scholarly journals Involvement of Stress-Related GenespolBandPA14_46880in Biofilm Formation of Pseudomonas aeruginosa

2014 ◽  
Vol 82 (11) ◽  
pp. 4746-4757 ◽  
Author(s):  
Sahar A. Alshalchi ◽  
Gregory G. Anderson
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Acute Infection ◽  
Regulatory Gene ◽  
Chronic Infections ◽  
Content Type ◽  
Abiotic Surfaces ◽  
Mutant Strains ◽  
In The Wild ◽  
Airway Cells

ABSTRACTChronic infections ofPseudomonas aeruginosaare generally established through production of biofilm. During biofilm formation, production of an extracellular matrix and establishment of a distinct bacterial phenotype make these infections difficult to eradicate. However, biofilm studies have been hampered by the fact that most assays utilize nonliving surfaces as biofilm attachment substrates. In an attempt to better understand the mechanisms behindP. aeruginosabiofilm formation, we performed a genetic screen to identify novel factors involved in biofilm formation on biotic and abiotic surfaces. We found that deletion of genespolBandPA14_46880reduced biofilm formation significantly compared to that in the wild-type strain PA14 in an abiotic biofilm system. In a biotic biofilm model, wherein biofilms form on cultured airway cells, the ΔpolBand ΔPA14_46880strains showed increased cytotoxic killing of the airway cells independent of the total number of bacteria bound. Notably, deletion mutant strains were more resistant to ciprofloxacin treatment. This phenotype was linked to decreased expression ofalgR, an alginate transcriptional regulatory gene, under ciprofloxacin pressure. Moreover, we found that pyocyanin production was increased in planktonic cells of mutant strains. These results indicate that inactivation ofpolBandPA14_46880may inhibit transition ofP. aeruginosafrom a more acute infection lifestyle to the biofilm phenotype. Future investigation of these genes may lead to a better understanding ofP. aeruginosabiofilm formation and chronic biofilm infections.

scholarly journals Pseudomonas aeruginosa AlgU Contributes to Posttranscriptional Activity by IncreasingrsmAExpression in amucA22Strain

2016 ◽  
Vol 198 (13) ◽  
pp. 1812-1826 ◽  
Author(s):  
Sean D. Stacey ◽  
Christopher L. Pritchett
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Immunocompromised Patients ◽  
Chronic Infections ◽  
Rnase Protection ◽  
Content Type ◽  
Mutant Strains ◽  
Life Threatening ◽  
Severe Infections

ABSTRACTPseudomonas aeruginosathrives in multiple environments and is capable of causing life-threatening infections in immunocompromised patients. RsmA is a posttranscriptional regulator that controls virulence factor production and biofilm formation. In this study, we investigated the expression and activity ofrsmAand the protein that it encodes, RsmA, inP. aeruginosamucAmutant strains, which are common in chronic infections. We determined that AlgU regulates a previously unknownrsmApromoter inP. aeruginosa. Western blot analysis confirmed that AlgU controlsrsmAexpression in both a laboratory strain and a clinical isolate. RNase protection assays confirmed the presence of tworsmAtranscripts and suggest that RpoS and AlgU regulatersmAexpression. Due to the increased amounts of RsmA inmucAmutant strains, a translational leader fusion of the RsmA target,tssA1, was constructed and tested inmucA,algU,retS,gacA, andrsmAmutant backgrounds to examine posttranscriptional activity. From these studies, we determined that RsmA is active inmucA22mutants, suggesting a role for RsmA inmucAmutant strains. Taken together, we have demonstrated that AlgU controlsrsmAtranscription and is responsible for RsmA activity inmucAmutant strains. We propose that RsmA is active inP. aeruginosamucAmutant strains and that RsmA also plays a role in chronic infections.IMPORTANCEP. aeruginosacauses severe infections in immunocompromised patients. The posttranscriptional regulator RsmA is known to control virulence and biofilm formation. We identify a newrsmApromoter and determine that AlgU is important in the control ofrsmAexpression. MutantmucAstrains that are considered mucoid were used to confirm increasedrsmAexpression from the AlgU promoter. We demonstrate, for the first time, that there is RsmA activity in mucoidP. aeruginosastrains. Our work suggests that RsmA may play a role during chronic infections as well as acute infections.

scholarly journals Fluorescence-Based Reporter for Gauging Cyclic Di-GMP Levels in Pseudomonas aeruginosa

