BacterPlate™ Two-Compartment Medium BA/MC

Ready-to-use medium on 90mm plates for for the detection and enumeration of enteric pathogens, including Salmonella and Shigella species.
Code: 05061
Packaging: 10 plates/ box or as per customer request.
Storage Conditions: 2–8°C.
Transportation: Ambient temperature.
Shelf Life: 04 months from the date of manufacture.

INTENDED USE

BacterPlate™ Two-Compartment Medium XLD/HE is used for the isolation, differentiation, and identification of enteric pathogens, specifically Salmonella and Shigella. It is commonly used in microbiological research, clinical diagnostics, and the microbiological quality control of food, water, and clinical samples.
The packaging with semi-permeable Cellophane film helps balance the humidity of the environment during storage.

PRINCIPLES

BacterPlate™ Two-Compartment Medium BA/MC:

XLD Compartment: Culture media containing Sodium deoxycholate inhibit the growth of contaminating Gram-positive bacteria. Xylose is fermented by most enteric pathogens except Shigella, which is how Shigella is distinguished from other species. After xylose is consumed, Salmonella decarboxylates lysine (via the enzyme lysine decarboxylase) to cadaverine, increasing the pH. Salmonella colonies resemble Shigella when the medium becomes alkaline. The colonies formed are red in the presence of phenol red indicator.
HE Compartment: The medium contains three carbohydrates: lactose, sucrose, and salicin. The high concentration of lactose facilitates visualization of enteric bacteria by avoiding the problem of slow fermentation. The other two carbohydrates are added to increase the discriminatory power and reduce the toxicity of the color indicators, thereby optimizing the recovery of Shigella. In the sodium thiosulfate medium, H₂S-producing bacteria reduce ferric ammonium citrate and are detected by the darkening due to the formation of iron sulfide at the center of the colony.

Allow the agar plates to reach room temperature before use.
Dry the agar plates in an incubator with the lid slightly open.
Inoculate the sample by spreading the sample evenly on the agar surface with a sterile inoculating stick or using an inoculating stick to brush the sample onto the surface of the environmental plate.
Incubate at 35 – 37°C for 18 – 24 hours.

RESULTS

XLD Compartment:

Microorganisms	Characteristics
Escherichia coli, Citrobacter, Enterobacter, Proteus, Serratia, Klebsiella	Yellow colonies, with or without a black center
Shigella, Providencia, Salmonella Paratyphi A	Red colonies without black center
Salmonella, Edwardsiella	Red colonies with black center

HE Compartment:

Salmonella present green or blue-green colonies, with a black center for the majority of strains.
Shigella present green or bluish droplet-like colonies, without a black center.
Coliforms appear as yellow-salmon colored colonies:

Micoorganisms	Characteristics
Escherichia coli, Citrobacter, Klebsiella, Enterobacter, Arizona, Serratia	Yellow-salmon colonies
Proteus vulgaris	Yellow-salmon colonies with a black center
Proteus mirabilis, Salmonella	Green colonies with a black center
Shigella, Salmonella, Providencia, Proteus morganii, Proteus rettgeri	Green or blue-green colonies
Pseudomonas (oxidase positive)	Small bluish to brownish colonies

BacterLab ensures the quality of each product batch by testing with ATCC reference strains.

Reference strains	Incubation conditions	Expected results
XLD Compartment
E. faecalis ATCC 29212	Incubate at 35–37°C for 18–24 hours.	Inhibition, no growth
E.coli ATCC 35218		Weak to no growth, yellow colonies
S. Enteritidis ATCC 13076		Good growth, red colonies with black centers
HE Compartment
S. typhimurium ATCC14028	Incubate at 35–37°C for 18–24 hours.	Good growth, colorless colonies with black centers
S. flexneri ATCC 12022		Good growth, colorless colonies
E. coli ATCC 35218		Partial inhibition, pink colonies
S. aureus ATCC 25923		Inhibition, no growth

For 1 liter of XLD medium

pH of the ready-to-use medium at 25°C: 7,4 ± 0,2

For 1 liter of HE medium