Gene Origin

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Origin of Genes

Acinetobacter baumannii has recently acquired a mass of antimicrobial and antibiotic resistant genes that enable a MDR phenotype and viability in the hospital environment. In A. baumannii strain AYE, it was found that it acquired 45 resistant genes that were clustered into an 86-kb genomic island.[1] From this genomic island, it was found that likely origins of the genes were from Pseudomonas sp. (44%), Salmonella sp. (34%), Escherichia sp. (17%), and other microorganisms (4%).[1] Fournier postulates that the reason there is a high amount of genetic material that is from Pseudomonas species into A. baumannii is due to their close evolutionary proximity, resulting in a facilitated gene transfer.[1]

(Fournier 2006)

Updated News

Recently however, there have been new genetic studies on a strain of Acinetobacter baumannii with a larger acquisition of resistance genes. In 2007 the genome of A. baumannii strain ATCC17978 was sequenced and found to contain 28 genomic islands, 16 of which pertain to virulence and holds about 74 potential drug-resistance genes.[2] Another epidemic MDR strain, A. baumannii ACICU, that is a different lineage found predominantly in European countries was also sequenced earlier in 2008, revealing 36 genomic islands (containing the 24 found in 2007).[3] Observance of the two islands may indicate that related resistance islands in both lineages could be derived from a genetic determinant acquired by a common A. baumannii ancestor.[3]

References

  1. 1.0 1.1 1.2 Fournier, P. et al. (2006). Comparative genomics of multidrug resistance in Acinetobacter baumannii. PLoS Genetics. 2, 62-72.
  2. Smith, MG, Gianoulis TA, Pukatzki S, Mekalanos JJ, Ornston LN, Gerstein M, Snyder M. (2007).New insights into Acinetobacter baumannii pathogenesis revealed by high-density pyrosequencing and transposon mutagenesis. Genes and Development. 21, 601-614.
  3. 3.0 3.1 Iacono, M, et al. (2008).Whole-genome pyrosequencing of an epidemic multidrug-resistant Acinetobacter baumannii strain belonging to the european clone II group. Antimicrobial Agents and Chemotherapy. 52, 2616-2625.


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