The role of pgaC in Klebsiella pneumoniae virulence and biofilm formation

2014 ◽  
Vol 77 ◽  
pp. 89-99 ◽  
Author(s):  
Kuang-Ming Chen ◽  
Ming-Ko Chiang ◽  
Meilin Wang ◽  
Han-Chen Ho ◽  
Min-Chi Lu ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation

scholarly journals Role of type 1 and type 3 fimbriae in Klebsiella pneumoniae biofilm formation

2010 ◽  
Vol 10 (1) ◽  
pp. 179 ◽  
Author(s):  
Casper Schroll ◽  
Kim B Barken ◽  
Karen A Krogfelt ◽  
Carsten Struve
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Type 3

scholarly journals oxyR, a LysR-Type Regulator Involved in Klebsiella pneumoniae Mucosal and Abiotic Colonization

2009 ◽  
Vol 77 (12) ◽  
pp. 5449-5457 ◽  
Author(s):  
Claire Hennequin ◽  
Christiane Forestier
Keyword(s):  
Gastrointestinal Tract ◽  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Defense Mechanisms ◽  
In Vitro Assays ◽  
Intestinal Epithelial ◽  
Bacterial Transcription ◽  
Host Interaction

ABSTRACT Colonization of the gastrointestinal tract is the first event in Klebsiella pneumoniae nosocomial infections, followed by colonization of the bladder or respiratory tract or entry into the bloodstream. To survive in the host, bacteria must harbor specific traits and overcome multiple stresses. OxyR is a conserved bacterial transcription factor with a key role both in the upregulation of defense mechanisms against oxidative stress and in pathogenesis by enhancing biofilm formation, fimbrial expression, and mucosal colonization. A homolog of oxyR was detected in silico in the K. pneumoniae sequenced genome and amplified from the LM21 wild-type strain. To determine the role of oxyR in K. pneumoniae host-interaction processes, an oxyR isogenic mutant was constructed, and its behavior was assessed. At concentrations lower than 107 ml−1, oxyR-deficient organisms were easily killed by micromolar concentrations of H2O2 and exhibited typical aerobic phenotypes. The oxyR mutant was impaired in biofilm formation and types 1 and 3 fimbrial gene expression. In addition, the oxyR mutant was unable to colonize the murine gastrointestinal tract, and in vitro assays showed that it was defective in adhesion to Int-407 and HT-29 intestinal epithelial cells. The behavior of the oxyR mutant was also determined under hostile conditions, reproducing stresses encountered in the gastrointestinal environment: deletion of oxyR resulted in higher sensitivity to bile and acid stresses but not to osmotic stress. These results show the pleiotropic role of oxyR in K. pneumoniae gastrointestinal colonization.

scholarly journals Identification of a Conserved Chromosomal Region Encoding Klebsiella pneumoniae Type 1 and Type 3 Fimbriae and Assessment of the Role of Fimbriae in Pathogenicity

2009 ◽  
Vol 77 (11) ◽  
pp. 5016-5024 ◽  
Author(s):  
Carsten Struve ◽  
Martin Bojer ◽  
Karen Angeliki Krogfelt
Keyword(s):  
Klebsiella Pneumoniae ◽  
Gene Cluster ◽  
Virulence Factor ◽  
Biofilm Formation ◽  
Regulatory Gene ◽  
Infection Model ◽  
Type 3

