scholarly journals Virulence Factors in Hypervirulent Klebsiella pneumoniae

2021 ◽  
Vol 12 ◽  
Author(s):  
Jie Zhu ◽  
Tao Wang ◽  
Liang Chen ◽  
Hong Du
Keyword(s):  
Membrane Proteins ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Virulence Factors ◽  
Outer Membrane Proteins ◽  
Pyogenic Liver Abscess ◽  
Secretion System ◽  
Asian Pacific ◽  
Shed Light ◽  
New Strategies

Hypervirulent Klebsiella pneumoniae (hvKP) has spread globally since first described in the Asian Pacific Rim. It is an invasive variant that differs from the classical K. pneumoniae (cKP), with hypermucoviscosity and hypervirulence, causing community-acquired infections, including pyogenic liver abscess, pneumonia, meningitis, and endophthalmitis. It utilizes a battery of virulence factors for survival and pathogenesis, such as capsule, siderophores, lipopolysaccharide, fimbriae, outer membrane proteins, and type 6 secretion system, of which the former two are dominant. This review summarizes these hvKP-associated virulence factors in order to understand its molecular pathogenesis and shed light on new strategies to improve the prevention, diagnosis, and treatment of hvKP-causing infection.

scholarly journals Roles of OmpA in Type III Secretion System-Mediated Virulence of Enterohemorrhagic Escherichia coli

Pathogens ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1496
Author(s):  
Hidetada Hirakawa ◽  
Kazutomo Suzue ◽  
Ayako Takita ◽  
Haruyoshi Tomita
Keyword(s):  
Escherichia Coli ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Type Iii Secretion ◽  
Parent Strain ◽  
Outer Membrane Proteins ◽  
Type Iii Secretion System ◽  
Bacterial Pathogenesis ◽  
Secretion System ◽  
Enterohemorrhagic Escherichia Coli

Outer membrane proteins are commonly produced by gram-negative bacteria, and they have diverse functions. A subgroup of proteins, which includes OmpA, OmpW and OmpX, is often involved in bacterial pathogenesis. Here we show that OmpA, rather than OmpW or OmpX, contributes to the virulence of enterohemorrhagic Escherichia coli (EHEC) through its type III secretion system (T3SS). Deletion of ompA decreased secretion of the T3SS proteins EspA and EspB; however, the expression level of the LEE genes that encode a set of T3SS proteins did not decrease. The ompA mutant had less abilities to form A/E lesions in host epithelial cells and lyse human red blood cells than the parent strain. Moreover, the virulence of an ompA mutant of Citrobacter rodentium (traditionally used to estimate T3SS-associated virulence in mice) was attenuated. Mice infected with the ompA mutant survived longer than those infected with the parent strain. Furthermore, mice infected with ompA developed symptoms of diarrhea more slowly than mice infected with the parent strain. Altogether, these results suggest that OmpA sustains the activity of the T3SS and is required for optimal virulence in EHEC. This work expands the roles of outer membrane proteins in bacterial pathogenesis.

scholarly journals Energy-Dependent Accumulation of Fluoroquinolones in Quinolone-Resistant Klebsiella pneumoniaeStrains

1998 ◽  
Vol 42 (7) ◽  
pp. 1850-1852 ◽  
Author(s):  
Luis Martínez-Martínez ◽  
Isabel García ◽  
Sofía Ballesta ◽  
Vicente Javier Benedí ◽  
Santiago Hernández-Allés ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Clinical Isolates ◽  
Intracellular Accumulation ◽  
Active Efflux ◽  
Energy Dependent ◽  
Isogenic Strains

The intracellular accumulation of norfloxacin and pefloxacin inKlebsiella pneumoniae was evaluated. The roles of lipopolysaccharide, capsule, and outer membrane proteins were not important for the intrabacterial accumulation of fluoroquinolones in isogenic strains with known outer membrane alterations. In fluoroquinolone-resistant clinical isolates also expressing GyrA alterations, an active efflux leading to decreased accumulation of the drugs enhanced their resistance to these agents.

scholarly journals Resistance of Klebsiella Pneumoniae clinical isolates: linkage of outer membrane proteins (omps) with production esbls

2011 ◽  
Vol 42 (2) ◽  
pp. 467-469
Author(s):  
Lívia Érika Carlos Marques ◽  
Danielle Ferreira de Oliveira ◽  
Márcia Maria Mendes Marques ◽  
Ana Raquel Araújo da Silva ◽  
Carlucio Roberto Alves ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Clinical Isolates

scholarly journals Surface Antigen Exposure by Bismuth Dimercaprol Suppression of Klebsiella pneumoniae Capsular Polysaccharide

1999 ◽  
Vol 67 (2) ◽  
pp. 664-669 ◽  
Author(s):  
Philip Domenico ◽  
J. M. Tomas ◽  
S. Merino ◽  
X. Rubires ◽  
Burke A. Cunha
Keyword(s):  
Membrane Proteins ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Capsular Polysaccharide ◽  
Outer Membrane Proteins ◽  
Defined Medium ◽  
Phagocytic Index ◽  
Dependent Manner ◽  
O Antigen ◽  
Bacterial Capsule

