scholarly journals Heteroresistance to Colistin in Klebsiella pneumoniae Associated with Alterations in the PhoPQ Regulatory System

2015 ◽  
Vol 59 (5) ◽  
pp. 2780-2784 ◽  
Author(s):  
Aurélie Jayol ◽  
Patrice Nordmann ◽  
Adrian Brink ◽  
Laurent Poirel
Keyword(s):  
Klebsiella Pneumoniae ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Single Amino Acid ◽  
Two Component System ◽  
Partial Deletion ◽  
Content Type ◽  
Reading Frame ◽  
Single Amino Acid Change ◽  
Inactive Protein

ABSTRACTA multidrug-resistantKlebsiella pneumoniaeisolate exhibiting heteroresistance to colistin was investigated. The colistin-resistant subpopulation harbored a single amino acid change (Asp191Tyr) in protein PhoP, which is part of the PhoPQ two-component system that activatespmrHFIJKLMexpression responsible forl-aminoarabinose synthesis and polymyxin resistance. Complementation assays with a wild-typephoPgene restored full susceptibility to colistin. Then, analysis of the colistin-susceptible subpopulation showed a partial deletion (25 bp) in thephoPgene compared to that in the colistin-resistant subpopulation. That deletion disrupted the reading frame ofphoP, leading to a longer and inactive protein (255 versus 223 amino acids long). This is the first report showing the involvement of mutation(s) in PhoP in colistin resistance. Furthermore, this is the first study to decipher the mechanisms leading to colistin heteroresistance inK. pneumoniae.

scholarly journals Resistance to Colistin Associated with a Single Amino Acid Change in Protein PmrB among Klebsiella pneumoniae Isolates of Worldwide Origin

2014 ◽  
Vol 58 (8) ◽  
pp. 4762-4766 ◽  
Author(s):  
Aurélie Jayol ◽  
Laurent Poirel ◽  
Adrian Brink ◽  
Maria-Virginia Villegas ◽  
Mesut Yilmaz ◽  
...  
Keyword(s):  
Amino Acid ◽  
Klebsiella Pneumoniae ◽  
Amino Acid Change ◽  
Sequence Type ◽  
Single Amino Acid ◽  
Wild Type ◽  
Two Component System ◽  
Content Type ◽  
Single Amino Acid Change ◽  
Two Component

ABSTRACTA series of colistin-resistantKlebsiella pneumoniaeisolates recovered from different countries was investigated in order to evaluate the involvement of the PmrA/PmrB two-component system in this resistance. Six isolates possessed a mutated PmrB protein, which is encoded by thepmrBgene, part of thepmrCABoperon involved in lipopolysaccharide modification. The same amino acid substitution (Thr157Pro) in PmrB was identified in the six isolates. The six isolates belonged to four distinct clonal groups, recovered in South Africa (sequence type 14 [ST14]), Turkey (ST101), and Colombia (ST258 and ST15). Three out of the four clones produced a carbapenemase, OXA-181, OXA-48, or KPC-3, while a single isolate did not produce any carbapenemase. Expression assays revealed an overexpression of thepmrA(70-fold),pmrB(70-fold),pmrC(170-fold), andpmrK(40-fold) genes in thepmrB-mutated isolate compared to expression of thepmrBwild-type isogenicK. pneumoniaeisolate, confirming that the PmrB substitution was responsible for increased expression levels of those genes. Complementation assays leading to the expression of a wild-type PmrB protein restored the susceptibility to colistin in all isolates, confirming that the substitution in PmrB was responsible for the resistance phenotype. This study identified a key amino acid located in the PmrB protein as being responsible for the overexpression ofpmrCABandpmrHFIJKLMoperons, leading to resistance to colistin.

scholarly journals Increased Pilus Production Conferred by a Naturally Occurring Mutation Alters Host-Pathogen Interaction in Favor of Carriage in Streptococcus pyogenes

2017 ◽  
Vol 85 (5) ◽  
Author(s):  
Anthony R. Flores ◽  
Randall J. Olsen ◽  
Concepcion Cantu ◽  
Kyler B. Pallister ◽  
Fermin E. Guerra ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Regulatory System ◽  
Single Amino Acid ◽  
Human Neutrophils ◽  
Gene Transcript ◽  
Gene Encoding ◽  
Content Type ◽  
Single Amino Acid Change ◽  
Invasive Strain ◽  
Genes Encoding

