Alcaligenes faecalis is a Gram-negative, rod-shaped bacterium widely distributed in diverse environments. Known for its adaptability, it thrives in various natural and human-influenced settings. Though originally identified in feces, Alcaligenes faecalis is now recognized as ubiquitous, found in environmental niches, living organisms, and industrial and clinical environments.
Environmental Habitats
Alcaligenes faecalis is commonly found in natural environmental settings, including soil, water, and air. In soil, it is a frequent inhabitant of various types, such as agricultural and forest soils, where some strains can act as biofertilizers or bioremediation agents. The bacterium contributes to processes like nitrogen fixation and the degradation of organic pollutants. Soil samples worldwide have yielded A. faecalis, including thermophilic strains from oil-contaminated soil.
It is also prevalent in aquatic environments, appearing in fresh water sources such as rivers, lakes, and groundwater. It can be isolated from marine environments, including oceans and estuaries, and is frequently detected in wastewater treatment facilities. Its ability to break down organic contaminants makes it relevant in sewage and industrial wastewater treatment. Beyond soil and water, Alcaligenes faecalis can become airborne, found in atmospheric dust and air samples. Its presence is noted in indoor air environments like waste sorting plants, highlighting its capacity to survive and disperse through air.
Presence in Living Organisms
Alcaligenes faecalis is associated with various living organisms, including animals and humans. In animals, it forms part of the normal gut microbiota in diverse species. It has been identified in the intestines and respiratory tracts of vertebrates. For instance, some strains have been isolated from donkey intestinal chyme.
In humans, Alcaligenes faecalis is a component of the normal gut flora. It is also found on human skin and other body sites. While often considered a commensal organism, meaning it can live in harmony with the host without causing harm, A. faecalis is also frequently isolated from clinical samples. These isolates often indicate its potential as an opportunistic organism, especially in individuals with compromised immune systems. Clinical specimens from which it has been isolated include urine, blood, wound discharge, cerebrospinal fluid, and respiratory secretions.
Industrial and Clinical Environments
Beyond natural habitats and living organisms, Alcaligenes faecalis is found in various industrial and clinical settings. In industrial environments, it can be present in water systems and food processing plants, where it may act as a potential contaminant. Its capacity to degrade a wide range of pollutants, including heavy metals, pesticides, and dyes, makes it relevant for bioremediation applications in industrial wastewater treatment. Some strains are also used in pharmaceutical industries for producing specific compounds.
In healthcare environments, Alcaligenes faecalis is isolated from hospital surfaces, medical equipment, and water systems within facilities. It has been found on various hospital surfaces and within medical devices like respirators, hemodialysis systems, and intravenous solutions. Its ability to form biofilms on surfaces, including medical devices, contributes to its persistence in these settings. Biofilms allow bacteria to adhere to surfaces and resist cleaning methods, making them a concern in healthcare facilities.