VITEK2 Compact系统中国定制药敏卡片检测 大肠埃希菌和克雷伯菌属结果准确性探讨

目的评估VITEK2Compact系统中国定制卡片AST-N334和AST-N335测定肠杆菌科细菌体外药敏试验的可靠性。方法选取2010年1月至2015年8月宁夏医科大学总医院医学实验中心分离的肠杆菌科细菌80株,其中大肠埃希菌30株,克雷伯菌属50株,采用琼脂稀释法/肉汤稀释法作为参考方法,评估AST-N334和AST-N335药敏卡检测结果与参考方法检测结果的分类标准符合率、非常重大错误、重大错误和一般错误。结果 AST-N334药敏卡检测大肠埃希菌、克雷伯菌属的分类标准符合率分别为94.5%、96.3%,AST-N335药敏卡检测大肠埃希菌、克雷伯菌属的分类标准符合率分别为95.1%、98.2%。两种卡片中大多数药物检测结果与稀释法的分类标准符合率均在90.0%以上,亚胺培南、阿米卡星、左氧氟沙星、美罗培南等均为100.0%,但其他药物出现不同类型的错误。结论中国定制卡片AST-N334和AST-N335检测大肠埃希菌和克雷伯菌属的药敏试验结果具有较高的准确性,与稀释法有较好的一致性,能满足临床要求。     

VITEK2 Compact全自动微生物分析仪对黏液型和非黏液型铜绿假单胞菌药敏检测评价

目的 评价VITEK2 Compact全自动微生物分析仪对黏液型和非黏液型铜绿假单胞菌药敏检测结果的准确性。方法 对某院分离的29株黏液型铜绿假单胞菌和30株非黏液型铜绿假单胞菌同时以VITEK2 Compact分析仪法及琼脂稀释法进行药物敏感性试验,以琼脂稀释法为参考方法进行统计学分析。结果黏液型铜绿假单胞菌VITEK2 Compact分析仪法药敏结果的标准符合率(CA)为84.69%,严重错误率(VME)为3.20%,重大错误率(ME)为2.13%,一般错误率(MIE)为9.96%; 非黏液型铜绿假单胞菌VITEK2 Compact分析仪法药敏结果的标准符合率(CA)为94.33%,严重错误率(VME)为0.67%,重大错误率(ME)为1.67%,一般错误率(MIE)为3.33%。两种铜绿假单胞菌VITEK2 Compact分析仪法药敏结果的VME,MIE,CA相比较,差异有统计学意义(χ²=5.02,10.44,14.55,P<0.05)。黏液型铜绿假单胞菌VITEK2 Compact分析仪法药敏结果的CA比非黏液型铜绿假单胞菌低,且<90%,而VME,MIE均比非黏液型铜绿假单胞菌高。结论 VITEK2Compact全自动微生物分析仪对非黏液型铜绿假单胞菌药敏检测结果准确可靠,对黏液型铜绿假单胞菌药敏检测结果准确性较低,黏液型铜绿假单胞菌建议用其它方法做药物敏感性试验。     

