The iQ-Check Real-Time PCR Kit from Bio-Rad for Rapid Detection of Pathogenic Aspergillus in Cannabis


Cannabis infused products and inhalational products are two of the fastest growing segments of the legal cannabis industry. Increased state legalization has made these products accessible to a growing number of consumers, both medicinal and recreational. Similar to areas such as the food industry, cultivators and producers must adhere to state regulatory requirements for testing to ensure products are safe for consumption.

Microbial contamination threatens cannabis products at all levels of production, from cultivation to consumption. Despite the importance, only a limited number of commercial microbial testing platforms exist for rapid analysis of pathogens in cannabis.

In response to this need, the new iQ-Check Aspergillus testing platform has been designed as a rapid and effective screening solution for cannabis processing operations. The fast and reliable kit has been vetted by leading testing labs and is compliant with the recently published AOAC Standard Method Performance Requirements (SMPRs) for detection of Aspergillus in cannabis. As such, the system offers critical first-line monitoring for health, safety, and quality of cannabis products.  

Background of microbial contamination in cannabis

Cannabis microbial contamination can occur at any time during cultivation, processing, distribution, and storage. Plant growth conditions can be impacted by excess moisture, the presence of pests, contaminants in water and fertilizers, and other factors. Poor hygiene practices among harvesters and processors can also serve as routes of microbial contaminant entry.

Three main microbial contaminants are the focus of current testing regulations, including pathogenic Salmonella and Shiga toxin-producing Escherichia coli (STEC) bacteria, and pathogenic species of Aspergillus sporulating fungi.

As a pathogenic contaminant of emerging significance, Aspergillus testing in cannabis is of critical importance for multiple reasons.

  • Pathogenic Aspergillus spp. pose serious health threats to cannabis users. Immunocompromised medical cannabis patients in particular can be especially susceptible to spores and mycotoxins, and as a consequence suffer from inhalational allergic broncho-aspergillus or develop severe invasive aspergillosis disease upon exposure.
  • There is a lack of definitive testing methods for microbial testing of cannabis in general, and Aspergillus in particular. Culture-based methods do not allow adequate differentiation of individual colony forming units (CFU). Moreover, they may not sufficiently decipher relatively harmless species from pathogenic species of Aspergillus -- A. niger, A. flavus, A. fumigatus, and A. terreus.
  • Despite required testing in a growing number of states, there is currently a lack of validated and approved testing platforms for pathogenic Aspergillus. Methods adopted by testing labs, including those based on peer-reviewed techniques, must be re-evaluated and validated in each subsequent lab setting, inline with ISO certifications. This greatly limits the use and transfer of non-standardized testing platforms.

These reasons and others highlight the urgent need for a stringent, decisive, and standardized platform for Aspergillus testing in cannabis products.

The iQ-Check RT-PCR kit for Aspergillus testing in cannabis

The iQ-Check testing kit platform leverages real-time PCR analysis for fast and reliable cannabis testing. Employing ready-to-use reagents coupled with the CFX96 Touch Deep Well Real-Time PCR System, the iQ-Check kits include everything needed for detection of pathogens in cannabis materials and infused products. Previously released iQ-Check kits include those testing for multiple serotypes and species of STEC, Salmonella, Enterobacteriaceae and other bacterial species found in cannabis.

The latest iQ-Check Aspergillus kit is suitable for simultaneous detection of the four pathogenic Aspergillus species of concern with high sensitivity and specificity in a range of cannabis sample backgrounds.

Features of the kit

The iQ-Check Aspergillus kit is centered around detection and accurate identification using enrichment, DNA extraction, and real-time polymerase chain reaction analysis.

  • The enrichment step prior to DNA extraction and amplification allows target bacteria in a sample to reach high enough concentration for reliable identification with low background. Aspergillus are notoriously slow growing organisms so proper enrichment time is critical for efficient detection.
  • The DNA extraction methods and reagents allow target isolation from enriched cultures. Specific oligonucleotides allow detection of the four pathogenic Aspergillus spp, - A. flavus, A. fumigatus, A. niger, and A. terreus – from the hundreds of ubiquitous non-pathogenic species.
  • The RT-PCR methods for target DNA amplification and detection promote fast, accurate, and precise measurement using Bio-Rad instrumentation. The flexibility of the kit allows testing for more than one pathogen at a time, while automation and data analysis tools significantly increase the throughput capabilities of the system.

Unique advantages

The iQ-Check Aspergillus kit offers several significant advantages over other non-standardized Aspergillus testing methods.

  • The single enrichment step and fast RT-PCR analysis enables results in 48 hr and a significantly faster turnaround time compared with culture techniques. This can be especially important for determining next steps in cannabis processing and distributions where time is of the essence.
  •  The all-in-one inclusion of methods, reagents, and instrument capability means replicate tests can be run on a central platform in parallel with other iQ-Check tests.
  •  An internal positive control reduces the risks of false negative results during test analysis.
  • The iQ-Check Aspergillus kit has been validated both internally and externally and adheres to third-party validation and certification requirements.

The importance of iQ-Check Aspergillus test validation and standards

External validation includes performance verification by third party laboratories following strict guidelines demonstrating optimal accuracy and quality. Inter-Laboratory Comparison and Proficiency Test (ILC/PT) programs are intended to unify testing results from participating labs and set benchmarks for performance among testing sites. Accordingly, the iQ-Check Aspergillus kit and several other iQ-Check kits have attained the Emerald Badge™ as affirmation of their ability to meet regulatory requirements for testing lab accreditation and licensure.

As a leader in analytical testing standards development, AOAC administers the Cannabis Analytical Science Program (CASP) to identify priority needs and to provide solutions for regulators, industry, and consumers. A major focus of this program is the development of globally accepted consensus-based standards and testing methods for hemp, cannabis, and cannabis-related ingredients and products.

Bio-Rad is a pioneering member of the CASP program and is closely involved in standard methods performance evaluation for detection of Aspergillus in cannabis and cannabis products. This involvement may foster universal testing standards and increased safety across the cannabis industry – goals the iQ-Check Aspergillus testing solution is designed to advance.

This article was written by LabX and published in collaboration with Bio-Rad.

View more information on the Cannabis Application page from Bio-Rad.

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