scholarly journals Light-Mediated Decreases in Cyclic di-GMP Levels Inhibit Structure Formation in Pseudomonas aeruginosa Biofilms

2020 ◽  
Vol 202 (14) ◽  
Author(s):  
Lisa Juliane Kahl ◽  
Alexa Price-Whelan ◽  
Lars E. P. Dietrich
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Research Attention ◽  
Content Type ◽  
Dependent Inhibition ◽  
Matrix Production ◽  
Biofilm Development ◽  
The Impact

ABSTRACT Light is known to trigger regulatory responses in diverse organisms, including slime molds, animals, plants, and phototrophic bacteria. However, light-dependent processes in nonphototrophic bacteria, and those of pathogens in particular, have received comparatively little research attention. In this study, we examined the impact of light on multicellular development in Pseudomonas aeruginosa, a leading cause of biofilm-based bacterial infections. We grew P. aeruginosa strain PA14 in a colony morphology assay and found that growth under prolonged exposure to low-intensity blue light inhibited biofilm matrix production and thereby the formation of vertical biofilm structures (i.e., “wrinkles”). Light-dependent inhibition of biofilm wrinkling was correlated with low levels of cyclic di-GMP (c-di-GMP), consistent with the role of this signal in stimulating matrix production. A screen of enzymes with the potential to catalyze c-di-GMP synthesis or degradation identified c-di-GMP phosphodiesterases that contribute to light-dependent inhibition of biofilm wrinkling. One of these, RmcA, was previously characterized by our group for its role in mediating the effect of redox-active P. aeruginosa metabolites called phenazines on biofilm wrinkle formation. Our results suggest that an RmcA sensory domain that is predicted to bind a flavin cofactor is involved in light-dependent inhibition of wrinkling. Together, these findings indicate that P. aeruginosa integrates information about light exposure and redox state in its regulation of biofilm development. IMPORTANCE Light exposure tunes circadian rhythms, which modulate the immune response and affect susceptibility to infection in plants and animals. Though molecular responses to light are defined for model plant and animal hosts, analogous pathways that function in bacterial pathogens are understudied. We examined the response to light exposure in biofilms (matrix-encased multicellular assemblages) of the nonphotosynthetic bacterium Pseudomonas aeruginosa. We found that light at intensities that are not harmful to human cells inhibited biofilm maturation via effects on cellular signals. Because biofilm formation is a critical factor in many types of P. aeruginosa infections, including burn wound infections that may be exposed to light, these effects could be relevant for pathogenicity.

scholarly journals Light-mediated decreases in cyclic di-GMP levels are potentiated by pyocyanin and inhibit structure formation in Pseudomonas aeruginosa biofilms

2019 ◽  
Author(s):  
Lisa Juliane Kahl ◽  
Alexa Price-Whelan ◽  
Lars E. P. Dietrich
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Infections ◽  
Phototrophic Bacteria ◽  
Slime Molds ◽  
Research Attention ◽  
Multicellular Development ◽  
Dependent Inhibition ◽  
Cellular Signal ◽  
Therapeutic Tools ◽  
The Impact

AbstractLight is known to trigger regulatory responses in diverse organisms including slime molds, animals, plants, and phototrophic bacteria. However, light-dependent processes in non-phototrophic bacteria, and those of pathogens in particular, have received comparatively little research attention. In this study, we examined the impact of light on multicellular development in Pseudomonas aeruginosa, a leading cause of biofilm-based bacterial infections, using a colony morphology assay. In this assay, P. aeruginosa strain PA14 grown in the dark forms vertical structures (i.e., “wrinkles”) on the third day of incubation. We found that growth in blue light inhibited wrinkle formation until the fifth day and that this required the phenazine pyocyanin, a redox-active metabolite produced by PA14. Light-dependent inhibition of wrinkling was also correlated with low levels of cyclic di-GMP (c-di-GMP), consistent with the role of this signal in stimulating biofilm matrix production. Though phenazine-null biofilms also showed lower levels of c-di-GMP and subtle effects on wrinkling when grown in the light, their overall levels of c-di-GMP were higher than those of the wild type. This indicates that phenazines and light simultaneously promote c-di-GMP degradation such that c-di-GMP is pushed to a minimum level, yielding a pronounced macroscopic phenotype. A screen of enzymes with the potential to catalyze c-di-GMP synthesis or degradation identified four proteins that contribute to light-dependent inhibition of biofilm wrinkling. Together, these results provide a foundation for understanding the significance of light-dependent regulation in P. aeruginosa.ImportanceThe response to light in non-phototrophic bacteria (i.e., chemotrophs) is relatively understudied in comparison to light-mediated behavior in eukaryotes and phototrophic bacteria. Though they do not depend on light for growth, chemotrophic bacteria could benefit from sensing this cue when it correlates with other parameters that are important for metabolism. In this paper, we describe light-dependent effects on a cellular signal that controls the development of multicellular assemblages, called biofilms, in Pseudomonas aeruginosa. We found that light at intensities that are not harmful to human cells inhibited biofilm maturation. P. aeruginosa is a leading cause of chronic lung infections in people with cystic fibrosis and of hospital-acquired infections. As P. aeruginosa’s recalcitrance to treatment is attributed in part to its facile formation of biofilms, this study provides insight into a mechanism that could be inhibited via new therapeutic tools, such as photodynamic therapy.

