改良碳青霉烯酶失活(mCIM)法检测锡拉克柠檬酸杆菌碳青霉烯酶活性。

IF 5.4 2区 医学 Q1 MICROBIOLOGY
D Garrett Brown, Matthew Surette, Sreejana Ray, Kevin Guo, Reagan Chan, Liusheng Huang, Sanchita Das
{"title":"改良碳青霉烯酶失活(mCIM)法检测锡拉克柠檬酸杆菌碳青霉烯酶活性。","authors":"D Garrett Brown, Matthew Surette, Sreejana Ray, Kevin Guo, Reagan Chan, Liusheng Huang, Sanchita Das","doi":"10.1128/jcm.00589-25","DOIUrl":null,"url":null,"abstract":"<p><p>Screening for carbapenemase-producing Enterobacterales is a necessity for hospitals serving high-risk patient populations. Detection methods often incorporate the modified carbapenemase inactivation method (mCIM) test to verify carbapenemase production in suspect isolates. Here, we demonstrate the case of a <i>Citrobacter sedlakii</i> isolate recovered from carbapenemase-surveillance culture that was strongly mCIM positive for carbapenemase production, but phenotypically nonresistant to carbapenems. The modified carbapenemase inactivation method with EDTA (eCIM) test, which suggests the presence of a metallo-β-lactamase, was positive as well. Liquid chromatography mass spectrometry additionally confirmed the loss of meropenem during the mCIM test. Whole-genome sequencing detected only the presence of the chromosomal class A serine β-lactamase SED-1 but did not identify any known carbapenemase or additional β-lactamases. Further characterization suggested that the large inoculum utilized in mCIM tests can give the impression of carbapenemase production in non-resistant isolates. Additionally, the large inoculum, combined with weak carbapenemase activity, can mimic the phenotype expected for metallo-β-lactamase in the eCIM test. These results suggest that utilization of the mCIM and eCIM tests without appropriate susceptibility testing can lead to erroneous detection of carbapenemase production.IMPORTANCEPhenotypic tests including the mCIM are often used for detection of carbapenemase production in Enterobacterales. The presence of a carbapenemase gene is confirmed by PCR assays and, while rarely seen, a positive mCIM assay and negative PCR can alert the laboratory to the presence of rare carbapenemases (such as GES and IMI). We report a false-positive mCIM test, which we demonstrate is due to the heavy inoculum of the organism used in the assay. Whole-genome sequencing showed that a class A β-lactamase (<i>bla<sub>SED-1</sub></i>) was present, and mass spectrometry demonstrated degradation of meropenem during the mCIM assay. The inoculum effect should be considered when interpreting mCIM and eCIM assays where a carbapenemase gene is not detected.</p>","PeriodicalId":15511,"journal":{"name":"Journal of Clinical Microbiology","volume":" ","pages":"e0058925"},"PeriodicalIF":5.4000,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Paradoxical carbapenemase activity detected by modified carbapenemase inactivation (mCIM) method in <i>Citrobacter sedlakii</i>.\",\"authors\":\"D Garrett Brown, Matthew Surette, Sreejana Ray, Kevin Guo, Reagan Chan, Liusheng Huang, Sanchita Das\",\"doi\":\"10.1128/jcm.00589-25\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Screening for carbapenemase-producing Enterobacterales is a necessity for hospitals serving high-risk patient populations. Detection methods often incorporate the modified carbapenemase inactivation method (mCIM) test to verify carbapenemase production in suspect isolates. Here, we demonstrate the case of a <i>Citrobacter sedlakii</i> isolate recovered from carbapenemase-surveillance culture that was strongly mCIM positive for carbapenemase production, but phenotypically nonresistant to carbapenems. The modified carbapenemase inactivation method with EDTA (eCIM) test, which suggests the presence of a metallo-β-lactamase, was positive as well. Liquid chromatography mass spectrometry additionally confirmed the loss of meropenem during the mCIM test. Whole-genome sequencing detected only the presence of the chromosomal class A serine β-lactamase SED-1 but did not identify any known carbapenemase or additional β-lactamases. Further characterization suggested that the large inoculum utilized in mCIM tests can give the impression of carbapenemase production in non-resistant isolates. Additionally, the large inoculum, combined with weak carbapenemase activity, can mimic the phenotype expected for metallo-β-lactamase in the eCIM test. These results suggest that utilization of the mCIM and eCIM tests without appropriate susceptibility testing can lead to erroneous detection of carbapenemase production.IMPORTANCEPhenotypic tests including the mCIM are often used for detection of carbapenemase production in Enterobacterales. The presence of a carbapenemase gene is confirmed by PCR assays and, while rarely seen, a positive mCIM assay and negative PCR can alert the laboratory to the presence of rare carbapenemases (such as GES and IMI). We report a false-positive mCIM test, which we demonstrate is due to the heavy inoculum of the organism used in the assay. Whole-genome sequencing showed that a class A β-lactamase (<i>bla<sub>SED-1</sub></i>) was present, and mass spectrometry demonstrated degradation of meropenem during the mCIM assay. The inoculum effect should be considered when interpreting mCIM and eCIM assays where a carbapenemase gene is not detected.</p>\",\"PeriodicalId\":15511,\"journal\":{\"name\":\"Journal of Clinical Microbiology\",\"volume\":\" \",\"pages\":\"e0058925\"},\"PeriodicalIF\":5.4000,\"publicationDate\":\"2025-08-25\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Clinical Microbiology\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1128/jcm.00589-25\",\"RegionNum\":2,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MICROBIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Clinical Microbiology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1128/jcm.00589-25","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0

