Project description:Citrobacter braakii and Citrobacter freundii are Gram-negative opportunistic pathogens associated with many infectious diseases, including septicemia, in humans and animals. Here, we report the draft genome sequences of seven C. braakii strains and one C. freundii strain isolated from Canadian wastewater treatment facilities.
Project description:Antibiotic resistance associated with the expression of the clinically significant carbapenemases, IMP, KPC, and NDM and OXA-48 in Enterobacteriaceae is emerging as a worldwide calamity to health care. In Australia, IMP-producing Enterobacteriaceae is the most prevalent carbapenemase-producing Enterobacteriaceae (CPE). Genomic characteristics of such carbapenemase-producing Enterobacteriaceae (CPE) are well described, but the corresponding proteome is poorly characterised. We have thus developed a method to analyse dynamic changes in the proteome of CPE under antibiotic pressure. Specifically, we have investigated the effect of meropenem at sub-lethal concentrations to develop a better understanding of how antibiotic pressure leads to resistance. Escherichia coli, producing either NDM, IMP or KPC type carbapenemase were included in this study, and their proteomes were analysed in growth conditions with or without meropenem.
Project description:Citrobacter braakii is a Gram-negative bacterium belonging to the Enterobacteriaceae family. Here, we report 5.2- and 5.0-Mb genome assemblies for C. braakii strains GTA-CB01 and GTA-CB04, respectively.
Project description:Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae have become widespread in hospitals and the environment. Here, we describe a blaKPC-2-carrying plasmid called pCRE3-KPC, which was recovered from a clinical multidrug-resistant Citrobacter braakii CRE3 strain in China. The complete nucleotide sequence of pCRE3-KPC was determined by combining MiSeq and MinION sequencing and then compared with those of three related plasmids. Plasmid conjugal transfer and electroporation tests, modified carbapenem inactivation method, and bacterial antimicrobial susceptibility test were carried out. We compared this plasmid with three related plasmids to verify that the backbone of pCRE3-KPC was composed of the backbones of the IncR plasmid and IncP6 plasmid. Further bioinformatics analysis showed that pCRE3-KPC carried two resistance-related regions (the blaKPC-2 gene cluster and the aacC2-tmrB-related region). The aacC2-tmrB-related region included two novel insertion sequences (ISCfr28 and ISCfr16).IMPORTANCE Reports of human-pathogenic C. braakii strains, especially of strains showing resistance to carbapenems, are rare. To the best of our knowledge, our results represent the first detection of carbapenemase gene blaKPC-2 in C. braakii strains. In addition, we have studied detailed genetic characteristics of the novel IncR/IncP6 hybrid plasmid pCRE3-KPC, which was isolated from a clinical multidrug-resistant Citrobacter braakii CRE3 strain. Our results may provide further insight into the horizontal transfer of multidrug resistance genes in bacteria and into the genomic diversity and molecular evolution of plasmids.
Project description:New and rapid antimicrobial susceptibility/resistance testing methods are required for bacteria from positive blood cultures. In the current study we developed and evaluated a targeted LC-MS/MS assay for the detection of beta-lactam, aminoglycoside and fluoroquinolone resistance mechanisms in blood cultures positive for E. coli or K. pneumoniae. Selected targets were the beta-lactamases SHV, TEM, OXA-1-like, CTX-M-1-like, CMY-2-like, chromosomal E. coli AmpC, OXA-48-like, NDM, VIM and KPC, the aminoglycoside modifying enzymes AAC(3)-Ia, AAC(3)-II, AAC(3)-IV, AAC(3)-VI, AAC(6’)-Ib, ANT(2”)-I and APH(3’)-VI, the 16S-RMTases ArmA, RmtB, RmtC and RmtF, the quinolone resistance mechanisms QnrA, QnrB, AAC(6’)-Ib-cr, the wildtype QRDR of GyrA, and for E. coli, the porins OmpC and OmpF. The developed assay was evaluated using 100 prospectively collected positive blood cultures, 100 negative blood cultures inoculated with isolates that were previously collected from blood cultures, and 48 isolates inoculated with isolates carrying genes of less prevalent resistance mechanisms.
