Chavada Ruchir, Maley Michael
Department of Microbiology and Infectious Diseases, Sydney South West Pathology Services(SSWPS), Corner Goulburn and Forbes Street, Liverpool Hospital, Liverpool, NSW-2170, Sydney, Australia.
Open Microbiol J. 2015 Aug 31;9:125-35. doi: 10.2174/1874285801509010125. eCollection 2015.
Community and healthcare associated infections caused by multi-drug resistant gram negative organisms (MDR GN) represent a worldwide threat. Nucleic Acid Detection tests are becoming more common for their detection; however they can be expensive requiring specialised equipment and local expertise. This study was done to evaluate the utility of a commercial multiplex tandem (MT) PCR for detection of MDR GN.
The study was done on stored laboratory MDR GN isolates from sterile and non-sterile specimens (n=126, out of stored 567 organisms). Laboratory validation of the MT PCR was done to evaluate sensitivity, specificity and agreement with the current phenotypic methods used in the laboratory. Amplicon sequencing was also done on selected isolates for assessing performance characteristics. Workflow and cost implications of the MT PCR were evaluated.
The sensitivity and specificity of the MT PCR were calculated to be 95% and 96.7% respectively. Agreement with the phenotypic methods was 80%. Major lack of agreement was seen in detection of AmpC beta lactamase in enterobacteriaceae and carbapenemase in non-fermenters. Agreement of the MT PCR with another multiplex PCR was found to be 87%. Amplicon sequencing confirmed the genotype detected by MT PCR in 94.2 % of cases tested. Time to result was faster for the MT PCR but cost per test was higher.
This study shows that with carefully chosen targets for detection of resistance genes in MDR GN, rapid and efficient identification is possible. MT PCR was sensitive and specific and likely more accurate than phenotypic methods.
由多重耐药革兰氏阴性菌（MDR GN）引起的社区和医疗保健相关感染是一种全球性威胁。核酸检测试验在其检测中越来越普遍；然而，它们可能成本高昂，需要专门设备和当地专业知识。本研究旨在评估一种商业多重串联（MT）PCR用于检测MDR GN的效用。
该研究针对来自无菌和非无菌标本的储存实验室MDR GN分离株进行（n = 126，来自储存的567种微生物）。对MT PCR进行实验室验证，以评估其敏感性、特异性以及与实验室当前使用的表型方法的一致性。还对选定的分离株进行扩增子测序以评估性能特征。评估了MT PCR的工作流程和成本影响。
MT PCR的敏感性和特异性经计算分别为95%和96.7%。与表型方法的一致性为80%。在检测肠杆菌科中的AmpCβ-内酰胺酶和非发酵菌中的碳青霉烯酶时，发现存在主要的不一致。发现MT PCR与另一种多重PCR的一致性为87%。在94.2%的测试病例中，扩增子测序证实了MT PCR检测到的基因型。MT PCR得出结果的时间更快，但每次检测的成本更高。
本研究表明，通过精心选择用于检测MDR GN中耐药基因的靶点，可以实现快速有效的鉴定。MT PCR敏感且特异，可能比表型方法更准确。
