Interspecies Communication among Commensal and Pathogenic Streptococci

ABSTRACTQuorum sensing (QS) regulates diverse and coordinated behaviors in bacteria, including the production of virulence factors, biofilm formation, sporulation, and competence development. It is now established that some streptococci utilize Rgg-type proteins in concert with short hydrophobic peptides (SHPs) to mediate QS, and sequence analysis reveals that several streptococcal species contain highly homologous Rgg/SHP pairs. In group A streptococcus (GAS), two SHPs (SHP2 and SHP3 [SHP2/3]) were previously identified to be important in GAS biofilm formation. SHP2/3 are detected by two antagonistic regulators, Rgg2 and Rgg3, which control expression of theshpgenes. In group B streptococcus (GBS), RovS is a known virulence gene regulator and ortholog of Rgg2, whereas no apparent Rgg3 homolog exists. Adjacent torovSis a gene (shp1520) encoding a peptide nearly identical to SHP2. Using isogenic mutant strains and transcriptional reporters, we confirmed that RovS/SHP1520 comprise a QS circuit in GBS. More important, we performed experiments demonstrating that production and secretion of SHP1520 by GBS can modulate Rgg2/3-regulated gene expression in GAS intrans; likewise, SHP2/3 production by GAS can stimulate RovS-mediated gene regulation in GBS. An isolate ofStreptococcus dysgalactiaesubsp.equisimilisalso produced a secreted factor capable of simulating the QS circuits of both GAS and GBS, and sequencing confirms the presence of an orthologous Rgg2/SHP2 pair in this species as well. To our knowledge, this is the first documented case of bidirectional signaling between streptococcal species in coculture and suggests a role for orthologous Rgg/SHP systems in interspecies communication between important human pathogens.IMPORTANCEPathogenic streptococci, such as group A (GAS) and group B (GBS) streptococcus, are able to persist in the human body without causing disease but become pathogenic under certain conditions that are not fully characterized. Environmental cues and interspecies signaling between members of the human flora likely play an important role in the transition to a disease state. Since quorum-sensing (QS) peptides have been consistently shown to regulate virulence factor production in pathogenic species, the ability of bacteria to signal via these peptides may prove to be an important link between the carrier and pathogenic states. Here we provide evidence of a bidirectional QS system between GAS, GBS, andStreptococcus dysgalactiaesubsp.equisimilis, demonstrating the possibility of evolved communication systems between human pathogens.

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Streptococcus pneumoniae, S. pyogenes and S. agalactiae membrane phospholipid remodelling in response to human serum

Microbiology ◽

10.1099/mic.0.001048 ◽

2021 ◽

Vol 167 (5) ◽

Author(s):

Luke R. Joyce ◽

Ziqiang Guan ◽

Kelli L. Palmer

Keyword(s):

Streptococcus Pneumoniae ◽

Human Serum ◽

Type Species ◽

Cellular Membrane ◽

Defined Medium ◽

Content Type ◽

Link Type ◽

Streptococcal Species ◽

Group A ◽

Group B

Streptococcus pneumoniae , S. pyogenes (Group A Streptococcus ; GAS) and S. agalactiae (Group B Streptococcus ; GBS) are major aetiological agents of diseases in humans. The cellular membrane, a crucial site in host–pathogen interactions, is poorly characterized in streptococci. Moreover, little is known about whether or how environmental conditions influence their lipid compositions. Using normal phase liquid chromatography coupled with electrospray ionization MS, we characterized the phospholipids and glycolipids of S. pneumoniae , GAS and GBS in routine undefined laboratory medium, streptococcal defined medium and, in order to mimic the host environment, defined medium supplemented with human serum. In human serum-supplemented medium, all three streptococcal species synthesize phosphatidylcholine (PC), a zwitterionic phospholipid commonly found in eukaryotes but relatively rare in bacteria. We previously reported that S. pneumoniae utilizes the glycerophosphocholine (GPC) biosynthetic pathway to synthesize PC. Through substrate tracing experiments, we confirm that GAS and GBS scavenge lysoPC, a major metabolite in human serum, thereby using an abbreviated GPC pathway for PC biosynthesis. Furthermore, we found that plasmanyl-PC is uniquely present in the GBS membrane during growth with human serum, suggesting GBS possesses unusual membrane biochemical or biophysical properties. In summary, we report cellular lipid remodelling by the major pathogenic streptococci in response to metabolites present in human serum.

