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: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:Polymyxins are increasingly used as the critical last-resort therapeutic options for multidrug-resistant gram-negative bacteria. Unfortunately, polymyxin resistance has increased gradually for the last few years. Although studies on mechanisms of polymyxin are expanding, system-wide analyses of the underlying mechanism for polymyxin resistance and stress response are still lacking. To understand how Klebsiella pneumoniae adapt to colistin (polymyxin E) pressure, we carried out proteomic analysis of Klebsiella pneumoniae strain cultured with different concentrations of colistin. Our results showed that the proteomic responses to colistin treatment in Klebsiella pneumoniae involving several pathways, including (i) gluconeogenesis and TCA cycle; (ii) arginine biosynthesis; (iii) porphyrin and chlorophyll metabolism; and (iv) enterobactin biosynthesis. Interestingly, decreased abundance of class A β-lactamases including TEM, SHV-11, SHV-4 were observed in cells treated with colistin. Moreover, we also present comprehensive proteome atlases of paired polymyxin-susceptible and -resistant Klebsiella pneumoniae strains. The polymyxin-resistant strain Ci, a mutant of Klebsiella pneumoniae ATCC BAA 2146, showed missense mutation in crrB. The crrB mutant Ci, which displayed lipid A modification with 4-amino-4-deoxy-L-arabinose (L-Ara4N) and palmitoylation, showed striking increases of CrrAB, PmrAB, PhoPQ, ArnBCADT and PagP. We hypothesize that crrB mutations induce elevated expression of the arnBCADTEF operon and pagP via PmrAB and PhoPQ. Moreover, multidrug efflux pump KexD, which was induced by crrB mutation, also contributed to colistin resistance. Overall, our results demonstrated proteomic responses to colistin treatment and the mechanism of CrrB-mediate colistin resistance, which may further offer valuable information to manage polymyxin resistance.
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:Traditional vaccines are difficult to deploy against the diverse antibiotic-resistant, nosocomial pathogens that cause Hospital Acquired Infections (HAIs). We developed a unique, protein-free vaccine to present antibiotic-resistant HAIs. This vaccine protected mice from invasive infections caused by methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, multidrug resistant Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Rhizopus delemar, and Candida albicans. Protection persisted even in neutropenic mice infected with A. baumannii or R. delemar. Protection was already apparent after 24 hours and lasted for up to 21 days after a single dose, with a second dose restoring efficacy. Protection persisted without lymphocytes but was abrogated with macrophages depletion. This vaccine induced trained immunity by altering the macrophage epigenetic landscape and the inflammatory response to infection.
Project description:Plasmids are extrachromosomal genetic elements commonly found in bacteria. Plasmids are known to fuel bacterial evolution through horizontal gene transfer (HGT), but recent analyses indicate that they can also promote intragenomic adaptations. However, the role of plasmids as catalysts of bacterial evolution beyond HGT remains poorly explored. In this study, we investigate the impact of a widespread conjugative plasmid, pOXA-48, on the evolution of various multidrug-resistant clinical enterobacteria. Combining experimental and within-patient evolution analyses, we unveil that plasmid pOXA-48 promotes bacterial evolution through the transposition of plasmid-encoded IS1 elements. Specifically, IS1-mediated gene inactivations expedite the adaptation rate of clinical strains in vitro and foster within-patient adaptation in the gut. We decipher the mechanism underlying the plasmid-mediated surge in IS1 transposition, revealing a negative feedback loop regulated by the genomic copy number of IS1. Given the overrepresentation of IS elements in bacterial plasmids, our findings propose that plasmid-mediated IS transposition represents a crucial mechanism for swift bacterial adaptation.
Project description:Antibiotic resistance is exacerbated by the exchange of antibiotic resistance genes (ARGs) between microbes from diverse habitats. Plasmids are important ARGs mobile elements and are spread by horizontal gene transfer (HGT). In this study, we demonstrated the presence of multi-resistant plasmids from inhalable particulate matter (PM) and its effect on gene horizontal transfer. Three transferable multi-resistant plasmids were identified from PM in a hospital, using conjugative mating assays and nanopore sequencing. pTAir-3 contained 26 horizontal transfer elements and 10 ARGs. Importantly pTAir-5 harbored carbapenem resistance gene (blaOXA) which shows homology to plasmids from human and pig commensal bacteria, thus indicating that PM is a media for antibiotic resistant plasmid spread. In addition, 125 μg/mL PM2.5 and PM10 significantly increased the conjugative transfer rate by 110% and 30%, respectively, and augmented reactive oxygen species (ROS) levels. Underlying mechanisms were revealed by identifying the upregulated expressional levels of genes related to ROS, SOS, cell membranes, pilus generation, and transposition via genome-wide RNA sequencing. The study highlights the airborne spread of multi-resistant plasmids and the impact of inhalable PM on the horizontal transfer of antibiotic resistance.