超广谱β—内酰胺酶的检测及耐药性分析

目的 了解超广谱β内酰胺酶（ＥＳＢＬｓ）细菌的检测及耐一的情况,以利于对ＥＳＢＬｓ的监控和治疗。方法 用ＮＣＣＬＳ推荐的初筛和确证实验及双纸片协同实验、Ｅ －ｔｅｓｔ、 Ｖｉｔｅｋ３２型全自动分析系统药敏检测卡ＧＮＳ－ＮＴ对１６０株大肠埃希菌和克雷伯菌属细菌进行ＥＳＢＬｓ的鉴定,并检测确证ＥＳＢＬｓ阳性菌株的药敏情况。结果 共检出ＥＬＳＬｓ菌株３３株,双纸片协同实验、Ｅ－ｔｅｓｔ、ＧＮＳ－ＮＧ三者     

Etest用于革兰阴性杆菌超广谱β-内酰胺酶测定

用ＥｔｅｓｔＥＳＢＬ试条测定２００株革兰阴性杆菌产超广谱β－内酰胺酶（ＥＳＢＬ），发现１８％大肠埃希菌，１９％肺炎克雷伯菌，１５％不动杆菌，１６％阴沟肠杆菌和１８％枸橼酸杆菌ＥＳＢＬ阳性，总检出率为１５％。此外，ＥｔｅｓｔＥＳＢＬ试盒可将上述检出率提高至少２．５％，且发现安曲南作为酶底物是本院ＥＳＢＬ的最佳指示剂     

三种方法检测超广谱β—内酰胺酶的结果比较

比较三种文坛法检测广州地区１２家医院临床分离的大肠埃希菌和克雷伯各产超广谱β－内酰胺酶（ＥＳＢＬｓ）敏感性,用纸片扩散初筛法,初筛出１６７株可疑产ＥＳＢＬｓ的菌株,然后进行纸片扩散确证法,双纸片协同法和浓度梯度法（Ｅｔｅｓｔ法）,结果有１４７株菌产ＥＳＢＬｓ（３２％大肠埃希菌的４２．６％克雷伯菌属ＥＳＢＬｓ菌性）,纸片扩散确下法和双纸片协同法检出率相似,但双纸片协同法的缺点的纸片中心间距不好控制,ＥｔｅｓｔＥＳＢＬ初筛试条检测ＥＳＢＬｓ有一定局限性,纸片扩散确证法适合临床常规测定。     

全自动细菌分析系统在检测产超广谱β—内酰胺酶细菌中的临？…

了解超广谱β－内酰胺酶细菌在医院分离及分布情况,以利用对ＥＳＢＬｓ细菌的监控和治疗。方法用ＶＴＴＥＫ３２型全自动细菌分析系统药敏检测卡ＧＮＳ－ＮＴ进行细菌ＥＳＢＬｓ的测定。结果在１３２株大肠埃希菌、１１９株肺炎克雷伯菌,６０株阴沟肠杆菌中ＥＳＢＬｓ的检出分别为２８．８％、１９．３％、５．０％,而７３株绿脓假单胞菌未检到ＥＳＢＬｓ菌;各病区产ＥＳＢＬｓ菌的分离率以重症监护病记最高（３３．６％）,其次     

肠道大肠艾希氏菌超广谱β—内酰胺酶的检测与耐药性分析

目的 了解肠道大肠艾希氏菌及肺炎克雷伯氏菌（ＥＳＢＬｓ）的携带情况。方法 细菌的鉴定和药敏试验采用仪器法。超广谱β－内酰胺酶（ＥＳＢＬｓ）的检测采用纸片扩散法初筛,双纸片雷同试验检测,Ｅｔｅｓｔ法确定。结果 ２０７株菌中,ＥＳＢＬｓ总检出率为１３．５％（２８株）,其中,大肠艾氏菌ＥＳＢＬｓ的检出率为１１％,肺炎克雷伯氏菌为３９％,后者明显高于前者。药敏结果显示：两种菌中产ＥＳＢＬｓ比非产ＥＳＢＬｓ耐药性要高。结论 肠道大肠艾氏菌和肺炎克雷伯氏菌ＥＳＢＬｓ的携带比较严重,尤其是后者。     