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Beta—tricalcium phosphate as a substitute for autograft in interbody fusion cages in the canine lumbar spine

Journal of Neurosurgery Spine ◽

10.3171/spi.2002.97.3.0350 ◽

2002 ◽

Vol 97 (3) ◽

pp. 350-354 ◽

Cited By ~ 10

Author(s):

Takashiro Ohyama ◽

Yoshichika Kubo ◽

Hiroo Iwata ◽

Waro Taki

Keyword(s):

Lumbar Spine ◽

Tricalcium Phosphate ◽

Interbody Fusion ◽

Donor Site ◽

Posterolateral Approach ◽

Content Type ◽

Spine Model ◽

Group A ◽

Group B ◽

Fine Print

Object. An interbody fusion cage has been introduced for cervical anterior interbody fusion. Autogenetic bone is packed into the cage to increase the rate of union between adjacent vertebral bodies. Thus, donor site—related complications can still occur. In this study a synthetic ceramic, β—tricalcium phosphate (TCP), was examined as a substitute for autograft bone in a canine lumbar spine model. Methods. In 12 dogs L-1 to L-4 vertebrae were exposed via a posterolateral approach, and discectomy and placement of interbody fusion cages were performed at two intervertebral disc spaces. One cage was filled with autograft (Group A) and the other with TCP (Group B). The lumbar spine was excised at 16 weeks postsurgery, and biomechanical, microradiographic, and histological examinations were performed. Both the microradiographic and histological examinations revealed that fusion occurred in five (41.7%) of 12 operations performed in Group A and in six (50%) of 12 operations performed in Group B. The mean percentage of trabecular bone area in the cages was 54.6% in Group A and 53.8% in Group B. There were no significant intergroup differences in functional unit stiffness. Conclusions. Good histological and biomechanical results were obtained for TCP-filled interbody fusion cages. The results were comparable with those obtained using autograft-filled cages, suggesting that there is no need to harvest iliac bone or to use allo- or xenografts to increase the interlocking strength between the cage and vertebral bone to achieve anterior cervical interbody fusion.

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Prevention of postoperative posterior tethering of spinal cord after resection of ependymoma

Journal of Neurosurgery Spine ◽

10.3171/spi.2003.99.2.0181 ◽

2003 ◽

Vol 99 (2) ◽

pp. 181-187 ◽

Cited By ~ 7

Author(s):

Takeo Goto ◽

Kenji Ohata ◽

Toshihiro Takami ◽

Misao Nishikawa ◽

Akimasa Nishio ◽

...

Keyword(s):

Spinal Cord ◽

Neurological Deterioration ◽

Fisher Exact Test ◽

Content Type ◽

Exact Test ◽

Spinal Ependymoma ◽

Group A ◽

Delayed Neurological Deterioration ◽

Group B ◽

Fine Print

Object. The authors evaluated an alternative method to avoid postoperative posterior tethering of the spinal cord following resection of spinal ependymomas. Methods. Twenty-five patients with spinal ependymoma underwent surgery between 1978 and 2002. There were 16 male and nine female patients whose ages at the time of surgery ranged from 14 to 64 years (mean 41.8 years). The follow-up period ranged from 6 to 279 months (mean 112.4 months). In the initial 17 patients (Group A), the procedure to prevent arachnoidal adhesion consisted of the layer-to-layer closure of three meninges and laminoplasty. In the subsequently treated eight patients (Group B), the authors performed an alternative technique that included pial suturing, dural closure with Gore-Tex membrane—assisted patch grafting, and expansive laminoplasty. In Group A, postoperative adhesion was radiologically detected in eight cases (47%), and delayed neurological deterioration secondary to posterior tethering of the cord was found in five cases. In Group B, there was no evidence of adhesive posterior tethering or delayed neurological deterioration. A significant intergroup statistical difference was demonstrated for radiologically documented posterior tethering (p < 0.05, Fisher exact test). Moreover, patients with radiologically demonstrated posterior tethering suffered a significant delayed neurological functional deterioration (p < 0.01, Fisher exact test). Conclusions. This new technique for closure of the surgical wound is effective in preventing of postoperative posterior spinal cord tethering after excision of spinal ependymoma.