ABSTRACT Studies of the human pathogen group A Streptococcus (GAS) define the carrier phenotype to be an increased ability to adhere to and persist on epithelial surfaces and a decreased ability to cause disease. We tested the hypothesis that a single amino acid change (Arg135Gly) in a highly conserved sensor kinase (LiaS) of a poorly defined GAS regulatory system contributes to a carrier phenotype through increased pilus production. When introduced into an emm serotype-matched invasive strain, the carrier allele (the gene encoding the LiaS protein with an arginine-to-glycine change at position 135 [liaS R135G]) recapitulated a carrier phenotype defined by an increased ability to adhere to mucosal surfaces and a decreased ability to cause disease. Gene transcript analyses revealed that the liaS mutation significantly altered transcription of the genes encoding pilus in the presence of bacitracin. Elimination of pilus production in the isogenic carrier mutant decreased its ability to colonize the mouse nasopharynx and to adhere to and be internalized by cultured human epithelial cells and restored the virulence phenotype in a mouse model of necrotizing fasciitis. We also observed significantly reduced survival of the isogenic carrier mutant compared to that of the parental invasive strain after exposure to human neutrophils. Elimination of pilus in the isogenic carrier mutant increased the level of survival after exposure to human neutrophils to that for the parental invasive strain. Together, our data demonstrate that the carrier mutation (liaS R135G) affects pilus expression. Our data suggest new mechanisms of pilus gene regulation in GAS and that the invasiveness associated with pilus gene regulation in GAS differs from the enhanced invasiveness associated with increased pilus production in other bacterial pathogens.

scholarly journals Genomic and Transcriptomic Analyses of Colistin-Resistant Clinical Isolates of Klebsiella pneumoniae Reveal Multiple Pathways of Resistance

2014 ◽  
Vol 59 (1) ◽  
pp. 536-543 ◽  
Author(s):  
Meredith S. Wright ◽  
Yo Suzuki ◽  
Marcus B. Jones ◽  
Steven H. Marshall ◽  
Susan D. Rudin ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Lipid A ◽  
Transcriptional Profiling ◽  
Membrane Integrity ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Kinase Gene ◽  
Content Type ◽  
Genetic Mechanisms

ABSTRACTThe emergence of multidrug-resistant (MDR)Klebsiella pneumoniaehas resulted in a more frequent reliance on treatment using colistin. However, resistance to colistin (Colr) is increasingly reported from clinical settings. The genetic mechanisms that lead to ColrinK. pneumoniaeare not fully characterized. Using a combination of genome sequencing and transcriptional profiling by RNA sequencing (RNA-Seq) analysis, distinct genetic mechanisms were found among nine Colrclinical isolates. Colrwas related to mutations in three different genes inK. pneumoniaestrains, with distinct impacts on gene expression. Upregulation of thepmrHoperon encoding 4-amino-4-deoxy-l-arabinose (Ara4N) modification of lipid A was found in all Colrstrains. Alteration of themgrBgene was observed in six strains. One strain had a mutation inphoQ. Common among these seven strains was elevated expression ofphoPQand unaltered expression ofpmrCAB, which is involved in phosphoethanolamine addition to lipopolysaccharide (LPS). In two strains, separate mutations were found in a previously uncharacterized histidine kinase gene that is part of a two-component regulatory system (TCRS) now designatedcrrAB. In these strains, expression ofpmrCAB,crrAB, and an adjacent glycosyltransferase gene, but not that ofphoPQ, was elevated. Complementation with the wild-type allele restored colistin susceptibility in both strains. ThecrrABgenes are present in mostK. pneumoniaegenomes, but not inEscherichia coli. Additional upregulated genes in all strains include those involved in cation transport and maintenance of membrane integrity. Because thecrrABgenes are present in only some strains, Colrmechanisms may be dependent on the genetic background.

scholarly journals RND-Type Efflux Pumps in Multidrug-Resistant Clinical Isolates of Acinetobacter baumannii: Major Role for AdeABC Overexpression and AdeRS Mutations

2013 ◽  
Vol 57 (7) ◽  
pp. 2989-2995 ◽  
Author(s):  
Eun-Jeong Yoon ◽  
Patrice Courvalin ◽  
Catherine Grillot-Courvalin
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Regulatory System ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Clinical Settings ◽  
Two Component System ◽  
Content Type ◽  
High Incidence ◽  
Two Component

