scholarly journals The Impact of Insertion Sequences on O-Serotype Phenotype and Its O-Locus-Based Prediction in Klebsiella pneumoniae O2 and O1

2020 ◽  
Vol 21 (18) ◽  
pp. 6572
Author(s):  
Daria Artyszuk ◽  
Radosław Izdebski ◽  
Anna Maciejewska ◽  
Marta Kaszowska ◽  
Aleksandra Herud ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Passive Immunization ◽  
In Silico Analysis ◽  
Clinical Isolates ◽  
Insertion Sequences ◽  
O Antigen ◽  
O Antigens ◽  
The Impact ◽  
K Antigen

Klebsiella pneumoniae is a nosocomial pathogen, pointed out by the World Helth Organisation (WHO) as “critical” regarding the highly limited options of treatment. Lipopolysaccharide (LPS, O-antigen) and capsular polysaccharide (K-antigen) are its virulence factors and surface antigens, determining O- and K-serotypes and encoded by O- or K-loci. They are promising targets for antibody-based therapies (vaccines and passive immunization) as an alternative to antibiotics. To make such immunotherapy effective, knowledge about O/K-antigen structures, drift, and distribution among clinical isolates is needed. At present, the structural analysis of O-antigens is efficiently supported by bioinformatics. O- and K-loci-based genotyping by polymerase chain reaction (PCR) or whole genome sequencing WGS has been proposed as a diagnostic tool, including the Kaptive tool available in the public domain. We analyzed discrepancies for O2 serotyping between Kaptive-based predictions (O2 variant 2 serotype) and the actual phenotype (O2 variant 1) for two K. pneumoniae clinical isolates. Identified length discrepancies from the reference O-locus resulted from insertion sequences (ISs) within rfb regions of the O-loci. In silico analysis of 8130 O1 and O2 genomes available in public databases indicated a broader distribution of ISs in rfbs that may influence the actual O-antigen structure. Our results show that current high-throughput genotyping algorithms need to be further refined to consider the effects of ISs on the LPS O-serotype.

scholarly journals Development of a new trend conjugate vaccine for the prevention of Klebsiella pneumoniae

2012 ◽  
Vol 4 (1) ◽  
pp. 33 ◽  
Author(s):  
Tarek A. Ahmad ◽  
Medhat Haroun ◽  
Ahmed A. Hussein ◽  
El Sayed H. El Ashry ◽  
Laila H. El-Sayed
Keyword(s):  
Klebsiella Pneumoniae ◽  
Respiratory Diseases ◽  
Capsular Polysaccharide ◽  
Outer Membrane Proteins ◽  
Immunological Methods ◽  
Easy Method ◽  
O Antigen ◽  
Bacterial Endotoxins ◽  
Tract Infections ◽  
Limited Spectrum

<em>Klebsiella pneumoniae</em> is a major cause of nosocomial pneumonia, septicemia and urinary tract infections, especially in newborns, blood cancer patients, and other immunocompromised candidates. The control of <em>K. pneumoniae</em> is a complicated issue due to its tight pathogenesis. Immuno-prophylactic preparations, especially those directed toward the <em>bacterium</em> O-antigen, showed to be the most successful way to prevent the infection incidence. However, all previously proposed preparations were either of limited spectrum or non-maternal, and hence not targeting the main <em>Klebsiella</em> patients. Moreover, all preparations were directed only to prevent the respiratory diseases due to that pathogen. This article addresses the development of a method originally used to purify the non-capsular bacterial- endotoxins, as a new and easy method for vaccine production against <em>K. pneumoniae</em>. The application of this method was preceded by a biotechnological control of capsular polysaccharide production in <em>K. pneumoniae</em>. The new produced natural conjugate between the bacterial O-antigen and its outer membrane proteins was evaluated by physicochemical and immunological methods to investigate its purity, integrity, safety and immunogenicity. It showed to be pure, stable, safe for use, and able to elicit a protective immunoglobulin titer against different <em>Klebsiella</em> infections. This immune-response proved to be transferable to the offspring of the vaccinated experimental rabbits via placenta.

scholarly journals The Capsular Polysaccharide of Acinetobacter baumannii Is an Obstacle for Therapeutic Passive Immunization Strategies

2017 ◽  
Vol 85 (12) ◽  
Author(s):  
Shun Xin Wang-Lin ◽  
Ruth Olson ◽  
Janet M. Beanan ◽  
Ulrike MacDonald ◽  
Joseph P. Balthasar ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Bactericidal Activity ◽  
Capsular Polysaccharide ◽  
Rapid Development ◽  
Outer Membrane Proteins ◽  
Passive Immunization ◽  
Clinical Isolates ◽  
Content Type ◽  
Resistant Strains

