scholarly journals Relationship between type III secretion toxins, biofilm formation, and antibiotic resistance in clinical Pseudomonas aeruginosa isolates

2021 ◽  
Vol 11 (6) ◽  
pp. 1075-1082
Author(s):  
S. Derakhshan ◽  
A. Rezaee ◽  
Sh. Mohammadi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Multidrug Resistance ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Virulence Gene ◽  
Microtiter Plate ◽  
P Value ◽  
Type Iii ◽  
Disk Diffusion Assay

Background and aim. Pseudomonas aeruginosa is considered as a notorious pathogen due to its multidrug resistance and life threatening infections. We investigated the relationship between type III secretion toxins, biofilm formation, and antibiotic resistance among clinical P. aeruginosa isolates. Methods. A total of 70 genetically distinct clinical P. aeruginosa isolates were characterized for antibiotic resistance by disk diffusion assay. Biofilm formation was evaluated by microtiter plate method and presence of four exo genes (exoS, exoU, exoT and exoY) was investigated by PCR. A p-value < 0.05 was regarded statistically significant. Results. The most effective antibiotics were Meropenem and Piperacillin. Multidrug resistance was more prevalent in the ciprofloxacin-resistant isolates than in the susceptible isolates. The most frequently identified exo was exoS (37.1%). Genotype exoS/exoT was found in 4 isolates, while genotype exoU/exoT was not found. Prevalence of exoS was generally higher in the susceptible isolates than in the resistant isolates. A significant association was found between the formation of strong biofilm and resistance to antibiotics (p < 0.05). Prevalence of exoY and exoU was higher in the non-strong biofilm producers compared to the strong biofilm producers. Conclusion. Our study revealed formation of strong biofilm along with antibiotic resistance and the presence of exo genes in P. aeruginosa isolates. Knowledge of virulence gene profiles and biofilm formation may be useful in deciding appropriate treatment.

scholarly journals Effects of Glycyrrhizin on Multi-Drug Resistant Pseudomonas aeruginosa

Pathogens ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 766
Author(s):  
Nicholas J. Carruthers ◽  
Sharon A. McClellan ◽  
Mallika Somayajulu ◽  
Ahalya Pitchaikannu ◽  
Denise Bessert ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Inhibitory Concentration ◽  
Drug Resistant ◽  
Liquid Chromatography Mass Spectrometry ◽  
Corneal Epithelial ◽  
Type Iii ◽  
Biofilm Dispersal

The effects of glycyrrhizin (GLY) on multi-drug resistant (MDR) systemic (MDR9) vs. ocular (B1045) Pseudomonas aeruginosa clinical isolates were determined. Proteomes of each isolate with/without GLY treatment were profiled using liquid chromatography mass spectrometry (LC-MS/MS). The effect of GLY on adherence of MDR isolates to immortalized human (HCET) and mouse (MCEC) corneal epithelial cells, and biofilm and dispersal was tested. Both isolates were treated with GLY (0.25 minimum inhibitory concentration (MIC), 10 mg/mL for MDR9 and 3.75 mg/mL for B1045) and subjected to proteomic analysis. MDR9 had a greater response to GLY (51% of identified proteins affected vs. <1% in B1045). In MDR9 vs. controls, GLY decreased the abundance of proteins for: antibiotic resistance, biofilm formation, and type III secretion. Further, antibiotic resistance and type III secretion proteins had higher control abundances in MDR9 vs. B1045. GLY (5 and 10 mg/mL) significantly reduced binding of both isolates to MCEC, and B1045 to HCET. MDR9 binding to HCET was only reduced at 10 mg/mL GLY. GLY (5 and 10 mg/mL) enhanced dispersal for both isolates, at early (6.5 h) but not later times (24–72 h). This study provides evidence that GLY has a greater effect on the proteome of MDR9 vs. B1045, yet it was equally effective at disrupting adherence and early biofilm dispersal.

scholarly journals YbeY controls the type III and type VI secretion systems and biofilm formation through RetS in Pseudomonas aeruginosa

2020 ◽  
Author(s):  
Yushan Xia ◽  
Congjuan Xu ◽  
Dan Wang ◽  
Yuding Weng ◽  
Yongxin Jin ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Small Rnas ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Chronic Infections ◽  
Type Iii ◽  
Type Vi Secretion

