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Habitat of Acinetobacter baumannii
- The first Acinetobacter found in soil was discovered in 1911 by M.W. Beijerinck.
- It is associated with aquatics environment.
- It has been recovered from soil, water, animals, and humans.
- Found in the respiratory and oropharynx secretions of infected individuals.
- Found in hospital environment and accounts for 10% nosocomial infections in ICU.
- It has been suggested that human skin could be the source of severe infections, such as bacteremia.
- The respiratory tract, blood, pleural fluid, urinary tract, surgical wounds, CNS, skin and eyes may be sites for infection or colonization.
- Acinetobacter baumannii specifically targets moist tissues such as mucous membranes or areas of the skin that are exposed, either through accident or injury.
- Acinetobacter baumannii is found only rarely as part of the normal skin microflora, with one study estimating that only 3% (at most) of the population are colonized by the bacterium.
- Patients that acquire artificial devices such as catheters, sutures, ventilators and those who have undergone dialysis or antimicrobial therapy within the past 90 days are also at risk of developing baumannii infections.
- Acinetobacter baumannii has the ability to form biofilms on the surface of the endotracheal tube, which may account for the relatively high levels of colonization in the lower part of the respiratory tract.
- Aerobic and opportunistic pathogen
- Survive in inanimate object for weeks.
- Recent studies have shown that A. baumannii can be found in unsuspected reservoirs, such as food or arthropods, and additional reservoirs remain to be discovered.
- Acinetobacter species isolates have been found in a variety of food items, including raw vegetables.
Morphology of Acinetobacter baumannii
- Gram negative rod, becomes spherical at stationary phase of growth.
- Size = 0.9 – 1.6 micrometers by 1.5 – 2.5 micrometers
- Grouped in pairs or in chain
- Non-motile (may exist twitching motility)
- It include porins and efflux channels which contribute to antibiotic resistance.
Genome of Acinetobacter baumannii
- A single circular chromosome
- Base Pairs = 3,976,747
- Protein Coding = 3,454
- One strain of A. baumannii called AYE contains an 86kb resistance island, called AbaR1, that is made up of 45 resistance genes.
- A. baumannii AYE has three plasmids, but none contain resistance markers.