三种方法检测超广谱β-内酰胺酶敏感性比较

目的　比较３ 种方法检测大肠埃希菌和肺炎克雷伯菌临床分离株所产的超广谱β内酰胺酶（ＥＳＢＬｓ） 的敏感性。方法　首先用纸片扩散初筛法从７３ 株大肠埃希菌和肺炎克雷伯菌中筛选出２０ 株可疑产ＥＳＢＬｓ 的菌株,同时用纸片扩散确证法、浓度梯度法（Ｅｔｅｓｔ） 法和双纸片协同法进行测定比较。结果　对可疑产生ＥＳＢＬｓ 的１４ 株大肠埃希菌和６ 株肺炎克雷伯菌,用纸片扩散确证法头孢噻肟和头孢噻肟克拉维酸组检测,此２０ 株全部为ＥＳＢＬｓ 株,而头孢他啶和头孢他啶克拉维酸组的１３ 株初筛株有１２ 株ＥＳＢＬｓ 阳性。Ｅｔｅｓｔ 法用头孢他啶和头孢他啶克拉维酸检测,有１２ 株ＥＳＢＬｓ 阳性。双纸片协同法用头孢噻肟检测此２０ 株全部为ＥＳＢＬｓ 阳性,用头孢他啶检出１４ 株ＥＳＢＬｓ 阳性。结论　头孢噻肟及头孢他啶双药检测ＥＳＢＬｓ 的３ 种方法证明,头孢噻肟检出ＥＳＢＬｓ 的敏感性明显高于头孢他啶。     

产超广谱β-内酰胺酶大肠埃希菌和肺炎克雷伯菌的检测

目的 选择和适用于检测产超广谱β－内酰安酶（ＥＳＢＬｓ）临床大肠埃希菌、肺炎克雷伯耐药菌株的最佳方案。方法 临床分离的１１０株大肠埃希菌和８４株肺炎克雷伯菌经初筛试验,用浓度梯度法（Ｅｔｅｓｔ）、单纸片加抑制剂舒巴坦扩散法、阿莫西林及氨苄西林双纸片协同试验,比较５种方法的检出率极度其差异。结果 Ｅｔｅｓｔ法对产ＥＳＢＬｓ大肠埃希菌和肺炎克雷伯菌的检出存在明显的差异（Ｐ〈０．０１）,肺炎克雷伯菌的检出率（４／２０）有显低于大肠埃希菌（１６／２６）;单纸片扩散法加克拉维酸对两种菌的检出均较高（１６／２６、１２／２０）。检测产ＥＳＢＬｓ大肠埃希菌时,除氨 苄西林双纸片协同法（８／２６）检出率低以外,其他４种方法的检出率无明显差异（Ｐ〉０．０５）,５种方法有较好的一致性。检测产ＥＳＢＬｓ肺炎克雷伯菌时,单纤片扩散法加克     

三种方法检测超广谱β—内酰胺酶敏感性比较

目的 比较３种方法检测大肠埃希菌和肺炎克雷伯菌临床分离株所产的超广谱β－内酰胺酶（ＥＳＢＬｓ）的敏感性。方法 首先用纸片扩散初筛法从７３株大埃希菌和肺炎克雷伯菌中筛选中２０株可疑产ＥＳＢＬｓ的菌株,同时用纸片扩散确证法、浓度梯度法（Ｅｔｅｓｔ）法和双纸片协同法进行测定比较。结果 对可疑产生ＥＳＢＬｓ的１４株大肠埃希菌和６株肺炎克雷伯菌,用纸片扩散确证法头孢噻肟和头怨噻肟－克拉维酸组检测,此２０株全     

仪器法与纸片协同法检测超广谱β—内酰胺酶的结果比较

目的 了解ＶＩＴＥＫ－ＡＭＳ检测大肠埃希菌和肺炎克雷伯菌产超广谱β－内酰胺酶（ＥＳＢＬｓ）的可靠性,并调查本院这两种菌的产ＥＳＢＬｓ情况。方法 用ＶＩＴＥＫ－ＡＭＳ专用药敏卡ＧＮＳ－５０６进行ＥＳＢＬｓ检测,并以头孢曲松、头孢噻肟、头孢他啶和氨曲南为底物,用纸片协同试验作对照。结果 仪器检测４８株肺炎克雷伯菌中有２４株ＥＳＢＬｓ为阳性,用纸片协同法对照结果一致。检测１０２株大肠埃希菌中,仪器检出４１株阳性,纸协同法对照也为阳性,但仪器检测的６１株阴性菌中,纸片协同法对照有１９株为阳性。结论 ＶＩＴＥＫ－ＡＭＳ检测本地区产ＥＳＢＬｓ菌株尚可能存在一定的局限性,建议各地根据感染菌株的特点及三代头孢菌素的使用情况,用多种底物检测ＥＳＢＬｓ。     