ABSTRACT The bacterial capsule is an important virulence determinant in animal and plant disease. Bacterial capsule and slime can be inhibited by bismuth compounds, especially when complexed with lipophilic thiol chelators. Bismuth dimercaprol (BisBAL) at 1 ppm of Bi3+repressed Klebsiella pneumoniae capsule expression in defined medium by nearly 90%, which exposed subsurface structures. The phagocytic index for BisBAL-treated bacteria increased from <10 to 360 bacteria per 100 neutrophils in the presence of complement and anticapsular or anti-O antigen antiserum. BisBAL treatment also enhanced the reactivity of monoclonal antibodies (MAbs) specific for the O1-antigen lipopolysaccharide (LPS) or the LPS core in a dose-dependent manner as indicated by the results of enzyme-linked immunosorbent assays. When anti-O1 MAb was used, the reactivity increased significantly for fully encapsulated O1:K1 or O1:K2 cells but not for O1:K− cells. Deposition of C3b also increased significantly for BisBAL-treated O1:K1 or O1:K2 cells but not for O1:K− cells. Survival of a serum-sensitive strain was <0.1% when nonimmune human serum absorbed with O1:K1 cells was used and 107% when BisBAL-treated cells were used for absorption. Outer membrane proteins were also more accessible on the surface of K. pneumoniae after BisBAL treatment. Thus, at subinhibitory levels, BisBAL inhibited capsule expression, which promoted phagocytosis, enhanced the reactivity of specific antibodies for LPS O antigen, LPS core epitopes, or outer-membrane proteins, and enhanced complement interaction with encapsulated K. pneumoniae. By unmasking bacterial surface structures and enhancing the immune system reactivity to bacteria, bismuth thiols may prove useful as adjuncts for vaccination.

scholarly journals A putative multicopper protein secreted by an atypical type II secretion system involved in the reduction of insoluble electron acceptors in Geobacter sulfurreducens

Microbiology ◽  
2006 ◽  
Vol 152 (8) ◽  
pp. 2257-2264 ◽  
Author(s):  
Teena Mehta ◽  
Susan E. Childers ◽  
Richard Glaven ◽  
Derek R. Lovley ◽  
Tünde Mester
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Secretion System ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Oxide Reduction ◽  
Type Ii Secretion System

Extracellular electron transfer onto Fe(III) oxides in Geobacter sulfurreducens is considered to require proteins that must be exported to the outer surface of the cell. In order to investigate this, the putative gene for OxpG, the pseudopilin involved in a type II general secretion pathway of Gram-negative bacteria, was deleted. The mutant was unable to grow with insoluble Fe(III) oxide as the electron acceptor. Growth on soluble Fe(III) was not affected. An analysis of proteins that accumulated in the periplasm of the oxpG mutant, but not in the wild-type, led to the identification of a secreted protein, OmpB. OmpB is predicted to be a multicopper protein, with highest homology to the manganese oxidase, MofA, from Leptothrix discophora. OmpB contains a potential Fe(III)-binding site and a fibronectin type III domain, suggesting a possible role for this protein in accessing Fe(III) oxides. OmpB was localized to the membrane fraction of G. sulfurreducens and in the supernatant of growing cultures, consistent with the type II secretion system exporting OmpB. A mutant in which ompB was deleted had the same phenotype as the oxpG mutant, suggesting that the failure to export OmpB was responsible for the inability of the oxpG-deficient mutant to reduce Fe(III) oxide. This is the first report that proposes a role for a multicopper oxidase-like protein in an anaerobic organism. These results further emphasize the importance of outer-membrane proteins in Fe(III) oxide reduction and suggest that outer-membrane proteins other than c-type cytochromes are required for Fe(III) oxide reduction in Geobacter species.

scholarly journals Roles of β-Lactamases and Porins in Activities of Carbapenems and Cephalosporins against Klebsiella pneumoniae

1999 ◽  
Vol 43 (7) ◽  
pp. 1669-1673 ◽  
Author(s):  
Luis Martínez-Martínez ◽  
Alvaro Pascual ◽  
Santiago Hernández-Allés ◽  
Dolores Alvarez-Díaz ◽  
Ana Isabel Suárez ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Carbapenem Resistance ◽  
Clinical Isolates ◽  
Extended Spectrum ◽  
Inoculum Effect

ABSTRACT Two clinical isolates of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae were noted to be less susceptible than expected to imipenem. Both were missing outer membrane proteins that serve as channels for antibiotic entry. The role of β-lactamase in resistance was investigated by eliminating the original ESBL and introducing plasmids encoding various ESBLs and AmpC β-lactamase types, by studying the effect of an increased inoculum, and by evaluating interactions with β-lactamase inhibitors. The contribution of porin deficiency was investigated by restoring a functional ompK36 gene on a plasmid. Plasmids encoding AmpC-type β-lactamases provided resistance to imipenem (up to 64 μg/ml) and meropenem (up to 16 μg/ml) in strains deficient in porins. Carbapenem resistance showed little inoculum effect, was not affected by clavulanate but was blocked by BRL 42715, and was diminished if OmpK36 porin was restored. Plasmids encoding TEM- and SHV-type ESBLs conferred resistance to cefepime and cefpirome, as well as to earlier oxyimino-β-lactams. This resistance was magnified with an increased inoculum, was blocked by clavulanate, and was also lowered by OmpK36 porin restoration. In addition, SHV-2 β-lactamase had a small effect on carbapenem resistance (imipenem MIC, 4 μg/ml, increasing to 16 μg/ml with a higher inoculum) when porins were absent. In K. pneumoniae porin loss can thus augment resistance provided either by TEM- or SHV-type ESBLs or by plasmid-mediated AmpC enzymes to include the latest oxyimino-β-lactams and carbapenems.

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