VITEK-2 Compact 检测奇异变形杆菌、摩根摩根菌、铜绿假单胞菌的部分药敏结果准确性评价

目的　探讨 VITEK-2 Compact 检测奇异变形杆菌、摩根摩根菌和铜绿假单胞菌的部分药敏结果的准确性。方法收集 2017 年 3 月 ~2020 年 3 月临床分离的 58 株奇异变形杆菌、32 株摩根摩根菌和 280 株铜绿假单胞菌，以纸片扩散法（K-B 法）为参考方法，用 VITEK 2 Compact AST-GN16 药敏卡检测前两种菌对亚胺培南（IPN）的敏感度，用 AST-GN09药敏卡检测铜绿假单胞菌对亚胺培南、美罗培南（MEM）和氨曲南（ATM）的敏感度。结果　仪器法与 K-B 法比较，经58 株奇异变形杆菌药敏结果显示，其标准符合率（CA）、一般错误率（MIE）、严重错误率（ME）和极严重错误率 (VME)分别为 3.45%，6.90%，0% 和 89.66%，两种方法之间的差异有统计学意义（χ 2 =186.66, P<0.05）；32 株摩根摩根菌药敏结果显示，其CA，MIE，ME和VME分别为12.5%，6.25%，81.25%和0%，即两种方法之间的差异有统计学意义（χ 2 =155.56，P<0.05）；280 株铜绿假单胞菌药敏结果显示，其 CA，MIE，ME 和 VME 分别为 88.93%，10.71%，0.36% 和 0%，即 IPN两种方法之间的差异有统计学意义（χ 2 =9.84，P<0.05）。MEM 和 ATM 的两种方法比较，其 CA，MIE，ME 和 VME 分别为 95.00%，5.00%，0 和 0；68.57%，27.86%，1.07% 和 2.5%，即两种方法药敏结果的差异无统计学意义（χ 2 =4.58，0.78，P>0.05）。两种方法检测的分类一致性中，只有 MEM 结果差异无统计学意义（χ 2 =5.12，P>0.05），其它均有统计学意义（χ 2 =11.72~186.68，均 P<0.05）。结论　用 VITEK-2 Compact AST-GN09 检测铜绿假单胞菌对 MEM 敏感度结果可靠，无需验证，而对 IPN 和 ATM 的敏感度结果不可靠，需验证；VITEK-2 Compact AST-GN16 检测奇异变形杆菌和摩根摩根菌的 IPN 敏感度结果也存在不同程度的差异，在工作中需采用 K-B 法进行补充修正，以便更加准确的指导临床用药。     

比较Thermo STP6F药敏测定卡与微量肉汤稀释法测定链球菌对抗菌药物的敏感性

目的为临床提供快速、准确、方便的链球菌药敏试验测定方法,比较Thermo STP6F药敏测定卡与金标准微量肉汤稀释法测定链球菌对抗菌药物的敏感性。方法按CLSI要求,用Thermo STP6F药敏测定卡检测199株链球菌(肺炎链球菌、化脓链球菌和无乳链球菌),与微量肉汤稀释法结果进行比较。结果两种药敏测试方法涵盖10种抗菌药物对肺炎链球菌的药敏试验结果,分类一致率(CA)为94.6%,基本一致率(EA)为95.5%,重大偏差(VMD)为0.5%,较大偏差(MD)为1.2%,次要偏差(mD)为4.6%;对化脓链球菌两种方法测试结果的CA为99.2%,EA为95.0%,VMD为0.8%,MD为0.8%,mD为0;对无乳链球菌两种方法测试结果的CA为97.8%,EA为93.6%,VMD为1.1%,MD为0.9%,mD为1.2%。Thermo STP6F药敏测定卡所得数值常比标准方法略高。结论 Thermo STP6F药敏测定卡对链球菌的检测结果与微量肉汤稀释法一致性较好,在用于检测肺炎链球菌对美罗培南敏感性时建议结合E试验法复核确认。     

全自动微生物鉴定药敏分析仪对临床相关细菌药敏测定能力的评估

目的评估Vitek 2 Compact全自动微生物鉴定药敏分析仪对临床相关革兰阴性菌和革兰阳性菌的药敏测定能力。方法选取89株北京协和医院临床菌株（革兰阴性菌48株，革兰阳性菌41株）和66株本实验室保存的参考菌株（革兰阴性菌41株，革兰阳性菌25株）为评估菌株，分别采用Vitek 2 Compact AST-GN09（革兰阴性菌）、AST-P536（葡萄球菌）、AST-P534（肠球菌和无乳链球菌）和AST-P533（肺炎链球菌）药敏卡进行药敏测定，测定结果与参考方法Etest结果进行对照。32株以CLSI纸片确证法检测为ESBL阳性的菌株（其中包括16株经PCR扩增测序确定产SHV或CTX-M型ESBLs的菌株），以Vitek 2 Compact检测其是否产ESBLs。结果根据临床和实验室标准协会（CLSI）规定的药敏折点，对Vitek 2 Compact和Etest法测得的药敏结果进行解释，在全部的1626株细菌一抗生素组合中，Vitek 2 Compact药敏测定的标准符合率（CA）为90．83％，严重错误（VME）为4．91％，重大错误（ME）为2．09％，一般错误（MIE）为6．40％。90％以上的肠杆菌科菌、非发酵糖菌、微球菌科菌和链球菌科菌分别在11、13、11和12h内完成测定。32株ESBL阳性菌以Vitek 2 Compact检测均为阳性。结论Vitek 2 Compact能够对临床相关革兰阴性菌和革兰阳性菌的药物敏感性进行准确、快速的测定，对ESBLs检测的敏感性、特异性高，是临床微生物实验室的有利工具。     

