Indicator organism testing is at the heart of an effective food safety environmental monitoring program (EMP). Rather than hunting for every possible pathogen in every sample, indicator organisms give food manufacturers practical, early-warning information about sanitation effectiveness, niche contamination risks, and trends over time.
Neogen’s Australian laboratory manager & technical specialist, Alexandra Cotton, said indicator organisms aren’t “villains” themselves so much as signals. When found, they indicate the potential for similar microorganisms to be present in the same environment.
“Some of the most useful indicator tests would include total (aerobic) plate counts, coliforms, and Enterobacteriaceae because they help determine the hygienic state of the facility and can be used to verify cleaning and sanitation,” said Cotton.
“Total plate counts reveal whether cleaning and sanitation programs are effectively controlling general microbial load, while Enterobacteriaceae and coliforms serve as signals of process-related contamination suggesting hygiene lapses.”
It’s an observation backed up in the second edition of Neogen’s Environmental Monitoring Handbook, produced in collaboration with Cornell University and available now as a free downloadable resource.
Featuring contributions from twenty food safety experts, the book places indicator testing at the centre of routine verification and provides practical guidance on sampling design, zone mapping and data-driven corrective actions. It describes how regular, targeted sampling and trending of these indicators show whether cleaning and control measures are working, where corrective action is needed, and whether a deeper pathogen investigation is warranted.
To best monitor indicator organisms, Neogen offers two distinct technical approaches that both deliver rapid, reliable, and scalable testing with strong data traceability: the Soleris Next Generation (NG) system and the Petrifilm ecosystem.
Cotton says both options provide significant advantages over traditional methods.
“Soleris and Petrifilm make things simple, reduce turnaround times and increase productivity,” she said.
“Where traditional microbiology methods will take days with preparing reagents, samples and incubating, both Petrifilm and Soleris cut the whole preparation of reagent stage out.”
According to Cotton, selecting which solution will provide the best outcomes for your business will depend on several factors, including which organisms that need to be monitored, whether requiring quantitative results, the matrix being tested, and what standards or validations that need to follow.
Soleris NG is an automated, optical-detection rapid microbiology platform designed for broad applications (total counts, coliforms, yeasts and moulds, etc). It accelerates time-to-result and is ideal where labs want automated, vial-based workflows and fast go/no-go decisions for product release or in-process checks. The system’s strength is speed and flexibility across a wide range of matrices.
Petrifilm is a proven, plate-based ecosystem. It utilises single-use compact plates for specific indicators that can be used manually on their own or scaled up with an AI-enabled Plate Reader that automates enumeration for speed, accuracy, and seamless integration into digital recordkeeping systems.
For large-scale testing operations, the Automated Feeder takes throughput to yet another level. Petrifilm’s advantages are simplicity, minimal media preparation, widely accepted interpretations for routine indicator testing, and highly efficient sample throughput when paired with the reader and feeder.
Importantly, the two technologies are not mutually exclusive. Cotton said many modern laboratories use both approaches where each fits best.
“A food business might have a specific need that favours one approach over the other, but a combination of both options is also common,” she said.
“The customer can get the fast result with Soleris and the quantification and confirmation with Petrifilm.”
Food and beverage companies in Australia and New Zealand are encouraged to reach out to Neogen for local expert support, validation resources, and product guidance to help implement the right mix of solutions.
Whether it is Soleris NG, Petrifilm, or a hybrid approach, the result will be indicator testing that’s not just a checkbox, but a practical, data-driven defence of product safety and brand reputation.
Learn more about how to best incorporate indicator testing into your EMP in chapter six of the Environmental Monitoring Handbook, available to download free at info.neogen.com/Environmental-Monitoring-Guide or visit neogenaustralasia.com.au to discover the full range of microbiological indicator solutions available from Neogen.