scholarly journals Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

2019 ◽  
Vol 202 (8) ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Protective Effects ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

scholarly journals Changes in the Use of Broad-Spectrum Antibiotics after Cefepime Shortage: a Time Series Analysis

2011 ◽  
Vol 56 (2) ◽  
pp. 989-994 ◽  
Author(s):  
C. Plüss-Suard ◽  
A. Pannatier ◽  
C. Ruffieux ◽  
A. Kronenberg ◽  
K. Mühlemann ◽  
...  
Keyword(s):  
Time Series ◽  
Pseudomonas Aeruginosa ◽  
Broad Spectrum ◽  
Interrupted Time Series ◽  
Antibiotic Policy ◽  
Content Type ◽  
Broad Spectrum Antibiotics ◽  
Before And After ◽  
Alternative Antibiotic ◽  
The Impact

ABSTRACTThe original cefepime product was withdrawn from the Swiss market in January 2007 and replaced by a generic 10 months later. The goals of the study were to assess the impact of this cefepime shortage on the use and costs of alternative broad-spectrum antibiotics, on antibiotic policy, and on resistance ofPseudomonas aeruginosatoward carbapenems, ceftazidime, and piperacillin-tazobactam. A generalized regression-based interrupted time series model assessed how much the shortage changed the monthly use and costs of cefepime and of selected alternative broad-spectrum antibiotics (ceftazidime, imipenem-cilastatin, meropenem, piperacillin-tazobactam) in 15 Swiss acute care hospitals from January 2005 to December 2008. Resistance ofP. aeruginosawas compared before and after the cefepime shortage. There was a statistically significant increase in the consumption of piperacillin-tazobactam in hospitals with definitive interruption of cefepime supply and of meropenem in hospitals with transient interruption of cefepime supply. Consumption of each alternative antibiotic tended to increase during the cefepime shortage and to decrease when the cefepime generic was released. These shifts were associated with significantly higher overall costs. There was no significant change in hospitals with uninterrupted cefepime supply. The alternative antibiotics for which an increase in consumption showed the strongest association with a progression of resistance were the carbapenems. The use of alternative antibiotics after cefepime withdrawal was associated with a significant increase in piperacillin-tazobactam and meropenem use and in overall costs and with a decrease in susceptibility ofP. aeruginosain hospitals. This warrants caution with regard to shortages and withdrawals of antibiotics.

scholarly journals Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

2015 ◽  
Vol 59 (6) ◽  
pp. 3059-3065 ◽  
Author(s):  
C. Pitart ◽  
F. Marco ◽  
T. A. Keating ◽  
W. W. Nichols ◽  
J. Vila
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistant Mutant ◽  
Fluoroquinolone Resistance ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Impact

ABSTRACTCeftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200Enterobacteriaceaeand 25Pseudomonas aeruginosastrains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistantEnterobacteriaceaestrains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBLEscherichia coli(MIC90of 0.25 mg/liter), ESBLKlebsiella pneumoniae(MIC90of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90of 1 mg/liter), non-ESBLE. coli(MIC90of ≤0.125 mg/liter), non-ESBLK. pneumoniae(MIC90of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistantP. aeruginosastrains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtainedin vitrofrom two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains ofEnterobacteriaceaeandP. aeruginosawere ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affectEnterobacteriaceaeandP. aeruginosasusceptibility to ceftazidime-avibactam; that is, there is no cross-resistance.

