉西林、环丙沙星、阿米卡星、丁胺卡那霉素和亚胺培南共10种抗菌药物对本院临床分离的295株大肠埃希菌的耐药性进行检测分析.结果 295株大肠埃希菌中检出产ESBLs菌株105株,检出率为35.6%.产ESBLs菌株和非产ESBLs菌株对亚胺培南均敏感、没有耐药株,对丁胺卡那霉素的耐药率无显著性差异(P>0.05).产ESBLs菌株对其余8种抗菌药物的耐药率均高于非产ESBLs菌株,差异具有统计学意义(P<0.01或P<0.05).结论 产生ESBLs是导致大肠埃希菌多重耐药的重要原因.亚胺培南是治疗产ESBLs大肠埃希菌的首选药物.临床治疗时应根据药敏试验结果合理地使用抗菌药物,以减少耐药菌的产生.     

尿路感染大肠埃希菌的耐药性及产超广谱β-内酰胺酶检测

目的探讨尿路感染大肠埃希菌的耐药性及产超广谱β-内酰胺酶(ESBLs)检测。方法对从尿路感染者中段尿标本中分离出的96株大肠埃希菌,采用纸片扩散(K-B)法检测其对15种抗生素的耐药率,采用改良的酶提取物三维试验法测定ESBLs。结果从96株大肠埃希菌中检出产ESBLs菌株31株,检出率高达32.29%。大肠埃希菌对头孢西丁、亚胺培南、氨苄西林舒巴坦和哌拉西林他唑巴坦的耐药率较低(<20%),对氨苄西林、哌拉西林、头孢唑林、头孢他啶、庆大霉素、复方新诺明、环丙沙星、左氧氟沙星的耐药率较高(>50%)。产ESBLs菌株对15种抗生素的耐药性大部分高于非产ESBLs菌株。结论对产ESBLs大肠埃希菌的尿路感染,经验用药可选择β-内酰胺类/β-内酰胺酶抑制剂和头霉类抗生素,对重症感染一般首选碳青霉烯类抗生素;但最好根据药敏试验结果选择敏感药物进行治疗。     

泌尿道感染大肠埃希菌476株耐药分析

目的：了解医院泌尿道感染的主要病原菌及大肠埃希菌的耐药性,指导临床合理用药。方法对2011年2月至2013年11月该院住院及门诊尿路感染患者尿培养分离出的476株大肠埃希菌进行药敏分析。结果尿路感染476株大肠埃希菌中产ESBLs菌株检出率为62.4%;大肠埃希菌对阿米卡星、美罗培南、亚胺培南、哌拉西林/他唑巴坦和头孢哌酮/舒巴坦耐药率最低,对青霉素类、头孢类及喹诺酮类耐药率较高,产ESBLs 株耐药率明显高于非产ESBLs。结论泌尿道感染中大肠埃希菌分离率最高,且细菌耐药严重,特别是产ESBLs株耐药更为严重,应当加强细菌耐药监测,指导临床合理选用抗菌药物,减缓耐药菌株的产生。     

In vitro activity of beta-lactams in combination with other antimicrobial agents against resistant strains of Pseudomonas aeruginosa

Using the chequerboard titration method, the activity in combination of beta-lactams, fluoroquinolones and aminoglycosides was investigated against 24 Pseudomonas aeruginosa isolates resistant to these antibiotics. Synergy was detected with one or more antimicrobial combinations against 15 of 24 (63%) isolates and partial synergy was detected with one or more combinations against all 24 isolates. No antagonism was seen with any combination. Ceftazidime and cefepime with aztreonam, amikacin and isepamicin showed synergy or partial synergy against 12-20 (50-80%) isolates. Imipenem and meropenem with amikacin and isepamicin showed synergy or partial synergy against eight to 12 (33-50%) isolates. The results of this study indicate that against P. aeruginosa, synergy may occur between beta-lactams, fluoroquinolones and aminoglycosides although the strains are resistant to the individual antibiotics.     

Antibiotic resistance rates and macrolide resistance phenotypes of viridans group streptococci from the oropharynx of healthy Greek children

A total of 200 isolates of viridans group streptococci isolated from the oropharynx of healthy Greek children were studied. Vancomycin, rifampicin, fluoroquinolones and dalfopristin/quinupristin were active against all tested isolates. High level resistance to gentamicin was not seen. Intermediate and high-level penicillin resistance was present in 28.5 and 14.5% isolates, respectively, with 41.3% of the latter group, being also resistant to cefotaxime. Resistance rates to other antimicrobials were as follows - erythromycin 38.5%, clarithromycin 33.5%, clindamycin 7.5% and tetracycline 23%. Penicillin resistance occurred more frequently in Streptococcus mitis isolates, while macrolide resistance was more frequent in S. oralis. MLSB resistance phenotype M was dominant (74%) among erythromycin resistant isolates, with phenotypes IR and CR being represented by 6 and 20% of isolates, respectively.     