对VITEK 2-Compact肺炎链球菌GP68药敏卡的性能评估

目的评估VITEK 2-Compact肺炎链球菌GP68药敏卡的性能,以E试验为参比方法。方法收集2015年1-12月98株肺炎链球菌,采用VITEK 2-Compact AST-GP68药敏卡进行药敏测定,结果与E试验结果进行对照。结果按CLSI标准,98株肺炎链球菌中青霉素的分类符合率(CA)为80.6%、严重错误(VME)为0、重大错误(ME)为12.2%、微小错误(mE)为7.1%;头孢曲松CA为90.8%、VME为0、ME为4.1%、mE为5.1%;头孢噻肟CA为91.8%、VME为0、ME为5.1%、mE为3.1%;美罗培南CA为85.7%、VME为0、ME为2.0%、mE为12.2%;阿莫西林、厄他培南、红霉素、四环素、氯霉素、泰利霉素、利奈唑胺、万古霉素、喹诺酮类(莫西沙星、氧氟沙星、左氧氟沙星)、甲氧苄啶-磺胺甲唑CA为100%。结论 VITEK 2-Compact AST-GP68由于检测原理缺陷使其对某些抗菌药物如青霉素、头孢曲松、头孢噻圬、美罗培南等的药敏试验结果出现假耐药现象,临床在遇到此类现象时,需采用其他方法进行复核确认。     

2种常用肺炎克雷伯菌碳青霉烯类抗菌药物敏感性试验卡性能评价

目的评价2种常用全自动微生物鉴定系统配套药物敏感性试验卡(GN13、NM38)检测肺炎克雷伯菌对碳青霉烯类抗菌药物敏感性的可靠性。方法收集2016年1月—2017年8月黄山市人民医院分离自临床样本的168株肺炎克雷伯菌,分别采用GN13、 NM38及微量肉汤稀释法测定其对碳青霉烯类抗菌药物的敏感性。以微量肉汤稀释法为金标准,对GN13和NM38的检测结果进行分析。采用改良碳青霉烯类灭活试验(mCIM)检测碳青霉烯酶,分析经仪器高级专家系统(AES)推测或预警提示为产碳青霉烯酶的可靠性。结果以微量肉汤稀释法为金标准, GN13与NM38检测结果的分类一致率(CA)均90%。检测结果经AES修正后,GN13对亚胺培南的一般错误(MIE)和重大错误(ME)均降低了0.6%,对厄他培南的MIE增加了0.6%,均未出现严重错误(VME); NM38对亚胺培南的MIE、ME、VME分别为1.19%、1.19%、2.97%,对厄他培南的MIE、ME、VME分别为3.6%、0.0%、0.6%。mCIM表型检测结果显示碳青霉烯酶阳性率为27.4%(46/168),经AES修正后GN13推测和NM38预测产碳青霉烯酶的阳性率分别为31.0%和30.4%,与mCIM一致(P0.05)。结论 GN13与NM38检测肺炎克雷伯菌对碳青霉烯类抗菌药物的性能均可靠,但应重视AES的修正或预警作用。     