Municipal response to the Great Recession

2018 ◽  
Vol 30 (4) ◽  
pp. 384-401 ◽  
Author(s):  
Cary Christian ◽  
Jonathan Bush
Keyword(s):  
Great Recession ◽  
Rural Areas ◽  
Property Tax ◽  
Research Attention ◽  
Content Type ◽  
Service Levels ◽  
The Great Recession ◽  
Financial Condition ◽  
The Impact ◽  
Practical Implications

Purpose The purpose of this paper is to examine the impact of the Great Recession on small- to medium-sized municipalities within the states of Georgia and Florida using a newly developed set of quantitative indices. Design/methodology/approach An examination of the methods and strategies utilized by individual cities to maintain public service levels despite distressed revenues is performed. From the data, performance measures are developed and used to evaluate the efficacy of the various strategies used by the cities. Outcomes of Georgia municipalities were compared to similarly sized Florida municipalities to study how underlying differences in tax structures and economies might have affected those outcomes. Findings Georgia and Florida municipalities relied on very different strategies for surviving the recession and its aftermath. Enterprise activities were critically important in both states with transfers to or from governmental activities rationalized in various ways. While Georgia is generally anti-property tax, more than half the Georgia municipalities relied on property tax increases to survive. Municipalities were unable to count on increased intergovernmental revenues during the recession. Finally, even with a tourist activity advantage, Florida municipalities fared only marginally better during and just after the recession, and fared worse four to six years post-recession. Practical implications The measures developed in this study provide a new, customizable methodology for the evaluation of financial condition that does not require in-depth comparisons to peers. Social implications Small- and medium-sized cities, and especially those in rural areas, are worthy of targeted research to better understand their unique problems. Originality/value This research is novel in utilizing a fiscal condition methodology that can be applied to a single municipality and does not require comparisons to peers for validity. However, it represents a very intuitive and customizable tool for making comparisons between municipalities of any size when such comparisons are desired. Additionally, the focus of this study is on small- to medium-sized municipalities which generally do not receive as much research attention as larger cities.

scholarly journals Pf Filamentous Phage Requires UvrD for Replication in Pseudomonas aeruginosa

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Eriel Martínez ◽  
Javier Campos-Gómez
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Dna Repair ◽  
Dna Helicase ◽  
Filamentous Phage ◽  
Rolling Circle Replication ◽  
Content Type ◽  
Rolling Circle ◽  
Initiator Protein ◽  
Biofilm Development ◽  
Filamentous Phages

ABSTRACT Biofilm development is a key component of the ability of Pseudomonas aeruginosa to evade host immune defenses and resist multiple drugs. Induction of the filamentous phage Pf, which usually is lysogenized in clinical and environmental isolates of P. aeruginosa, plays an important role in biofilm assembly, maturation, and dispersal. Despite the clinical relevance of Pf, the molecular biology of this phage is largely unknown. In this study, we found that rolling circle replication of Pf depends on UvrD, a DNA helicase normally involved in DNA repair. We also identified the initiator protein of Pf and found that it shares structural similarity with that of Vibrio cholerae phages CTXφ and VGJφ, which also use UvrD for replication. Our results reveal that, in addition to DNA repair, UvrD plays an essential role in rolling circle replication of filamentous phages among diverse bacteria genera, adding a new, previously unrecognized function of this accessory helicase. Pf is a lysogenic filamentous phage that promotes biofilm development in Pseudomonas aeruginosa. Pf replicates by a rolling circle replication system which depends on a phage-encoded initiator protein and host factors usually involved in chromosome replication. Rep, an accessory replicative DNA helicase, is crucial for replication of filamentous phages in Escherichia coli. In contrast, here we show that, instead of depending on Rep, Pf replication depends on UvrD, an accessory helicase implicated in DNA repair. In this study, we also identified the initiator protein of Pf and found that it shares similarities with that of Vibrio phages CTXφ and VGJφ, which also depend on UvrD for replication. A structural comparative analysis of the initiator proteins of most known filamentous phages described thus far suggested that UvrD, known as a nonreplicative helicase, is involved in rolling circle replication of filamentous phages in diverse bacteria genera. This report consolidates knowledge on the new role of UvrD in filamentous phage replication, a function previously thought to be exclusive of Rep helicase. IMPORTANCE Biofilm development is a key component of the ability of Pseudomonas aeruginosa to evade host immune defenses and resist multiple drugs. Induction of the filamentous phage Pf, which usually is lysogenized in clinical and environmental isolates of P. aeruginosa, plays an important role in biofilm assembly, maturation, and dispersal. Despite the clinical relevance of Pf, the molecular biology of this phage is largely unknown. In this study, we found that rolling circle replication of Pf depends on UvrD, a DNA helicase normally involved in DNA repair. We also identified the initiator protein of Pf and found that it shares structural similarity with that of Vibrio cholerae phages CTXφ and VGJφ, which also use UvrD for replication. Our results reveal that, in addition to DNA repair, UvrD plays an essential role in rolling circle replication of filamentous phages among diverse bacteria genera, adding a new, previously unrecognized function of this accessory helicase.

