Project description:Enterobacter cloacae is a Gram-negative nosocomial pathogen of the ESKAPE (Enterococcus, Staphylococcus, Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter spp.) priority group with increasing multi-drug resistance via the acquisition of resistance plasmids. However, E. cloacae can also display forms of antibiotic refractoriness, such as heteroresistance and tolerance. Here, we report that E. cloacae displays transient heteroresistance to aminoglycosides, which is accompanied with the formation of small colony variants (SCVs) with increased minimum inhibitor concentration (MIC) of gentamicin and other aminoglycosides used in the clinic, but not other antibiotic classes. To explore the underlying mechanisms, we performed RNA sequencing of heteroresistant bacteria, which revealed global gene-expression changes and a signature of the CpxRA cell envelope stress response. Deletion of the cpxRA two-component system abrogated aminoglycoside heteroresistance and SCV formation, pointing to its indispensable role in these processes. The introduction of a constitutively active allele of cpxA led to high aminoglycoside MICs, consistent with cell envelope stress response driving these behaviours in E. cloacae. Cell envelope stress can be caused by environmental cues, including heavy metals. Indeed, bacterial exposure to copper increased gentamicin MIC in the wild-type, but not in the ΔcpxRA mutant. Moreover, copper exposure also elevated the gentamicin MICs of clinical isolates from bloodstream infections, suggesting that CpxRA- and copper-dependent aminoglycoside resistance is broadly conserved in E. cloacae strains. Altogether, we establish that E. cloacae relies on transcriptional reprogramming via the envelope stress response pathway for transient resistance to a major class of frontline antibiotic.
Project description:The exchange of mobile genomic islands (MGIs) between microorganisms is often mediated by phages. As a consequence, not only phage genes are transferred, but also genes that have no particular function in the phage's lysogenic cycle. If they provide benefits to the phage's host, such genes are referred to as ‘morons’. The present study was aimed at characterizing a set of Enterobacter cloacae, Klebsiella pneumoniae and Escherichia coli isolates with exceptional antibiotic resistance phenotypes from patients in a neonatal ward. Unexpectedly, these analyses unveiled the existence of a novel family of closely related MGIs in Enterobacteriaceae. The respective MGI from E. cloacae was named MIR17-GI. Importantly, our observations show that MIR17-GI-like MGIs harbor genes associated with high-level resistance to cephalosporins. Further, we show that MIR17-GI-like islands are associated with integrated P4-like prophages. This implicates phages in the spread of cephalosporin resistance amongst Enterobacteriaceae. The discovery of a novel family of MGIs spreading ‘cephalosporinase morons’ is of high clinical relevance, because high-level cephalosporin resistance has serious implications for the treatment of patients with Enterobacteriaceal infections.
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
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:Klebsiella pneumoniae is an arising threat to human health. However, host immune responses in response to this bacterium remain to be elucidated. The goal of this study was to identify the dominant host immune responses associated with Klebsiella pneumoniae pulmonary infection. Pulmonary mRNA profiles of 6-8-weeks-old BALB/c mice infected with/without Klebsiella pneumoniae were generated by deep sequencing using Illumina Novaseq 6000. qRT–PCR validation was performed using SYBR Green assays. Using KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, we identified several immune associated pathways, including complement and coagulation cascades, Toll-like receptor signaling pathway, Rap1 signaling pathway, chemokine signaling pathway, TNF signaling pathway, phagosome and NOD-like receptor signaling pathway, were involved in Klebsiella pneumoniae pulmonary infection. Using ICEPOP (Immune CEll POPulation) analysis, we found that several cell types were involved in the host immune response to Klebsiella pneumoniae pulmonary infection, including dendritic cells, macrophages, monocytes, NK (natural killer) cells, stromal cells. Further, IL-17 chemokines were significantly increased during Klebsiella pneumoniae infection. This study provided evidence for further studying the pathogenic mechanism of Klebsiella pneumoniae pneumonia infection.
Project description:This SuperSeries is composed of the following subset Series: GSE35746: Comparative analysis of regulatory elements between Escherichia coli and Klebsiella pneumoniae by genome-wide transcription start site profiling [tiling arrays] GSE35821: Comparative analysis of regulatory elements between Escherichia coli and Klebsiella pneumoniae by genome-wide transcription start site profiling [TSS-Seq] Refer to individual Series