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A positron emission tomography study of cerebrovascular reserve before and after shunt surgery in patients with idiopathic chronic hydrocephalus

Journal of Neurosurgery ◽

10.3171/jns.1999.91.4.0605 ◽

1999 ◽

Vol 91 (4) ◽

pp. 605-609 ◽

Cited By ~ 41

Author(s):

Petra M. Klinge ◽

Georg Berding ◽

Thomas Brinker ◽

Wolfram H. Knapp ◽

Madjid Samii

Keyword(s):

Positron Emission Tomography ◽

Emission Tomography ◽

Chronic Hydrocephalus ◽

Content Type ◽

Cerebrovascular Reserve ◽

Shunt Placement ◽

Positron Emission ◽

Group A ◽

Group B ◽

Fine Print

Object. In this study the authors use positron emission tomography (PET) to investigate cerebral blood flow (CBF) and cerebrovascular reserve (CVR) in chronic hydrocephalus.Methods. Ten patients whose mean age was 67 ± 10 years (mean ± standard deviation [SD]) were compared with 10 healthy volunteers who were 25 ± 3 years of age. Global CBF and CVR were determined using 15O—H2O and PET prior to shunt placement and 7 days and 7 months thereafter. The CVR was measured using 1 g acetazolamide. Neurological status was assessed based on a score assigned according to the methods of Stein and Langfitt.Seven months after shunt placement, five patients showed clinical improvement (Group A) and five did not (Group B). The average global CBF before shunt deployment was significantly reduced in comparison with the control group (40 ± 8 compared with 61 ± 7 ml/100 ml/minute; mean ± SD, p < 0.01). In Group A the CBF values were significantly lower than in Group B (36 ± 7 compared with 44 ± 8 ml/100 ml/minute; p < 0.05). The CVR before surgery, however, was not significantly different between groups (Group A = 43 ± 21%, Group B = 37 ± 29%). After shunt placement, there was an increase in the CVR in Group A to 52 ± 37% after 7 days and to 68 ± 47% after 7 months (p < 0.05), whereas in Group B the CVR decreased to 14 ± 18% (p < 0.05) after 7 days and returned to the preoperative level (39 ± 6%) 7 months after shunt placement.Conclusions. The preliminary results indicate that a reduced baseline CBF before surgery does not indicate a poor prognosis. Baseline CBF before shunt placement and preoperative CVR are not predictive of clinical outcome. A decrease in the CVR early after shunt placement, however, is related to poor late clinical outcome, whereas early improvement in the CVR after shunt placement indicates a good prognosis.

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Whole-Genome Sequencing of Invasion-Resistant Cells Identifies Laminin α2 as a Host Factor for Bacterial Invasion

mBio ◽

10.1128/mbio.02128-16 ◽

2017 ◽

Vol 8 (1) ◽

Cited By ~ 18

Author(s):

Xander M. van Wijk ◽

Simon Döhrmann ◽

Björn M. Hallström ◽

Shangzhong Li ◽

Bjørn G. Voldborg ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Endothelial Cells ◽

Pathogenic Bacteria ◽

Bacterial Invasion ◽

Human Pathogens ◽

Specific Domain ◽

Cellular Invasion ◽

Group A ◽

Group B ◽

Laminin Α2

ABSTRACT To understand the role of glycosaminoglycans in bacterial cellular invasion, xylosyltransferase-deficient mutants of Chinese hamster ovary (CHO) cells were created using clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated gene 9 (CRISPR-cas9) gene targeting. When these mutants were compared to the pgsA745 cell line, a CHO xylosyltransferase mutant generated previously using chemical mutagenesis, an unexpected result was obtained. Bacterial invasion of pgsA745 cells by group B Streptococcus (GBS), group A Streptococcus, and Staphylococcus aureus was markedly reduced compared to the invasion of wild-type cells, but newly generated CRISPR-cas9 mutants were only resistant to GBS. Invasion of pgsA745 cells was not restored by transfection with xylosyltransferase, suggesting that an additional mutation conferring panresistance to multiple bacteria was present in pgsA745 cells. Whole-genome sequencing and transcriptome sequencing (RNA-Seq) uncovered a deletion in the gene encoding the laminin subunit α2 (Lama2) that eliminated much of domain L4a. Silencing of the long Lama2 isoform in wild-type cells strongly reduced bacterial invasion, whereas transfection with human LAMA2 cDNA significantly enhanced invasion in pgsA745 cells. The addition of exogenous laminin-α2β1γ1/laminin-α2β2γ1 strongly increased bacterial invasion in CHO cells, as well as in human alveolar basal epithelial and human brain microvascular endothelial cells. Thus, the L4a domain in laminin α2 is important for cellular invasion by a number of bacterial pathogens. IMPORTANCE Pathogenic bacteria penetrate host cellular barriers by attachment to extracellular matrix molecules, such as proteoglycans, laminins, and collagens, leading to invasion of epithelial and endothelial cells. Here, we show that cellular invasion by the human pathogens group B Streptococcus, group A Streptococcus, and Staphylococcus aureus depends on a specific domain of the laminin α2 subunit. This finding may provide new leads for the molecular pathogenesis of these bacteria and the development of novel antimicrobial drugs. IMPORTANCE Pathogenic bacteria penetrate host cellular barriers by attachment to extracellular matrix molecules, such as proteoglycans, laminins, and collagens, leading to invasion of epithelial and endothelial cells. Here, we show that cellular invasion by the human pathogens group B Streptococcus, group A Streptococcus, and Staphylococcus aureus depends on a specific domain of the laminin α2 subunit. This finding may provide new leads for the molecular pathogenesis of these bacteria and the development of novel antimicrobial drugs.