2012 ◽  
Vol 78 (15) ◽  
pp. 5060-5069 ◽  
Author(s):  
Morten T. Rybtke ◽  
Bradley R. Borlee ◽  
Keiji Murakami ◽  
Yasuhiko Irie ◽  
Morten Hentzer ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Fluorescent Protein ◽  
Subsequent Development ◽  
Cellular Level ◽  
Host Immune System ◽  
Chronic Infections ◽  
Content Type ◽  
Genes Encoding ◽  
Green Fluorescent

ABSTRACTThe increased tolerance toward the host immune system and antibiotics displayed by biofilm-formingPseudomonas aeruginosaand other bacteria in chronic infections such as cystic fibrosis bronchopneumonia is of major concern. Targeting of biofilm formation is believed to be a key aspect in the development of novel antipathogenic drugs that can augment the effect of classic antibiotics by decreasing antimicrobial tolerance. The second messenger cyclic di-GMP is a positive regulator of biofilm formation, and cyclic di-GMP signaling is now regarded as a potential target for the development of antipathogenic compounds. Here we describe the development of fluorescent monitors that can gauge the cellular level of cyclic di-GMP inP. aeruginosa. We have created cyclic di-GMP level reporters by transcriptionally fusing the cyclic di-GMP-responsivecdrApromoter to genes encoding green fluorescent protein. We show that the reporter constructs give a fluorescent readout of the intracellular level of cyclic di-GMP inP. aeruginosastrains with different levels of cyclic di-GMP. Furthermore, we show that the reporters are able to detect increased turnover of cyclic di-GMP mediated by treatment ofP. aeruginosawith the phosphodiesterase inducer nitric oxide. Considering that biofilm formation is a necessity for the subsequent development of a chronic infection and therefore a pathogenicity trait, the reporters display a significant potential for use in the identification of novel antipathogenic compounds targeting cyclic di-GMP signaling, as well as for use in research aiming at understanding the biofilm biology ofP. aeruginosa.

scholarly journals Potentiation of Tobramycin by Silver Nanoparticles against Pseudomonas aeruginosa Biofilms

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Marc B. Habash ◽  
Mara C. Goodyear ◽  
Amber J. Park ◽  
Matthew D. Surette ◽  
Emily C. Vis ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Silver Nanoparticles ◽  
Bacterial Infections ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Acute Infection ◽  
Public Health Problem ◽  
Chronic Infections ◽  
Content Type

ABSTRACT Increasing antibiotic resistance among pathogenic bacterial species is a serious public health problem and has prompted research examining the antibacterial effects of alternative compounds and novel treatment strategies. Compounding this problem is the ability of many pathogenic bacteria to form biofilms during chronic infections. Importantly, these communities are often recalcitrant to antibiotic treatments that show effectiveness against acute infection. The antimicrobial properties of silver have been known for decades, but recently silver and silver-containing compounds have seen renewed interest as antimicrobial agents for treating bacterial infections. The goal of this study was to assess the ability of citrate-capped silver nanoparticles (AgNPs) of various sizes, alone and in combination with the aminoglycoside antibiotic tobramycin, to inhibit established Pseudomonas aeruginosa biofilms. Our results demonstrate that smaller 10-nm and 20-nm AgNPs were more effective at synergistically potentiating the activity of tobramycin. Visualization of biofilms treated with combinations of 10-nm AgNPs and tobramycin reveals that the synergistic bactericidal effect may be caused by disrupting cellular membranes. Minimum biofilm eradication concentration (MBEC) assays using clinical P. aeruginosa isolates shows that small AgNPs are more effective than larger AgNPs at inhibiting biofilms, but that the synergy effect is likely a strain-dependent phenomenon. These data suggest that small AgNPs synergistically potentiate the activity of tobramycin against P. aeruginosa in vitro and may reveal a potential role for AgNP/antibiotic combinations in treating patients with chronic infections in a strain-specific manner.

scholarly journals Genome Sequences of Two Pseudomonas aeruginosa Isolates with Defects in Type III Secretion System Gene Expression from a Chronic Ankle Wound Infection

2021 ◽  
Author(s):  
Sardar Karash ◽  
Robert Nordell ◽  
Egon A. Ozer ◽  
Timothy L. Yahr
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Secretion System ◽  
Chronic Infections ◽  
Genome Sequences ◽  
Content Type ◽  
Chronic Colonization ◽  
Host Tolerance

A common feature of microorganisms that cause chronic infections is a stealthy lifestyle that promotes immune avoidance and host tolerance. During chronic colonization of cystic fibrosis (CF) patients, Pseudomonas aeruginosa acquires numerous adaptations that include reduced expression of some factors, such as motility, O antigen, and the T3SS, and increased expression of other traits, such as biofilm formation.