YbeY is a highly conserved RNase in bacteria and plays essential roles in the maturation of 16S rRNA, regulation of small RNAs (sRNAs) and bacterial responses to environmental stresses. Previously, we verified the role of YbeY in rRNA processing and ribosome maturation in Pseudomonas aeruginosa and demonstrated YbeY-mediated regulation of rpoS through a sRNA ReaL. In this study, we demonstrate that mutation of the ybeY gene results in upregulation of the type III secretion system (T3SS) genes as well as downregulation of the type VI secretion system (T6SS) genes and reduction of biofilm formation. By examining the expression of the known sRNAs in P. aeruginosa, we found that mutation of the ybeY gene leads to downregulation of the small RNAs RsmY/Z that control the T3SS, the T6SS and biofilm formation. Further studies revealed that the reduced levels of RsmY/Z are due to upregulation of retS. Taken together, our results reveal the pleiotropic functions of YbeY and provide detailed mechanisms of YbeY-mediated regulation in P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa causes a variety of acute and chronic infections in humans. The type III secretion system (T3SS) plays an important role in acute infection and the type VI secretion system (T6SS) and biofilm formation are associated with chronic infections. Understanding of the mechanisms that control the virulence determinants involved in acute and chronic infections will provide clues for the development of effective treatment strategies. Our results reveal a novel RNase mediated regulation on the T3SS, T6SS and biofilm formation in P. aeruginosa.

scholarly journals Correlation of biofilm production with antibiotic susceptibility pattern of Pseudomonas aeruginosa from various clinical specimens

2022 ◽  
Vol 13 (1) ◽  
pp. 88-92
Author(s):  
M Swapna ◽  
G Sumathi ◽  
M Anitha
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Antibiotic Sensitivity ◽  
Microtiter Plate ◽  
Resistance Pattern ◽  
Sensitivity Testing ◽  
Clinical Specimens ◽  
Biofilm Production ◽  
Microbiological Methods

Background: Pseudomonas aeruginosa is one of the most prevalent nosocomial pathogens that cause a life-threatening infection. One of the important characteristics of P. aeruginosa is biofilm formation which leads to antibiotic resistance. Aims and Objectives: The aim of the study was to study the antibiotic resistance pattern of P. aeruginosa isolates and correlation with their biofilm-production. Materials and Methods: A total of 87 P. aeruginosa isolates from different clinical specimens were processed and confirmed by conventional microbiological methods as per standard methodology. Antibiotic sensitivity testing was done for all isolates. Biofilm producing isolates were identified by the microtiter plate method (MTPM). Results: Of 87 P. aeruginosa isolates, majority were from pus 33 (38%), followed by urine 26 (30%), sputum 19 (22%), body fluids 7 (8%), and blood 2 (2%). Biofilm producing isolates showed more resistance in comparison to non-biofilm producers. The observed difference between biofilm formation for multidrug resistant and susceptible isolates was found to be statistically significant. Conclusion: MTPM method was an effective test for detection of biofilm formation and was also able to verify biofilm production by P. aeruginosa. This indicated a higher propensity among the clinical isolates of P. aeruginosa to form biofilm and revealed a positive correlation between biofilm formation and antibiotic resistance. This indicates the need for testing of even susceptible isolates for virulence factors such as biofilm production.

scholarly journals The Pseudomonas aeruginosa Magnesium Transporter MgtE Inhibits Transcription of the Type III Secretion System

2009 ◽  
Vol 78 (3) ◽  
pp. 1239-1249 ◽  
Author(s):  
Gregory G. Anderson ◽  
Timothy L. Yahr ◽  
Rustin R. Lovewell ◽  
George A. O'Toole
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Epithelial Cells ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Bacterial Biofilm ◽  
Magnesium Transport ◽  
Type Iii ◽  
Magnesium Transporter

