I've got a good and new set of CLED agars (not expired). I grew Proteus mirabilis on it, and interestingly, it still swarms on the agar, although slower if compared to its growth on a nutrient agar. But I thought CLED is meant to prevent the swarming. How is this possible?
CLED Agar is recommended for the isolation, enumeration, and presumptive identification of urinary pathogens on the basis of lactose fermentation, while controlling the swarming of Proteus spp. Final medium Cystine Lactose Electrolyte-Deficient (CLED) Agar is reported as ideal for dip-slide techniques and for general urinary bacteriology and colony differentiation. CLED Agar also lacks sodium chloride, which helps to prevent the swarming of Proteus spp. CLED Agar is recommended for use in the spread plate technique for detection of bacteria in urine. The medium contains enzymatic digest of casein, enzymatic digest of gelatin, and beef extract, which provide nitrogen, vitamins, and carbon to support microbial growth. Lactose is added as the carbohydrate source. L-cystine is a growth supplement for cystine-dependent coliforms. Organisms capable of fermenting lactose will lower the pH and change the color of the medium to yellow. Consequently, bromothymol blue is the pH indicator. Agar acts as the solidifying agent. CLED Agar supports the growth of all potential urinary pathogens, and a number of contaminants such as diphtheroids, lactobacilli, and micrococci. Urine samples containing mixed flora are typical of urethral or vaginal contamination. Research demonstrates the best results are obtained when inoculation occurs as soon after sample collection as possible. Otherwise, confluent or semiconfluent growth may occur when CFU counts exceed 105 per ml of urine.CLED Agar (Cystine-Lactose-Electrolyte-Deficient Agar) is a differential culture medium for use in enumerating bacteria in urine. It supports the growth of urinary pathogens and contaminants but prevents undue swarming of Proteus species due to its lack
of electrolytes.
Both MacConkey and CLED media differentiates between lactose fermenting & non lactose fermenting. Both CLED & MacConkey media inhibits swarming of proteus, Both show greenish colour, matt surface & rough periphery of pseudomonas colonies. CLED media is preferred over MacConkeys for the culture of coliform and other bacteria from infected urine because it has the advantage in supporting growth of certain Staphylococcus, Streptococci and Candida strain.
What is the characteristic features of Proteus species in CLED
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