碳青霉烯类耐药革兰阴性菌对黏菌素和多黏菌素B的药敏试验方法学评价

目的评估各种药敏试验方法检测碳青霉烯类耐药菌株对黏菌素和多黏菌素B敏感性结果的可靠性。方法以肉汤微量稀释法为参比方法,采用E试验法、VITEK 2-Compact法、纸片扩散法、MIC测试条(MTS)和梳状条(E strip)法5种药敏试验方法测定1 040株碳青霉烯类耐药的肺炎克雷伯菌(CRKP)、铜绿假单胞菌(CRPA)和鲍曼不动杆菌(CRAB)对黏菌素和多黏菌素B的敏感性。结果 E试验法、VITEK 2-Compact法和纸片扩散法测定377株CRKP对黏菌素的敏感率分别为97.1%、96.3%和98.1%;317株CRPA的敏感率分别为95.3%、100%和99.1%;346株CRAB的敏感率分别为100%、99.7%和99.7%。MTS、E strip法和纸片扩散法测定CRKP对多黏菌素B的敏感率分别为97.3%、97.3%和99.2%;317株CRPA的敏感率分别为98.7%、99.4%和99.7%;346株CRAB的敏感率分别为100%、100%和99.7%。与肉汤微量稀释法测定结果相比,5种方法检测黏菌素或多黏菌素B的分类一致率(CA)均95%。对于CRKP,5种方法的非常重大误差(VME)为1/9～5/7,重大误差(ME)为0.3%～66.7%;对于CRPA菌株,E试验法和MTS法的基本一致率(EA)90%,5种方法均未检出VME;E试验法检测黏菌素的ME为0.3%～17.6%;对于CRAB菌株,除VITEK 2-Compact法外其他4种方法的VME为1/3～1/1,ME为0～0.3%。结论 E试验法、VITEK 2-Compact法、纸片扩散法、MTS和E strip法等检测黏菌素和多黏菌素B对碳青霉烯类耐药革兰阴性菌的药敏,均存在EA偏低或假敏感现象(即VME),需引起实验室和临床高度重视,实验室仍应按美国临床和实验室标准化协会(CLSI)文件采用标准肉汤微量稀释法进行多黏菌素药敏试验。     

不同方法检测黏液型铜绿假单胞菌药物敏感性结果准确性探讨

目的探讨黏液型铜绿假单胞菌(PA)药物敏感性检测方法准确性,以找出适合临床开展的、准确的药物敏感性检测方法。方法分别用药物敏感性纸片琼脂扩散法(K-B法)、假单胞菌和非发酵菌药物敏感性试剂盒(ATB PSE5)、仪器法(MicroScan WalkAway 96 plus和VITEK 2)和微量肉汤稀释法同时检测66株黏液型PA,以微量肉汤稀释法作为参考方法,其余方法作为测试方法进行对照分析。结果 K-B法与微量肉汤稀释法的完全符合率(CA)为92.63%,严重错误(VME)为0.30%,重大错误(ME)为3.13%,一般错误(MIE)为3.94%;ATB PSE5与与微量肉汤稀释法的CA为88.89%,VME为0.83%,ME为5.83%,MIE为4.44%;MicroScan仪器法与微量肉汤稀释法的CA为89.38%,VME为0.34%,ME为5.19%,MIE为5.07%。VITEK 2因结果缺失严重未进行比较。结论临床常用检测PA药物敏感性的方法中,以K-B法检测黏液型PA最为可靠,但应延长孵育时间至48 h或放至CO2孵箱24 h后读取结果更为直观、准确。     