ABSTRACT Acinetobacter baumannii has become an important concern for human health due to rapid development and wide spread of antimicrobial-resistant strains and high mortality associated with the infection. Passive immunizations with antisera targeting outer membrane proteins (OMPs) have shown encouraging results in protecting mice from A. baumannii infection, but monoclonal anti-OMP antibodies have not been developed, and their potential therapeutic properties have not been explored. The goal of this report is to evaluate the antibacterial activity of monoclonal antibodies (MAbs) targeting outer membrane protein A (OmpA) of A. baumannii. Five anti-OmpA MAbs were developed using hybridoma technology and showed strong binding to strain ATCC 19606. However, low antibody binding was observed when they were tested against six clinical isolates, which included extensively drug-resistant strains. In contrast, high binding to an isogenic K1 capsule-negative mutant (AB307.30) was shown, suggesting that capsular polysaccharide mediated the inhibition of MAb binding to OmpA. Anti-OmpA MAbs increased the macrophage-mediated bactericidal activity of AB307.30 but failed to increase phagocytic killing of capsule-positive strains. Capsular polysaccharide was also protective against complement-mediated bactericidal activity in human ascites in the presence and absence of opsonization. Lastly, passive immunization with anti-OmpA MAbs did not confer protection against challenge with AB307-0294, the encapsulated parent strain of AB307.30, in a mouse sepsis infection model. These results reveal the important role of capsule polysaccharide in shielding OmpA and thereby inhibiting anti-OmpA MAb binding to clinical isolates. This property of capsule hindered the therapeutic utility of anti-OmpA MAbs, and it may apply to other conserved epitopes in A. baumannii.

scholarly journals Genetic diversity of capsular polysaccharide biosynthesis in Klebsiella pneumoniae clinical isolates

Microbiology ◽  
2009 ◽  
Vol 155 (12) ◽  
pp. 4170-4183 ◽  
Author(s):  
Hung-Yu Shu ◽  
Chang-Phone Fung ◽  
Yen-Ming Liu ◽  
Keh-Ming Wu ◽  
Ying-Tsong Chen ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Sequence Data ◽  
Gene Clusters ◽  
Epidemiological Studies ◽  
Clinical Isolates ◽  
Polysaccharide Biosynthesis ◽  
Bacterial Surface ◽  
Polysaccharide Synthesis ◽  
Hospital Acquired

Klebsiella pneumoniae is an enteric pathogen causing community-acquired and hospital-acquired infections in humans. Epidemiological studies have revealed significant diversity in capsular polysaccharide (CPS) type and clinical manifestation of K. pneumoniae infection in different geographical areas of the world. We have sequenced the capsular polysaccharide synthesis (cps) region of seven clinical isolates and compared the sequences with the publicly available cps sequence data of five strains: NTUH-K2044 (K1 serotype), Chedid (K2 serotype), MGH78578 (K52 serotype), A1142 (K57 serotype) and A1517. Among all strains, six genes at the 5′ end of the cps clusters that encode proteins for CPS transportation and processing at the bacterial surface are highly similar to each other. The central region of the cps gene clusters, which encodes proteins for polymerization and assembly of the CPS subunits, is highly divergent. Based on the collected sequence, we found that either the wbaP gene or the wcaJ gene exists in a given K. pneumoniae strain, suggesting that there is a major difference in the CPS biosynthesis pathway and that the K. pneumoniae strains can be classified into at least two distinct groups. All isolates contain gnd, encoding gluconate-6-phosphate dehydrogenase, at the 3′ end of the cps gene clusters. The rmlBADC genes were found in CPS K9-positive, K14-positive and K52-positive strains, while manC and manB were found in K1, K2, K5, K14, K62 and two undefined strains. Our data indicate that, while overall genomic organization is similar between different pathogenic K. pneumoniae strains, the genetic variation of the sugar moiety and polysaccharide linkage generate the diversity in CPS molecules that could help evade host immune attack.

scholarly journals Development of Resistance during Antimicrobial Therapy Caused by Insertion Sequence Interruption of Porin Genes

1999 ◽  
Vol 43 (4) ◽  
pp. 937-939 ◽  
Author(s):  
Santiago Hernández-Allés ◽  
Vicente J. Benedí ◽  
Luis Martínez-Martínez ◽  
Álvaro Pascual ◽  
Alicia Aguilar ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Antimicrobial Therapy ◽  
Insertion Sequence ◽  
Common Type ◽  
Clinical Isolates ◽  
Insertion Sequences ◽  
Development Of Resistance