scholarly journals 2,3-Dihydroxybenzoic Acid-Containing Nanofiber Wound Dressings Inhibit Biofilm Formation by Pseudomonas aeruginosa

2014 ◽  
Vol 58 (4) ◽  
pp. 2098-2104 ◽  
Author(s):  
Jayesh J. Ahire ◽  
Leon M. T. Dicks
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Iron Chelator ◽  
Wound Dressings ◽  
Tissue Destruction ◽  
Dihydroxybenzoic Acid ◽  
Chronic Infections ◽  
Content Type ◽  
Cell Numbers ◽  
Time Required

ABSTRACTPseudomonas aeruginosaforms biofilms in wounds, which often leads to chronic infections that are difficult to treat with antibiotics. Free iron enhances biofilm formation, delays wound healing, and may even be responsible for persistent inflammation, increased connective tissue destruction, and lipid peroxidation. Exposure ofP. aeruginosaXen 5 to the iron chelator 2,3-dihydroxybenzoic acid (DHBA), electrospun into a nanofiber blend of poly(d,l-lactide) (PDLLA) and poly(ethylene oxide) (PEO), referred to as DF, for 8 h decreased biofilm formation by approximately 75%. This was shown by a drastic decline in cell numbers, from 7.1 log10CFU/ml to 4.8 log10CFU/ml when biofilms were exposed to DF in the presence of 2.0 mM FeCl36H2O. A similar decline in cell numbers was recorded in the presence of 3.0 mM FeCl36H2O and DF. The cells were more mobile in the presence of DHBA, supporting the observation of less biofilm formation at lower iron concentrations. DHBA at MIC levels (1.5 mg/ml) inhibited the growth of strain Xen 5 for at least 24 h. Our findings indicate that DHBA electrospun into nanofibers inhibits cell growth for at least 4 h, which is equivalent to the time required for all DHBA to diffuse from DF. This is the first indication that DF can be developed into a wound dressing to treat topical infections caused byP. aeruginosa.

scholarly journals Signal Sensing and Transduction Are Conserved between the Periplasmic Sensory Domains of BifA and SagS

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Jozef Dingemans ◽  
Rebecca E. Al-Feghali ◽  
Holger Sondermann ◽  
Karin Sauer
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Structural Similarity ◽  
Opportunistic Pathogen ◽  
Sequence Conservation ◽  
Sensor Kinase ◽  
Antibiotic Tolerance ◽  
Bacterial Cells ◽  
Chronic Infections ◽  
Content Type

ABSTRACT The hybrid sensor kinase SagS of Pseudomonas aeruginosa plays a key role in the transition from the planktonic to the biofilm mode of growth. Recently, we have shown that distinct sets of residues in its periplasmic HmsP sensory domain are involved in the regulation of biofilm formation or antibiotic tolerance. Interestingly, the HmsP domain of the phosphodiesterase BifA shows great predicted structural similarity to that of SagS, despite moderate sequence conservation and only a number of residues involved in SagS signaling being conserved between both proteins. Based on this observation, we hypothesized that BifA and SagS may use similar mechanisms to sense and transduce signals perceived at their periplasmic HmsP domains and, therefore, may be interchangeable. To test this hypothesis, we constructed SagS hybrids in which the HmsP domain of SagS was replaced by that of BifA (and vice versa) or by the DISMED2 sensory domain of NicD. The SagS-BifA hybrid restored attachment and biofilm formation by the ΔbifA mutant. Likewise, while the NicD-SagS hybrid was nonfunctional, the BifA-SagS hybrid partially restored pathways leading to biofilm formation and antibiotic tolerance in a ΔsagS mutant background. Furthermore, alanine substitution of key residues previously associated with the biofilm formation and antibiotic tolerance pathways of SagS impaired signal transduction by the BifA-SagS hybrid in a similar way to SagS. In conclusion, our data indicate that the nature of the sensory domain is important for proper functionality of the cytoplasmic effector domains and that signal sensing and transduction are likely conserved in SagS and BifA. IMPORTANCE Biofilms have been associated with more than 60% of all recalcitrant and chronic infections and can render bacterial cells up to a thousand times more resistant to antibiotics than planktonic cells. Although it is known that the transition from the planktonic to the biofilm mode of growth involves two-component regulatory systems, increased c-di-GMP levels, and quorum sensing systems among others, the exact signaling events that lead to biofilm formation remain unknown. In the opportunistic pathogen Pseudomonas aeruginosa, the hybrid sensor kinase SagS regulates biofilm formation and antibiotic tolerance through two independent pathways via distinct residues in its periplasmic sensory domain. Interestingly, the sensory domains of SagS and BifA show great predicted structural similarity despite moderate sequence conservation. Here we show that the sensory domains of BifA and SagS are functionally interchangeable and that they use a similar mechanism of signal sensing and transduction, which broadens our understanding of how bacteria perceive and transduce signals when transitioning to the biofilm mode of growth.