摘要

筛选产碳青霉烯酶肠杆菌是医院为高危患者提供服务的必要条件。检测方法通常采用改良碳青霉烯酶失活法(mCIM)测试来验证可疑分离株的碳青霉烯酶产量。在这里,我们展示了从碳青霉烯酶监测培养中恢复的锡拉克柠檬酸杆菌分离物的情况,该分离物在碳青霉烯酶生产方面呈强烈的mCIM阳性,但在表型上对碳青霉烯类不耐药。经EDTA (eCIM)检测的碳青霉烯酶失活方法也呈阳性,表明存在金属β-内酰胺酶。液相色谱-质谱法也证实了mCIM试验中美罗培南的损失。全基因组测序仅检测到染色体A类丝氨酸β-内酰胺酶SED-1的存在,但未发现任何已知的碳青霉烯酶或其他β-内酰胺酶。进一步的表征表明,在mCIM试验中使用的大接种量可以给非耐药菌株产生碳青霉烯酶的印象。此外,大接种量,结合弱碳青霉烯酶活性,可以模拟eCIM试验中金属β-内酰胺酶的预期表型。这些结果表明,使用mCIM和eCIM试验而不进行适当的药敏试验可能导致碳青霉烯酶产生的错误检测。包括mCIM在内的表型检测常用于肠杆菌中碳青霉烯酶的检测。碳青霉烯酶基因的存在可以通过PCR检测得到证实,虽然很少见到,但mCIM检测阳性和PCR阴性可以提醒实验室注意罕见的碳青霉烯酶(如GES和IMI)的存在。我们报告了一个假阳性的mCIM测试,我们证明这是由于在试验中使用的生物体的大量接种。全基因组测序显示存在a类β-内酰胺酶(blaSED-1),质谱分析显示在mCIM检测中美罗培南降解。在解释未检测到碳青霉烯酶基因的mCIM和eCIM检测时,应考虑接种量效应。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Paradoxical carbapenemase activity detected by modified carbapenemase inactivation (mCIM) method in Citrobacter sedlakii.

Screening for carbapenemase-producing Enterobacterales is a necessity for hospitals serving high-risk patient populations. Detection methods often incorporate the modified carbapenemase inactivation method (mCIM) test to verify carbapenemase production in suspect isolates. Here, we demonstrate the case of a Citrobacter sedlakii isolate recovered from carbapenemase-surveillance culture that was strongly mCIM positive for carbapenemase production, but phenotypically nonresistant to carbapenems. The modified carbapenemase inactivation method with EDTA (eCIM) test, which suggests the presence of a metallo-β-lactamase, was positive as well. Liquid chromatography mass spectrometry additionally confirmed the loss of meropenem during the mCIM test. Whole-genome sequencing detected only the presence of the chromosomal class A serine β-lactamase SED-1 but did not identify any known carbapenemase or additional β-lactamases. Further characterization suggested that the large inoculum utilized in mCIM tests can give the impression of carbapenemase production in non-resistant isolates. Additionally, the large inoculum, combined with weak carbapenemase activity, can mimic the phenotype expected for metallo-β-lactamase in the eCIM test. These results suggest that utilization of the mCIM and eCIM tests without appropriate susceptibility testing can lead to erroneous detection of carbapenemase production.IMPORTANCEPhenotypic tests including the mCIM are often used for detection of carbapenemase production in Enterobacterales. The presence of a carbapenemase gene is confirmed by PCR assays and, while rarely seen, a positive mCIM assay and negative PCR can alert the laboratory to the presence of rare carbapenemases (such as GES and IMI). We report a false-positive mCIM test, which we demonstrate is due to the heavy inoculum of the organism used in the assay. Whole-genome sequencing showed that a class A β-lactamase (blaSED-1) was present, and mass spectrometry demonstrated degradation of meropenem during the mCIM assay. The inoculum effect should be considered when interpreting mCIM and eCIM assays where a carbapenemase gene is not detected.

求助全文
通过发布文献求助,成功后即可免费获取论文全文。 去求助
来源期刊
Journal of Clinical Microbiology
Journal of Clinical Microbiology 医学-微生物学
CiteScore
17.10
自引率
4.30%
发文量
347
审稿时长
3 months
期刊介绍: The Journal of Clinical Microbiology® disseminates the latest research concerning the laboratory diagnosis of human and animal infections, along with the laboratory's role in epidemiology and the management of infectious diseases.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:604180095
Book学术官方微信