scholarly journals Estimation of pathogenic potential of an environmental Pseudomonas aeruginosa isolate using comparative genomics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Carola Berger ◽  
Christian Rückert ◽  
Jochen Blom ◽  
Korneel Rabaey ◽  
Jörn Kalinowski ◽  
...  

AbstractThe isolation and sequencing of new strains of Pseudomonas aeruginosa created an extensive dataset of closed genomes. Many of the publicly available genomes are only used in their original publication while additional in silico information, based on comparison to previously published genomes, is not being explored. In this study, we defined and investigated the genome of the environmental isolate P. aeruginosa KRP1 and compared it to more than 100 publicly available closed P. aeruginosa genomes. By using different genomic island prediction programs, we could identify a total of 17 genomic islands and 8 genomic islets, marking the majority of the accessory genome that covers ~ 12% of the total genome. Based on intra-strain comparisons, we are able to predict the pathogenic potential of this environmental isolate. It shares a substantial amount of genomic information with the highly virulent PSE9 and LESB58 strains. For both of these, the increased virulence has been directly linked to their accessory genome before. Hence, the integrated use of previously published data can help to minimize expensive and time consuming wetlab work to determine the pathogenetic potential.

2020 ◽  
Author(s):  
Carola Berger ◽  
Christian Rückert ◽  
Jochen Blom ◽  
Korneel Rabaey ◽  
Jörn Kalinowski ◽  
...  

Abstract BackgroundNew strains of Pseudomonas aeruginosa are continuously being isolated and sequenced to increase the genomic accessibility of this important pathogen. This has led to the generation of an impressive dataset of closed P. aeruginosa genomes. To understand the difference between the strains, investigations are focused on the accessory genome, thereby constantly extending the known pan genome of P. aeruginosa as a species. Apart from follow-up studies, many of the publicly available genomes are only used in their original publication while additional in silico information, based on comparison to previously published genomes, is not being explored. In this study, we defined and investigated the genome of the environmental isolate P. aeruginosa KRP1 and compared it to more than 100 publicly available closed P. aeruginosa genomes. ResultsPseudomonas spp. KRP1 could clearly be identified as a P. aeruginosa isolate, via comparative genomics. By using different genomic island prediction programs, we could identify a total of 25 genomic islands that cover ~12% of the genome of P. aeruginosa KRP1. Based on intra-strain comparisons, we are able to predict the pathogenic potential of this environmental isolate. It shares a substantial amount of its genomic information with the highly virulent PSE9 and LESB58 strains. For both of these clones, their increased virulence has been directly linked to their accessory genome before. ConclusionsHere we show, how the integrated use of previously published genomic data today, can help to replace expensive and time consuming wetlab work to determine the pathogenetic potential of environmental isolates. This knowledge is vital to understand what makes an isolate a potential pathogen as it helps design effective treatment.


2020 ◽  
Vol 44 (6) ◽  
pp. 740-762
Author(s):  
Changhan Lee ◽  
Jens Klockgether ◽  
Sebastian Fischer ◽  
Janja Trcek ◽  
Burkhard Tümmler ◽  
...  

ABSTRACT The environmental species Pseudomonas aeruginosa thrives in a variety of habitats. Within the epidemic population structure of P. aeruginosa, occassionally highly successful clones that are equally capable to succeed in the environment and the human host arise. Framed by a highly conserved core genome, individual members of successful clones are characterized by a high variability in their accessory genome. The abundance of successful clones might be funded in specific features of the core genome or, although not mutually exclusive, in the variability of the accessory genome. In clone C, one of the most predominant clones, the plasmid pKLC102 and the PACGI-1 genomic island are two ubiquitous accessory genetic elements. The conserved transmissible locus of protein quality control (TLPQC) at the border of PACGI-1 is a unique horizontally transferred compository element, which codes predominantly for stress-related cargo gene products such as involved in protein homeostasis. As a hallmark, most TLPQC xenologues possess a core genome equivalent. With elevated temperature tolerance as a characteristic of clone C strains, the unique P. aeruginosa and clone C specific disaggregase ClpG is a major contributor to tolerance. As other successful clones, such as PA14, do not encode the TLPQC locus, ubiquitous denominators of success, if existing, need to be identified.