scholarly journals Tobramycin-Treated Pseudomonas aeruginosa PA14 Enhances Streptococcus constellatus 7155 Biofilm Formation in a Cystic Fibrosis Model System

2015 ◽  
Vol 198 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Katherine E. Price ◽  
Amanda A. Naimie ◽  
Edward F. Griffin ◽  
Charles Bay ◽  
George A. O'Toole
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Deep Sequencing ◽  
Biofilm Formation ◽  
Interspecies Interaction ◽  
Content Type ◽  
Streptococcus Constellatus ◽  
Sequencing Studies ◽  
Airway Cells

ABSTRACTCystic fibrosis (CF) is a human genetic disorder which results in a lung environment that is highly conducive to chronic microbial infection. Over the past decade, deep-sequencing studies have demonstrated that the CF lung can harbor a highly diverse polymicrobial community. We expanded our existingin vitromodel ofPseudomonas aeruginosabiofilm formation on CF-derived airway cells to include this broader set of CF airway colonizers to investigate their contributions to CF lung disease, particularly as they relate to the antibiotic response of the population. Using this system, we identified an interspecies interaction betweenP. aeruginosa, a bacterium associated with declining lung function and worsening disease, andStreptococcus constellatus, a bacterium correlated with the onset of pulmonary exacerbations in CF patients. The growth rate and cytotoxicity ofS. constellatus7155 andP. aeruginosaPA14 were unchanged when grown together as mixed biofilms in the absence of antibiotics. However, the addition of tobramycin, the frontline maintenance therapy antibiotic for individuals with CF, to a mixed biofilm ofS. constellatus7155 andP. aeruginosaPA14 resulted in enhancedS. constellatusbiofilm formation. Through a candidate genetic approach, we showed thatP. aeruginosarhamnolipids were reduced upon tobramycin exposure, allowing forS. constellatus7155 biofilm enhancement, and monorhamnolipids were sufficient to reduceS. constellatus7155 biofilm viability in the absence of tobramycin. While the findings presented here are specific to a biofilm ofS. constellatus7155 andP. aeruginosaPA14, they highlight the potential of polymicrobial interactions to impact antibiotic tolerance in unanticipated ways.IMPORTANCEDeep-sequencing studies have demonstrated that the CF lung can harbor a diverse polymicrobial community. By recapitulating the polymicrobial communities observed in the CF lung and identifying mechanisms of interspecies interactions, we have the potential to select the best therapy for a given bacterial community and reveal potential opportunities for novel therapeutic interventions. Using anin vitromodel of bacterial infection on CF airway cells, we tested how a particular polymicrobial community grows, damages human cells, and responds to antibiotics in single and mixed infections. We describe here the mechanism of an interspecies interaction between two pathogens in the CF lung,P. aeruginosaandS. constellatus, which is potentiated by a commonly prescribed antibiotic, tobramycin.

scholarly journals SuhB Is a Regulator of Multiple Virulence Genes and Essential for Pathogenesis of Pseudomonas aeruginosa

mBio ◽  
2013 ◽  
Vol 4 (6) ◽  
Author(s):  
Kewei Li ◽  
Chang Xu ◽  
Yongxin Jin ◽  
Ziyu Sun ◽  
Chang Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Regulatory Networks ◽  
Virulence Genes ◽  
Chronic Infections ◽  
Content Type ◽  
Factors Associated ◽  
Acute Infections