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes life-long pneumonia in individuals with cystic fibrosis (CF). These long-term infections are maintained by bacterial biofilm formation in the CF lung. We have recently developed a model of P. aeruginosa biofilm formation on cultured CF airway epithelial cells. Using this model, we discovered that mutation of a putative magnesium transporter gene, called mgtE, led to increased cytotoxicity of P. aeruginosa toward epithelial cells. This altered toxicity appeared to be dependent upon expression of the type III secretion system (T3SS). In this study, we found that mutation of mgtE results in increased T3SS gene transcription. Through epistasis analyses, we discovered that MgtE influences the ExsE-ExsC-ExsD-ExsA gene regulatory system of T3SS by either directly or indirectly inhibiting ExsA activity. While variations in calcium levels modulate T3SS gene expression in P. aeruginosa, we found that addition of exogenous magnesium did not inhibit T3SS activity. Furthermore, mgtE variants that were defective for magnesium transport could still complement the cytotoxicity effect. Thus, the magnesium transport function of MgtE does not fully explain the regulatory effects of MgtE on cytotoxicity. Overall, our results indicate that MgtE modulates expression of T3SS genes.

scholarly journals Molecular Basis of Azithromycin-Resistant Pseudomonas aeruginosa Biofilms

2005 ◽  
Vol 49 (9) ◽  
pp. 3858-3867 ◽  
Author(s):  
Richard J. Gillis ◽  
Kimberly G. White ◽  
Kyoung-Hee Choi ◽  
Victoria E. Wagner ◽  
Herbert P. Schweizer ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Dna Microarrays ◽  
Efflux Pumps ◽  
Planktonic Cells ◽  
Specific Mechanism ◽  
Type Iii ◽  
Rnd Efflux Pumps ◽  
Biofilm Development

ABSTRACT Pseudomonas aeruginosa biofilms are extremely recalcitrant to antibiotic treatment. Treatment of cystic fibrosis patients with azithromycin (AZM) has shown promise. We used DNA microarrays to identify differentially expressed transcripts in developing P. aeruginosa biofilms exposed to 2 μg/ml AZM. We report that transcripts for multiple restriction-nodulation-cell division (RND) efflux pumps, known to be involved in planktonic antibiotic resistance, and transcripts involved in type III secretion were upregulated in the resistant biofilms that developed in the presence of AZM. Interestingly, the MexAB-OprM and MexCD-OprJ efflux pumps, but not type III secretion, appear to be integral to biofilm formation in the presence of AZM, as evidenced by the fact that a mutant deleted in both mexAB-oprM and mexCD-oprJ was unable to form a biofilm in the presence of AZM. A mutant deleted in type III secretion was still able to form biofilms in the presence of drug. Furthermore, single mexAB-oprM- and mexCD-oprJ-null mutants were able to form a biofilm in the presence of drug, indicating that either of the pumps can confer resistance to AZM during biofilm development. In contrast to planktonically grown cells, where no mexC expression was detectable regardless of the presence of AZM, biofilms exhibited induction of mexC expression from the outset of their formation, but only in the presence of AZM. mexA, which is constitutively expressed in planktonic cells, was uniformly expressed in biofilms regardless of the presence of AZM. These data indicate that the MexCD-OprJ pump acts as a biofilm-specific mechanism for AZM resistance.

scholarly journals HigB Reciprocally Controls Biofilm Formation and the Expression of Type III Secretion System Genes through Influencing the Intracellular c-di-GMP Level in Pseudomonas aeruginosa

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 424 ◽  
Author(s):  
Yueying Zhang ◽  
Bin Xia ◽  
Mei Li ◽  
Jing Shi ◽  
Yuqing Long ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Regulatory Mechanism ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Regulatory Pathways ◽  
Type Iii

Toxin-antitoxin (TA) systems play important roles in bacteria persister formation. Increasing evidence demonstrate the roles of TA systems in regulating virulence factors in pathogenic bacteria. The toxin HigB in Pseudomonas aeruginosa contributes to persister formation and regulates the expression of multiple virulence factors and biofilm formation. However, the regulatory mechanism remains elusive. In this study, we explored the HigB mediated regulatory pathways. We demonstrate that HigB decreases the intracellular level of c-di-GMP, which is responsible for the increased expression of the type III secretion system (T3SS) genes and repression of biofilm formation. By analyzing the expression levels of the known c-di-GMP metabolism genes, we find that three c-di-GMP hydrolysis genes are up regulated by HigB, namely PA2133, PA2200 and PA3825. Deletion of the three genes individually or simultaneously diminishes the HigB mediated regulation on the expression of T3SS genes and biofilm formation. Therefore, our results reveal novel functions of HigB in P. aeruginosa.

