INFECTIOUS DISEASES
An Evaluation of Spartan Bioscience ’ s Environmental
Legionella pneumophila qPCR Field Test
By Elizabeth Toure , MPH , senior specialist , Respiratory Diseases
The rapid identification of environmental sources of
Legionella linked to transmission during an outbreak is critical in limiting exposure and further illness . Infection with Legionella spp .— most commonly L . pneumophila — can lead to severe respiratory illnesses , including Legionnaires ’ disease . Quantitative polymerase chain reaction ( qPCR ) tests for use on environmental samples in the field offer more rapid detection of Legionella spp . for outbreak response . One such test , the Spartan Biosciences L . pneumophila test , reportedly quantifies the amount of live L . pneumophila in a water source in 45 minutes using their portable qPCR system , the Spartan Cube .
The public health laboratories participated in a two-phased evaluation between March 2020 and March 2021 . The first phase evaluated intra- and inter-laboratory enumeration variance using the Spartan L . pneumophila test with spiked sterile water samples of L .
APHL neither endorses nor promotes any product mentioned in this article . At the time of publication , Spartan Biosciences was undergoing a business restructure ; they continue to support their Legionella products during this time .
pneumophila serogroup 1 , L . pneumophila serogroups 2 – 15 , and a mixture of L . pneumophila serogroups . In the second phase , enumeration precision was evaluated as a factor of water sample holding times using spiked potable and non-potable water matrices to simulate on-site testing vs . transport back to the laboratory . A third phase in which the devices would be field tested was not completed due to the ongoing COVID-19 pandemic response .
Results from this evaluation indicate that the Spartan L . pneumophila test performed as expected . Average results from the first phase agreed between PHLs within one log , displaying an improved level of precision over traditional spread plate culture enumeration methods that typically vary by about 1.5 logs . 1 Results from the second phase simulating a 48-hour hold time of the water samples were variable and further evaluation is needed . Approximately 13 % of test runs had errors that required retesting the sample .
Based on this initial evaluation , participating state laboratories identified both benefits and drawbacks to incorporating the Spartan Cube into their Legionella testing workflow . The device ’ s portability , small sample volume required , ease of use and speed of results make it a useful tool for screening water samples . The device could be of particular use for a mobile laboratory . Results could be used to rapidly provide appropriate guidance for suspected sources of Legionella transmission while awaiting final confirmation of results by culture .
Participating state laboratories reported that the limited throughput ( one sample per 45 minutes ) is a challenge for incorporating the Spartan Cube into their testing workflow — a facility-based outbreak may require concurrent testing of dozens of environmental samples . Other drawbacks include the error rate due to the delicate nature of the system , potential inhibition due to poor water quality , the waste generated by the single-use extraction kits ( a recycling program is available , though shipping may be costly ) and the high cost of the test kits relative to standard PCR reagents .
Spartan currently offers an L . pneumophila test , but they plan to release an L . pneumophila serogroup 1 test in the future , which may increase public health utility . Further evaluation of the Spartan Cube , including deploying the devices in the field and evaluating the upcoming L . pneumophila serogroup 1 test , is necessary to better understand the value of this technology for public health responses . n
References
1 . C . Lucas et al . ( 2011 ) “ Accuracy and precision of Legionella isolation by US laboratories in the ELITE program pilot study .” Water Res 45:4428-4436 .
22 LAB MATTERS Summer 2021