scholarly journals Azithromycin in Pseudomonas aeruginosa Biofilms: Bactericidal Activity and Selection of nfxB Mutants

2009 ◽  
Vol 53 (4) ◽  
pp. 1552-1560 ◽  
Author(s):  
Xavier Mulet ◽  
María D. Maciá ◽  
Ana Mena ◽  
Carlos Juan ◽  
José L. Pérez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bactericidal Activity ◽  
Cross Resistance ◽  
Resistance Development ◽  
Viable Cells ◽  
Knockout Mutants ◽  
Lung Infections ◽  
Selection Of

ABSTRACT Azithromycin (AZM) has shown promising results in the treatment of Pseudomonas aeruginosa chronic lung infections such as those occurring in cystic fibrosis (CF) patients. We evaluated the effect of hypermutation and alginate hyperproduction on the bactericidal activity and resistance development to AZM in P. aeruginosa biofilms. Strains PAO1, its mucA mutant (PAOMA), and their respective mutS-deficient hypermutable derivatives (PAOMS and PAOMSA) were used. Biofilms were incubated with several AZM concentrations for 1, 2, 4, or 7 days, and the numbers of viable cells were determined. During the first 2 days, AZM showed bactericidal activity for all the strains, but in extended AZM incubation for strain PAOMS and especially strain PAOMSA, a marked increased in the number of viable cells was observed, particularly at 4 μg/ml. Biofilms formed by the lineages recovered from the 7-day experiments showed enhanced AZM resistance. Furthermore, most of the independent lineages studied, including those obtained from biofilms treated with AZM concentrations as low as 0.5 μg/ml, showed MexCD-OprJ hyperexpression and mutations in nfxB. The role of nfxB mutation in AZM resistance was further confirmed through the characterization of nfxB and mexD knockout mutants. Results from this work show that, although AZM exhibits bactericidal activity against P. aeruginosa biofilms, resistant mutants are readily selected and that, furthermore, they frequently show cross-resistance to other unrelated antipseudomonal agents such as ciprofloxacin or cefepime but hypersusceptibility to others such as imipenem or tobramycin. Therefore, these results should help guide the selection of appropriate antipseudomonal therapies in CF patients under AZM maintenance treatment.

scholarly journals Role of single and mixed culture of Pseudomonas aeruginosa and Serratia ficaria in utilization of petroleum wastes of Dora- refineries.

2007 ◽  
Vol 4 (4) ◽  
pp. 542-548
Author(s):  
Baghdad Science Journal
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mixed Culture ◽  
Bacterial Culture ◽  
Bacterial Cultures ◽  
Viable Cells ◽  
Nacl Concentration ◽  
Agitated Culture ◽  
Growth Of Bacteria ◽  
Better Than

The ability of single and mixed bacterial culture to utilize Dora-refineries petroleum wastes was compared. Pseudomonas aeruginosa and Serratia ficaria mixed culture consumed the wastes better than the single bacterial cultures. The highest log. number of viable cells in mixed culture was 6.842 , while in single bacterial cultures it was 6.683 and 5.631, respectively. after 3 days in API medium containing the refinery wastes. The effect of some environmental conditions on the degradation of petroleum wastes was studied included aeration , NaCl concentration , pH and temperature. The growth of bacteria in the agitated culture was higher than stagnant culture the log. of cell no. was 6.021 in the first culture. The highest log. of cell no. stagnant culture was 5.771. Pseudomonas aeruginosa AA22 and Serratia ficaria AA39 were able to grow in medium containing 5 , 7 % NaCl , they favorite pH 7. The mixed culture of the two bacteria grew well of 45 oC.

scholarly journals Evidence for the Predisposition of Fungicide-Resistant Isolates of Venturia inaequalis to a Preferential Selection for Resistance to Other Fungicides

2001 ◽  
Vol 91 (8) ◽  
pp. 776-781 ◽  
Author(s):  
Wolfram Köller ◽  
W. F. Wilcox
Keyword(s):  
Fungicide Resistance ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
The United States ◽  
Cross Resistance ◽  
Resistance Development ◽  
Flexible Response ◽  
Sterol Demethylation Inhibitors ◽  
Selection For ◽  
Selection Of

