scholarly journals The Klebsiella pneumoniae wabG Gene: Role inBiosynthesis of the Core Lipopolysaccharide andVirulence

2003 ◽  
Vol 185 (24) ◽  
pp. 7213-7221 ◽  
Author(s):  
Luis Izquierdo ◽  
Núria Coderch ◽  
Nuria Piqué ◽  
Emiliano Bedini ◽  
Maria Michela Corsaro ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Animal Models ◽  
Klebsiella Pneumoniae ◽  
Gene Cluster ◽  
Capsular Polysaccharide ◽  
Outer Core ◽  
Wild Type ◽  
The Core ◽  
Hydrophobic Compounds ◽  
Type Strains

ABSTRACT To determine the function of the wabG gene in the biosynthesis of the core lipopolysaccharide (LPS) of Klebsiella pneumoniae, we constructed wabG nonpolar mutants. Data obtained from the comparative chemical and structural analysis of LPS samples obtained from the wild type, the mutant strain, and the complemented mutant demonstrated that the wabG gene is involved in attachment toα -l-glycero-d-manno-heptopyranose II (l,d-HeppII) at the O-3 position of anα -d-galactopyranosyluronic acid (α-d-GalAp) residue. K. pneumoniae nonpolar wabG mutants were devoid of the cell-attached capsular polysaccharide but were still able to produce capsular polysaccharide. Similar results were obtained with K. pneumoniae nonpolar waaC and waaF mutants, which produce shorter LPS core molecules than do wabG mutants. Other outer core K. pneumoniae nonpolar mutants in the waa gene cluster were encapsulated. K. pneumoniae waaC, waaF, and wabG mutants were avirulent when tested in different animal models. Furthermore, these mutants were more sensitive to some hydrophobic compounds than the wild-type strains. All these characteristics were rescued by reintroduction of the waaC, waaF, and wabG genes from K. pneumoniae.

scholarly journals A Gene, uge, Is Essential for Klebsiella pneumoniae Virulence

2004 ◽  
Vol 72 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Miguel Regué ◽  
Beatriz Hita ◽  
Nuria Piqué ◽  
Luis Izquierdo ◽  
Susana Merino ◽  
...  
Keyword(s):  
Urinary Tract ◽  
Animal Models ◽  
Klebsiella Pneumoniae ◽  
Urinary Tract Infections ◽  
Outer Core ◽  
Single Mutation ◽  
Wild Type ◽  
Core Oligosaccharide ◽  
O Antigen ◽  
Tract Infections

ABSTRACT Klebsiella pneumoniae strains typically express both smooth lipopolysaccharide (LPS) with O antigen molecules and capsule polysaccharide (K antigen) on the surface. A single mutation in a gene that codes for a UDP galacturonate 4-epimerase (uge) renders a strain with the O−:K− phenotype (lack of capsule and LPS without O antigen molecules and outer core oligosaccharide). The uge gene was present in all the K. pneumoniae strains tested. The K. pneumoniae uge mutants were unable to produce experimental urinary tract infections in rats and were completely avirulent in two different animal models (septicemia and pneumonia). Reintroduction of the single uge wild-type gene in the corresponding mutants completely restored the wild-type phenotype (presence of capsule and smooth LPS) independently of the O or K serotype of the wild type. Furthermore, complemented uge mutants recovered the ability to produce experimental urinary tract infections in rats and virulence in the septicemia and pneumonia animal models.

scholarly journals The PTS Components in Klebsiella pneumoniae Affect Bacterial Capsular Polysaccharide Production and Macrophage Phagocytosis Resistance

2021 ◽  
Vol 9 (2) ◽  
pp. 335
Author(s):  
Novaria Sari Dewi Panjaitan ◽  
Yu-Tze Horng ◽  
Chih-Ching Chien ◽  
Hung-Chi Yang ◽  
Ren-In You ◽  
...  
Keyword(s):  
Survival Rate ◽  
Klebsiella Pneumoniae ◽  
Laser Scanning ◽  
Bacterial Resistance ◽  
Capsular Polysaccharide ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Intracellular Bacteria ◽  
Wild Type ◽  
Macrophage Phagocytosis

