Project description:Antibiotic use can lead to expansion of multi-drug resistant pathobionts within the gut microbiome that can cause life-threatening infections. Selective alternatives to conventional antibiotics are in dire need. Here, we describe a Klebsiella PhageBank that enables the rapid design of antimicrobial bacteriophage cocktails to treat multi-drug resistant Klebsiella pneumoniae. Using a transposon library in carbapenem-resistant K. pneumoniae, we identified host factors required for phage infection in major Klebsiella phage families. Leveraging the diversity of the PhageBank and experimental evolution strategies, we formulated combinations of phages that minimize the occurrence of phage resistance in vitro. Optimized bacteriophage cocktails selectively suppressed the burden of multi-drug resistant K. pneumoniae in the mouse gut microbiome and drove bacterial populations to lose key virulence factors that act as phage receptors. Further, phage-mediated diversification of bacterial populations in the gut enabled co-evolution of phage variants with higher virulence and a broader host range. Altogether, the Klebsiella PhageBank represents a roadmap for both phage researchers and clinicians to enable phage therapy against a critical multidrug-resistant human pathogen.
Project description:The emergence and spread of polymyxin resistance, especially among Klebsiella pneumoniae isolates threaten the effective management of infections. This study profiled for polymyxin resistance mechanisms and investigated the activity of polymyxins plus vancomycin against carbapenem- and polymyxin-resistant K. pneumoniae.
Project description:The increasing antibiotic resistance of Klebsiella pneumoniae poses a serious threat to global public health. To investigate the antibiotic resistance mechanism of Klebsiella pneumonia, we performed gene expression profiling analysis using RNA-seq data for clinical isolates of Klebsiella pneumonia, KPN16 and ATCC13883. Our results showed that mutant strain KPN16 is likely to act against the antibiotics through increased increased butanoate metabolism and lipopolysaccharide biosynthesis, and decreased transmembrane transport activity.
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:Klebsiella pneumoniae has risen to prominence as a major threat to human health, with hypervirulent and drug-resistant lineages spreading globally. Given their antimicrobial resistant phenotypes, new therapies are required for the treatment of these infections, and bacteriophages (phages) that kill Klebsiella are being identified for use in phage therapy. In order to circumvent the evolution of phage-resistance taking hold the way that drug-resistance has, clear and considered actions are needed in selecting the phages that would be used in therapeutic cocktails. It is known that annotation of phage genomes is poor, potentially obscuring those phages with the most therapeutic potential. Here we show that phages isolated from infrequently sampled environments have features of therapeutic potential and developed a computational tool called STEP3 to understand the evolutionary features that distinguish the component parts of diverse phages, features that proved particularly suitable to detection of virion proteins with only distantly related homologies. These features were integrated into an ensemble framework to achieve a stable and robust prediction performance by STEP3. Proteomics-based analysis of two phages validated the prediction accuracy of STEP3 and revealed the virions contain component parts that include DNA-binding factors, otherwise unrecognizable capsule degradation enzymes and membrane translocation factors.
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:Klebsiella pneumoniae is an antibiotic-resistant bacteria associated with severe infections, which has led to the search for new antimicrobial drugs to face these infections. Antimicrobial peptides (AMPs) are antimicrobials that exert anti-K. pneumoniae activity. Consequently, AMPs have been explored as a therapeutic option. However, similarly to other antimicrobials, K. pneumoniae can develop resistance against AMPs, although it is less frequent. Therefore, understanding the resistance mechanisms developed by K. pneumoniae against AMPs could aid in the design and development of more effective AMPs. This study aimed to identify via a label-free quantitative proteomic approach the resistance mechanisms involved in the resistance response of K. pneumoniae against the AMP PaDBS1R1.
Project description:Klebsiella pneumoniae is a leading cause of global deaths due to antibiotic resistance. Of particular concern, is the rapid expansion within K. pneumoniae lineages of resistance to beta-lactams, the most prescribed class of antibiotics. Additionally, the environmental factors that influence pathogen physiology and, subsequently, antibiotic resistance remain poorly understood. Here we demonstrate that physiologically-relevant drops in culture medium pH result in increased antibiotic resistance particularly towards beta-lactams that inhibit cell division. We identified two genes that contribute to acid-dependent beta-lactam resistance, the class A PBP, PBP1b, and the paralogous class B PBP, PBP3PARA. Loss of either gene increases K. pneumoniae susceptibility to beta-lactams at low pH. Our data suggests that functional redundancy among cell wall synthesis enzymes allows for specialization and ensures that cell wall synthesis occurs robustly across a range of pH conditions.
Project description:Klebsiella pneumoniae is a major pathogen that causes a variety of human infections, posing a significant public health threat. Understanding its pathogenesis is essential for devising effective treatment strategies. In this study, we aim to identify critical virulence factors in K. pneumoniae through analyzing virulence-associated genes that were identified in three transposon mutagenesis libraries. Two genes, wzi and kvrB, are consistently detected across these libraries, indicating their potential as critical virulence factors. While Wzi has usually been implicated in virulence through CPS, its actual function in K. pneumoniae pathogenicity has rarely been explored. Wzi deficiency reduces CPS production in K. pneumoniae, contrasting with its effect in Escherichia coli. Importantly, Wzi exerts a pivotal role in K. pneumoniae pathogenicity in vitro and in vivo, functioning through both CPS-dependent and -independent pathways. Wzi inhibits the secretion of IFN-γ-related cytokines at early infection stage to promote K. pneumoniae survival in the host. Wzi triggers sustained neutrophil recruitment during infection through the upregulation of CXCL1 expression, resulting in the pulmonary barrier damage and increased K. pneumoniae invasion into the bloodstream. Concurrently, Wzi confers K. pneumoniae to counteract neutrophil-mediated clearance in a CPS-dependent manner. Sequence polymorphisms of wzi significantly affect bacterial resistance to serum killing, with alleles frequently associated with hypervirulent K. pneumoniae exhibiting the highest resistance. Collectively, our findings highlight that the dual role of Wzi as a CPS-dependent and -independent virulence factor that combats host clearance during K. pneumoniae infection, representing a promising target for the development of anti-infective treatment against the bug.