ABSTRACTIncreased expression of chromosomal genes for resistance-nodulation-cell division (RND)-type efflux systems plays a major role in the multidrug resistance (MDR) ofAcinetobacter baumannii. However, the relative contributions of the three most prevalent pumps, AdeABC, AdeFGH, and AdeIJK, have not been evaluated in clinical settings. We have screened 14 MDR clinical isolates shown to be distinct on the basis of multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) for the presence and overexpression of the three Ade efflux systems and analyzed the sequences of the regulators AdeRS, a two-component system, for AdeABC and AdeL, a LysR-type regulator, for AdeFGH. GeneadeBwas detected in 13 of 14 isolates, andadeGand the intrinsicadeJgene were detected in all strains. Significant overexpression ofadeBwas observed in 10 strains, whereas only 7 had moderately increased levels of expression of AdeFGH, and none overexpressed AdeIJK. Thirteen strains had reduced susceptibility to tigecycline, but there was no correlation between tigecycline MICs and the levels of AdeABC expression, suggesting the presence of other mechanisms for tigecycline resistance. No mutations were found in the highly conserved LysR regulator of the nine strains expressing AdeFGH. In contrast, functional mutations were found in conserved domains of AdeRS in all the strains that overexpressed AdeABC with two mutational hot spots, one in AdeS near histidine 149 suggesting convergent evolution and the other in the DNA binding domain of AdeR compatible with horizontal gene transfer. This report outlines the high incidence of AdeABC efflux pump overexpression in MDRA. baumanniias a result of a variety of single mutations in the corresponding two-component regulatory system.

scholarly journals Identification of a Second Two-Component Signal Transduction System That Controls Fosfomycin Tolerance and Glycerol-3-Phosphate Uptake

2014 ◽  
Vol 197 (5) ◽  
pp. 861-871 ◽  
Author(s):  
Kumiko Kurabayashi ◽  
Yuko Hirakawa ◽  
Koichi Tanimoto ◽  
Haruyoshi Tomita ◽  
Hidetada Hirakawa
Keyword(s):  
Phosphate Uptake ◽  
Response Regulator ◽  
Anaerobic Respiration ◽  
Regulatory System ◽  
Carbon Substrate ◽  
Two Component System ◽  
Component System ◽  
Content Type ◽  
Two Component ◽  
Biological Cost

Particular interest in fosfomycin has resurfaced because it is a highly beneficial antibiotic for the treatment of refractory infectious diseases caused by pathogens that are resistant to other commonly used antibiotics. The biological cost to cells of resistance to fosfomycin because of chromosomal mutation is high. We previously found that a bacterial two-component system, CpxAR, induces fosfomycin tolerance in enterohemorrhagicEscherichia coli(EHEC) O157:H7. This mechanism does not rely on irreversible genetic modification and allows EHEC to relieve the fitness burden that results from fosfomycin resistance in the absence of fosfomycin. Here we show that another two-component system, TorSRT, which was originally characterized as a regulatory system for anaerobic respiration utilizing trimethylamine-N-oxide (TMAO), also induces fosfomycin tolerance. Activation of the Tor regulatory pathway by overexpression oftorR, which encodes the response regulator, or addition of TMAO increased fosfomycin tolerance in EHEC. We also show that phosphorylated TorR directly represses the expression ofglpT, a gene that encodes a symporter of fosfomycin and glycerol-3-phosphate, and activation of the TorR protein results in the reduced uptake of fosfomycin by cells. However, cells in which the Tor pathway was activated had an impaired growth phenotype when cultured with glycerol-3-phosphate as a carbon substrate. These observations suggest that the TorSRT pathway is the second two-component system to reversibly control fosfomycin tolerance and glycerol-3-phosphate uptake in EHEC, and this may be beneficial for bacteria by alleviating the biological cost. We expect that this mechanism could be a potential target to enhance the utility of fosfomycin as chemotherapy against multidrug-resistant pathogens.

scholarly journals Genomic evolution and local epidemiology of Klebsiella pneumoniae from a major hospital in Beijing, China, over a 15 year period: dissemination of known and novel high-risk clones

2021 ◽  
Author(s):  
Mattia Palmieri ◽  
Kelly L. Wyres ◽  
Caroline Mirande ◽  
Zhao Qiang ◽  
Ye Liyan ◽  
...  
Keyword(s):  
High Risk ◽  
Klebsiella Pneumoniae ◽  
Type Species ◽  
Treatment Options ◽  
Multidrug Resistant ◽  
Virulence Plasmid ◽  
Content Type ◽  
Origin And Evolution ◽  
Link Type ◽  
Beijing China