Capsular polysaccharide (CPS) is a crucial virulence factor for Klebsiella pneumoniae infection. We demonstrated an association of CPS production with two phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTSs). Deficiency of crr, encoding enzyme IIA of PTS, in K. pneumoniae enhanced the transcriptional activities of galF, wzi and gnd, which are in the cps gene cluster, leading to high CPS production. A crr mutant exhibited a higher survival rate in 1% hydrogen peroxide than the wild-type. The crr mutant showed less sensitivity to engulfment by macrophage (RAW 264.7) than the wild-type by observing the intracellular bacteria using confocal laser scanning microscopy (CLSM) and by calculating the colony-forming units (CFU) of intracellular bacteria. After long-term incubation, the survival rate of the intracellular crr mutant was higher than that of the wild-type. Deficiency of crr enhanced the transcriptional activities of etcABC which encodes another putative enzyme II complex of a PTS. Deletion of etcABC in the crr mutant reduced CPS production and the transcriptional activities of galF compared to those of the crr mutant. These results indicated that one PTS component, Crr, represses CPS production by repressing another PTS component, EtcABC, in K. pneumoniae. In addition, PTS plays a role in bacterial resistance to macrophage phagocytosis.

scholarly journals The Sialylated Lipooligosaccharide Outer Core in Campylobacter jejuni Is an Important Determinant for Epithelial Cell Invasion

2008 ◽  
Vol 76 (10) ◽  
pp. 4431-4438 ◽  
Author(s):  
Rogier Louwen ◽  
Astrid Heikema ◽  
Alex van Belkum ◽  
Alewijn Ott ◽  
Michel Gilbert ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Campylobacter Jejuni ◽  
Outer Core ◽  
Wild Type ◽  
Epithelial Cell Lines ◽  
Bacterial Gastroenteritis ◽  
Important Virulence Factor ◽  
Epithelial Invasion ◽  
Type Strains ◽  
Formalin Fixed

ABSTRACT Campylobacter jejuni is a frequent cause of bacterial gastroenteritis worldwide. Lipooligosaccharide (LOS) has been identified as an important virulence factor that may play a role in microbial adhesion and invasion. Here we specifically address the question of whether LOS sialylation affects the interaction of C. jejuni with human epithelial cells. For this purpose, 14 strains associated with Guillain-Barré syndrome (GBS), 34 enteritis-associated strains, the 81-176 reference strain, and 6 Penner serotype strains were tested for invasion of two epithelial cell lines. C. jejuni strains expressing sialylated LOS (classes A, B, and C) invaded cells significantly more frequently than strains expressing nonsialylated LOS (classes D and E) (P < 0.0001). To further explore this observation, we inactivated the LOS sialyltransferase (Cst-II) via knockout mutagenesis in three GBS-associated C. jejuni strains expressing sialylated LOS (GB2, GB11, and GB19). All knockout strains displayed significantly lower levels of invasion than the respective wild types. Complementation of a Δcst-II mutant strain restored LOS sialylation and reset the invasiveness to wild-type levels. Finally, formalin-fixed wild-type strains GB2, GB11 and GB19, but not the isogenic Δcst-II mutants that lack sialic acid, were able to inhibit epithelial invasion by viable GB2, GB11, and GB19 strains. We conclude that sialylation of the LOS outer core contributes significantly to epithelial invasion by C. jejuni and may thus play a role in subsequent postinfectious pathologies.

scholarly journals Role of Lung Epithelial Cells in Defense against Klebsiella pneumoniae Pneumonia

2002 ◽  
Vol 70 (3) ◽  
pp. 1075-1080 ◽  
Author(s):  
Guadalupe Cortés ◽  
Dolores Álvarez ◽  
Carles Saus ◽  
Sebastián Albertí
Keyword(s):  
Epithelial Cells ◽  
Klebsiella Pneumoniae ◽  
Type Strain ◽  
Pathogenic Bacteria ◽  
Wild Type Strain ◽  
Capsular Polysaccharide ◽  
Defense Mechanism ◽  
Lung Epithelial Cells ◽  
Wild Type ◽  
Lung Epithelial