2020 ◽  
Vol 64 (7) ◽  
Author(s):  
José Manuel Ortiz de la Rosa ◽  
Patrice Nordmann ◽  
Laurent Poirel

ABSTRACT Many transferable quinolone resistance mechanisms have been identified in Gram-negative bacteria. The plasmid-encoded 65-amino-acid-long ciprofloxacin-modifying enzyme CrpP was recently identified in Pseudomonas aeruginosa isolates. We analyzed a collection of 100 clonally unrelated and multidrug-resistant P. aeruginosa clinical isolates, among which 46 were positive for crpP-like genes, encoding five CrpP variants conferring variable levels of reduced susceptibility to fluoroquinolones. These crpP-like genes were chromosomally located as part of pathogenicity genomic islands.


2006 ◽  
Vol 188 (11) ◽  
pp. 4037-4050 ◽  
Author(s):  
Bridget R. Kulasekara ◽  
Hemantha D. Kulasekara ◽  
Matthew C. Wolfgang ◽  
Lisa Stevens ◽  
Dara W. Frank ◽  
...  

ABSTRACT ExoU is a potent Pseudomonas aeruginosa cytotoxin translocated into host cells by the type III secretion system. A comparison of genomes of various P. aeruginosa strains showed that that the ExoU determinant is found in the same polymorphic region of the chromosome near a tRNALys gene, suggesting that exoU is a horizontally acquired virulence determinant. We used yeast recombinational cloning to characterize four distinct ExoU-encoding DNA segments. We then sequenced and annotated three of these four genomic regions. The sequence of the largest DNA segment, named ExoU island A, revealed many plasmid- and genomic island-associated genes, most of which have been conserved across a broad set of β- and γ-Proteobacteria. Comparison of the sequenced ExoU-encoding genomic islands to the corresponding PAO1 tRNALys-linked genomic island, the pathogenicity islands of strain PA14, and pKLC102 of clone C strains allowed us to propose a mechanism for the origin and transmission of the ExoU determinant. The evolutionary history very likely involved transposition of the ExoU determinant onto a transmissible plasmid, followed by transfer of the plasmid into different P. aeruginosa strains. The plasmid subsequently integrated into a tRNALys gene in the chromosome of each recipient, where it acquired insertion sequences and underwent deletions and rearrangements. We have also applied yeast recombinational cloning to facilitate a targeted mutagenesis of ExoU island A, further demonstrating the utility of the specific features of the yeast capture vector for functional analyses of genes on large horizontally acquired genetic elements.


2008 ◽  
Vol 190 (21) ◽  
pp. 7130-7140 ◽  
Author(s):  
Scott E. Battle ◽  
Folker Meyer ◽  
Jordi Rello ◽  
Vanderlene L. Kung ◽  
Alan R. Hauser

ABSTRACT Most known virulence determinants of Pseudomonas aeruginosa are remarkably conserved in this bacterium's core genome, yet individual strains differ significantly in virulence. One explanation for this discrepancy is that pathogenicity islands, regions of DNA found in some strains but not in others, contribute to the overall virulence of P. aeruginosa. Here we employed a strategy in which the virulence of a panel of P. aeruginosa isolates was tested in mouse and plant models of disease, and a highly virulent isolate, PSE9, was chosen for comparison by subtractive hybridization to a less virulent strain, PAO1. The resulting subtractive hybridization sequences were used as tags to identify genomic islands found in PSE9 but absent in PAO1. One 99-kb island, designated P. aeruginosa genomic island 5 (PAGI-5), was a hybrid of the known P. aeruginosa island PAPI-1 and novel sequences. Whereas the PAPI-1-like sequences were found in most tested isolates, the novel sequences were found only in the most virulent isolates. Deletional analysis confirmed that some of these novel sequences contributed to the highly virulent phenotype of PSE9. These results indicate that targeting highly virulent strains of P. aeruginosa may be a useful strategy for identifying pathogenicity islands and novel virulence determinants.