scholarly journals Vfr Directly ActivatesexsATranscription To Regulate Expression of the Pseudomonas aeruginosa Type III Secretion System

2016 ◽  
Vol 198 (9) ◽  
pp. 1442-1450 ◽  
Author(s):  
Anne E. Marsden ◽  
Peter J. Intile ◽  
Kayley H. Schulmeyer ◽  
Ethan R. Simmons-Patterson ◽  
Mark L. Urbanowski ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Virulence Gene ◽  
Type Iv Pili ◽  
Global Regulator ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Type Iii ◽  
Type Iv

ABSTRACTThePseudomonas aeruginosacyclic AMP (cAMP)-Vfr system (CVS) is a global regulator of virulence gene expression. Regulatory targets include type IV pili, secreted proteases, and the type III secretion system (T3SS). The mechanism by which CVS regulates T3SS gene expression remains undefined. Single-cell expression studies previously found that only a portion of the cells within a population express the T3SS under inducing conditions, a property known as bistability. We now report that bistability is altered in avfrmutant, wherein a substantially smaller fraction of the cells express the T3SS relative to the parental strain. Since bistability usually involves positive-feedback loops, we tested the hypothesis that virulence factor regulator (Vfr) regulates the expression ofexsA. ExsA is the central regulator of T3SS gene expression and autoregulates its own expression. AlthoughexsAis the last gene of theexsCEBApolycistronic mRNA, we demonstrate that Vfr directly activatesexsAtranscription from a second promoter (PexsA) located immediately upstream ofexsA. PexsApromoter activity is entirely Vfr dependent. Direct binding of Vfr to a PexsApromoter probe was demonstrated by electrophoretic mobility shift assays, and DNase I footprinting revealed an area of protection that coincides with a putative Vfr consensus-binding site. Mutagenesis of that site disrupted Vfr binding and PexsApromoter activity. We conclude that Vfr contributes to T3SS gene expression through activation of the PexsApromoter, which is internal to the previously characterizedexsCEBAoperon.IMPORTANCEVfr is a cAMP-dependent DNA-binding protein that functions as a global regulator of virulence gene expression inPseudomonas aeruginosa. Regulation by Vfr allows for the coordinate production of related virulence functions, such as type IV pili and type III secretion, required for adherence to and intoxication of host cells, respectively. Although the molecular mechanism of Vfr regulation has been defined for many target genes, a direct link between Vfr and T3SS gene expression had not been established. In the present study, we report that Vfr directly controlsexsAtranscription, the master regulator of T3SS gene expression, from a newly identified promoter located immediately upstream ofexsA.

Biofilms and type III secretion are not mutually exclusive in Pseudomonas aeruginosa

Microbiology ◽  
2009 ◽  
Vol 155 (3) ◽  
pp. 687-698 ◽  
Author(s):  
H. Mikkelsen ◽  
N. J. Bond ◽  
M. E. Skindersoe ◽  
M. Givskov ◽  
K. S. Lilley ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Acute Infection ◽  
Effector Proteins ◽  
Bacterial Biofilm ◽  
Planktonic Cells ◽  
Chronic Infections ◽  
Type Iii

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes acute and chronic infections in immunocompromised individuals. It is also a model organism for bacterial biofilm formation. Acute infections are often associated with planktonic or free-floating cells, high virulence and fast growth. Conversely, chronic infections are often associated with the biofilm mode of growth, low virulence and slow growth that resembles that of planktonic cells in stationary phase. Biofilm formation and type III secretion have been shown to be reciprocally regulated, and it has been suggested that factors related to acute infection may be incompatible with biofilm formation. In a previous proteomic study of the interrelationships between planktonic cells, colonies and continuously grown biofilms, we showed that biofilms under the growth conditions applied are more similar to planktonic cells in exponential phase than to those in stationary phase. In the current study, we investigated how these conditions influence the production of virulence factors using a transcriptomic approach. Our results show that biofilms express the type III secretion system, whereas planktonic cells do not. This was confirmed by the detection of PcrV in the cellular and secreted fractions of biofilms, but not in those of planktonic cells. We also detected the type III effector proteins ExoS and ExoT in the biofilm effluent, but not in the supernatants of planktonic cells. Biofilm formation and type III secretion are therefore not mutually exclusive in P. aeruginosa, and biofilms could play a more active role in virulence than previously thought.

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