Klebsiella pneumoniae is a frequent cause of nosocomial and severe community-acquired infections. Multidrug-resistant (MDR) and hypervirulent (hv) strains represent major threats, and tracking their emergence, evolution and the emerging convergence of MDR and hv traits is of major importance. We employed whole-genome sequencing (WGS) to study the evolution and epidemiology of a large longitudinal collection of clinical K. pneumoniae isolates from the H301 hospital in Beijing, China. Overall, the population was highly diverse, although some clones were predominant. Strains belonging to clonal group (CG) 258 were dominant, and represented the majority of carbapenemase-producers. While CG258 strains showed high diversity, one clone, ST11-KL47, represented the majority of isolates, and was highly associated with the KPC-2 carbapenemase and several virulence factors, including a virulence plasmid. The second dominant clone was CG23, which is the major hv clone globally. While it is usually susceptible to multiple antibiotics, we found some isolates harbouring MDR plasmids encoding for ESBLs and carbapenemases. We also reported the local emergence of a recently described high-risk clone, ST383. Conversely to strains belonging to CG258, which are usually associated to KPC-2, ST383 strains seem to readily acquire carbapenemases of different types. Moreover, we found several ST383 strains carrying the hypervirulence plasmid. Overall, we detected about 5 % of simultaneous carriage of AMR genes (ESBLs or carbapenemases) and hypervirulence genes. Tracking the emergence and evolution of such strains, causing severe infections with limited treatment options, is fundamental in order to understand their origin and evolution and to limit their spread. This article contains data hosted by Microreact.

scholarly journals Epigenomics, genomics, resistome, mobilome, virulome and evolutionary phylogenomics of carbapenem-resistant Klebsiella pneumoniae clinical strains

2020 ◽  
Vol 6 (12) ◽  
Author(s):  
Katlego Kopotsa ◽  
Nontombi M. Mbelle ◽  
John Osei Sekyere
Keyword(s):  
Klebsiella Pneumoniae ◽  
Multidrug Resistant ◽  
Type I ◽  
Bacteriophage Therapy ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Plasmid Replicon ◽  
Size Number ◽  
Plasmid Size ◽  
Epidemiological Trends

Carbapenem-resistant Klebsiella pneumoniae (CRKP) remains a major clinical pathogen and public health threat with few therapeutic options. The mobilome, resistome, methylome, virulome and phylogeography of CRKP in South Africa and globally were characterized. CRKP collected in 2018 were subjected to antimicrobial susceptibility testing, screening by multiplex PCR, genotyping by repetitive element palindromic (REP)-PCR, plasmid size, number, incompatibility and mobility analyses, and PacBio’s SMRT sequencing (n=6). There were 56 multidrug-resistant CRKP, having bla OXA-48-like and bla NDM-1/7 carbapenemases on self-transmissible IncF, A/C, IncL/M and IncX3 plasmids endowed with prophages, traT, resistance islands, and type I and II restriction modification systems (RMS). Plasmids and clades detected in this study were respectively related to globally established/disseminated plasmids clades/clones, evincing transboundary horizontal and vertical dissemination. Reduced susceptibility to colistin occurred in 23 strains. Common clones included ST307, ST607, ST17, ST39 and ST3559. IncFIIk virulent plasmid replicon was present in 56 strains. Whole-genome sequencing of six strains revealed least 41 virulence genes, extensive ompK36 mutations, and four different K- and O-loci types: KL2, KL25, KL27, KL102, O1, O2, O4 and O5. Types I, II and III RMS, conferring m6A (G A TC, G A TGNNNNNNTTG, CA A NNNNNNCATC motifs) and m4C (C C WGG) modifications on chromosomes and plasmids, were found. The nature of plasmid-mediated, clonal and multi-clonal dissemination of blaOXA-48-like and blaNDM-1 mirrors epidemiological trends observed for closely related plasmids and sequence types internationally. Worryingly, the presence of both bla OXA-48 and bla NDM-1 in the same isolates was observed. Plasmid-mediated transmission of RMS, virulome and prophages influence bacterial evolution, epidemiology, pathogenicity and resistance, threatening infection treatment. The influence of RMS on antimicrobial and bacteriophage therapy needs urgent investigation.

scholarly journals Complete Genome Sequence of Klebsiella pneumoniae Phage Sweeny

2019 ◽  
Vol 8 (39) ◽  
Author(s):  
Nicholas Martinez ◽  
Eric Williams ◽  
Heather Newkirk ◽  
Mei Liu ◽  
Jason J. Gill ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Complete Genome Sequence ◽  
Protein Level ◽  
Multidrug Resistant ◽  
Content Type ◽  
Hospital Acquired Infections ◽  
Multidrug Resistant Bacterium ◽  
Protein Encoding ◽  
Hospital Acquired ◽  
Encoding Genes

Klebsiella pneumoniae is a multidrug-resistant bacterium causing many severe hospital-acquired infections. Here, we describe siphophage Sweeny that infects K. pneumoniae. Of its 78 predicted protein-encoding genes, a functional assignment was given to 36 of them. Sweeny is most closely related to T1-like phages at the protein level.