评价三种筛选方法检测超广谱β-内酰胺酶及其临床应用

目的　评价３ 种超广谱β内酰胺酶（ Ｅ Ｓ Ｂ Ｌｓ） 筛选方法检测产 Ｅ Ｓ Ｂ Ｌｓ 大肠埃希菌和肺炎克雷伯菌的可靠性与临床应用。方法　以头孢三嗪、头孢噻肟、头孢他啶和氨曲南为指示底物,用双纸片协同试验、三维试验和双纸片增效试验３ 种方法检测４５ 株 Ｅ Ｓ Ｂ Ｌｓ 阳性和６４ 株 Ｅ Ｓ Ｂ Ｌｓ 阴性大肠埃希菌和肺炎克雷伯菌及临床分离的７４ 株大肠埃希菌和３１ 株肺炎克雷伯菌 Ｅ Ｓ Ｂ Ｌｓ 产生情况。结果　３ 种方法的敏感性分别为８６ ．７ ％ 、９５ ．６ ％ 和８４ ．４ ％ ,特异性分别为１００ ％ 、９８ ．５ ％ 和１００ ％ ,检测效率分别为９４ ．５ ％ 、９７ ．３ ％ 和９３ ．６ ％ 。临床分离大肠埃希菌和肺炎克雷伯菌 Ｅ Ｓ Ｂ Ｌｓ 检出率分别为３２ ．４ ％ 和２５ ．８ ％ 。头孢三嗪和头孢噻肟为本院检测 Ｅ Ｓ Ｂ Ｌｓ 最适指示底物。结论　三维试验是一种敏感、可靠的 Ｅ Ｓ Ｂ Ｌｓ 筛选方法,但操作繁琐,仅适用于标本量较少的医院;双纸片协同试验和双纸片增效试验操作简便、结果可靠,适合于各级医院常规应用。     

High incidence of Klebsiella pneumoniae clinical isolates to extended-spectrum B-lactam drugs in intensive care units

A prospective study conducted among Jordanian ICU patients in 1997 using Etest identified resistance rates among isolates of E. coli (25%-44%), Enterobacter spp. (54%-62%), and Klebsiella spp. (30%-80%) to extended-spectrum B-lactams (ESBLs): ceftazidime, cefotaxime, ceftriaxone, and aztreonam. All these isolates were susceptible to imipenem and showed low resistance rate to ciprofloxacin (5%-19%) and amikacin (13%-18%). Higher and significant resistance rates of Klebsiella isolates to ceftazidime (80%) and aztreonam (65%) were observed in 1997 compared with a previous study performed in 1994. The majority of Klebsiella pneumoniae (70%) express different ESBL phenotypes that were almost resistant to aztreonam and ceftazidime but susceptible or resistant to cefotaxime and/or ceftriaxone. This prospective study strongly suggests that ESBL production of Klebsiella pneumoniae isolates have been highly disseminated among ICU patients during 1997.     

广州地区下呼吸道感染常见病原菌的分布与耐药性

目的 :探讨广州地区下呼吸道感染常见病原菌分布与耐药情况。方法 :收集广州地区 13所医院下呼吸道感染患者痰标本分离的 1778株病原菌 ,按美国国家临床实验室标准委员会 (NCCLS)标准进行药敏试验。结果 :主要菌群有铜绿假单胞菌 (2 2 .7% )、克雷伯菌属 (15 .8% )、不动杆菌属 (12 .5 % )和肠杆菌属 (10 .5 % )等。甲氧西林耐药株分别占金黄色葡萄球菌和凝固酶阴性葡萄球菌的 75 .7%和 92 .9% ,未发现万古霉素耐药株。大肠埃希菌和克雷伯菌属产超广谱 β内酰胺酶 (ESBLs)的发生率是 4 6 .8%和 37.0 % ,产ESBLs菌株对各种抗菌药物的耐药率明显高于不产ESBLs菌株。铜绿假单胞菌对头孢哌酮 舒巴坦、头孢他啶、头孢吡肟和亚胺培南的敏感率较高。结论 :广州地区下呼吸道感染主要病原菌是革兰阴性杆菌 ,其对常用抗菌药物耐药性较高 ,开展细菌耐药性监测十分重要。     