评估VITEK 2-Compact GN13测定肺炎克雷伯菌体外亚胺培南药敏及高级专家系统修正的可靠性

目的评估VITEK 2-Compact GN13测定肺炎克雷伯菌体外亚胺培南药敏及高级专家系统(AES)修正的可靠性。方法回顾性研究2014—2015年南昌大学第一附属医院分离的157株肺炎克雷伯菌,分别采用纸片扩散法、VITEK2-Compact GN13法及以微量肉汤稀释法作为参考方法测定该菌对亚胺培南的敏感性。分别评估纸片扩散法、VITEK2-Compact GN13与参考方法的分类一致率(CA%)。对经AES修正药敏的肺炎克雷伯菌采用改良Hodge试验等表型确证试验及PCR、测序法等分子生物学方法,对AES中提示的耐药机制进行验证,评估AES修正GN13测定肠杆菌科细菌体外亚胺培南药敏试验结果的可靠性。结果 157株菌中64株经微量肉汤稀释法检测为耐药株,8株为中介;纸片扩散法检测52株为耐药株,10株为中介;VITEK 2-Compact GN13检测54株为耐药株,13株为中介,而经AES修正后70株为耐药株,3株为中介。纸片扩散法和VITEK 2-Compact GN13与参考方法的一致率均90%;但在使用VITEK 2-Compact GN13与纸片扩散法测定亚胺培南时会出现一定比例的大错误(ME,3.8%)和极大错误(VME,0.6%)。AES对16株菌株进行了亚胺培南药敏修正,虽然消除了0.6%的VME,但却增加1.3%的ME和1.9%的小错误(MIE)出现。表型验证显示75.0%(12/16)表现为产ESBL联合产碳青霉烯酶,与AES推测相符,PCR及测序显示62.5%(10/16)为IMP-4/KPC-2/NDM-1联合产ESBL。结论无论采用VITEK 2-Compact GN13还是纸片扩散法,对肺炎克雷伯菌亚胺培南体外药敏的测定均较可靠,但都应注意可能出现ME及VME,使用AES修正虽可避免VME的出现,但会增加ME和MIE的出现,这或与碳青霉烯酶表达降低有关。     

EUCAST和CLSI微量稀释法检测曲霉体外药物敏感试验差异比较

目的比较欧洲抗菌药物敏感试验委员会（European Committeeon Antimicrobial Susceptibility Testing,EUCAST）和美国临床实验室标准化协会（Clinicaland Laboratory Standards Institute,CLSI）微量稀释法检测曲霉体外药物敏感性的差异。方法分别用EUCAST方法和CLSI方法检测116株曲霉对两性霉素B、伏立康唑、伊曲康唑、卡？白芬净和米卡芬净的敏感性,比较两种方法的基本符合率、药敏符合率、极重大误差率和重大误差率。结果EUCAST方法和CLSI方法对116株曲霉药敏检测的基本符合率为96．3％～100％。两方法检测烟曲霉对伏立康唑的药敏符合率98．8％,重大误差为1．2％,极重大误差率为0。烟曲霉和黑曲霉对两性霉素B以及烟曲霉和黄曲霉对伊曲康唑的药敏符合率均为100％,重大误差率和极重大误差率均为0。结论EUCAST方法和CLSI方法对检测曲霉体外药物敏感性具有良好的一致性。     

Accuracy of the Vitek system for antimicrobial susceptibility testing Enterobacteriaceae bloodstream infection isolates: use of “direct” inoculation from Bactec 9240 blood culture bottles

A recent investigation indicates that rapid antimicrobial susceptibility tests (AST) can affect patient therapy leading to reductions in health-care costs for some patient populations. However, there is little information relative to the often performed direct inoculation of positive blood culture bottles into rapid AST systems. AST results of direct inoculated Vitek (bioMerieux Vitek, Hazelwood, MO, USA) GNS cards were compared to those inoclated per package insert recommendations and a reference broth microdilution test using 50 consecutive Enterobacteriaceae bloodstream infection isolates. Escherichia coli (44% of isolates), Klebsiella ssp. (30%), and six other members of this family were tested against 15 antimicrobial agents. The direct inoculation method produced only two false-susceptible (0.3%), seven false-resistant (0.9%; six different drugs), and 48 minor errors (6.4%). The GNS cards inoculated in the usual, recommended manner had no very major error, and 7.5% combined major and minor errors. If the results of the urinary infection-specific drugs (nitrofurantoin, trimethoprim/sulfamethoxazole; not appropriate for bacteremia therapy) and ampicillin/sulbactam were deleted, both Vitek inoculation methods yielded results well within acceptable limits (≤4.5% overall error). These results indicate that the direct inoculation method of Vitek GNS cards from Enterobacteriaceae bloodstream infections (detected by Bactec 9240, Becton-Dickinson, Cockeysville, MD, USA) performed as well as the NCCLS broth microdilution test. Thus, a procedural modification of this type could further accelerate rapid access to accurate AST data.     