scholarly journals In Vitro Activity of Sulbactam-Durlobactam against Acinetobacter baumannii-calcoaceticus Complex Isolates Collected Globally in 2016 and 2017

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Sarah M. McLeod ◽  
Samir H. Moussa ◽  
Meredith A. Hackel ◽  
Alita A. Miller
Keyword(s):  
Acinetobacter Baumannii ◽  
Antibacterial Activities ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Single Amino Acid ◽  
Content Type ◽  
Level Of Activity ◽  
Severe Infections ◽  
Sources Of Infection

ABSTRACT Acinetobacter baumannii-calcoaceticus complex (ABC) organisms cause severe infections that are difficult to treat due to preexisting antibiotic resistance. Sulbactam-durlobactam (formerly sulbactam-ETX2514) (SUL-DUR) is a β-lactam–β-lactamase inhibitor combination antibiotic designed to treat serious infections caused by ABC organisms, including multidrug-resistant (MDR) strains. The in vitro antibacterial activities of SUL-DUR and comparator agents were determined by broth microdilution against 1,722 clinical isolates of ABC organisms collected in 2016 and 2017 from 31 countries across Asia/South Pacific, Europe, Latin America, the Middle East, and North America. Over 50% of these isolates were resistant to carbapenems. Against this collection of global isolates, SUL-DUR had a MIC50/MIC90 of 1/2 μg/ml compared to a MIC50/MIC90 of 8/64 μg/ml for sulbactam alone. This level of activity was found to be consistent across organisms, regions, sources of infection, and subsets of resistance phenotypes, including MDR and extensively drug-resistant isolates. The SUL-DUR activity was superior to those of the tested comparators, with only colistin having similar potency. Whole-genome sequencing of the 39 isolates (2.3%) with a SUL-DUR MIC of >4 μg/ml revealed that these strains encoded either the metallo-β-lactamase NDM-1, which durlobactam does not inhibit, or single amino acid substitutions near the active site of penicillin binding protein 3 (PBP3), the primary target of sulbactam. In summary, SUL-DUR demonstrated potent antibacterial activity against recent, geographically diverse clinical isolates of ABC organisms, including MDR isolates.

scholarly journals Complex Response of the CpxAR Two-Component System to β-Lactams on Antibiotic Resistance and Envelope Homeostasis in Enterobacteriaceae

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Muriel Masi ◽  
Elizabeth Pinet ◽  
Jean-Marie Pagès
Keyword(s):  
Efflux Pump ◽  
Multidrug Resistant ◽  
Diaminopimelic Acid ◽  
Single Amino Acid ◽  
Dependent Manner ◽  
Content Type ◽  
Promising Therapeutic Target ◽  
Abnormal Accumulation ◽  
A Cell ◽  
Mutational Activation

ABSTRACT The Cpx stress response is widespread among Enterobacteriaceae. We previously reported a mutation in cpxA in a multidrug-resistant strain of Klebsiella aerogenes isolated from a patient treated with imipenem. This mutation yields a single-amino-acid substitution (Y144N) located in the periplasmic sensor domain of CpxA. In this work, we sought to characterize this mutation in Escherichia coli by using genetic and biochemical approaches. Here, we show that cpxAY144N is an activated allele that confers resistance to β-lactams and aminoglycosides in a CpxR-dependent manner, by regulating the expression of the OmpF porin and the AcrD efflux pump, respectively. We also demonstrate the effect of the intimate interconnection between the Cpx system and peptidoglycan integrity on the expression of an exogenous AmpC β-lactamase by using imipenem as a cell wall-active antibiotic or by inactivating penicillin-binding proteins. Moreover, our data indicate that the Y144N substitution abrogates the interaction between CpxA and CpxP and increases phosphotransfer activity on CpxR. Because the addition of a strong AmpC inducer such as imipenem is known to cause abnormal accumulation of muropeptides (disaccharide-pentapeptide and N-acetylglucosamyl-1,6-anhydro-N-acetylmuramyl-l-alanyl-d-glutamy-meso-diaminopimelic-acid-d-alanyl-d-alanine) in the periplasmic space, we propose these molecules activate the Cpx system by displacing CpxP from the sensor domain of CpxA. Altogether, these data could explain why large perturbations to peptidoglycans caused by imipenem lead to mutational activation of the Cpx system and bacterial adaptation through multidrug resistance. These results also validate the Cpx system, in particular, the interaction between CpxA and CpxP, as a promising therapeutic target.

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