Distribution of putative iron-utilization genes in European clinical strains of Acinetobacter baumannii

Abstract number: P1962

Antunes L.C., Imperi F., Towner K.J., Visca P.

Objective: Iron is an essential nutrient for bacteria and, as such, bacterial iron uptake mechanisms are important factors for pathogenesis. A gene cluster in Acinetobacter baumannii is known to be responsible for synthesis of the siderophore acinetobactin. Genomic analysis of sequenced A. baumannii strains enabled us to identify further gene clusters putatively involved in biosynthesis/transport of other siderophores, haem utilisation and ferrous iron uptake. The aim of this study was to investigate the distribution of these genes in a collection of 42 representative A. baumannii strains from 17 European countries.

Methods: PCR primers were designed to screen for 16 of the putative iron-utilisation genes identified from the genotypic sequence analysis. These primers were used in standard PCRs to screen a diverse collection of 42 European clinical A. baumannii strains of known sequence groups. In addition, the reference strain ATCC 19606 and the sequenced and annotated strains ACICU, AYE, ATCC 17978 and SDF were also investigated. The distribution of iron-utilisation genes among the different strains and sequence groups was analysed.

Results: Two putative siderophore gene clusters, including that coding for acinetobactin, were conserved among the clinical isolates of A. baumannii, while a third cluster was present in less than 5% of strains. Furthermore, a putative haem utilisation gene cluster was conserved in all strains, while a second haem utilisation cluster was found in approximately 50% of strains. Lastly, the Feo cluster, putatively coding for genes involved in the uptake of ferrous iron, was conserved in all strains. Notably, no apparent correlation was found between the sequence group (lineage) of the strains and the presence/absence of specific iron-utilisation genes.

Conclusions: The apparent universal distribution of the acinetobactin gene cluster, an additional and previously undescribed siderophore cluster, the Feo cluster for the uptake of ferrous iron, and one of two haem uptake clusters, indicates their potential importance for the survival and/or virulence of A. baumannii in the clinical setting. It remains to be determined if a second haem uptake cluster, present in approximately 50% of strains, and/or a third siderophore cluster, present in less than 5% of strains, further enhance the survival and/or virulence properties of specific A. baumannii strains.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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