A complete of 525 cerebrospinal fluid (CSF) samples submitted during the
April 4, 2017
A complete of 525 cerebrospinal fluid (CSF) samples submitted during the 2007 and 2008 enteroviral seasons were included in a study to determine the prevalence of and potential risk factors for invalid Cepheid GeneXpert enterovirus assay (GXEA) results as well as you can solutions for the problem. (EnV) meningitis can be difficult to distinguish from disease caused by other etiologic providers when individuals present with nonspecific pathogenic symptoms and indications such as fever headache and stiff neck and pleocytosis in cerebrospinal fluid (CSF) (4 8 9 Nucleic acid amplification-based methods for the detection of EnV RNA in CSF have replaced cell tradition as the test of choice (10 11 14 The GeneXpert BCX 1470 methanesulfonate enterovirus assay (GXEA; Cepheid Sunnyvale CA) is designed as a system combining specimen processing EnV amplification and detection in a disposable cartridge which requires 2.5 h to detect EnV from CSF BCX 1470 methanesulfonate BCX 1470 methanesulfonate (6 7 12 It is designed for on-demand screening such that “stat” PCR effects can be returned to the emergency room physicians in time for patient management decisions to be made in real time. The system includes an internal control that provides a means to detect amplification inhibitors. When the internal control does not amplify the presence of an amplification inhibitor is definitely assumed and the result is definitely reported as “invalid.” Invalid results if and when they happen could delay patient management in the emergency establishing. We performed a 2-yr prospective study to determine the prevalence of invalid GXEA results and explore the potential risk factors related to the event of invalid results. We also validated two alternate procedures to minimize the event of these invalid results for EnV detection in CSF. (This study was presented in part at the 25th Annual Meeting of the Pan American Society for Clinical Virology Daytona Beach FL 19 to 22 April 2009 Clinical samples. CSF specimens submitted to Vanderbilt University Medical Center between 1 April 2007 and 20 September 2008 for detection of EnV by PCR were collected consecutively. Specimens with enough leftover volume and still unfrozen after the completion of diagnostic testing were included in the study. Determination of CSF characteristics. Each CSF sample was visually examined for visible red blood cells (RBCs) clotting and the presence of xanthochromia. RBC visibility was graded semiquantatively on a scale using rankings of clear 1 2 3 and 4+. These grades were based on specimen colors and turbidities which roughly correspond to CSF RBC counts of <200/μl (clear) BCX 1470 methanesulfonate 200 to 5 0 (1+) 5 0 to 75 Tmem47 0 (2+) 75 0 to 150 0 (3+) and >150 0 (4+). GXEA. The GXEA kit was purchased from Cepheid (Sunnyvale CA). The information from each kit lot was recorded. CSF samples were tested using the GXEA as previously described (6 7 In brief 140 μl of CSF was added to the GeneXpert cartridge and then processed automatically for the different steps of sample preparation and amplification. After the diagnostic procedure was completed the following two additional procedures were performed within 48 h on unfrozen CSF specimens with enough leftover volume prior to the routine GXEA procedure: (i) a 1:5 dilution in which a CSF specimen was diluted once with saline in a 1:5 ratio; and/or (ii) a freeze-thaw cycle in which a CSF specimen was quickly frozen in dry ice and thawed in a 37°C water bath one time. During the study period a total of 525 CSF specimens were submitted to the diagnostic laboratories. The samples spanned two EnV seasons with 301 collected in 2007 and 224 collected in 2008. The patients’ ages ranged from less than 1 day old to 74 years old with an average age of 8 years. The ratio of males to females was 0.56:0.44. Among the 525 CSF samples enrolled in this research 95 had been positive for EnV from the GXEA providing a positive price of 18.1%. Invalid GXEA outcomes had been reported for 43 (8.2%) specimens through the 2-yr research period. The invalid-result price was 9.6% in 2007 and 6.3% in 2008 without significant modification in the invalid-result price from 2007 to 2008 (χ2 = 1.96 > 0.05). Contained in the evaluation had been GXEA products with seven different great deal numbers purchased through the 2-yr research period and invalid outcomes had been equally distributed among the seven plenty. Let’s assume that the built-in inner control was working properly to detect inhibitory or interfering chemicals we next evaluated potential factors from the event of invalid outcomes. Invalid outcomes correlated with noticeable RBCs in the CSF specimens examined (Desk ?(Desk1).1). From the 525 CSF.