ABSTRACT The airway epithelium represents a primary site for the entry of pathogenic bacteria into the lungs. It has been suggested for many respiratory pathogens, including Klebsiella pneumoniae, that adhesion and invasion of the lung epithelial cells is an early stage of the pneumonia process. We observed that poorly encapsulated K. pneumoniae clinical isolates and an isogenic unencapsulated mutant invaded lung epithelial cells more efficiently than highly encapsulated strains independent of the K type. By contrast, the unencapsulated mutant was completely avirulent in a mouse model of pneumonia, unlike the wild-type strain, which produced pneumonia and systemic infection. Furthermore, the unencapsulated mutant bound more epithelially produced complement component C3 than the wild-type strain. Our results show that lung epithelial cells play a key role as a host defense mechanism against K. pneumoniae pneumonia, using two different strategies: (i) ingestion and control of the microorganisms and (ii) opsonization of the microorganisms. Capsular polysaccharide avoids both mechanisms and enhances the virulence of K. pneumoniae.

scholarly journals In vivo Selection of Imipenem Resistance Among Ceftazidime-Avibactam-Resistant, Imipenem-Susceptible Klebsiella pneumoniae Isolate With KPC-33 Carbapenemase

2021 ◽  
Vol 12 ◽  
Author(s):  
Chunlei Wang ◽  
Jiankang Zhao ◽  
Zhibo Liu ◽  
Aihua Sun ◽  
Lingxiao Sun ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Clinical Significance ◽  
Capsular Polysaccharide ◽  
Selective Pressure ◽  
Dynamic Change ◽  
Wild Type ◽  
First Report ◽  
Emergence Of Resistance

We describe in vivo evolution of carbapenem and ceftazidime-avibactam resistance by analyzing four longitudinal Klebsiella pneumoniae clinical isolates from a patient with pneumonia following antimicrobial treatment. The patient had fever, cough associated with expectoration, and new infiltration was found on the chest CT. Antimicrobial susceptibility was determined, and whole genome sequencing (WGS) was performed to investigate its dynamic change of resistance phenotype. Population analysis profile was performed to investigate the population of Klebsiella pneumoniae. The infection started with a KPC-2-producing K. pneumoniae (ZRKP01, ceftazidime-avibactam-S/carbapenem-R). Then, after ceftazidime-avibactam treatment, the strain switched to D179Y mutant that is KPC-33 (ZRKP02, ceftazidime-avibactam-R/carbapenem-S), which restored carbapenem susceptibility. However, the restored carbapenem susceptibility in vivo was not stable and the subsequent use of imipenem against KPC-33-producing K. pneumoniae infection resulted in a reversion of KPC-2 producers (ZRKP03 and ZRKP04, ceftazidime-avibactam-S/carbapenem-R). Genetic analysis demonstrated that all four K. pneumoniae isolates belonged to sequence type 11and had identical capsular polysaccharide (KL47), identical porin genes, and same plasmid replicon types. Phylogenetic analysis indicated that four K. pneumoniae isolates showed a high degree of relatedness. Single nucleotide polymorphisms analysis indicated that the number of mutations observed in the KPC-33 isolate was more than in the wild-type KPC-2 isolates and the four KPC-Kp isolates evolved from a longitudinal evolution of K. pneumoniae harboring blaKPC-2 gene. This is the first report to observe the in vivo evolution of wild-type KPC-2 to KPC-33 and then the reversion to its original wild-type KPC-2. Through WGS, we demonstrated the role of selective pressure of antibiotic in the mutation and reversion of blaKPC genes, which leading to the dynamic change of KPC enzymes and the dynamic emergence of resistance to ceftazidime-avibactam and carbapenems.Statement: Recently, studies reported the emergence of ceftazidime-avibactam-resistant strains. The KPC mutations mediating ceftazidime-avibactam resistance are generally associated with the restoration of carbapenem susceptibility. However, clinical significance of this observation is unclear. In this manuscript, we demonstrate the role of selective pressure of antibiotic in the mutation and reversion of blaKPC genes, which leading to the dynamic change of KPC enzymes and the dynamic emergence of resistance to ceftazidime-avibactam and carbapenems. To the best of our knowledge, this is the first report to observe the in vivo evolution of wild-type KPC-2 to KPC-33 and then the reversion to its original wild-type KPC-2. It should be noted that understanding the clinical significance of this observation is of critical importance, and reversion to carbapenem susceptibility would not imply a potential role for carbapenems monotherapy. We hope our study will draw attention to clinicians, so that this agent can be used most effectively for the longest period of time.