In the United States, populations of the apple scab pathogen Venturia inaequalis have progressed through three consecutive rounds of fungicide resistance development, first to dodine, then to the benzimidazoles, and most recently to the sterol demethylation inhibitors (DMIs). Analysis of extensive monitoring data have to date provided no indication of detectable cross-resistance or partial cross-resistance of V. inaequalis populations to the three unrelated classes of fungicides prior to the selection of resistant subpopulations. However, in this study, resistance to both benomyl and DMIs developed to significantly higher frequencies within the previously established dodine-resistant population than in the population sensitive to dodine. Accelerated selection of phenotypes double resistant to dodine and the DMI fenarimol was apparent over the course of distinct seasons of apple scab management with either dodine or fenarimol. The data provide evidence for an accelerated speed of resistance development among phenotypes of V. inaequalis already resistant to an unrelated fungicide. This finding represents a departure from the previous model, which assumed entirely independent rounds of resistance developments. The data indicate that phenotypes of V. inaequalis might not only be selected for the trait of fungicide resistance but also for traits allowing a more flexible response to changes in the environment where they compete.

Genotypic Characterization of Pseudomonas aeruginosa Isolates from Eyes with Keratitis and Healthy Conjunctival Sacs

2021 ◽  
Author(s):  
Xiubin Ma ◽  
Qing Liu ◽  
Fangying Song ◽  
Yusen Huang
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Group Versus ◽  
Therapeutic Interventions ◽  
Corneal Epithelial ◽  
Go Enrichment ◽  
Polymerase Chain ◽  
Upregulated Genes ◽  
Bacterial Secretion ◽  
Selection Of

Abstract Pseudomonas aeruginosa(P. aeruginosa) was a second most common commensal bacterium in healthy conjunctival sacs. When the corneal epithelial barrier is damaged, P. aeruginosa could cause keratitis, which progresses rapidly and results in corneal perforation and the loss of vision. However, the similarities and differences in characteristics between P. aeruginosa isolates from the eyes with keratitis and those from healthy conjunctival sacs are still poorly understood. In this study, four P. aeruginosa isolates from eyes with keratitis and three P. aeruginosa isolates from healthy conjunctival sacs were obtained, and genotypically characterized using Illumina high-throughput RNA sequencing. A total of 557 differentially expressed genes (DEGs) were found and included 332 upregulated genes and 225 downregulated genes in the keratitis group versus the healthy conjunctival sacs group. Of 557 DEGs, 11 DEGs analyzed with GO enrichment and the KEGG pathway were involved with the bacterial secretion system and pyoverdine metabolism and validated using quantitative reverse-transcription polymerase chain reaction. P. aeruginosa from eyes with keratitis induced more severe corneal infection and higher clinical scores in the mice. These results will contribute to develop alternative therapeutic interventions targeting virulence factors in these DEGs and facilitate the selection of therapeutic strategies.

scholarly journals Role of efflux pump inhibitor in decreasing antibiotic cross-resistance of Pseudomonas aeruginosa in a burn hospital in Iran

2016 ◽  
Vol 10 (06) ◽  
pp. 600-604 ◽  
Author(s):  
Mahshid Talebi-Taher ◽  
َAli Majidpour ◽  
Abbas Gholami ◽  
Samira Rasouli-Kouhi ◽  
Maryam Adabi
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Cross Resistance ◽  
Beta Lactams ◽  
Efflux Pump Inhibitor ◽  
Efflux Pump Inhibitors

