【 Principle 】

When Listeria grows on this medium, it hydrolyzes seven leaf glycosides to produce 6,7-dihydroxycoumarin, which reacts with iron ions in ammonium citrate in the medium to produce a black substance, thereby turning the medium black; Some Listeria can ferment mannitol to produce acid, causing the phenol red indicator to turn yellow. But non Listeria bacteria such as Staphylococcus and Enterococcus can occasionally grow on this medium, using mannitol to produce acid to make the colony and its surrounding medium yellow..

Main components

It is composed of yeast extract powder, glucose, phenol red, seven leaf glycoside, ammonium iron citrate, agar, lithium chloride, mannitol, casein pancreatic digest, cardiac trypsin digest, corn starch, meat stomach enzyme digest, sodium chloride, distilled water, polymyxin B, acridine hydrochloride, and cefotaxime.

Storage conditions and expiration date

Storage conditions: This product should be stored in a dark environment at 2-8 ℃.

Validity period: The unopened original packaging has a validity period of 6 months.

This product is a disposable product.

Isolation and identification of Listeria monocytogenes in food: Fresh meat, dairy products, etc. are streaked after Fraser enrichment, and specific isolation of Listeria monocytogenes is carried out, accompanied by national standard testing.

Foodborne infection screening: quickly screen for suspected Listeria monocytogenes colonies in patient feces, vomit, and contaminated food.

Import and export quarantine: Customs inspects refrigerated, fresh, and pre packaged foods as confirmed Listeria monocytogenes isolation plates.

Purification of positive samples: Fraser darkened and turbid tubes were transferred to agar plates to obtain characteristic single colonies for biochemical and serum typing.

Laboratory quality control: Positive control for Listeria monocytogenes (green colony+black halo), negative control for Escherichia coli and Staphylococcus aureus, to verify the antibacterial and colorimetric system.

Listeria monocytogenes

Biological characteristics: Gram positive Bacillus subtilis, facultative anaerobic, cold loving, tolerant to high lithium chloride, acridine flavin, and nalidixic acid;

Hydrolyzable seven leaf glycoside, the product forms a black complex with iron ions; Fermentation of sugars to produce acid;

Foodborne pathogens can cause meningitis, sepsis, and miscarriage in pregnant women.

PALCAM colony characteristics: Colony gray green/olive green, round convex, smooth; A characteristic black halo surrounds the periphery of the colony (color developed by hydrolysis of seven leaf glycosides); The colony diameter is relatively small, the background is clean, and there are very few miscellaneous bacteria.