A rapid microbiological method for enumerating Escherichia coli from broiler chicken carcasses

Area of Science:

• Food Microbiology
• Food Safety Analytics
• Bacteriology

Background:

• Accurate enumeration of Escherichia coli (E. coli) on broiler carcasses is crucial for food safety.
• Traditional methods for E. coli detection can be time-consuming, delaying product release.
• The U.S. Department of Agriculture Food Safety and Inspection Service mandates pathogen reduction regulations, including E. coli testing.

Purpose of the Study:

• To evaluate a rapid conductance-based method for enumerating E. coli on broiler chicken carcasses.
• To compare the rapid method with traditional plating techniques (Petrifilm E. coli count plates).
• To assess the correlation between temperature abuse time, E. coli counts, and detection times.

Main Methods:

• Broiler carcasses were subjected to temperature abuse (0-12 hours at 37°C) and rinsed.
• E. coli enumeration was performed using Petrifilm E. coli count plates (PC) and a rapid conductance method (CMD) at 44°C.
• Detection time (DT) from the CMD was recorded, and samples were confirmed using plate counts and species identification.

Main Results:

• The rapid conductance method demonstrated excellent specificity for E. coli, even in mixed microflora, with identification rates ranging from 97% (0h) to 61% (12h).
• Significant linear correlations were found between time of abuse (TA) and log10 PC (LPC) (R² = 0.86), and TA and DT (R² = -0.90).
• A strong negative correlation was observed between LPC and DT (R² = -0.92), indicating faster detection times with higher E. coli levels.

Conclusions:

• The rapid conductance method (1-7.6 hours) is effective for enumerating E. coli on chicken carcasses.
• This method allows for timely E. coli level determination before product shipment.
• The technique supports the poultry industry in complying with USDA pathogen reduction regulations.