Project description:Colistin is a crucial last-line drug used for the treatment of life-threatening infections caused by multi-drug resistant strains of the Gram-negative bacteria, Acinetobacter baumannii. However, colistin resistant A. baumannii isolates can be isolated following failed colistin therapy. Resistance is most often mediated by the addition of phosphoethanolamine (pEtN) to lipid A by PmrC, following missense mutations in the pmrCAB operon encoding PmrC and the two-component signal transduction system PmrA/PmrB. We recovered an isogenic pair of A. baumannii isolates from a single patient before (6009-1) and after (6009-2) failed colistin treatment that displayed low/intermediate and high levels of colistin resistance, respectively. To understand how increased colistin-resistance arose, we genome sequenced each isolate which revealed that 6009-2 had an extra copy of the insertion sequence element ISAba125 within a gene encoding an H-NS-family transcriptional regulator. Consequently, transcriptomic analysis of the clinical isolates identified was performed and more than 150 genes as differentially expressed in the colistin-resistant, hns mutant, 6009-2. Importantly, the expression of eptA, encoding a second lipid A-specific pEtN transferase, but not pmrC, was significantly increased in the hns mutant. This is the first time an H-NS-family transcriptional regulator has been associated with a pEtN transferase and colistin resistance.
Project description:Salmonella enterica causes serious global burden of morbidity and mortality and is a major cause of infant bacteremia in sub Saharan Africa. Diseases caused by Salmonella are treatable with antibiotics but successful antibiotic treatment has become difficult due to antimicrobial resistance. An effective vaccine together with public health effort may therefore be a better strategy to control these infections. Protective immunity against Salmonella depends primarily on T cell-mediated immune responses and therefore identifying relevant T cell antigens is necessary for Salmonella vaccine development. Our laboratory has used an immunoproteomics approach to identify Chlamydia T cell antigens that exhibited significant protection against Chlamydia infection in mice. In this study, we infected murine bone marrow derived dendritic cells from C57BL/6 mice with Salmonella enterica strain SL1344 followed by isolation of MHC class I and II- molecules and elution of bound peptides. The sequences of the peptides were then identified using tandem mass spectrometry. We identified 87 MHC class II and 23 MHC class I Salmonella derived peptides. Four of 12 peptides stimulated IFN-? production by CD4 T cells from the spleens of mice with persistent Salmonella infection. These antigens will be useful for Salmonella immunobiology research and are potential Salmonella vaccine candidates.
Project description:This experiment set includes 64 arrays representing 26 serovars and strains of Salmonella spp. including many representatives of subspecies I, Arizona from subsp. IIIa, and S. bongori from subsp. V. The genomic DNA from all strains were labeled with Cy5 and hybridized against an equal amount (1.5 ug) of S. typhimurium SL1344 reference genomic DNA that was labeled with Cy3, all on an S. typhimurium SL1344 spotted DNA microarray. Most of the arrays are present in triplicate to account for variability in probe generation, hybridization, and slide quality. Several are represented in duplicate, and a few without any replicates. Set of arrays organized by shared biological context, such as organism, tumors types, processes, etc. Keywords: Logical Set
Project description:Here we investigated colistin effects on A. baumannii, employing a Mass spectrometry approach and comparing a colistin-susceptible multidrug-resistantclinical isolate to its colistin-dependent subpopulation obtained by subsequent passages in moderate colistin concentrations. Colistin dependence might represent a stepping-stone to resistance, but the mechanisms of colistin dependence are far from clear.
Project description:Salmonella enterica subsp. enterica serovar Rissen Genome with antibiotic-multinresistance profile including mcr-1 mediated resistance to Colistin sequencing and assembly
Project description:FabR ChIP-chip on Salmonella enterica subsp. enterica serovar Typhimurium SL1344 using anti-Myc antibody against strain with chromosomally 9Myc-tagged FabR (IP samples) and wildtype strain (mock IP samples)