ABSTRACT Type 3 fimbriae are expressed by most clinical Klebsiella pneumoniae isolates and mediate adhesion to host structures in vitro. However, the role of type 3 fimbriae in K. pneumoniae virulence has not been evaluated by use of in vivo infection models. In this study, the type 3 fimbrial gene cluster (mrk) of the clinical isolate C3091 is described in detail. The mrk gene cluster was revealed to be localized in close proximity to the type 1 fimbrial gene cluster. Thus, a 20.4-kb fimbria-encoding region was identified and found to be highly conserved among different K. pneumoniae isolates. Interestingly, a homologue to PecS, known as a global regulator of virulence in Erwinia chrysanthemi, was identified in the fimbria-encoding region. Comparison to the previously characterized plasmid encoded mrk gene cluster revealed significant differences, and it is established here that the putative regulatory gene mrkE is not a part of the chromosomally encoded type 3 fimbrial gene cluster. To evaluate the role of type 3 fimbriae in virulence, a type 3 fimbria mutant and a type 1 and type 3 fimbria double mutant was constructed. Type 3 fimbria expression was found to strongly promote biofilm formation. However, the fimbria mutants were as effective at colonizing the intestine as the wild type, and their virulence was not attenuated in a lung infection model. Also, in a urinary tract infection model, type 3 fimbriae did not influence the virulence, whereas type 1 fimbriae were verified as an essential virulence factor. Thus, type 3 fimbriae were established not to be a virulence factor in uncomplicated K. pneumoniae infections. However, since type 3 fimbriae promote biofilm formation, their role in development of infections in catheterized patients needs to be elucidated.

scholarly journals Role of MrkJ, a Phosphodiesterase, in Type 3 Fimbrial Expression and Biofilm Formation in Klebsiella pneumoniae

2010 ◽  
Vol 192 (15) ◽  
pp. 3944-3950 ◽  
Author(s):  
Jeremiah G. Johnson ◽  
Steven Clegg
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Surface Expression ◽  
Reverse Transcription Pcr ◽  
Genes Encoding ◽  
Bacterial Genes ◽  
Type 3

ABSTRACT Klebsiella pneumoniae is an opportunistic pathogen that has been shown to adhere to human extracellular matrices using the type 3 fimbriae. Introduction of plasmids carrying genes known to alter intracellular cyclic-di-GMP pools in Vibrio parahaemolyticus revealed that these genes also altered type 3 fimbrial surface expression in K. pneumoniae. Immediately adjacent to the type 3 fimbrial gene cluster is a gene, mrkJ, that is related to a family of bacterial genes encoding phosphodiesterases. We identify here a role for MrkJ, a functional phosphodiesterase exhibiting homology to EAL domain-containing proteins, in controlling type 3 fimbria production and biofilm formation in K. pneumoniae. Deletion of mrkJ resulted in an increase in type 3 fimbria production and biofilm formation as a result of the accumulation of intracellular cyclic-di-GMP. This gene was shown to encode a functional phosphodiesterase via restoration of motility in a V. parahaemolyticus strain previously shown to accumulate cyclic-di-GMP and in vitro using phosphodiesterase activity assays. The effect of the mrkJ mutation on type 3 fimbrial expression was shown to be at the level of mrkA gene transcription by using quantitative reverse transcription-PCR. These results reveal a previously unknown role for cyclic-di-GMP in type 3 fimbrial production.

scholarly journals SdiA, a Quorum-Sensing Regulator, Suppresses Fimbriae Expression, Biofilm Formation, and Quorum-Sensing Signaling Molecules Production in Klebsiella pneumoniae

2021 ◽  
Vol 12 ◽  
Author(s):  
Thaisy Pacheco ◽  
Ana Érika Inácio Gomes ◽  
Nathália Maria Gonçalves Siqueira ◽  
Lucas Assoni ◽  
Michelle Darrieux ◽  
...  
Keyword(s):  
Cell Division ◽  
Quorum Sensing ◽  
Klebsiella Pneumoniae ◽  
Mutant Strain ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Bacterial Cells ◽  
Gram Negative

