Rapid Microplate Tests to Replace Traditional Culture Media - Salmonella, E. coli & Listeria

SFS has developed a rapid microbial test platform that provides fast, simple, on-site detection and enumeration of dangerous bacteria like Salmonella, E. coli and Listeria, in 15 (± 2) hours, with low limits of detection and no enrichment required (unique formulation for each pathogen test). These three pathogens account for the majority of all multi-state foodborne pathogen outbreaks in the U.S. and pose a serious public health risk to consumers. They also pose a serious financial risk for farms, mills and processors who could suffer catastrophic damage to brand and company from a major recall event.

Food Processors Need a Rapid, Easy to Use Method for On-Site Testing of Dangerous Pathogens

Microbial testing is a routine part of daily operations for food processors, fruit/veg farmers and packers, and municipal water authorities. Prevalence testing (presence/absence) of target pathogens (e.g., Salmonella, E. coli or Listeria) in raw, finished product prior to shipment is done with molecular diagnostic methods (e.g., PCR), which require expensive equipment, specialized personnel and shipment of samples to off-site labs for analysis, delaying results 24-48 hours and adding to hold time and cost.

Traditional culture media are used to enumerate these and other microorganisms in water and processing environment samples as part of routine HACCP (hazard analysis and critical control point) monitoring of food safety and sanitation risks in operations (note: PCR is not used for these upstream environmental samples, due to cost of equipment, need for specialized personnel and off-site lab logistics). The problem with traditional culture methods for enumeration is that they are laborious, require separate culturing steps and numerous plates (or tubes) for enumeration, and can take 2-3 days for results, which limits operational capacity to respond to contamination issues in a timely manner and raises downstream risks of infection, outbreak and recall. 

SFS Rapid Microplate Tests

SFS has miniaturized the culturing process for detection and enumeration of target pathogens from a 30 ml plate/sample down to a single, 2 ml well of a 96-well microplate the size of a postcard, enabling detection testing of 96 samples in a single plate (or 8 quantitative tests per plate, 4 dilution levels/test)). Each test is based on a patent-pending, multi-layer formulation designed to facilitate simultaneous growth of target organism and selectivity and differentiation from non-target organisms.

Easy to Use for On-Site Testing

SFS tests require minimal prep time, counter space and materials, and no expensive equipment or specialized personnel, just a pipette and incubator. Detection is based on a color change in the medium. Enumeration follows standard 3-tube MPN methodology. Limit of Detection: 10^0 CFU/ml.

Fast Turnaround

SFS tests deliver results in 15 (± 2) hours, with no enrichment step. The tests would offer significant time and labor savings compared to existing culture methods used in HACCP monitoring. On-site use as a screening test of raw, finished product would overcome logistics delays from sending samples to off-site labs for analysis, resulting in shorter product hold times, lower storage costs, and longer shelf-life at stores.

Bio-Mapping of Target Pathogens

SFS tests would enable fast, on-site, quantitative tracking of target pathogens (not just indicator organisms) in the processing chain to expedite and inform corrective actions. This would strengthen risk assessment models for HACCP, help minimize pathogen contamination risks in the processing chain, and reduce downstream risks of infection, outbreak and recall.

Customizable Microplates

In the future, SFS will expand into tests for indicator organisms currently monitored by HACCP, e.g., total aerobic bacteria, Enterobacteriaceae, and total coliforms. It will be possible for users to customize their microplates to include formulations for more than one test. For example, if the user needed to run tests for Salmonella, E. coli, Enterobacteriaceae, and total coliforms on a single sample, the 96-well microplate could accommodate formulations for each, with columns 1-3 of the plate containing the Salmonella formulation, columns 4-6 the E. coli formulation, and so on.

Rapid Salmonella spp. Microplate Test

Black : positive | Orange/Yellow : negative

(Above) Microplate test with pre-set agar layers. Enables detection testing of 96 samples per plate.

(Below) Time-lapse photos show quantitative testing of raw poultry samples over 13 hours (4 dilutions levels per sample).