Project description:Phages have emerged as prime suspects in the adaptation of pathogens to new hosts and the emergence of new pathogens or epidemic clones. Here we describe the genomic features of “swarms” of three related prophages (Ab105-1ϕ, Ab105-2ϕ and Ab105-3ϕ) present in the ST-2 epidemic clone of Acinetobacter baumannii clinical strain Ab105 GEIH-2010 and not present in genetically related Ab155 GEIH-2000 strain isolated 10 years before. The “Quasicore genome” of Ab105-1ϕ, Ab105-2ϕ and Ab105-3ϕ prophages revealed genes that promote bacterial-host fitness. The results of microarray analysis under stress conditions, SOS response and Quorum Sensing (QS) activation revealed 42% and 21% of genes expressed by Ab105-2ϕ and Ab105-3ϕ prophages (which produce bacterial lysis) in the first case and underexpression of these genes from prophages in the second case. Hence, the QS system plays a major role in the evolution of phages in their natural hosts and environments. Interestingly, in host-virus interactions, RT-PCR showed several mechanisms of overexpression of the SOS response in relation to phage defence mechanisms: i) SAM or AdoMet-MTase (methyltransferases) and MazG protein (pyrophosphohydrolase) associated with phage defence in response to bacterial attack; ii) eukaryotic-like protein kinase (glutamate 5-kinase) associated with prevention of secondary infection by the same or a closely related virus. Overexpression of secretory virulence factors such as oxidoreductase (DsbA-like), anfo-nitrogenase and chromosome segregation proteins were also observed. Moreover, under iron-deficient growth, there was an overexpression by RT-PCR of the a new interesting cluster of genes located following a “Moron” organization in the Ab105-3ϕ prophage being associated with iron uptake systems (Xanthine dehydrogenase gene cluster, Anthranilate operon, ABC transporter and TonB dependent receptor). In conclusion, study of the co-evolution of phages (virus) and bacteria may be essential in the search for means of combatting multi-resistant epidemic clones. Two parental clinical strains of A. baumannii (90% identity, indicated by PFGE, and ST2, indicated by Multilocus Sequence Typing, MLST) isolated in the same Intensive Care Unit (ICU) of a Spanish hospital, in 2000 and 2010, during the “I Multicenter Study GEIH-REIPI-Ab-2000” (Ab155 GEIH-2000) and “II Multicenter Study GEIH-REIPI-Ab-2010” (Ab105 GEIH-2010), respectively. Three replicates from RNA of the AB105 GEIH-2010 strain x 2 conditions (SOS response by Mitomycin C) and (Quorum Sensing activation by AHLs mixture).
Project description:Using Nanopore sequencing, our study has revealed a close correlation between genomic methylation levels and antibiotic resistance rates in Acinetobacter Baumannii. Specifically, the combined genome-wide DNA methylome and transcriptome analysis revealed the first epigenetic-based antibiotic-resistance mechanism in A. baumannii. Our findings suggest that the precise location of methylation sites along the chromosome could provide new diagnostic markers and drug targets to improve the management of multidrug-resistant A. baumannii infections.
Project description:Two Acinetobacter baumannii strains with low susceptibility to fosmidomycin and two reference with high susceptibility to fosmidomycin were DNA-sequenced to investigate the genomic determinants of fosmidomycin resistance.
Project description:Acinetobacter baumannii A1S_1874 gene encodes as a LysR-type transcriptional regulator. LysR family regulators known to regulate biofilm formation, antibiotic resistance, and the expression of diverse genes in other Gram-negative bacteria. However, A1S-1874 has never been characterized in Acinetobacter baumannii, and the studies about the regulon of A1S-1874 are not discovered. In this study we revealed that A1S_1874 differentially regulates at least 302 genes including the csu pilus operon, N-acylhomoserine lactone synthese gene, A1S_0112-A1S_0118 operon, type 1v secretion system related genes that are involved in biofilm formation, surface motility, adherence, quorum sensing and virulence. Overall, our data suggests that A1S-1874 is a key regulator of Acinetobacter baumannii biofilm formation and gene expression.
Project description:The goal of this RNA-Seq study was to determine Acinetobacter baumannii's transcriptiional response to sub-MIC concentrations of benzalkonium chloride in Acinetobacter baumannii. This RNA-seq data was then utilized to aide in the determination of the sub-MIC mechanism of action for benzalkonium chloride.