KLIGLER IRON AGAR SLANT (10 Slants)

Kligler Iron Agar is a ready-to-use differentiation media. It is a differential culture medium capable of identifying and differentiating Gram negative enteric bacilli by the presence of respective abilities to ferment glucose (dextrose) and lactose, produce hydrogen sulfide (H2S), and produce gas. This culture medium is used extensively in clinical, diagnostic, food, water and research laboratories as a biochemical media for identifying members of the Enterobacteriaceae.

It contains nutritive components which provided nutrients needed for growth namely peptone, beef extract and yeast extract. The mixture of glucose and lactose in different concentration in order to differentiate lactose non-fermenters from fermenters. Phenol red is used here as the pH indicator. The medium is red at the beginning and turns yellow after acid production during fermentation of the carbohydrate.

Since there is little sugar i.e. dextrose, acid production is very limited and therefore a reoxidation of the indicator is produced on the surface of the medium, and the indicator remains red. However, when lactose is fermented, the large amount of acid produced, avoids reoxidation and therefore the entire medium turns yellow. If the bacteria do not ferment any carbohydrate the medium remains a red color.

Kligler Iron Agar has sodium thiosulphate and ferrous sulphate, which allow differentiation of bacteria based on the production of hydrogen sulfide (H2S). Bacteria that produce H2S as a byproduct of metabolism will react with ferrous ions resulting in a black precipitate as an indicator, providing a further biochemical marker for identification of bacteria. Gas production in the fermentation of carbohydrates is seen as bubbles, cracks and lifting of the agar within the tube.

This medium is especially helpful in differentiating important enteric pathogens, such as Salmonella, Shigella and other Enterobacteriaceae, that show distinct fermentation patterns and activity. After stabbing the butt and streaking the slant, the tubes are incubated at suitable laboratory conditions and reactions are interpreted by visual assessment of colour changes, gas production and blackening.

Kligler Iron Agar continues to be a critical medium for routine microbiological analysis, enabling rapid initial identification of enteric bacteria and remaining an integral part of an established group of biochemical tests for quality control, clinical, and microbiological studies.

Kligler Iron Agar is a differential culture medium used to identify gram negative enteric bacilli based on glucose and lactose fermentation, hydrogen sulfide (H2S) formation and gas production. The tube contains phenol red as a pH indicator and ferrous sulphate and sodium thiosulphate for the visual detection of hydrogen sulfide formation. It uses indicator colour change and the formation of a black precipitate and gas production to aid in differentiation of organisms such as Salmonella, Shigella and other members of the Enterobacteriaceae. Kligler Iron Agar is used in the clinical, food, water and research laboratories for routine microbiology and preliminary biochemical analysis.