Coliforms and Enterobacteriaceae Isolates from Selected Foods.

Area of Science:

• Food microbiology
• Microbial detection methods
• Food safety analysis

Background:

• Coliforms and Enterobacteriaceae are indicators of microbial contamination in food.
• Accurate enumeration of these bacteria is crucial for assessing food safety.
• Different selective media may yield varying results in bacterial quantification.

Purpose of the Study:

• To compare the efficacy of violet red bile agar (VRB) and VRB + 1% glucose (VRBG) media for detecting coliforms and Enterobacteriaceae in various food products.
• To identify the predominant bacterial species isolated from these foods using the specified media.
• To determine the proportion of fecal coliforms and Escherichia coli recovered from different food matrices.

Main Methods:

• Samples of five food products were analyzed using VRB and VRBG media for bacterial enumeration.
• Colonies were randomly selected, identified using the R-B Enteric Differential System, and confirmed through LST, BGLB, and EC broth tests.
• IMViC reaction patterns were determined for EC-positive cultures.

Main Results:

• Violet red bile agar (VRB) yielded higher percentages of fecal coliforms (34.1%) and Escherichia coli (33.5%) compared to VRBG (20.7% and 19.7%, respectively).
• Approximately 80% of VRB isolates from broiler skin and mechanically deboned poultry meat (MDPM) met fecal coliform criteria, versus 62.5% and 36.5% for VRBG isolates.
• Escherichia coli was predominant in poultry, Enterobacter agglomerans in chicken pot pie and pork sausage, and Serratia liquefaciens in ground beef.

Conclusions:

• VRB medium appears more effective than VRBG for detecting fecal coliforms and E. coli in certain food products, particularly poultry.
• Bacterial recovery and speciation varied significantly depending on the food matrix and the selective medium used.
• Accurate identification of bacterial isolates is essential for reliable food safety assessments.