scholarly journals Working conditions, health and retirement intentions: a case study of truck drivers

2018 ◽  
Vol 11 (3) ◽  
pp. 114-129 ◽  
Author(s):  
Inês C. Sousa ◽  
Sara Ramos
Keyword(s):  
Working Conditions ◽  
Prolonged Exposure ◽  
Time Pressure ◽  
Psychosocial Support ◽  
Good Health ◽  
Truck Drivers ◽  
Temporal Perspective ◽  
Content Type ◽  
The Impact ◽  
Retirement Intentions

Purpose Being a professional truck driver implies prolonged exposure to physical and psychosocial risks, which can affect health and work ability in the short and long term. The purpose of this paper is to examine the role of working conditions in truck drivers’ perceived health and retirement intentions in a Portuguese transportation company. Design/methodology/approach Using ergonomic work analysis (EWA), this study incorporates document analysis, observation and 16 interviews. Content analysis is applied to interviews’ transcripts. Findings In line with previous research, drivers acknowledged their activity as physically demanding (e.g. static postures, repetitive movements, heavy lifting) and psychologically demanding (e.g. high time pressure, lack of control, lack of work–family balance). Despite that, drivers report themselves to be in good health, with only some complaints related to back and knee pain. However, hard working conditions associated with ageing can contribute to gradual health deterioration, leading them to desire to retire before the legal retirement age. Practical implications The company can promote drivers’ health by creating a unit to provide psychosocial support and career orientation, improving the mentoring programme, and investing in training on occupational risk prevention. Originality/value This study is the first to use EWA to examine the impact of the complex relationship between truck drivers’ work and health in their retirement intentions, adopting a temporal perspective.

Implementation and normalization process of asynchronous video interviewing practices in the hospitality industry

2018 ◽  
Vol 30 (2) ◽  
pp. 685-701 ◽  
Author(s):  
Cynthia Mejia ◽  
Edwin N. Torres
Keyword(s):  
Hospitality Industry ◽  
Selection Process ◽  
New Technology ◽  
Implementation Process ◽  
Structured Interviews ◽  
Research Attention ◽  
Content Type ◽  
Recruitment And Selection ◽  
The Impact ◽  
Normalization Process

Purpose Asynchronous video interviews (AVIs) enable recruiters and job candidates to conduct and review employment interviews at different points in time, promising improved cost and time efficiencies for all users. This research aims to investigate the implementation and normalization process of AVI in the hospitality industry with the unified theory of acceptance and use of technology (UTAUT) and the normalization process theory (NPT) providing theoretical support. Design/methodology/approach Semi-structured interviews have been conducted with hiring managers from three different hospitality companies, which were in different stages of the implementation process. The data have been recorded, transcribed and coded according to the UTAUT and NPT constructs, revealing emergent themes. Findings Five overarching themes emerged: AVI effort and efficiency expectation; augmentation to the interview process; challenges for the applicant; challenges for the recruiter; and issues with applicant interviewing aesthetics. Additional coding and analysis with NPT identified the following in terms of evaluation of the implementation process: participants’ implementation activities showed a tendency to emanate from cognitive participation (relationship work), leading to coherence (sense-making work), followed by collective action (enactment of work/operational work) and finally reflexive monitoring (appraisal work). Practical implications Findings from this research include recommendations for the best practices integrating AVI into the hospitality employee selection process. Originality/value Given the increased demands on the recruitment and selection of talent in the hospitality industry, several organizations have turned to mechanized HR software platforms. The impact of interview modalities and particularly AVI has received limited research attention, thus this study expanded this new stream of literature. Furthermore, this research is among a nascent stream using NPT to evaluate the implementation and normalization of this new technology.

scholarly journals Predictors of Mortality in Bloodstream Infections Caused by Pseudomonas aeruginosa and Impact of Antimicrobial Resistance and Bacterial Virulence

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Raúl Recio ◽  
Mikel Mancheño ◽  
Esther Viedma ◽  
Jennifer Villa ◽  
María Ángeles Orellana ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Resistance ◽  
Multivariate Logistic Regression Analysis ◽  
Empirical Therapy ◽  
Bloodstream Infections ◽  
Multivariate Logistic Regression ◽  
Related Factors ◽  
Content Type ◽  
Crude Mortality ◽  
The Impact