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.     

Antimicrobial susceptibility and serogroups of Salmonella isolates from Riyadh, Saudi Arabia

The antimicrobial susceptibility and serogroups of 153 Salmonella strains isolated during a period of 22 months from both children and adults at a major teaching hospital in Riyadh, Saudi Arabia were studied. Antimicrobial susceptibility testing by comparative disc method and MIC determination by E-test method were performed on selected antimicrobial agents. For nalidixic acid and trimethoprim only the comparative disc method was used. Discrepancy between the two methods were noticed only in 1.3% of isolates. The majority of isolates from children (41%) were serogroup B, while those from adults (43%) were serogroup C1. The overall resistance was 16% to ampicillin and ampicillin/sulbactam, 13% to nalidixic acid, and 11% to chloramphenicol and trimethoprim/sulphamethoxazole. The resistance of Salmonella isolates to the so-called first line anti-Salmonella agents, i.e. ampicillin, chloramphenicol and trimethoprim/sulphamethoxazole, has increased compared to that reported 4 years ago from this Institution. Almost all isolates were susceptible to the second, and third generation cephalosporins, fluoroquinolones, aztreonam, mecillinam and gentamicin. Multiple drug resistance to two or more drugs was noticed in 16% of isolates, most of which were serogroup B. The majority of these multiple drug resistant isolates (96%) were ampicillin resistant and β-lactamase producers. Although these isolates showed reduced MICs to ampicillin/sulbactam, their MICs were still higher than the susceptibility breakpoint for this combination. The nalidixic acid-resistant isolates showed higher MICs to the fluoroquinolones compared to the nalidixic acid-sensitive isolates. Isolates from children showed higher resistance to some of the antimicrobial agents compared to those from adults.     

Phenotypic and genotypic analysis of levofloxacin-resistant clinical isolates of Streptococcus pneumoniae collected in 13 countries during 1999-2000

During 1999-2000, 5015 isolates were collected from 13 countries and tested against levofloxacin. Overall, levofloxacin resistance minimum inhibitory concentration (MIC>or =8 mg/l) was found in 40 isolates (0.8%). The highest resistance rates were in Hong Kong (8.0%), China (3.3%) and Spain (1.6%). Levofloxacin retained an MIC(90) of 1 mg/l in all countries. Pulsed-field gel electrophoresis analysis of resistant isolates demonstrated the presence of clones in countries where levofloxacin resistance exceeded 1%, suggesting that the elevated resistance rates could result from resistant clones within participating hospitals. DNA-sequence analysis of the quinolone-resistance-determining regions of gyrA, gyrB, parC and parE genes showed that the most common mutations were in GyrA (Ser81Phe), ParC (Ser79Phe, Lys137Asn) and ParE (Ile460Val), accounting for 40% of the isolates tested. Levofloxacin-resistant isolates were generally non-susceptible to other fluoroquinolones tested. Future studies to characterise resistant isolates by other molecular methods may ensure that the appropriate counter-measures can be taken to control the spread of resistant isolates.     

6种氟喹诺酮类药物对临床分离金葡萄的抗菌活性比较

目的：观察临床分离金葡萄对6种氟喹诺酮类药物的耐药情况。方法：用琼脂稀释法测定诺氟沙星（NFLX）、氧氟沙星（OFLX）、氟罗沙星（FLRX）、环丙沙星（CPFX）、司帕沙星（SPFX）、托舒沙星（TFLX）6种2、3代氟喹诺桐类药物对成都地区155株临床分离金葡菌的体外抗菌活性。结果：金葡菌对6种药物的耐药率分别为诺氟沙星35.5%。氟罗沙星34.19%,环丙沙星27.75%,托舒沙星27.75% ,氧氟沙星25.81%,司帕沙星25.81%。结论：氟喹诺酮类药物的广泛应用已使细菌的耐药性明显增高,各药MIC90均超过16mg.L^-1,比以往文献报道的本地区金葡萄耐药性明显升高,提示要合理应用氟喹诺酮类药物,减少耐药菌株的增加。     

Susceptibility of Canadian isolates of Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae to oral antimicrobial agents

