Hospital Pathogens Carbapenem-Resistant Organisms (CRO)
October 27, 2017
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Blogs: Know About Hospital Pathogens: Acinetobacter baumanii

Blogs: Know About Hospital Pathogens

A vigilant eye on Hospital pathogens cannot be ignored, and much work remains to be done to

combat healthcare associated infections (HAIs).

Let us take a look at a few serious organisms that cause significant concern.


Acinetobacter is gram-negative, oxidase negative, belonging to a class of Gammaproteobacteria. “Acinetobacter” comes from Greek word akineto means non-motile and bacter just means bacteria shaped, so rod shaped. The word akineto when translated into English means acineto. Acinetobacter baumannii lacks a flagellum, but it is a very efficient swarming bacterium that moves via pili through twitching motility. A frequently isolated nosocomial pathogens is particularly prevalent in ICUs where many cases are reported globally. Although many species of Acinetobacter cause human diseases, Acinetobacter baumanii is responsible for 80 percent of nosocomial infections. In addition it is associated with various other infections, including skin and wound bacteremia. Acinetobacter iwoffii is frequently associated with meningitis.

Ranging from pneumonia to serious blood or wound infections Acinetobacter is associated with variety of diseases. Especially in tracheostomy sites or open wounds, Acinetobacter may also colonize a patient without causing infections or symptoms, People with weakened immune systems, diabetes or chronic lung diseases are more susceptible to infections associated with Acinetobacter than healthy people. Patients with a prolonged stay at hospitals, very ill patients associated with ventilators, patients who have open wound, operated patients with urinary catheters are also at greater risk for Acinetobacter infection. Acinetobacter can be spread to susceptible person by person-to-person contact or contact with contaminated surfaces. Acinetobacter can live on the skin and may survive in the environment for several days and form biofilms. Proper infection control procedures such as hand hygiene and environmental cleaning can reduce the risk of transmission.

BIOFILM Formation in Acineobacter baumanii

Acinetobacter baumannii is responsible for biofilm formation through its pili.  The biofilm formation ability of Acinetobacter baumanii helps the organism to survive on artificial surfaces for a long period of time.  The metabolism of microorganisms within the biofilm reduces the antibiotic sensitivity.

What Happens Inside the BIOFILM?

Very deep within the biofilm, there is an availability of fewer nutrients, which slower the metabolism that can prevent the bacteria from taking up an antibiotic or performing a vital function fast enough for particular antibiotics to have an effect. Biofilm also serve as a physical barrier against larger molecules and may prevent desiccation of the bacteria.

Recent study (Mirhoseini et al., 2016) revealed that Acinetobacter species and Acinetobacter baumanii were prevalent in hospital air. They are particularly resistance to beta-lactam group of antibiotics (BLRB). The report insisted on improvement of infection control measurements of hospital air.

Interesting facts about Acinetobacter baumanii

According to a recent discovery, blue light may be able to stop the swarming of the bacterium Acinetobacter baumanii. The researchers found that swarming was most active in the dark but  exposure to blue light stopped their swarming activity.

What is happening here?

A protein, called BlsA (Blue light Sensing protein A) in Acinetobacter baumanii that contained a BLUF (blue light sensing using flavin) domain which is responsible for light sensitivity. The researchers mutated blsA and the light sensitivity moved out. Blue light is able to disrupt the formation of biofilms and pellicles, which are particularly relevant in the development of human disease. Question is raised now, could it be possible that a bacterium that is so difficult to treat, in part due to its inherent resistance to most antibiotics, could be inhibited by a blue light? Time will tell but as was expertly written at the bottom of the commentary in the Journal of Bacteriology “microbiologists should open their incubators and let the sun shine in. The results may be illuminating.”


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