ABSTRACT Whether multidrug resistance (MDR) is associated with mortality in patients with Pseudomonas aeruginosa bloodstream infections (BSI) remains controversial. Here, we explored the prognostic factors of P. aeruginosa BSI with emphasis on antimicrobial resistance and virulence. All P. aeruginosa BSI episodes in a 5-year period were retrospectively analyzed. The impact in early (5-day) and late (30-day) crude mortality of host, antibiotic treatment, and pathogen factors was assessed by multivariate logistic regression analysis. Of 243 episodes, 93 (38.3%) were caused by MDR-PA. Crude 5-day (20%) and 30-day (33%) mortality was more frequent in patients with MDR-PA (34.4% versus 11.3%, P < 0.001 and 52.7% versus 21.3%, P < 0.001, respectively). Early mortality was associated with neutropenia (adjusted odds ratio [aOR], 9.21; 95% confidence interval [CI], 3.40 to 24.9; P < 0.001), increased Pitt score (aOR, 2.42; 95% CI, 1.34 to 4.36; P = 0.003), respiratory source (aOR, 3.23; 95% CI,2.01 to 5.16; P < 0.001), inadequate empirical therapy (aOR, 4.57; 95% CI, 1.59 to 13.1; P = 0.005), shorter time to positivity of blood culture (aOR, 0.88; 95% CI, 0.80 to 0.97; P = 0.010), an exoU-positive genotype (aOR, 3.58; 95% CI, 1.31 to 9.79; P = 0.013), and the O11 serotype (aOR, 3.64; 95% CI, 1.20 to 11.1; P = 0.022). These risk factors were similarly identified for late mortality, along with an MDR phenotype (aOR, 2.18; 95% CI, 1.04 to 4.58; P = 0.040). Moreover, the O11 serotype (15.2%, 37/243) was common among MDR (78.4%, 29/37) and exoU-positive (89.2%, 33/37) strains. Besides relevant clinical variables and inadequate empirical therapy, pathogen-related factors such as an MDR phenotype, an exoU-positive genotype, and the O11 serotype adversely affect the outcome of P. aeruginosa BSI.

scholarly journals Characterization of Temporal Protein Production in Pseudomonas aeruginosa Biofilms

2005 ◽  
Vol 187 (23) ◽  
pp. 8114-8126 ◽  
Author(s):  
Christopher J. Southey-Pillig ◽  
David G. Davies ◽  
Karin Sauer
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Protein Production ◽  
Developmental Stages ◽  
Developmental Process ◽  
Developmental Cycle ◽  
Specific Proteins ◽  
Biofilm Development ◽  
The Impact

ABSTRACT Phenotypic and genetic evidence supporting the notion of biofilm formation as a developmental process is growing. In the present work, we provide additional support for this hypothesis by identifying the onset of accumulation of biofilm-stage specific proteins during Pseudomonas aeruginosa biofilm maturation and by tracking the abundance of these proteins in planktonic and three biofilm developmental stages. The onset of protein production was found to correlate with the progression of biofilms in developmental stages. Protein identification revealed that proteins with similar function grouped within similar protein abundance patterns. Metabolic and housekeeping proteins were found to group within a pattern separate from virulence, antibiotic resistance, and quorum-sensing-related proteins. The latter were produced in a progressive manner, indicating that attendant features that are characteristic of biofilms such as antibiotic resistance and virulence may be part of the biofilm developmental process. Mutations in genes for selected proteins from several protein production patterns were made, and the impact of these mutations on biofilm development was evaluated. The proteins cytochrome c oxidase, a probable chemotaxis transducer, a two-component response regulator, and MexH were produced only in mature and late-stage biofilms. Mutations in the genes encoding these proteins did not confer defects in growth, initial attachment, early biofilm formation, or twitching motility but were observed to arrest biofilm development at the stage of cell cluster formation we call the maturation-1 stage. The results indicated that expression of theses genes was required for the progression of biofilms into three-dimensional structures on abiotic surfaces and the completion of the biofilm developmental cycle. Reverse transcription-PCR analysis confirmed the detectable change in expression of the respective genes ccoO, PA4101, and PA4208. We propose a possible mechanism for the role of these biofilm-specific proteins in biofilm formation.

Sign in / Sign up

Export Citation Format

Share Document