2006 ◽  
Vol 189 (6) ◽  
pp. 2443-2459 ◽  
Author(s):  
Jens Klockgether ◽  
Dieco Würdemann ◽  
Oleg Reva ◽  
Lutz Wiehlmann ◽  
Burkhard Tümmler

ABSTRACT The known genomic islands of Pseudomonas aeruginosa clone C strains are integrated into tRNALys (pKLC102) or tRNAGly (PAGI-2 and PAGI-3) genes and differ from their core genomes by distinctive tetranucleotide usage patterns. pKLC102 and the related island PAPI-1 from P. aeruginosa PA14 were spontaneously mobilized from their host chromosomes at frequencies of 10% and 0.3%, making pKLC102 the most mobile genomic island known with a copy number of 30 episomal circular pKLC102 molecules per cell. The incidence of islands of the pKLC102/PAGI-2 type was investigated in 71 unrelated P. aeruginosa strains from diverse habitats and geographic origins. pKLC102- and PAGI-2-like islands were identified in 50 and 31 strains, respectively, and 15 and 10 subtypes were differentiated by hybridization on pKLC102 and PAGI-2 macroarrays. The diversity of PAGI-2-type islands was mainly caused by one large block of strain-specific genes, whereas the diversity of pKLC102-type islands was primarily generated by subtype-specific combination of gene cassettes. Chromosomal loss of PAGI-2 could be documented in sequential P. aeruginosa isolates from individuals with cystic fibrosis. PAGI-2 was present in most tested Cupriavidus metallidurans and Cupriavidus campinensis isolates from polluted environments, demonstrating the spread of PAGI-2 across habitats and species barriers. The pKLC102/PAGI-2 family is prevalent in numerous beta- and gammaproteobacteria and is characterized by high asymmetry of the cDNA strands. This evolutionarily ancient family of genomic islands retained its oligonucleotide signature during horizontal spread within and among taxa.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Syed A. K. Shifat Ahmed ◽  
Michelle Rudden ◽  
Sabrina M. Elias ◽  
Thomas J. Smyth ◽  
Roger Marchant ◽  
...  

AbstractPseudomonas aeruginosa uses quorum sensing (QS) to modulate the expression of several virulence factors that enable it to establish severe infections. The QS system in P. aeruginosa is complex, intricate and is dominated by two main N-acyl-homoserine lactone circuits, LasRI and RhlRI. These two QS systems work in a hierarchical fashion with LasRI at the top, directly regulating RhlRI. Together these QS circuits regulate several virulence associated genes, metabolites, and enzymes in P. aeruginosa. Paradoxically, LasR mutants are frequently isolated from chronic P. aeruginosa infections, typically among cystic fibrosis (CF) patients. This suggests P. aeruginosa can undergo significant evolutionary pathoadaptation to persist in long term chronic infections. In contrast, mutations in the RhlRI system are less common. Here, we have isolated a clinical strain of P. aeruginosa from a CF patient that has deleted the transcriptional regulator RhlR entirely. Whole genome sequencing shows the rhlR locus is deleted in PA80 alongside a few non-synonymous mutations in virulence factors including protease lasA and rhamnolipid rhlA, rhlB, rhlC. Importantly we did not observe any mutations in the LasRI QS system. PA80 does not appear to have an accumulation of mutations typically associated with several hallmark pathoadaptive genes (i.e., mexT, mucA, algR, rpoN, exsS, ampR). Whole genome comparisons show that P. aeruginosa strain PA80 is closely related to the hypervirulent Liverpool epidemic strain (LES) LESB58. PA80 also contains several genomic islands (GI’s) encoding virulence and/or resistance determinants homologous to LESB58. To further understand the effect of these mutations in PA80 QS regulatory and virulence associated genes, we compared transcriptional expression of genes and phenotypic effects with isogenic mutants in the genetic reference strain PAO1. In PAO1, we show that deletion of rhlR has a much more significant impact on the expression of a wide range of virulence associated factors rather than deletion of lasR. In PA80, no QS regulatory genes were expressed, which we attribute to the inactivation of the RhlRI QS system by deletion of rhlR and mutation of rhlI. This study demonstrates that inactivation of the LasRI system does not impact RhlRI regulated virulence factors. PA80 has bypassed the common pathoadaptive mutations observed in LasR by targeting the RhlRI system. This suggests that RhlRI is a significant target for the long-term persistence of P. aeruginosa in chronic CF patients. This raises important questions in targeting QS systems for therapeutic interventions.