Introduction: Multidrug resistance in Pseudomonas aeruginosa may be due to efflux pump overexpression. This study phenotypically examined the role of efflux pump inhibitors in decreasing antibiotic cross-resistance between beta-lactams, fluoroquinolones, and aminoglycosides in P. aeruginosa isolates from burn patients in Iran. Methodology: A total of 91 phenotypically and genotypically confirmed P. aeruginosa samples were studied. Multidrug cross-resistance was determined using the disk diffusion method and minimum inhibitory concentration (MIC) test. The contribution of efflux pumps was determined by investigating MIC reduction assay to markers of beta-lactams, fluoroquinolones, and aminoglycosides in the absence and presence of an efflux pump inhibitor. All the isolates were also tested by polymerase chain reaction for the presence of mexA, mexC, and mexE efflux genes. Results: Of the isolates, 81 (89%) and 83 (91.2%) were multidrug resistant according to the disk diffusion and MIC method, respectively. Cross-resistance was observed in 67 (73.6%) and 68 (74.7%) of isolates according to the disk diffusion and MIC method, respectively. In the presence of the efflux pump inhibitor, twofold or higher MIC reduction to imipenem, cefepime, ciprofloxacin, and gentamicin was observed in 59, 65, 55, and 60 isolates, respectively. Except for two isolates that were negative for mexC, all isolates were positive for mexA, mexC, and mexE genes simultaneously. Conclusion: Efflux pumps could cause different levels of resistance based on their expression in clinical isolates. Early detection of different efflux pumps in P. aeruginosa could allow the use of other antibiotics and efflux pump inhibitors in combination with antibiotic therapy.

scholarly journals Functional Characterization of MigA and WapR: Putative Rhamnosyltransferases Involved in Outer Core Oligosaccharide Biosynthesis of Pseudomonas aeruginosa

2008 ◽  
Vol 190 (6) ◽  
pp. 1857-1865 ◽  
Author(s):  
Karen K. H. Poon ◽  
Erin L. Westman ◽  
Evgeny Vinogradov ◽  
Shouguang Jin ◽  
Joseph S. Lam
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Functional Characterization ◽  
Outer Core ◽  
Resonance Spectroscopy ◽  
Core Oligosaccharide ◽  
Strain Pao1 ◽  
The Core ◽  
O Antigen ◽  
Knockout Mutants

ABSTRACT Pseudomonas aeruginosa lipopolysaccharide (LPS) contains two glycoforms of core oligosaccharide (OS); one form is capped with O antigen through an α-1,3-linked l-rhamnose (l-Rha), while the other is uncapped and contains an α-1,6-linked l-Rha. Two genes in strain PAO1, wapR (PA5000) and migA (PA0705), encode putative glycosyltransferases associated with core biosynthesis. We propose that WapR and MigA are the rhamnosyltransferases responsible for the two linkages of l-Rha to the core. Knockout mutants with mutations in both genes were generated. The wapR mutant produced LPS lacking O antigen, and addition of wapR in trans complemented this defect. The migA mutant produced LPS with a truncated outer core and showed no reactivity to outer core-specific monoclonal antibody (MAb) 5C101. Complementation of this mutant with migA restored reactivity of the LPS to MAb 5C101. Interestingly, LPS from the complemented migA strain was not reactive to MAb 18-19 (specific for the core-plus-one O repeat). This was due to overexpression of MigA in the complemented strain that caused an increase in the proportion of the uncapped core OS, thereby decreasing the amount of the core-plus-one O repeat, indicating that MigA has a regulatory role. The structures of LPS from both mutants were elucidated using nuclear magnetic resonance spectroscopy and mass spectrometry. The capped core of the wapR mutant was found to be truncated and lacked α-1,3-l-Rha. In contrast, uncapped core OS from the migA mutant lacked α-1,6-l-Rha. These results provide evidence that WapR is the α-1,3-rhamnosyltransferase, while MigA is the α-1,6-rhamnosyltransferase.

Characterization of the role of global regulator FliA in the pathophysiology of Pseudomonas aeruginosa infection

2018 ◽  
Vol 169 (3) ◽  
pp. 135-144 ◽  
Author(s):  
Yi-Ling Lo ◽  
Chyi-Liang Chen ◽  
Lunda Shen ◽  
Ying-Ching Chen ◽  
Yi-Hsin Wang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Global Regulator ◽  
Pseudomonas Aeruginosa Infection

scholarly journals Structural and Genetic Characterization of Glycosylation of Type a Flagellin in Pseudomonas aeruginosa

2004 ◽  
Vol 186 (9) ◽  
pp. 2523-2531 ◽  
Author(s):  
M. Schirm ◽  
S. K. Arora ◽  
A. Verma ◽  
E. Vinogradov ◽  
P. Thibault ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Gene Cluster ◽  
Genetic Characterization ◽  
Type A ◽  
Protein Backbone ◽  
Central Surface