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Quorum Sensing Influences Burkholderia thailandensis Biofilm Development and Matrix Production

Journal of Bacteriology ◽

10.1128/jb.00047-16 ◽

2016 ◽

Vol 198 (19) ◽

pp. 2643-2650 ◽

Cited By ~ 23

Author(s):

Boo Shan Tseng ◽

Charlotte D. Majerczyk ◽

Daniel Passos da Silva ◽

Josephine R. Chandler ◽

E. Peter Greenberg ◽

...

Keyword(s):

Quorum Sensing ◽

Biofilm Formation ◽

Bacterial Species ◽

Matrix Material ◽

Close Relative ◽

Wild Type ◽

Flow Conditions ◽

Burkholderia Thailandensis ◽

Content Type ◽

Biofilm Development

ABSTRACTMembers of the genusBurkholderiaare known to be adept at biofilm formation, which presumably assists in the survival of these organisms in the environment and the host. Biofilm formation has been linked to quorum sensing (QS) in several bacterial species. In this study, we characterizedBurkholderia thailandensisbiofilm development under flow conditions and sought to determine whether QS contributes to this process.B. thailandensisbiofilm formation exhibited an unusual pattern: the cells formed small aggregates and then proceeded to produce mature biofilms characterized by “dome” structures filled with biofilm matrix material. We showed that this process was dependent on QS.B. thailandensishas three acyl-homoserine lactone (AHL) QS systems (QS-1, QS-2, and QS-3). An AHL-negative strain produced biofilms consisting of cell aggregates but lacking the matrix-filled dome structures. This phenotype was rescued via exogenous addition of the three AHL signals. Of the threeB. thailandensisQS systems, we show that QS-1 is required for proper biofilm development, since abtaR1mutant, which is defective in QS-1 regulation, forms biofilms without these dome structures. Furthermore, our data show that the wild-type biofilm biomass, as well as the material inside the domes, stains with a fucose-binding lectin. ThebtaR1mutant biofilms, however, are negative for fucose staining. This suggests that the QS-1 system regulates the production of a fucose-containing exopolysaccharide in wild-type biofilms. Finally, we present data showing that QS ability during biofilm development produces a biofilm that is resistant to dispersion under stress conditions.IMPORTANCEThe saprophyteBurkholderia thailandensisis a close relative of the pathogenic bacteriumBurkholderia pseudomallei, the causative agent of melioidosis, which is contracted from its environmental reservoir. Since most bacteria in the environment reside in biofilms,B. thailandensisis an ideal model organism for investigating questions inBurkholderiaphysiology. In this study, we characterizedB. thailandensisbiofilm development and sought to determine if quorum sensing (QS) contributes to this process. Our work shows thatB. thailandensisproduces biofilms with unusual dome structures under flow conditions. Our findings suggest that these dome structures are filled with a QS-regulated, fucose-containing exopolysaccharide that may be involved in the resilience ofB. thailandensisbiofilms against changes in the nutritional environment.

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Temporal Variability of Coastal Planctomycetes Clades at Kabeltonne Station, North Sea

Applied and Environmental Microbiology ◽

10.1128/aem.02931-10 ◽

2011 ◽

Vol 77 (14) ◽

pp. 5009-5017 ◽

Cited By ~ 38

Author(s):

Ilaria Pizzetti ◽

Bernhard M. Fuchs ◽

Gunnar Gerdts ◽

Antje Wichels ◽

Karen H. Wiltshire ◽

...