Klebsiella pneumoniae is a Gram-negative pathogen that has become a worldwide concern due to the emergence of multidrug-resistant isolates responsible for various invasive infectious diseases. Biofilm formation constitutes a major virulence factor for K. pneumoniae and relies on the expression of fimbrial adhesins and aggregation of bacterial cells on biotic or abiotic surfaces in a coordinated manner. During biofilm aggregation, bacterial cells communicate with each other through inter- or intra-species interactions mediated by signallng molecules, called autoinducers, in a mechanism known as quorum sensing (QS). In most Gram-negative bacteria, intra-species communication typically involves the LuxI/LuxR system: LuxI synthase produces N-acyl homoserine lactones (AHLs) as autoinducers and the LuxR transcription factor is their cognate receptor. However, K. pneumoniae does not produce AHL but encodes SdiA, an orphan LuxR-type receptor that responds to exogenous AHL molecules produced by other bacterial species. While SdiA regulates several cellular processes and the expression of virulence factors in many pathogens, the role of this regulator in K. pneumoniae remains unknown. In this study, we describe the characterization of sdiA mutant strain of K. pneumoniae. The sdiA mutant strain has increased biofilm formation, which correlates with the increased expression of type 1 fimbriae, thus revealing a repressive role of SdiA in fimbriae expression and bacterial cell adherence and aggregation. On the other hand, SdiA acts as a transcriptional activator of cell division machinery assembly in the septum, since cells lacking SdiA regulator exhibited a filamentary shape rather than the typical rod shape. We also show that K. pneumoniae cells lacking SdiA regulator present constant production of QS autoinducers at maximum levels, suggesting a putative role for SdiA in the regulation of AI-2 production. Taken together, our results demonstrate that SdiA regulates cell division and the expression of virulence factors such as fimbriae expression, biofilm formation, and production of QS autoinducers in K. pneumoniae.

scholarly journals The In Vitro Ability of Klebsiella pneumoniae to Form Biofilm and the Potential of Various Compounds to Eradicate it from Urinary Catheters

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 42
Author(s):  
Monika Oleksy-Wawrzyniak ◽  
Adam Junka ◽  
Malwina Brożyna ◽  
Migdał Paweł ◽  
Bartłomiej Kwiek ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
High Frequency ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Flow Conditions ◽  
Urinary Infections ◽  
Efficient Reduction ◽  
Intraspecies Variability

Urinary infections related to the presence of bacterial biofilm on catheters are responsible for loss of patients’ health and, due to their high frequency of occurrence, generate a significant economic burden for hospitals. Klebsiella pneumoniae is a pathogen frequently isolated from this type of infection. In this study, using a cohesive set of techniques performed under stationary and flow conditions, we assessed the ability of 120 K. pneumoniae strains to form biofilm on various surfaces, including catheters, and evaluated the usefulness of clinically applied and experimental compounds to remove biofilm. The results of our study indicate the high impact of intraspecies variability with respect to K. pneumoniae biofilm formation and its susceptibility to antimicrobials and revealed the crucial role of mechanical flushing out of the biofilm from the catheter’s surface with use of locally active antimicrobials. Therefore, our work, although of in vitro character, may be considered an important step in the direction of efficient reduction of K. pneumoniae biofilm-related hospital infections associated with the presence of urine catheters.

Defensive Role of Plant-Derived Secondary Metabolites: Indole and Its’ Derivatives

2020 ◽  
Vol 9 (2) ◽  
pp. 78-88
Author(s):  
Mulugeta Mulat ◽  
Raksha Anand ◽  
Fazlurrahman Khan
Keyword(s):  
Biofilm Formation ◽  
Growth And Development ◽  
Functional Role ◽  
Plant Pathogens ◽  
Bacterial Species ◽  
Indole Derivatives ◽  
Resistance Level ◽  
Defensive Role ◽  
Insect Attack

The diversity of indole concerning its production and functional role has increased in both prokaryotic and eukaryotic systems. The bacterial species produce indole and use it as a signaling molecule at interspecies, intraspecies, and even at an interkingdom level for controlling the capability of drug resistance, level of virulence, and biofilm formation. Numerous indole derivatives have been found to play an important role in the different systems and are reported to occur in various bacteria, plants, human, and plant pathogens. Indole and its derivatives have been recognized for a defensive role against pests and insects in the plant kingdom. These indole derivatives are produced as a result of the breakdown of glucosinolate products at the time of insect attack or physical damages. Apart from the defensive role of these products, in plants, they also exhibit several other secondary responses that may contribute directly or indirectly to the growth and development. The present review summarized recent signs of progress on the functional properties of indole and its derivatives in different plant systems. The molecular mechanism involved in the defensive role played by indole as well as its’ derivative in the plants has also been explained. Furthermore, the perspectives of indole and its derivatives (natural or synthetic) in understanding the involvement of these compounds in diverse plants have also been discussed.

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