ABSTRACT Type a flagellins from two strains of Pseudomonas aeruginosa, strains PAK and JJ692, were found to be glycosylated with unique glycan structures. In both cases, two sites of O-linked glycosylation were identified on each monomer, and these sites were localized to the central, surface-exposed domain of the monomer in the assembled filament. The PAK flagellin was modified with a heterogeneous glycan comprising up to 11 monosaccharide units that were O linked through a rhamnose residue to the protein backbone. The flagellin of JJ692 was less complex and had a single rhamnose substitution at each site. The role of the glycosylation island gene cluster in the production of each of these glycosyl moieties was investigated. These studies revealed that the orfA and orfN genes were required for attachment of the heterologous glycan and the proximal rhamnose residue, respectively.

scholarly journals Characterization of Imipenem Unsusceptible Pseudomonas Aeruginosa Isolates from Inpatients without Carbapenem Treatment

2013 ◽  
Vol 2 (1) ◽  
pp. 1-5
Author(s):  
Yi-hai Gu ◽  
Xiao Zhu ◽  
Jing-yun Li ◽  
Jun Zhang ◽  
Qing-yuan Zhou ◽  
...  
Keyword(s):  
Risk Factors ◽  
Pseudomonas Aeruginosa ◽  
Wide Spectrum ◽  
Mechanism Analysis ◽  
Antimicrobial Susceptibility Test ◽  
Resistance Development ◽  
Carbapenem Resistant ◽  
Drug Classes ◽  
Imipenem Resistance

Abstract Objective To identify the risk factors for imipenem resistance development and transmission of clinical Pseudomonas aeruginosa isolates. Methods Thirty-seven imipenem unsusceptible Pseudomonas aeruginosa isolates collected from patients in absence of carbapenem treatment were characterized by antimicrobial susceptibility test, pulsed field gel electrophoresis (PFGE) and carbapenem resistant mechanism analysis. Results Before the collection of imipenem unsusceptible Pseudomonas aeruginosa isolates, the average time of patients treated with more than one antimicrobial (20.0 ± 9.5 days, n = 16) was significantly longer than those treated with only one antimicrobial (12.6 ± 4.4 days, n = 21; t-test, Welch, t = -2.9004, P < 0.01). And 32 isolates showed resistance to more than 3 classes of antimicrobials. Six PFGE clusters were identified and 26 isolates were grouped into one dominant cluster (C2). An ISpa1328 sequence insertion in oprD was detected in 33 isolates and the function of efflux was observed in all 37 isolates in the presence of a wide spectrum efflux inhibitor. Conclusions Our data demonstrated that exposure to non-carbapenem drug classes, especially fluoroquinolones and β-lactams, may be important risk factors for the spread of carbapenem resistant Pseudomonas aeruginosa.

scholarly journals Section 2: Patient Records: Integrating Bioinformatics into Clinical Practice: Progress and Evaluation

2007 ◽  
Vol 16 (01) ◽  
pp. 106-108
Author(s):  
E. Lang ◽  
Keyword(s):  
Reference Data ◽  
Careful Evaluation ◽  
Ongoing Research ◽  
New Methods ◽  
Excellent Research ◽  
Bioinformatic Approaches ◽  
Evaluation Of Methods ◽  
Selection Of

SummaryTo summarize current excellent research in the field of bioinformatics.Synopsis of the articles selected for the IMIA Yearbook 2007.Current research in the field of bioinformatics is characterized by careful evaluation of methods and by improved integration of methods into clinical workflows. Ongoing research on genetic causes of diseases is performed on more and better sources of reference data (genome sets and respective annotations), but is still hampered by insufficient, lacking or biased patient data. The application area of bioinformatics has been broadened, leading to amendment or even replacement of traditional methods in fields like characterization of microorganisms. Researchers carry out thorough statistical analyses in order to ensure quality and methodological correctness of new methods based on bioinformatic approaches which are more and more competitive compared to well-established techniques.The best paper selection of articles on bioinformatics shows examples of excellent research on methods concerning original development as well as quality assurance of previously reported studies. The crucial role of reliable and comprehensive data sources is affirmed, while technical development draws attention to the increasing problem of comparability of data derived some years ago with weaker equipment and those that are of up-to-date quality.

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