Keyword(s):

16S Rrna ◽

North Sea ◽

16S Rrna Genes ◽

Rrna Genes ◽

Content Type ◽

Group A ◽

Related Group ◽

Group B ◽

Card Fish ◽

Group D

ABSTRACTMembers of the bacterial phylumPlanctomycetesare reported in marine water samples worldwide, but quantitative information is scarce. Here we investigated the phylogenetic diversity, abundance, and distribution ofPlanctomycetesin surface waters off the German North Sea island Helgoland during different seasons by 16S rRNA gene analysis and catalyzed reporter deposition fluorescencein situhybridization (CARD-FISH). GenerallyPlanctomycetesare more abundant in samples collected in summer and autumn than in samples collected in winter and spring. Statistical analysis revealed thatPlanctomycetesabundance was correlated to theCentralesdiatom bloom in spring 2007. The analysis of size-fractionated seawater samples and of macroaggregates showed that ∼90% of thePlanctomycetesreside in the >3-μm size fraction. Comparative sequence analysis of 184 almost full-length 16S rRNA genes revealed three dominant clades. The clades, namedPlanctomyces-related group A, unculturedPlanctomycetesgroup B, andPirellula-related group D, were monitored by CARD-FISH using newly developed oligonucleotide probes. All three clades showed recurrent abundance patterns during two annual sampling campaigns. UnculturedPlanctomycetesgroup B was most abundant in autumn samples, whilePlanctomyces-related group A was present in high numbers only during late autumn and winter. The levels ofPirellula-related group D were more constant throughout the year, with elevated counts in summer. Our analyses suggest that the seasonal succession of thePlanctomycetesis correlated with algal blooms. We hypothesize that the niche partitioning of the different clades might be caused by their algal substrates.

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CovRS-Regulated Transcriptome Analysis of a Hypervirulent M23 Strain of Group A Streptococcus pyogenes Provides New Insights into Virulence Determinants

Journal of Bacteriology ◽

10.1128/jb.00511-15 ◽

2015 ◽

Vol 197 (19) ◽

pp. 3191-3205 ◽

Cited By ~ 13

Author(s):

Yun-Juan Bao ◽

Zhong Liang ◽

Jeffrey A. Mayfield ◽

Shaun W. Lee ◽

Victoria A. Ploplis ◽

...

Keyword(s):

Streptococcus Pyogenes ◽

Broad Spectrum ◽

Virulence Genes ◽

Expression Profiles ◽

Altered Expression ◽

Content Type ◽

Metabolic Genes ◽

A Genome ◽

Group A ◽

Regulated Gene Expression

ABSTRACTThe two-componentcontrolofvirulence (Cov) regulator (R)-sensor (S) (CovRS) regulates the virulence ofStreptococcus pyogenes(group AStreptococcus[GAS]). Inactivation of CovS during infection switches the pathogenicity of GAS to a more invasive form by regulating transcription of diverse virulence genes via CovR. However, the manner in which CovRS controls virulence through expression of extended gene families has not been fully determined. In the current study, the CovS-regulated gene expression profiles of a hypervirulentemm23GAS strain (M23ND/CovS negative [M23ND/CovS−]) and a noninvasive isogenic strain (M23ND/CovS+), under different growth conditions, were investigated. RNA sequencing identified altered expression of ∼349 genes (18% of the chromosome). The data demonstrated that M23ND/CovS−achieved hypervirulence by allowing enhanced expression of genes responsible for antiphagocytosis (e.g.,hasABC), by abrogating expression of toxin genes (e.g.,speB), and by compromising gene products with dispensable functions (e.g.,sfb1). Among these genes, several (e.g.,parEandparC) were not previously reported to be regulated by CovRS. Furthermore, the study revealed that CovS also modulated the expression of a broad spectrum of metabolic genes that maximized nutrient utilization and energy metabolism during growth and dissemination, where the bacteria encounter large variations in available nutrients, thus restructuring metabolism of GAS for adaption to diverse growth environments. From constructing a genome-scale metabolic model, we identified 16 nonredundant metabolic gene modules that constitute unique nutrient sources. These genes were proposed to be essential for pathogen growth and are likely associated with GAS virulence. The genome-wide prediction of genes associated with virulence identifies new candidate genes that potentially contribute to GAS virulence.IMPORTANCEThe CovRS system modulates transcription of ∼18% of the genes in theStreptococcus pyogenesgenome. Mutations that inactivate CovR or CovS enhance the virulence of this bacterium. We determined complete transcriptomes of a naturally CovS-inactivated invasive deep tissue isolate of anemm23strain ofS. pyogenes(M23ND) and its complemented avirulent variant (CovS+). We identified diverse virulence genes whose altered expression revealed a genetic switching of a nonvirulent form of M23ND to a highly virulent strain. Furthermore, we also systematically uncovered for the first time the comparative levels of expression of a broad spectrum of metabolic genes, which reflected different metabolic needs of the bacterium as it invaded deeper tissue of the human host.

