Alcaligenes faecalis

Alcaligenes faecalis

Alcaligenes faecalis stained under a microscope.

Alcaligenes faecalis is a Gram-negative bacterium that is commonly found in the environment, particularly in soil and water. It is known for its ability to survive in diverse environments and is often isolated from clinical specimens, although it is not typically considered a primary pathogen.

Characteristics

Alcaligenes faecalis is a non-fermentative, obligate aerobe that is motile due to the presence of peritrichous flagella. It is oxidase positive and catalase positive, which are key biochemical characteristics used in its identification. The bacterium is rod-shaped and does not form spores.

Habitat

This bacterium is widely distributed in nature and can be found in soil, water, and various clinical environments. It is often isolated from the respiratory tract of humans, although it is usually considered a contaminant rather than a pathogen.

Clinical Significance

While Alcaligenes faecalis is not typically associated with disease, it can be an opportunistic pathogen, particularly in immunocompromised individuals. It has been isolated from cases of bacteremia, urinary tract infections, and pneumonia. Infections are rare and usually occur in hospital settings.

Laboratory Identification

In the laboratory, Alcaligenes faecalis can be identified by its characteristic growth on MacConkey agar, where it does not ferment lactose, resulting in colorless colonies. It can also be identified by its positive oxidase test and its ability to produce a fruity odor when grown on nutrient agar.

Related pages

• Gram-negative bacteria
• Opportunistic infection
• Bacteremia
• Urinary tract infection

Gallery

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  Alcaligenes faecalis stained under a microscope.

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