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P.aeruginosa the real story

P. Aeruginosa Proves to be a Tough Foe

The invasive gram-negative bacteria are notorious for their intrinsic (natural) resistance to multiple classes of antibiotics and for their ability to mutate and develop resistance to virtually any antibiotic used for therapy. Serious infections with P.aueuginosa have become a desperate problem in hospitals, and now some strains are resistant to all common classes of antibiotics used for treatment.
P.aeruginosa causes a range of chronic and acute infections in patients who are hospitalized and critically ill. In the United States, it is responsible for about 10% of all hospital acquired infections, and in the ICUs, it is the second most frequently recovered pathogen from patients. It is the first or second leading cause of ventilator-associated pneumonia9VAP) and is among the top five causes of hospital acquired bacteremia.
P.aeruginosa causes 18.1% of all hospital acquired pneumonias, as well as 16% of UTI’s, 9.5% of surgical wound infections and 3.4% of blood stream infections.
After colonization, P.aeruginosa bacteria produce an arsenal of virulence factors made up of toxic proteins that interfere with the body’s immune system and cause extensive tissue damage, bloodstream invasion and dissemination. Many of these virulence factors are thought to be controlled by a complex regulatory system involving bacterial cell-to-cell signaling that allows the bacteria to regulate virulence by communicating via “signal molecules” released into the host environment. During the infection, as the number of bacteria increases, the concentration of signal molecules increases as well, allowing the bacteria to sense their population density—a phenomenon known as “quorum sensing”. When the bacteria “sense” that a quorum has been reached, they release virulence factors to overwhelm the host defense mechanism. Quorum sensing ensures that virulence factors are not released early in an infection, when only a small number of invading bacteria is present. This prevents the early recognition and eradication of the bacteria by the host’s immune system. Virulence factors are released only when they can be produced at high enough levels to overcome host defenses. These bacteria produce biofilms that encase the bacteria for protection. The biofilm is sticky matrix of extra cellular polysaccharides. These biofilms allow the bacteria to live adhered to living and nonliving surfaces. Biofilms are important survival mechanisms for the P.aeruginosa. Bacteria living in a biofilm are up to 3,000 times more resistant to free chlorine than individual (plank-tonic) bacterial cells.
Biofilms of P. aeroginosa are common in tanks, pipes, and plumbing fixtures in hospital water systems. When the biofilms forms close to the point of water use, such as a faucet or showerhead, it becomes a reservoir of microorganisms and constantly disperses bacteria into the water stream. Patients are exposed to the bacteria while bathing, showering and consuming tap water. About 1,400 deaths occur each year in the US from waterborne, hospital acquired P.aeruginosa pneumonias. Outbreaks are linked to sinks, faucets, tubs, respiratory equipment, bronchoscopes, and endoscopes. Nurses can recommend disposable sterile sponges to bathe patients who are immuno-suppresed, using only sterile not distilled water for rinsing respiratory devices and provide sterilized water to drink for compromised patients.

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