Evaluation of a new cefepime-clavulanate ESBL Etest to detect extended-spectrum beta-lactamases in an Enterobacteriaceae strain collection

OBJECTIVES: In this study, we evaluated the performance of a new ESBL Etest configuration based on clavulanate synergy with cefepime compared with cefotaxime-clavulanate and ceftazidime-clavulanate ESBL Etest strips for the detection of extended-spectrum beta-lactamases (ESBL) in an Enterobacteriaceae strain collection, with special focus on Enterobacter spp. METHODS: Overall, a total of 54 clinical isolates of ESBL-producing Enterobacteriaceae species were evaluated: Enterobacter aerogenes (n=3), Enterobacter cloacae (n=10), Escherichia coli (n=10), Klebsiella oxytoca (n=3), Klebsiella pneumoniae (n=25) and Proteus mirabilis (n=3). To check Etest behaviour with resistance phenotypes similar to ESBL, our panel was expanded by six clinical isolates of K. oxytoca that were identified as putative producers of their chromosomal K1 beta-lactamase. RESULTS: With this panel, ESBL Etest was 98% sensitive with cefepime-clavulanate, 83% with cefotaxime-clavulanate, and 74% with ceftazidime-clavulanate strips. Concentrating on Enterobacter spp., reliable ESBL detection could only be achieved by the new cefepime-clavulanate strip since it confirmed ESBL production in all strains (100% sensitivity) whereas only 4/13 (31%) of Enterobacter strains were positive using cefotaxime-clavulanate or ceftazidime-clavulanate strips. A limitation of using the new cefepime strip was less than optimal specificity with K1 phenotypes of K. oxytoca: among six strains, four isolates were scored false-positive by Etest strips containing cefepime-clavulanate. CONCLUSION: The new Etest ESBL strip containing cefepime-clavulanate is a valuable supplement to current methods for detection of ESBLs. In our study collection, the cefepime-clavulanate strip was the best configuration for detection of ESBLs, particularly in Enterobacter spp.     

某三级结核病专科医院多重耐药菌分布及耐药性

目的分析安徽省胸科医院（结核病专科医院）2016年临床分离多重耐药菌的分布及对常见抗菌药物的耐药状况。 方法对安徽省胸科医院2016年1至12月期间送检标本中分离出的165株多重耐药菌进行回顾性分析,分析分离菌株的构成、多重耐药菌标本来源构成、年龄段和患者来源构成以及药敏结果。 结果多重耐药菌主要以产超广谱β内酰胺酶（ESBLs）大肠埃希菌、ESBLs肺炎克雷伯菌、耐碳青霉烯类抗菌药物鲍曼不动杆菌（CR-AB）、耐甲氧西林金黄色葡萄球菌（MRSA）、耐甲氧西林凝固酶阴性葡萄球菌（MRCNS）、多重耐药铜绿假单胞菌（MDRPA）组成,其分离标本主要来自痰液、灌洗液、中段尿。CR-AB对氨基糖苷类药物阿米卡星耐药率最低为57.0%,ESBLs大肠埃希菌对碳青霉烯类药物亚胺培南和美罗培南耐药率最低均为0%,ESBLs肺炎克雷伯菌对碳青霉烯类药物亚胺培南和美罗培南的敏感率均达到86.8%。MDRPA对氨基糖苷类药物阿米卡星和庆大霉素耐药率低,分别为11.6%和17.3%,MRSA、MRCNS对万古霉素和利奈唑胺敏感率均为100%。 结论虽然多重耐药菌对大部分药物产生高的耐药性,但亚胺培南、美罗培南在ESBLs肺炎克雷伯菌和ESBLs大肠埃希菌的治疗中还是具有很好的抗菌活性,但还是已经检出耐碳青酶烯酶类肠杆菌科菌株;而阿米卡星和庆大霉素在CR-AB和MDRPA的治疗中还具有比较好的抗菌活性,万古霉素和利奈唑胺对MRSA、MRCNS的抗菌活性均最强。     

Evaluation of the MicroScan ESBL plus confirmation panel for detection of extended-spectrum beta-lactamases in clinical isolates of oxyimino-cephalosporin-resistant Gram-negative bacteria

