TITLE:
Evaluation of the Performance and Stability of the VRBG Culture Medium Prepared In-House at the Laboratory—Senegal
AUTHORS:
Babacar Ngom, Cheikh Beye, Khadidiatou Drame, Serigne Fallou Wade, Médoune Gaye Sarr, Rokhaya Diagne
KEYWORDS:
VRBG, Enterobacteriaceae, Stability, Microbiological Performance, ISO 11133:2014
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.14 No.11,
October
30,
2026
ABSTRACT: Violet Red Bile Glucose Agar (VRBG) is used for the enumeration of Enterobacteriaceae in food microbiology. According to ISO 11133:2014, its maximum usable time after preparation is four hours, unless its stability and performance are validated by the laboratory. Thus, the objective of our study was to evaluate the microbiological performance and stability of VRBG medium prepared in-house at the Laboratory of Food Safety and Environmental Hygiene (LSAHE) of the Pasteur Institute over a two-month period. Five independent batches of VRBG medium were prepared and subjected to physicochemical and microbiological tests conducted on Day 0, Day 15, Day 30, Day 45, and Day 60. The physicochemical tests involved measuring the pH and visually inspecting the medium, while the microbiological tests assessed sterility, productivity, and selectivity. The microbiological tests were performed using reference strains adapted to the requirements of ISO 11133:2014. The results showed that the VRBG medium maintained physicochemical characteristics within the acceptance criteria throughout the sixty days of storage. The microbiological tests confirmed that sterility was maintained, along with satisfactory productivity—with productivity ratios exceeding the acceptance threshold set by the standard, and good selectivity against non-target microorganisms. These results suggest that the in-house prepared VRBG medium can be used for a period of two months under the storage and testing conditions evaluated, provided that its stability and performance are validated by the laboratory in accordance with the requirements of ISO 11133:2014.