Klebsiella oxytoca is a bacterium that belongs to the Klebsiella genus, which is known for its pathogenic potential and association with various infections in humans. To identify and characterize Klebsiella oxytoca in a clinical or laboratory setting, biochemical tests are commonly employed.
Biochemical tests used for the identification of Klebsiella oxytoca
Gram Staining: The first step in identifying any bacterium is to perform a Gram stain. Klebsiella oxytoca is a Gram-negative bacterium, meaning it stains pink/red when subjected to the Gram stain procedure.
MacConkey Agar: Klebsiella oxytoca is typically cultured on MacConkey agar, which is a selective and differential medium. It allows for the growth of Gram-negative bacteria while inhibiting the growth of Gram-positive bacteria. Klebsiella oxytoca colonies on MacConkey agar will typically appear pink or red due to lactose fermentation.
Lactose Fermentation: Klebsiella oxytoca, like other Klebsiella species, is known for its ability to ferment lactose. This can be observed on MacConkey agar, as mentioned earlier, where lactose-fermenting bacteria produce pink or red colonies due to the acid byproducts of lactose fermentation.
Citrate Utilization Test: Klebsiella oxytoca can be tested for its ability to utilize citrate as a sole carbon source. The Simmons citrate agar test is commonly used for this purpose. A positive result is indicated by a color change from green to blue on the agar slant, suggesting that the bacterium can use citrate.
Indole Production Test: The indole production test helps differentiate between different Enterobacteriaceae species. Klebsiella oxytoca is typically indole-negative, meaning it does not produce indole from tryptophan.
Voges-Proskauer (VP) Test: This test is used to detect the production of acetoin, a precursor to the neutral end product of glucose fermentation. Klebsiella oxytoca is often VP-positive, producing a red color in the presence of alpha-naphthol and potassium hydroxide (KOH).
Urease Test: Klebsiella oxytoca is positive for the urease test, indicating its ability to hydrolyze urea. This test is often used to differentiate it from other bacteria, as not all Enterobacteriaceae possess urease activity.
Methyl Red (MR) Test: Klebsiella oxytoca is usually MR-negative, which means it does not produce stable acid products when fermenting glucose.
Catalase Test: Like most bacteria, Klebsiella oxytoca is catalase-positive, producing bubbles when hydrogen peroxide is applied, as it breaks down into water and oxygen.
Properties ( Klebsiella oxytoca)
Growth in KCN
MR (Methyl Red)
Cylindrical rod shaped which appear singly, in pairs or in short chains