Acinetobacter species are ubiquitous gram negative and non-fermenting coccobacilli. Members of Acinetobacter genus include major pathogens and biotechnologically important species. In nature they can be found in different environmental sources such as hydrocarbon contaminated areas, activated sludge, sewage, dump sites, but also on vegetables, animals, and humans. The ability to dominate in so many ecological niches led thus some authors to consider these bacteria as microbial weeds.4 The genus is very ancient and extremely diverse that occupies different natural ecosystems and play an increasing causative role in human infections. Acinetobacter species are among the most frequent causes of hospital-acquired bacterial infections, with A. baumannii is the most frequently identified pathogen. Clinical cases typically involve not only ventilator-associated pneumonia and septicemia, but also endocarditis, meningitis, burn and surgical wound infections, and urinary tract infections. Of significant concern is the fact that many Acinetobacter-induced infections are caused by multiply-drug resistant strains. Specifically, A. baumannii, A. pittii, and A. nosocomialis have become the most medically important members of the genus as they are most frequently isolated from health care facilities as well as human tissues.1 Antimicrobial-resistant A. baumannii has high potential to spread among ill patients in intensive care units. The ability of Acinetobacter to persist in health care facilities is due to the mechanisms utilized to resist antimicrobial therapy, desiccation, and disinfectants. Bacterial factors known to be important for disease include outer membrane porins, surface structures including capsule and lipopolysaccharide, enzymes such as phospholipase D, iron acquisition systems, and regulatory proteins.

Multidrug-resistant Acinotobacter

Acinobacter species have been isolated from animals such as ducks, pigeons, chicken, donkey, rabbits, pets (cats, dogs), mules, livestock (goats, pigs, cattle, caws), horses, lice and arthropods. These bacteria can be part of the human flora of the skin and mucous membranes, hands, groin, toe webs, forehead, ears, human milk, and intestines, suggesting that human could constitute a potential reservoir for this opportunistic bacterium.5

Several Acinetobacter species have also been isolated from food: A. guillouiae, A. calcoaceticus, A. pittii, A. lwoffii, and A. bereziniae on garden vegetables as well as in fish, meat, cheese and milk, including a carbepenem resistant A. calcoaceticus from vegetables.

Hydrocarbons and polysaccharides are macromolecules available in the environment and may constitute a primary substrate for these microorganisms. Acinetobacter species can vreak down the polysaccharides via the production of xylanase which is a key enzyme to degrade complex extracellular substances such as hemicelluloses. It has also been shown that pollution of environmental sites either with fuel oil or metals can affect the microbial diversity and only few types of bacteria such as Acinetobacter species are able to resist and dominate such polluted areas.5


  1. The Genomic Diversification of the Whole Acinetobacter Genus: Origins, Mechanisms, and Consequences. Marie Touchon et al.
  2. Medically Relevant Acinetobacter Species Require a Type II Secretion System and Specific Membrane-Associated Chaperones for the Export of Multiple Substrates and Full Virulence. Christian M. Harding et al.
  3. Acinetobacter baumannii: Evolution of Antimicrobial Resistance—Treatment Options. Yohei Doi et al.
  4. Reservoirs of Non-baumannii Acinetobacter Species. Ahmad Al Atrouni et al.
  5. Reservoirs of Non-baumannii Acinetobacter Species. Ahmad Al Atrouni et al.



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