Standardized methods to generate mock (spiked) clinical specimens by spiking blood or plasma with cultured pathogens

Aims: To demonstrate standardized methods for spiking pathogens into human matrices for evaluation and comparison among diagnostic platforms.

Methods and results: This study presents detailed methods for spiking bacteria or protozoan parasites into whole blood and virus into plasma. Proper methods must start with a documented, reproducible pathogen source followed by steps that include standardized culture, preparation of cryopreserved aliquots, quantification of the aliquots by molecular methods, production of sufficient numbers of individual specimens and testing of the platform with multiple mock specimens. Results are presented following the described procedures that showed acceptable reproducibility comparing in-house real-time PCR assays to a commercially available multiplex molecular assay.

Conclusions: A step by step procedure has been described that can be followed by assay developers who are targeting low prevalence pathogens.

Significance and impact of the study: The development of diagnostic platforms for detection of low prevalence pathogens such as biothreat or emerging agents is challenged by the lack of clinical specimens for performance evaluation. This deficit can be overcome using mock clinical specimens made by spiking cultured pathogens into human matrices. To facilitate evaluation and comparison among platforms, standardized methods must be followed in the preparation and application of spiked specimens.