氨苄西林预报粪肠球菌和屎肠球菌亚胺培南敏感性的可行性研究

目的 评价氨苄西林预报粪肠球菌和屎肠球菌亚胺培南敏感性的可行性.方法 收集23家医院的127株粪肠球菌和124株屎肠球菌非重复临床分离株.采用微量肉汤稀释法和纸片扩散法测定粪肠球菌和屎肠球菌对青霉素、氨苄西林、亚胺培南的敏感性.结果 纸片扩散法青霉素和氨苄西林均敏感或均耐药的粪肠球菌,微量肉汤稀释法氨苄西林-亚胺培南的...     

Comparison of results of fluconazole and voriconazole disk diffusion testing for Candida spp. with results from a central reference laboratory in the ARTEMIS DISK Global Antifungal Surveillance Program

The accuracy of antifungal susceptibility testing is important for reliable resistance surveillance and for the clinical management of patients with serious infections due to Candida spp. Our primary objective was to compare the results of fluconazole and voriconazole disk diffusion testing of 3227 Candida spp. performed by 47 centers participating in the ARTEMIS program with disk diffusion and MIC results obtained by the central reference laboratory. The overall categoric agreement between participant disk diffusion test results and reference MIC results was 87% for fluconazole and 95.2% for voriconazole. Likewise good agreement was observed between participant disk diffusion test results and reference laboratory disk diffusion test results, with an agreement of 90.5%, 1% very major error (VME), and 3.4% major error (ME) for fluconazole and 94.2%, 1.1% VME, and 2.5% ME for voriconazole. The disk diffusion test was reliable for detecting those isolates of Candida spp. that were characterized as resistant to fluconazole and voriconazole by MIC testing. External quality assurance data obtained by surveillance programs such as the ARTEMIS Global Antifungal Surveillance Program ensure the generation of useful surveillance data and result in the continued improvement of antifungal susceptibility testing protocols.     

Elution methods to evaluate colistin susceptibility of Gram-negative rods

Recently it was developed the Colistin Broth Disk Elution test which uses colistin disks as a source of these antibiotics. The aim of this study was to evaluate the performance of protocols that used diminished volumes of the reagents: the Colistin Broth Microelution (CBM) (1 mL) and the Microelution-Plates Test (MPT) (200 μL), as well as the Colistin Susceptibility Test Tube (CSTT), which uses only one colistin disk added to a tube containing broth. The tests were performed with 85 Gram-negative isolates collected from surveillance studies. The CBM, MPT, and CSTT tests presented a good Categorical Agreement (CA), Essential Agreement (EA), sensitivity and specificity to Enterobacterales isolates, however the ME and VME were less satisfactory. The results for non-fermentative isolates were not satisfactory. In conclusion, the proposed methods, mainly the CSTT, can be used as screening tests to detect colistin resistant among Enterobacterales, as they are an easy and inexpensive option to the reference method.     

Clinical evaluation of the Vitek automated system with cards GNS 122 and 127 and VTK-R07.01 software for antimicrobial susceptibility testing of Pseudomonas aeruginosa

The performance of the Vitek Automated Susceptibility Testing System software version VTKR07.01 (bioMerieux Vitek, Hazelwood, MO), for testing Pseudomonas aeruginosa was evaluated by comparing results for 200 clinical isolates with those of disk diffusion and manual broth microtiter dilution testing. For cefepime, the restricted major error rate was 0.53% and the minor error rate was 12.5%. For piperacillin, the restricted major error rate was 2.15%. For ticarcillin/clavulanic acid, restricted very major and major error rates of 6.5% and 3.2%, respectively, occurred. The results of our study indicate that the Vitek system performs within acceptable limits when testing piperacillin, but remains problematic for testing cefepime and ticarcillin-clavulanic acid.     