OBJECTIVE: We aimed to assess the performance of the MicroScan ESBL plus confirmation panel using a series of 87 oxyimino-cephalosporin-resistant Gram-negative bacilli of various species. METHODS: Organisms tested included 57 extended-spectrum beta-lactamase (ESBL) strains comprising Enterobacter aerogenes (3), Enterobacter cloacae (10), Escherichia coli (11), Klebsiella pneumoniae (26), Klebsiella oxytoca (3) and Proteus mirabilis (4). Also included were 30 strains resistant to oxyimino cephalosporins but lacking ESBLs, which were characterized with other resistance mechanisms, such as inherent clavulanate susceptibility in Acinetobacter spp. (4), hyperproduction of AmpC enzyme in Citrobacter freundii (2), E. aerogenes (3), E. cloacae (3), E. coli (4), Hafnia alvei (1) and Morganella morganii (1), production of plasmid-mediated AmpC beta-lactamase in K. pneumoniae (3) and E. coli (3) or hyperproduction of K1 enzyme in K. oxytoca (6). RESULTS: The MicroScan MIC-based clavulanate synergy correctly classified 50 of 57 ESBL strains as ESBL-positive and 23 of 30 non-ESBL strains as ESBL-negative (yielding a sensitivity of 88% and a specificity of 76.7%, respectively). False negatives among ESBL producers were highest with Enterobacter spp. due to masking interactions between ESBL and AmpC beta-lactamases. False-positive classifications occurred in two Acinetobacter spp., one E. coli producing plasmid-mediated AmpC beta-lactamase and two K. oxytoca hyperproducing their chromosomal K1 beta-lactamase. CONCLUSION: The MicroScan clavulanate synergy test proved to be a valuable tool for ESBL confirmation. However, this test has limitations in detecting ESBLs in Enterobacter spp. and in discriminating ESBL-related resistance from the K1 enzyme and from inherent clavulanate susceptibility in Acinetobacter spp.     

儿科院内感染细菌分布及耐药性监测

目的:了解儿科院内感染常见细菌分布并监测其耐药性.方法:收集惠儿标本,进行常规细菌培养及K-B法药敏试验.结果:分离出238株痛原菌,以克雷伯菌属为最多123株(51.7%).其次为凝固酶阴性葡萄球菌(coagulase negative staphylococci,CNS)50株(21.0%);123株克雷伯菌属中产ESBLs的菌株96株(78.0%);19株大肠埃希菌中产ESBLs的菌株12株(63.2%).产ESBLs克雷伯菌属和大肠埃希菌对抗菌药物的耐药率明显高于非产ESBLs的相应细菌.检出41株(80.2%)凝固酶阴性耐甲氧西林葡萄球菌(meahicillin resistant coagulase negative staphylococci,MRCNS),未检出耐甲氧西林的金黄色葡萄球菌(meahicillin resistant staphylococcus aureus,MRSA).凝固酶阴性葡萄球菌和金黄色葡萄球菌对青霉素全部耐药.结论:儿科的院内感染革兰阴性茵以克雷伯菌属最多见,革兰阳性菌以凝固酶阴性葡萄球菌居多,两类痛原菌多重耐药现象比较严重.     

对头孢吡肟敏感的疑似产超广谱β内酰胺酶大肠埃希菌和克雷伯菌属的分子生物学特征

目的 了解初筛试验疑似产超广谱β内酰胺酶(ESBLs)但确证试验未能确认,而对头孢吡肟敏感的大肠埃希菌和克雷伯菌属中的ESBLs和质粒介导的AmpC酶.方法 纸片扩散法检测18株细菌对常用抗菌药物的敏感性;PCR及多重PCR法检测细菌中的ESBLs和质粒AmpC酶基因;质粒转移接合试验检测耐药质粒的可传递性;细菌基因间重复一致序列(ERIC)-PCR法检测供体大肠埃希菌和受体E.coli J53及其接合子的同源性;脉冲场凝胶电泳(PFGE)对11株大肠埃希菌和6株肺炎克雷伯菌进行同源性分析.结果 18株细菌均为2005年1月至12月期间上海华山医院临床分离的菌株,其中大肠埃希菌11株,肺炎克雷伯菌6株,产酸克雷伯菌1株,按常规方法对细菌进行重新鉴定和药敏试验.18株细菌经美国临床和实验室标准协会(CLSI)推荐的ESBLs初筛试验结果均为ESBLs产生可疑菌株,但确证试验未能确认;所有菌株的头孢吡肟抑菌圈直径均在18 mm以上,显示敏感.PCR检测结果显示,11株大肠埃希菌中有9株产CIT型质粒AmpC酶,DNA测序及序列比对结果证实为CMY-2型AmpC酶,未发现TEM、SHV、CTX-M、PER、VEB、SFO等广谱或ESBLs;6株肺炎克雷伯菌中有5株产DHA型质粒AmpC酶,DNA测序及序列比对结果证实为DHA-1型AmpC酶;5株产DHA-1型AmpC酶的肺炎克雷伯菌株中,4株同时伴有广谱或ESBLs:其中2株产SHV-11型广谱酶,另2株分别产CTX-M-14型ESBLs和SHV-62型ESBLs;1株产酸克雷伯菌亦单产DHA-1型AmpC酶;质粒转移接合试验结果表明,携带耐药基因的质粒可从供体菌转移至敏感细胞中;PFGE结果显示,6株肺炎克雷伯菌的谱型各不相同,而11株大肠埃希菌可分为5种谱型,其中B型包含7株细菌,这7株细菌均产生质粒介导的CMY-2型AmpC酶,并分离自外科病房,提示可能存在克隆菌株的流行传播.结论在确证试验未能确认的疑似产ESBLs中,对头孢吡肟敏感的大肠埃希菌和克雷伯菌属细菌主要产生质粒介导的AmpC酶,但尚有少数菌株同时伴有产ESBLs.对同时产生ESBLs和AmpC酶的菌株,临床微生物实验室必须报告这些菌株对头孢吡肟耐药.     

