Acinetobacter baumannii

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Acinetobacter baumannii

It is a species of pathogenic bacteria, referred to as an aerobic gram-negative bacterium, which is resistant to most antibiotics and is known to cause oppurtunistic infections.

[edit] Surface Characteristics

Acinetobacter baumannii consists of a characteristic lipopolysaccharide [LPS] on its outer surface. Acinetobacter LPSs consist of a polysaccharide covalently linked to a lipid component, termed lipid A, which anchors the LPS in the outer membrane. This polysaccharide is divided into the core oligosaccharide (linked to lipid A) and the O-polysaccharide or O-antigen. This type of LPS is referred to as the smooth- or S-form phenotype; the O-antigens are characteristic for a given LPS and the parental bacterial strain. All recently investigated LPSs from Acinetobacter strains have been shown to be of the smooth phenotype, a serotyping scheme for identification of members of this genus may also be possible.

[edit] Transmission

It enters into the body through open wounds, catheters, and breathing tubes. It usually infects those with compromised immune systems, such as the wounded, the elderly, children or those with immune diseases

[edit] Pathogenic Activity

Acinetobacter baumannii is the most relevant human pathogen within the Acinetobacter genus. As a result of its resistance to drug treatment, some estimates state the disease is killing tens of thousands of U.S. hospital patients each year and specialists say "they could emerge as a bigger threat." It forms opportunistic infections. Multi-drug resistant Acinetobacter baumannii is abbreviated as MDRAB. Multidrug-resistant Acinetobacter is not a new phenomenon; it has always been inherently resistant to multiple antibiotics. It causes a wide variety of serious infections in humans, mostly in compromised patients. Recently, A. baumannii has emerged as an important pathogen among wounded soldiers, threatening civilian and military patients.

[edit] Virulence

This opportunistic pathogen expresses a myriad of factors that could play a role in human pathogenesis. Some of the factors are: the attachment to and persistence on solid surfaces, the acquisition of essential nutrients such as iron, the adhesion to epithelial cells and their subsequent killing by apoptosis, and the production and/or secretion of enzymes and toxic products that damage host tissues. However, very little is known about the molecular nature of most of these processes and factors and almost nothing has been shown with regard to their role in bacterial virulence and the pathogenesis of serious infectious diseases. Fortunately, some of these gaps can now be filled by testing appropriate isogenic derivatives in relevant animal models that mimic the infections in humans, particularly the outcome of deadly pneumonia. Such an approach should provide new and relevant information on the virulence traits of this normally underestimated bacterial human pathogen.

[edit] References

Wikipedia

Ralph Pantophlet, Lore Brade, and Helmut Brade. [1999] Identification of Acinetobacter baumannii Strains with Monoclonal Antibodies against the O Antigens of Their Lipopolysaccharides. Clin Diagn Lab Immunol 6(3): 323–329 PMCID: PMC103717