ABSTRACTDuring initial colonization and chronic infection, pathogenic bacteria encounter distinct host environments. Adjusting gene expression accordingly is essential for the pathogenesis.Pseudomonas aeruginosahas evolved complicated regulatory networks to regulate different sets of virulence factors to facilitate colonization and persistence. The type III secretion system (T3SS) and motility are associated with acute infections, while biofilm formation and the type VI secretion system (T6SS) are associated with chronic persistence. To identify novel regulatory genes required for pathogenesis, we screened aP. aeruginosatransposon (Tn) insertion library and foundsuhBto be an essential gene for the T3SS gene expression. The expression ofsuhBwas upregulated in a mouse acute lung infection model, and loss ofsuhBresulted in avirulence. Suppression of T3SS gene expression in thesuhBmutant is linked to a defective translation of the T3SS master regulator, ExsA. Further studies demonstrated thatsuhBmutation led to the upregulation of GacA and its downstream small RNAs, RsmY and RsmZ, triggering T6SS expression and biofilm formation while inhibiting the T3SS. Our results demonstrate that anin vivo-inducible gene,suhB, reciprocally regulates genes associated with acute and chronic infections and plays an essential role in the pathogenesis ofP. aeruginosa.IMPORTANCEA variety of bacterial pathogens, such asPseudomonas aeruginosa, cause acute and chronic infections in humans. During infections, pathogens produce different sets of virulence genes for colonization, tissue damage, and dissemination and for countering host immune responses. Complex regulatory networks control the delicate tuning of gene expression in response to host environments to enable the survival and growth of invading pathogens. Here we identifiedsuhBas a critical gene for the regulation of virulence factors inP. aeruginosa. The expression ofsuhBwas upregulated during acute infection in an animal model, and mutation ofsuhBrenderedP. aeruginosaavirulent. Moreover, we demonstrate that SuhB is required for the activation of virulence factors associated with acute infections while suppressing virulence factors associated with chronic infections. Our report provides new insights into the multilayered regulatory network of virulence genes inP. aeruginosa.

scholarly journals AraC-Type Regulator Rsp Adapts Staphylococcus aureus Gene Expression to Acute Infection

2015 ◽  
Vol 84 (3) ◽  
pp. 723-734 ◽  
Author(s):  
Tianming Li ◽  
Lei He ◽  
Yan Song ◽  
Amer E. Villaruz ◽  
Hwang-Soo Joo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Regulatory Networks ◽  
Acute Infection ◽  
Toxin Production ◽  
Transcriptional Analysis ◽  
Chronic Infections ◽  
Accessory Gene ◽  
Content Type ◽  
Regulatory Impact

Staphylococcus aureusis an important human pathogen that can cause two categories of severe infections. Acute infections are characterized by pronounced toxin production, while chronic infections often involve biofilm formation. However, it is poorly understood howS. aureuscontrols the expression of genes associated with acute versus biofilm-associated virulence. We here identified an AraC-type transcriptional regulator, Rsp, that promotes the production of key toxins while repressing major biofilm-associated genes and biofilm formation. Genome-wide transcriptional analysis and modeling of regulatory networks indicated that upregulation of the accessory gene regulator (Agr) and downregulation of theicaoperon coding for the biofilm exopolysaccharide polysaccharide intercellular adhesin (PIA) were central to the regulatory impact of Rsp on virulence. Notably, the Rsp protein directly bound to theagrP2andicaADBCpromoters, resulting in strongly increased levels of the Agr-controlled toxins phenol-soluble modulins (PSMs) and alpha-toxin and reduced production of PIA. Accordingly, Rsp was essential for the development of bacteremia and skin infection, representing major types of acuteS. aureusinfection. Our findings give important insight into howS. aureusadapts the expression of its broad arsenal of virulence genes to promote different types of disease manifestations and identify the Rsp regulator as a potential target for strategies to control acuteS. aureusinfection.

scholarly journals Pharmacological Inhibition of the Pseudomonas aeruginosa MvfR Quorum-Sensing System Interferes with Biofilm Formation and Potentiates Antibiotic-Mediated Biofilm Disruption

2017 ◽  
Vol 61 (12) ◽  
Author(s):  
Damien Maura ◽  
Laurence G. Rahme
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Great Promise ◽  
Content Type ◽  
Pharmacological Inhibition ◽  
Sensing System ◽  
Abiotic Surfaces ◽  
Biofilm Disruption ◽  
Antibiofilm Agents

ABSTRACT Pseudomonas aeruginosa biofilms contribute to its survival on biotic and abiotic surfaces and represent a major clinical threat due to their high tolerance to antibiotics. Therefore, the discovery of antibiofilm agents may hold great promise. We show that pharmacological inhibition of the P. aeruginosa quorum-sensing regulator MvfR (PqsR) using a benzamide-benzimidazole compound interferes with biofilm formation and potentiates biofilm sensitivity to antibiotics. Such a strategy could have great potential against P. aeruginosa persistence in diverse environments.

Sign in / Sign up

Export Citation Format

Share Document