scholarly journals Klebsiella pneumoniae Capsule Expression Is Necessary for Colonization of Large Intestines of Streptomycin-Treated Mice

1999 ◽  
Vol 67 (11) ◽  
pp. 6152-6156 ◽  
Author(s):  
Sabine Favre-Bonté ◽  
Tine Rask Licht ◽  
Christiane Forestier ◽  
Karen Angeliki Krogfelt
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Bacterial Cells ◽  
Mucus Layer ◽  
Wild Type ◽  
Bacterial Strains ◽  
Gut Colonization ◽  
Defective Mutant ◽  
Polysaccharide K ◽  
Colonization Ability

ABSTRACT The role of the Klebsiella pneumoniae capsular polysaccharide (K antigen) during colonization of the mouse large intestine was assessed with wild-type K. pneumoniae LM21 and its isogenic capsule-defective mutant. When bacterial strains were fed alone to mice, the capsulated bacteria persisted in the intestinal tract at levels of 108 CFU/g of feces while the capsule-defective strain colonized at low levels, 104 CFU/g of feces. In mixed-infection experiments, the mutant was rapidly outcompeted by the wild type. In situ hybridization on colonic sections revealed that bacterial cells of both strains were evenly distributed in the mucus layer at day 1 after infection, while at day 20 the wild type remained dispersed and the capsule-defective strain was seen in clusters in the mucus layer. These results suggest that capsular polysaccharide plays an important role in the gut colonization ability of K. pneumoniae.

Phase variation of F1651 (Prs-like) fimbriae from Escherichia coli causing septicaemia in animals

2000 ◽  
Vol 46 (12) ◽  
pp. 1101-1107 ◽  
Author(s):  
Josée Harel ◽  
France Daigle ◽  
Céline Forget ◽  
Marie-Catherine Tessier ◽  
Cécile Crost ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Regulatory Region ◽  
Phase Variation ◽  
Immunofluorescence Staining ◽  
Wild Type ◽  
Young Pigs ◽  
Dam Methylation ◽  
Structural Subunit ◽  
Type Strains

Escherichia coli O115:F165 strains are associated with septicaemia in young pigs and synthesize fimbriae involved in virulence, designated as F1651. F1651 fimbriae belong to the P fimbrial family and are encoded by the foo gene cluster. The foo regulatory region of strain 5131 possesses characteristics similar to that of members of the P regulatory family, including papI and papB homologues, and two GATC sites separated by 102 bp, targets of differential Dam methylation. In wild-type strains, the synthesis of F1651 is repressed by leucine and the fimbriae undergo phase variation. Immunofluorescence staining showed that phase variation of F1651 results in a majority of cells (98%) in the ON phase, in contrast with phase variation of other members of this regulatory family, for which the majority of the cells are in the OFF state. Using a translational fusion in strain 5131 between phoA and fooA, encoding for the major structural subunit of F1651, it was shown that leucine inhibits the OFF to ON switch and modulates the basal transcription of the foo operon.Key words: Escherichia coli, fimbriae, phase variation, regulation, septicaemia.

scholarly journals Comparison of the Host Responses to Wild-Type and cpsB Mutant Klebsiella pneumoniae Infections

2006 ◽  
Vol 74 (9) ◽  
pp. 5402-5407 ◽  
Author(s):  
Matthew S. Lawlor ◽  
Scott A. Handley ◽  
Virginia L. Miller
Keyword(s):  
Klebsiella Pneumoniae ◽  
Mouse Model ◽  
Type Strain ◽  
Wild Type Strain ◽  
Capsular Polysaccharide ◽  
Cytokine Production ◽  
Host Responses ◽  
Cellular Infiltration ◽  
Wild Type ◽  
Highly Virulent

ABSTRACT Previously, we established an intranasal mouse model of Klebsiella pneumoniae infection and validated its utility using a highly virulent wild-type strain and an avirulent capsular polysaccharide mutant. In the present study we compare the host responses to both infections by examining cytokine production, cellular infiltration, pulmonary histology, and intranasal immunization.

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