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Suboccipital and cervical chordomas: the value of aggressive treatment at first presentation of the disease

Journal of Neurosurgery ◽

10.3171/jns.2002.97.5.1070 ◽

2002 ◽

Vol 97 (5) ◽

pp. 1070-1077 ◽

Cited By ~ 55

Author(s):

Alexandre Carpentier ◽

Marc Polivka ◽

Alexandre Blanquet ◽

Guillaume Lot ◽

Bernard George

Keyword(s):

Clinical Symptoms ◽

Rank Test ◽

Aggressive Treatment ◽

Actuarial Survival ◽

High Tendency ◽

Content Type ◽

Log Rank Test ◽

Group A ◽

Group B ◽

Fine Print

Object. Chordoma is a locally invasive tumor with a high tendency for recurrence for which radical resection is generally recommended. To assess the benefits of aggressive treatment of chordomas, the authors compared results in patients treated aggressively at the first presentation of this disease with results in patients who were similarly treated, but after recurrence. Methods. Among 36 patients with cervical chordomas who were treated at the authors' institution, 22 underwent primary aggressive treatment (Group A) and 14 were treated secondarily after tumor recurrence (Group B). Two cases were excluded from Group A because of unrelated early deaths and three from Group B because of insufficient pre- or postoperative data. Most tumors were located at the suboccipital level and only eight cases at a level below C-2. Radiotherapy and proton therapy were similarly conducted in both groups of patients. The actuarial survival rates were 80 and 65% at 5 and 10 years, respectively, in Group A patients and 50 and 0% at 5 and 10 years, respectively, in Group B patients (p = 0.049, log-rank test). The actuarial recurrence-free rates were 70 and 35% at 5 and 10 years, respectively, in Group A and 0% at 3 years in Group B (p < 0.0001, log-rank test). The numbers of recurrences per year were 0.15 in Group A and 0.62 in Group B (p > 0.05). All other parameters that were analyzed (patient age, delay before diagnosis, clinical symptoms, chondroid type of lesion, and histological features) did not prove to influence prognosis in a statistically significant manner. Conclusions. Aggressive therapy, combining as radical a resection as possible with radiotherapy, seems to improve the prognoses of suboccipital and cervical chordomas when applied at the patient's first presentation with the disease.

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Identification of FDA-Approved Drugs as Antivirulence Agents Targeting the pqs Quorum-Sensing System of Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01296-18 ◽

2018 ◽

Vol 62 (11) ◽

Cited By ~ 27

Author(s):

Francesca D'Angelo ◽

Valerio Baldelli ◽

Nigel Halliday ◽

Paolo Pantalone ◽

Fabio Polticelli ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Biofilm Formation ◽

Antifungal Drugs ◽

Phenotypic Characterization ◽

Resistant Bacteria ◽

Gram Positive ◽

Active Inhibitor ◽

Content Type ◽

Approved Drugs

ABSTRACT The long-term use of antibiotics has led to the emergence of multidrug-resistant bacteria. A promising strategy to combat bacterial infections aims at hampering their adaptability to the host environment without affecting growth. In this context, the intercellular communication system quorum sensing (QS), which controls virulence factor production and biofilm formation in diverse human pathogens, is considered an ideal target. Here, we describe the identification of new inhibitors of the pqs QS system of the human pathogen Pseudomonas aeruginosa by screening a library of 1,600 U.S. Food and Drug Administration-approved drugs. Phenotypic characterization of ad hoc engineered strains and in silico molecular docking demonstrated that the antifungal drugs clotrimazole and miconazole, as well as an antibacterial compound active against Gram-positive pathogens, clofoctol, inhibit the pqs system, probably by targeting the transcriptional regulator PqsR. The most active inhibitor, clofoctol, specifically inhibited the expression of pqs-controlled virulence traits in P. aeruginosa, such as pyocyanin production, swarming motility, biofilm formation, and expression of genes involved in siderophore production. Moreover, clofoctol protected Galleria mellonella larvae from P. aeruginosa infection and inhibited the pqs QS system in P. aeruginosa isolates from cystic fibrosis patients. Notably, clofoctol is already approved for clinical treatment of pulmonary infections caused by Gram-positive bacterial pathogens; hence, this drug has considerable clinical potential as an antivirulence agent for the treatment of P. aeruginosa lung infections.

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