Lab Matters Summer 2018 | Page 73

APHL 2018 Annual Meeting Poster Abstracts
rRT-PCR , three were positive for dengue type 1 virus ( 0.21 %) and one was positive for chikungunya virus ( 0.07 %). NYC PHL ’ s rapid response and testing flexibility enabled NYC to better monitor and manage the ZIKV outbreak .
Presenter : Bisram Deocharan , PhD , New York City Public Health Laboratory , New York , NY , Phone : 212.671.5734 , Email : bdeochar @ health . nyc . gov
Zika Virus Antibody Testing Using the DiaSorin LIAISON XL Zika Capture IgM Assay
D . Liu 1 , V . Streva 2 , W . Ren 2 , M . Younis 2 , R . Basea 2 , H . Doo 2 , S . Sayeed 2 , M . Moy 2 , A . Dupuis 2 , L . Kramer 2 , A . Shukla 3 , R . Limberger 2 , J . Rakeman 1 ; 1 New York City Public Health Laboratory , New York , NY , 2 New York City Department of Health and Mental Hygiene , New York , NY , 3 Diasorin , Inc ., Stillwater , MN
HON . MENTION 2018
Zika virus has spread through the Americas and the outbreak has been declared a public health emergency by the WHO . Because of the risk of harm to the fetus , rapid and accurate diagnosis of Zika virus infection is critical . Definitive diagnosis can be made by detection of Zika virus-specific RNA , however the viremic period is short and may be missed . Serology is a critical diagnostic and commonly includes a screening test for Zika IgM followed by PRNT . This study compared two methods used to screen for Zika IgM : a high-throughput DiaSorin LIAISON XL Zika Capture IgM and the CDC MAC-ELISA using 583 specimens . The CDC MAC-ELISA assay uses a pan-flavivirus antibody , 6b6c-1 and Zika virus E glycoprotein , which likely results in a high level of cross-reactivity with other flaviviruses . The LIAISON XL Zika Capture IgM uses a Zika NS1 peptide antigen that is more specific to Zika virus and less subject to the effects of non-specific binding by antibodies against other related flaviviruses . This first comprehensive analysis provides evidence for reproducible results and improved clinical testing sensitivity . Compared to the CDC MAC-ELISA , the LIAISON XL Zika Capture IgM Assay has a 95.2 % negative agreement , a 69.1 % positive agreement and an overall agreement of 78.0 %. The 69.1 % positive agreement is likely due to differences in testing methodology resulting in non-specific flavivirus IgM cross-reactivity in the CDC MAC-ELISA . About 80 % of the discrepant specimens were PRNT positive for Zika and dengue . This difference was further investigated by testing the discrepant specimens with the EuroImmun Zika IgM assay which also uses Zika NS1 protein and PRNT . The overall agreement between the LIAISON XL Zika Capture IgM and the EuroImmun Zika IgM was 97.8 % supporting the accuracy of the LIAISON XL Zika Capture IgM assay testing results . All of the specimens with inconclusive results from the CDC MAC-ELISA test had negative results on the LIAISON XL Zika Capture IgM assay , indicating that CDC MAC-ELISA specimens with inconclusive results likely represent true Zika IgM negatives with nonspecific interference causing a non-negative result on the CDC MAC-ELISA . Additionally , our data show that 50 out of 132 total equivocal CDC MAC-ELISA specimens were positive for Zika virus IgM when tested using the LIAISON XL Zika Capture IgM , suggesting an improved clinical testing sensitivity for the LIAISON XL Zika Capture IgM assay , allowing for a definitive result with a decreased turnaround time . Finally , the LIAISON XL Zika Capture IgM Assay has a Zika IgM intra-run precision of 2.4 % of 66578.9 RLU and an inter-run precision of 4.1 % of 66117.2 RLU . The LIAISON XL Zika Capture IgM will be a useful tool for laboratories to differentiate Zika virus infections from infections with other flaviviruses and will enable more rapid serological testing of potential Zika virus infected patients .
Presenter : Dakai Liu , PhD , New York City Public Health Laboratory , New York , NY , Phone : 212.447.2858 , Email : dliu @ health . nyc . gov
Impact of Rapid Mycobacterium tuberculosis Complex Identification on Turnaround Time and Drug Resistance Predictions at the New York City Public Health Laboratory
J . Lemon , C . Courtney , Q . Liu and J . Rakeman , New York City Public Health Laboratory , New York , NY
New York City encounters an above average rate of tuberculosis cases , 6.9 per 100,000 people in 20161 ; most cases are in foreign born individuals . The NYC Public Health Laboratory ( PHL ) serves as the primary diagnostic testing laboratory for Health Department Chest Center clinics and tests approximately 5000 primary specimens per year . PHL also performs testing on ~ 600 referral isolates per year . The development of rapid molecular testing options for the diagnosis of Mycobacterium tuberculosis complex ( MTBC ) from primary patient specimens has presented an exciting opportunity to decrease diagnostic turnaround time ( TAT ), which has long been a challenge in the field . In this study , we evaluated the impact of implementing the Cepheid GeneXpert MTB / RIF assay in place of the HAIN GenoType MTBDR Line Probe Assay for molecular detection of MTBC . Molecular testing is routinely performed on smear positive primary specimens only . We retrospectively analyzed results from HAIN Line Probe assays performed in 2016 . This set included data from 315 specimens from 290 patients , of which 110 were positive for MTBC by the HAIN Line Probe assay . One advantage of the HAIN Line Probe Assay is its ability to detect mutations associated with resistance to both rifampin ( RIF ) and isoniazid ( INH ). In contrast , the Xpert MTB / RIF assay detects mutations only associated with RIF resistance . Therefore , we analyzed the 110 MTBC positive specimens to determine the percentage of INH mono-resistance detected by the Hain Line Probe Assay and found that for one year of testing , only five patients ( 4.5 %) had INH mono-resistance which would have been missed by the Xpert MTB / RIF Assay . We also evaluated the impact of switching assays on TAT for reporting molecular results . The HAIN Line Probe Assay required seven hours of personnel time , which was typically completed the day after reporting a positive microscopy result . Implementation of the Xpert MTB / RIF Assay would decrease personnel time from seven hours to > 1 hour , affording the opportunity for molecular testing to be completed on the same day as microscopy . This would allow for the release of a preliminary report a full working day earlier than the current algorithm allows . We determined that by performing an IQCP we would be able to meet regulatory requirements and discontinue the practice of performing daily quality control . This allowed the change of testing assays to have a minimal impact on cost despite the difference in cost between the two test kits . Our analysis demonstrates that implementation of a new molecular testing stratagem can result in minimal impact on drug resistance predictions , reduce TAT for results reporting , while maintaining overall testing costs and providing a viable solution for the future of MTBC molecular diagnostic testing in New York City .
1 . New York City Department of Health and Mental Hygiene . Bureau of Tuberculosis Control Annual Summary , 2016 .
Presenter : Jamie Lemon , PhD , D ( ABMM ), New York City Public Health Laboratory , New York , NY , Phone : 212.671.5668 , Email : jlemon @ health . nyc . gov
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Summer 2018 LAB MATTERS 71