Carbapenem susceptibility testing errors using three automated systems, disk diffusion, Etest, and broth microdilution and carbapenem resistance genes in isolates of Acinetobacter baumannii-calcoaceticus complex

The Acinetobacter baumannii-calcoaceticus complex (ABC) is associated with increasing carbapenem resistance, necessitating accurate resistance testing to maximize therapeutic options. We determined the accuracy of carbapenem antimicrobial susceptibility tests for ABC isolates and surveyed them for genetic determinants of carbapenem resistance. A total of 107 single-patient ABC isolates from blood and wound infections from 2006 to 2008 were evaluated. MICs of imipenem, meropenem, and doripenem determined by broth microdilution (BMD) were compared to results obtained by disk diffusion, Etest, and automated methods (the MicroScan, Phoenix, and Vitek 2 systems). Discordant results were categorized as very major errors (VME), major errors (ME), and minor errors (mE). DNA sequences encoding OXA beta-lactamase enzymes (bla(OXA-23-like), bla(OXA-24-like), bla(OXA-58-like), and bla(OXA-51-like)) and metallo-β-lactamases (MBLs) (IMP, VIM, and SIM1) were identified by PCR, as was the KPC2 carbapenemase gene. Imipenem was more active than meropenem and doripenem. The percentage of susceptibility was 37.4% for imipenem, 35.5% for meropenem, and 3.7% for doripenem. Manual methods were more accurate than automated methods. bla(OXA-23-like) and bla(OXA-24-like) were the primary resistance genes found. bla(OXA-58-like), MBLs, and KPC2 were not present. Both automated testing and manual testing for susceptibility to doripenem were very inaccurate, with VME rates ranging between 2.8 and 30.8%. International variability in carbapenem breakpoints and the absence of CLSI breakpoints for doripenem present a challenge in susceptibility testing.     

Can antimicrobial susceptibility testing results for ciprofloxacin or levofloxacin predict susceptibility to a newer fluoroquinolone, gatifloxacin?: Report from The SENTRY Antimicrobial Surveillance Program (1997-99)

A serious problem confronting clinical laboratories and hospital formulary practices is the delayed availability of approved, commercially prepared susceptibility test reagents for newer antimicrobials. A current example is gatifloxacin, a new 8-methoxy fluoroquinolone with expanded potency against many Gram-positive pathogens. This study addresses the use of "surrogate marker" fluoroquinolones to predict susceptibility for gatifloxacin. Reference broth microdilution MIC results for 29,632 strains isolated in United States medical centers (SENTRY Antimicrobial Surveillance Program, 1997-99) were used: staphylococci (9,940 strains), enterococci (2,570), Streptococcus pneumoniae (3,784), Enterobacteriaceae (10,670) and Pseudomonas aeruginosa (2,668). Gatifloxacin interpretation categories were compared to those of ciprofloxacin and levofloxacin by regression statistics and error rate bounding analyses. For the Enterobacteriaceae, the absolute categorical agreement was 97.9 to 98.7% (false-susceptible or very-major error [VME], 0.03%-0.1%) for comparisons of both ciprofloxacin and levofloxacin with gatifloxacin. P. aeruginosa testing was more problematic (higher minor error rates), but acceptable at 0.6% to 1.1% VME and a 85.7% to 89.9% overall agreement. Ciprofloxacin results used to predict gatifloxacin in Gram-positive species was almost without VME (0.0%-0.2%) because gatifloxacin was significantly superior against these species, especially for S. pneumoniae, where gatifloxacin (MIC(90,) 0.5 microg/ml) was fourfold more potent than levofloxacin (MIC(90,) 2 microg/ml). The preferred gatifloxacin predictor drug was ciprofloxacin for all species except S. pneumoniae and P. aeruginosa, where levofloxacin results had a slightly greater predictive value. Susceptibility testing results for selected currently available fluoroquinolones can be used to predict susceptibility to gatifloxacin with high confidence. Many Gram-positive cocci, however, will be categorized as false-resistant by this interim method since gatifloxacin has a 11% to 34% wider spectrum of activity compared to ciprofloxacin when testing staphylococci and enterococci. Clinical laboratories can reliably use these suggested "surrogate markers" until reliable tests for gatifloxacin become available.