产ESBLs的大肠埃希菌和肺炎克雷伯菌的药敏分析及其CTX-M基因型的研究

[目的]通过对产ESBLs大肠埃希菌和克雷伯菌的表型、基因型检测和耐药性分析，了解产ESBLs的大肠埃希菌和克雷伯菌的基因分布及耐药特性，为临床抗感染治疗提供有力证据。[方法]用NCCLS推荐的纸片确认试验检测产ESBLs大肠埃希菌和克雷伯菌，用PCR方法对ESBLs阳性菌进行CTX-M基因型检测；用K-B法对其进行药物敏感性试验，并进行耐药性分析。[结果]产ESBLs的大肠埃希菌和肺炎克雷伯菌大部分同时以CTX和CAZ为底物，单用CAZ-CAZ／CLA作底物会造成30．3％的漏检。ESBLs阳性菌对头孢菌素及广谱青霉素的耐药率高，对亚胺培南则均为敏感。对其基因型分析显示CTX-M型在肺炎克雷伯菌中占71．4％，而大肠埃希菌仅为15．8％。[结论]ESBLs是大肠埃希菌和肺炎克雷伯菌对头孢菌素产生耐药的主要原因，ESBLs菌耐药性强且多重耐药，ESBLs表型检测应同时选择2种以上底物，CTX-M基因型检出率为39．4％。     

In vitro evaluation of cefepime and other broad-spectrum beta-lactams in eight medical centers in Thailand. The Thailand Antimicrobial Resistance Study Group

The introduction of cephalosporins has had an important impact on the resistance rates to several clinically utilized beta-lactam antimicrobial agents. Most Thailand medical centers have not documented the levels of emerging resistant pathogens causing invasive infections. This study shows using reference-quality MIC techniques (Etest, AB BIODISK, Solna, Sweden), that carbapenem), "fourth-generation" cephalosporins (cefepime and cefpirome), and piperacillin/tazobactam were the most active agents tested against Gram-negative bacilli (Escherichia coli, Klebsiella spp., Enterobacter spp., Citrobacter spp., Serratia spp., indole-positive Proteae, Acinetobacter spp., Pseudomonas aeruginosa, and oxacillin-susceptible Staphylococcus spp. when compared to "third-generation" cephalosporins (ceftazidime and ceftriaxone). The rank order of activity for all species was imipenem (2.9% resistant) > cefepime (7.7%) > piperacillin/tazobactam (11.1%) > cefpirome (13.4%) > ceftriaxone (21.1%) > ceftazidime (29.9%). The incidence of extended spectrum beta-lactamase production among E. coli (15.7%) and K. pneumoniae (45.6%) was significant. Cefepime and imipenem were active against the majority of these isolates. The activity of cefepime was also shown to be very good against, 1) organisms capable of producing AmpC enzymes, 2) staphylococci species that were susceptible to oxacillin, and 3) many strains of nonfermentative Gram-negative bacilli. The prevalence of antimicrobial resistance in Thailand seems to be quite high among certain commonly encountered pathogens, and imipenem and cefepime have activity (susceptible and intermediate potency) against > 90% of these organisms.