Lab Matters Fall Winter 2021 | Page 21

INDUSTRY MATTERS

By Steven Kelly , technical product manager , Streck and Chris Connelly , PhD , director , Research & Development , Streck

When it was established five years ago , the US Centers for Disease Control and Prevention ’ s ( CDC ’ s ) Antibiotic Resistance Laboratory Network ’ s ( AR Lab Network ) mission was to expand laboratory capacity for the rapid detection of antibiotic resistance and help local health officials prevent the spread of antibiotic / antimicrobial resistance ( AR ). It does this by combining the laboratory resources of 56 public health laboratories in all 50 states , as well as the District of Columbia , the US Virgin Islands , Guam and Puerto Rico . These laboratories report results to CDC for tracking emerging resistance and current resistance trends nationally to support rapid response to outbreaks .

Generally , when a laboratory receives a suspected isolate , it first confirms AR phenotypically through antimicrobial susceptibility testing ( AST ). Phenotypic test results are then confirmed through genetic testing methods . AR Lab Network laboratories are free to determine their own methods and techniques for both phenotypic and genetic testing of AR .

In 2016 , Streck introduced the Streck ARM-D ^® Kit , ß-Lactamase , a multiplex quantitative polymerase chain reaction ( qPCR ) kit capable of detecting over 450 AR variants across nine resistance gene families , including the Carbapenemresistant Enterobacteriaceae ( CRE ) of greatest concern , NDM , KPC , OXA-48 , VIM and IMP . Consequently , this kit has been adopted by over a dozen AR Lab Network laboratories for testing bacterial isolates and is being established as a best choice for genetic testing of AR resistance toward improved surveillance and antimicrobial stewardship . There are several reasons these laboratories use the Streck ARM-D ^® Kit , ß-Lactamase :

• Broader Gene Variant Coverage , Lower Cost Broader gene coverage reduces the need to perform repeat testing due to false negative genetic test results , which are used to confirm phenotypically positive isolates . For example , at the 2019 APHL Conference , the City of Houston Public Health Laboratory ( CHPHL ) presented validation data demonstrating the Streck ARM-D ^® Kit , ß-Lactamase more frequently detected the correct AR gene because of the expanded coverage of AR gene variants included in the kit . Ultimately , CHPHL adopted the kit for its AR Lab Network work due to the decrease in repeat testing and overall cost savings compared to cartridge-based qPCR systems ($ 20 vs . $ 50 per test ).

• Sample Batching The ability to simultaneously screen many isolates for AR gene variants was a major reason the State of Illinois Public Health Laboratory switched from its previous genetic screening method to the Streck ARM-D Kit ^® , ß-Lactamase . Having the ability to screen nine resistance gene families in three qPCR reactions allows a laboratory to batch dozens of isolates at one time resulting in improved efficiency and resource allocation .

• Screening Isolates Prior to Whole Genome Sequencing At ASM-Microbe in 2018 , CDC presented a poster demonstrating the Streck ARM-D ^® Kit , ß-Lactamase was 100 % concordant with its whole genome sequencing ( WGS ) techniques for genetic confirmation . Additionally , evaluation of over 900 isolates resulted in 100 % sensitivity and specificity . In fact , due to the lower cost of the Streck kit versus WGS , CDC found it more cost effective to first screen suspect isolates with the ß-Lactamase kit and use the WGS method to subsequently confirm positive results .

The Streck ARM-D ^® Kit , ß-Lactamase is a comprehensive and cost-effective method for the genetic confirmation of the five CREs of interest to the AR Lab Network laboratories . The kit is utilized by the most common qPCR instruments in the laboratory , making the purchase of new equipment to perform genetic AR confirmation tests unnecessary .

Streck ARM-D ^® Kit , ß-Lactamase is For Research Use Only . Not for use in diagnostic procedures . A CE version of this kit is also available . n

Streck is an APHL Gold Level Sustaining Member .

ARM-D kits are multiplex qPCR tests designed to detect a wide range of antimicrobial resistance gene variants . Photo : Streck