Project description:The study aimed to characterize plasmids mediating carbepenem resistance in Klebsiella pneumoniae in Pretoria, South Africa. We analysed 56 K. pneumoniae isolates collected from academic hospital around Pretoria. Based on phenotypic and molecular results of these isolates, 6 representative isolates were chosen for further analysis using long reads sequencing platform. We observed multidrug resistant phenotype in all these isolates, including resistance to aminoglycosides, tetracycline, phenicol, fosfomycin, floroquinolones, and beta-lactams antibiotics. The blaOXA-48/181 and blaNDM-1/7 were manily the plasmid-mediated carbapenemases responsible for carbapenem resistance in the K. pneumoniae isolates in these academic hospitals. These carbapenemase genes were mainly associated with plasmid replicon groups IncF, IncL/M, IncA/C, and IncX3. This study showed plasmid-mediated carbapenemase spread of blaOXA and blaNDM genes mediated by conjugative plasmids in Pretoria hospitals.
Project description:To investigate the whole-genome gene expression difference between the wild-type and capsule deletion mutant in Klebsiella pneumoniae MGH 78578. The mutants analyzed in this study are further described in Huang T.W., Stapleton J.C., Chang H.Y., Tsai S.F., Palsson B.O., Charusanti P. Capsule removal via lambda-Red knockout system perturbs biofilm formation and fimbriae extression in Klesiella pneumoniae MGH 78578 (manuscript submission) A six chip study using total RNA recovered from three separate wild-type cultures and three separate cultures of a capsule deltion mutant of Klebsiella pneumoniae MGH 78578. The capsule gene cluster (KPN_02493 to KPN_02515) was entirely removed in the capsule deletion mutant. Each chip measures the expression level of 5,305 genes from Klebsiella pneumoniae MGH 78578 and the associated five plasmids (pKPN3, pKPN4, pKPN5, pKPN6 and pKPN7) with 50-mer oligo tiling array with 30-mer spacer.
Project description:Investigation of whole genome gene expression level in Klebsiella pneumoniae MGH78578 grown up to mid-exponential phase in M9 minimal media supplemented with 0.2% glucose A two chip study using total RNA recovered from MGH78578 grown up to OD600nm 0.5 (mid-exponential phase) in M9 minimal media supplemented with 0.2% glucose. The high-density oligonucleotide tiling arrays used were consisted of 392,778 oligonucleotide probes spaced 30 bp apart (20-bp overlap between two probes) across the K. pneumoniae main genome and plasmids.
Project description:With increasingly concerning strains of antimicrobial resistant strains of the commensal, gram-negative bacteria Klebsiella pneumoniae emerging, there is a pressing need to better understand the pathogen and mechanisms behind its pathogenicity. This study investigated the regulatory mechanisms in strain MGH 78578 of two major sigma factors, the house-keeping sigma factor RpoD, and the general stress response sigma factor RpoS, in mid-exponential and early stationary phase using chromatin immunoprecipitation with exonuclease treatment (ChIP-exo) followed by deep sequencing. Combining ChIP-exo and transcriptome analysis allowed for the determination of sigma factor binding sites, binding motifs, and genes included in the phase-specific sigmulons. The number of genes included in the RpoS sigmulon was greater than in the RpoD sigmulon, with 1,833 and 1,690 genes included, respectively; however, a majority of sigmulon genes were found in all phase-specific sigmulons. Focussing on pathogenicity genes, 20 antimicrobial resistance genes (ARGs) and 155 virulence genes, only two ARGs were found exclusively in one phase-specific sigmulon, an oxacillin-hydrolysing class D beta-lactamase and chloramphenicol efflux MFS transporter CmlA5, which were found in the RpoD sigmulon in early stationary phase. Notably, six unnamed proteins that are or pertain to fimbrial proteins were found uniquely in the RpoS sigmulon in early stationary phase. From this, it can be hypothesised that early stationary phase might be an important phase for pathogenicity gene regulation. While there is little conservation in RpoS sigmulons from strain to strain, RpoS appears to have a consistent overarching role across strains, including a role as a regulator of pathogenicity genes.