Author(s):  
Antony T Vincent ◽  
Laurent Intertaglia ◽  
Victor Loyer ◽  
Valérie E Paquet ◽  
Émilie Adouane ◽  
...  

Abstract Genomic islands (Aeromonas salmonicida genomic islands, AsaGEIs) are found worldwide in many isolates of Aeromonas salmonicida subsp. salmonicida, a fish pathogen. To date, five variants of AsaGEI (1a, 1b, 2a, 2b and 2c) have been described. Here, we investigate a sixth AsaGEI, which was identified in France between 2016 and 2019 in 20 A. salmonicida subsp. salmonicida isolates recovered from sick salmon all at the same location. This new AsaGEI shares the same insertion site in the chromosome as the other AsaGEI2s as they all have a homologous integrase gene. This new AsaGEI was thus named AsaGEI2d, and has 5 unique genes compared to the other AsaGEIs. The isolates carrying AsaGEI2d also bear the plasmid pAsa7, which was initially found in an isolate from Switzerland. This plasmid provides resistance to chloramphenicol thanks to a cat gene. This study reveals more about the diversity of the AsaGEIs.


2021 ◽  
Vol 9 (2) ◽  
pp. 388
Author(s):  
Marta Hernández-García ◽  
María García-Castillo ◽  
Sergio García-Fernández ◽  
Diego López-Mendoza ◽  
Jazmín Díaz-Regañón ◽  
...  

CrpP enzymes have been recently described as a novel ciprofloxacin-resistance mechanism. We investigated by whole genome sequencing the presence of crpP-genes and other mechanisms involved in quinolone resistance in MDR/XDR-Pseudomonas aeruginosa isolates (n = 55) with both ceftolozane-tazobactam susceptible or resistant profiles recovered from intensive care unit patients during the STEP (Portugal) and SUPERIOR (Spain) surveillance studies. Ciprofloxacin resistance was associated with mutations in the gyrA and parC genes. Additionally, plasmid-mediated genes (qnrS2 and aac(6′)-Ib-cr) were eventually detected. Ten chromosomal crpP-like genes contained in related pathogenicity genomic islands and 6 different CrpP (CrpP1-CrpP6) proteins were found in 65% (36/55) of the isolates. Dissemination of CrpP variants was observed among non-related clones of both countries, including the CC175 (Spain) high-risk clone and CC348 (Portugal) clone. Interestingly, 5 of 6 variants (CrpP1-CrpP5) carried missense mutations in an amino acid position (Gly7) previously defined as essential conferring ciprofloxacin resistance, and decreased ciprofloxacin susceptibility was only associated with the novel CrpP6 protein. In our collection, ciprofloxacin resistance was mainly due to chromosomal mutations in the gyrA and parC genes. However, crpP genes carrying mutations essential for protein function (G7, I26) and associated with a restored ciprofloxacin susceptibility were predominant. Despite the presence of crpP genes is not always associated with ciprofloxacin resistance, the risk of emergence of novel CrpP variants with a higher ability to affect quinolones is increasing. Furthermore, the spread of crpP genes in highly mobilizable genomic islands among related and non-related P. aeruginosa clones alert the dispersion of MDR pathogens in hospital settings.


2012 ◽  
Vol 53 (1) ◽  
pp. 111-113 ◽  
Author(s):  
Dhamodharan Bakkiyaraj ◽  
Chandran Sivasankar ◽  
Shunmugiah Karutha Pandian

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