We measured the susceptibility of Canadian isolates of three respiratory tract pathogens (Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae) to several currently approved antimicrobial agents by two different methods. We also measured the susceptibility of isolates to seven fluoroquinolones. Beta-lactamase was produced by 123/566 (21.7%) of H. influenzae isolates compared with 178/200 (89%) of M. catarrhalis isolates. For S. pneumoniae 83/374 (22.2%) isolates were penicillin resistant and of these 2.1% (8/374) showed high level resistance (MIC≥2 mg/l). Regardless of methodology, all fluoroquinolones were highly active against H. influenzae (MIC₉₀ ≤0.031 mg/l) and M. catarrhalis (MIC₉₀ ≤0.064 mg/l) isolates. Susceptibility of H. influenzae to cefuroxime and amoxycillin/clavulanic acid was 99–100% whereas 84–85.5% were susceptible to cefaclor and cefprozil. Azithromycin susceptibility ranged from 82.6 to 99.2% depending on the method. M. catarrhalis isolates were uniformly susceptible to all agents tested except amoxycillin. Cross-resistance in S. pneumoniae to all non-quinolone agents was concurrent with increasing penicillin resistance as shown by increasing MIC₉₀ values. For the fluoroquinolones tested, the rank order of potency based on MIC₉₀ values was as follows: gemifloxacin (0.031–0.063 mg/l), trovafloxacin (0.125 mg/l), moxifloxacin (0.125–0.25 mg/l), grepafloxacin (0.125–0.25 mg/l), gatifloxacin (0.5 mg/l), levofloxacin (1 mg/l) and ciprofloxacin (2 mg/l). Our study confirms either a high or increasing prevalence of antimicrobial resistant respiratory pathogens in Canada and also compares the new and old fluoroquinolones and their potential role as therapy for community-acquired infections. The prevalence of β-lactamase positive H. influenzae may have decreased from levels reported in previous studies.     

In vitro synergism of beta-lactams with ciprofloxacin and moxifloxacin against genetically distinct multidrug-resistant isolates of Pseudomonas aeruginosa

In vitro combinations of beta-lactams with fluoroquinolones against multidrug-resistant (MDR) Pseudomonas aeruginosa were tested. From a total of 200 isolates, 24 genetically distinct isolates defined by pulsed-field gel electrophoresis (PFGE) were selected. The isolates were exposed over time to imipenem, meropenem and ceftazidime as well as to their combinations with ciprofloxacin and moxifloxacin. All isolates were resistant to all agents tested at concentrations equal to their average serum level. Synergy of any of the tested combinations was found in 10 isolates (41.7%). This was shown after 4h and 6h of exposure accompanied by re-growth after 24h. Not all the tested combinations were active against the same isolates. The combinations of imipenem+ciprofloxacin, ceftazidime+ciprofloxacin and imipenem+moxifloxacin were the most active. When time-kill assays were repeated for the latter isolates at antimicrobial concentrations equal to their maximum serum levels, synergy was prolonged to 24h. The present findings should be interpreted with caution for the management of infections by MDR P. aeruginosa. They underscore the potential interest of reporting synergism between beta-lactams and fluoroquinolones in the nosocomial setting when a MDR isolate emerges.     

Geographically-based evaluation of multidrug resistance trends among Streptococcus pneumoniae in the USA: findings of the FAST surveillance initiative (2003-2004)

Surveillance initiatives to track Streptococcus pneumoniae resistance trends are important for understanding the current in vitro effectiveness of available antimicrobial agents. The antimicrobial susceptibility profiles of S. pneumoniae (n = 1479 isolates) collected from 17 geographical areas across the USA (2003–2004) were analysed; 36.8% of isolates were resistant to one or more agents (24.4% were multidrug-resistant, i.e. resistant to two or more antimicrobial classes). Multidrug resistance involved resistance to β-lactams, macrolides, tetracycline and trimethoprim/sulphamethoxazole, but rarely fluoroquinolones (>96% of multidrug-resistant isolates were fluoroquinolone-susceptible). Multidrug resistance rates were prominent regardless of the geographical region surveyed. As this trend continues, the empirical therapeutic options for S. pneumoniae infections will diminish and there will be an ongoing need to evaluate the effectiveness of potent fluoroquinolones such as gemifloxacin.     

In vitro activity of four fluoroquinolones against clinical isolates of Pseudomonas aeruginosa determined by the E test

Ciprofloxacin, levofloxacin, ofloxacin, and trovafloxacin were tested by the E-test against 100 clinical isolates of Pseudomonas aeruginosa. Ciprofloxacin was the most active of the tested agents with 82% of isolates having a MIC 8). Levofloxacin and trovafloxacin had nearly identical potency: 75% and 76% of the isolates were inhibited by 8 for levofloxacin; 0.19->8 for trovafloxacin). Ofloxacin was the least active of the four quinolones, with 43% of the isolates having a MIC >2 mg/l. All isolates resistant to ciprofloxacin were also resistant to the other agents, i.e. resistance to ciprofloxacin predicted resistance to all the quinolones tested in every case. This data demonstrates that fluoroquinolones are active agents against P. aeruginosa. In vitro susceptibility testing, however, is crucial to assess the resistance pattern in any specific location and for each individual agent.