ABSTRACT We have demonstrated by using an in vitro approach that interruption of the OmpK36 porin gene by insertion sequences (ISs) is a common type of mutation that causes loss of porin expression and increased resistance to cefoxitin in Klebsiella pneumoniae. This mechanism also operates in vivo: of 13 porin-deficient cefoxitin-resistant clinical isolates ofK. pneumoniae, 4 presented ISs in their ompK36gene.

scholarly journals Investigation of the Antibacterial Activity and Efflux Pump Inhibitory Effect of Cycas thouarsii R.Br. Extract against Klebsiella pneumoniae Clinical Isolates

2021 ◽  
Vol 14 (8) ◽  
pp. 756
Author(s):  
Walaa A. Negm ◽  
Mona El-Aasr ◽  
Amal Abo Kamer ◽  
Engy Elekhnawy
Keyword(s):  
Antibacterial Activity ◽  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Membrane Integrity ◽  
Membrane Depolarization ◽  
Clinical Isolates ◽  
Resistant Bacteria ◽  
Outer Membrane Permeability ◽  
The Impact

The vast spread of multidrug-resistant bacteria has encouraged researchers to explore new antimicrobial compounds. This study aimed to investigate the phytochemistry and antibacterial activity of Cycas thouarsii R.Br. leaves extract against Klebsiella pneumoniae clinical isolates. The minimum inhibitory concentration (MIC) values of C. thouarsii extract ranged from 4 to 32 µg/mL. The impact of the treatment of the isolates with sub-inhibitory concentrations of C. thouarsii extract was investigated on the bacterial growth, membrane integrity, inner and outer membrane permeability, membrane depolarization, and bacterial morphology using a scanning electron microscope (SEM) and on the efflux activity using qRT-PCR. Interestingly, most K. pneumoniae isolates treated with C. thouarsii extract showed growth inhibition—a decrease in membrane integrity. In addition, we observed various morphological changes, a significant increase in inner and outer membrane permeability, a non-significant change in membrane depolarization, and a decrease in efflux activity after treatment. The phytochemical investigation of C. thouarsii extract revealed the isolation of one new biflavonoid, 5,7,7”,4”’-tetra-O-methyl-hinokiflavone (3), and five known compounds, stigmasterol (1), naringenin (2), 2,3-dihydrobilobetin (4), 4’,4’’’-O-dimethyl amentoflavone (5), and hinokiflavone (6), for the first time. Moreover, the pure compounds’ MICs’ ranged from 0.25 to 2 µg/mL. Thus, C. thouarsii could be a potential source for new antimicrobials.

scholarly journals The impact of Grammosciadium platycarpum Boiss. & Hausskn. extract on oqxA efflux pump gene expression in antibiotic resistant clinical isolates of Klebsiella pneumoniae using real time PCR

2020 ◽  
Vol 19 (75) ◽  
pp. 291-304
Author(s):  
Faezeh Mohammadpour Bishak ◽  
Fatemeh Ashrafi ◽  
Soheila Moradi Bidhendi ◽  
Amir Mirzaie ◽  
Hassan Noorbazargan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Klebsiella Pneumoniae ◽  
Real Time ◽  
Real Time Pcr ◽  
Efflux Pump ◽  
Clinical Isolates ◽  
Antibiotic Resistant ◽  
The Impact

scholarly journals Diversity of Capsular Polysaccharide Gene Clusters in Kpc-Producing Klebsiella pneumoniae Clinical Isolates of Sequence Type 258 Involved in the Italian Epidemic

PLoS ONE ◽  
2014 ◽  
Vol 9 (5) ◽  
pp. e96827 ◽  
Author(s):  
Marco Maria D’Andrea ◽  
Francesco Amisano ◽  
Tommaso Giani ◽  
Viola Conte ◽  
Nagaia Ciacci ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Capsular Polysaccharide ◽  
Gene Clusters ◽  
Sequence Type ◽  
Clinical Isolates

scholarly journals Antibiogram Typing and Biochemical Characterization of Klebsiella pneumoniae after Biofield Treatment

2017 ◽  
Author(s):  
Dahryn Trivedi
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biochemical Characterization ◽  
Biochemical Study ◽  
Enterobacter Aerogenes ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Control Group ◽  
Biochemical Reactions ◽  
Antimicrobial Sensitivity ◽  
The Impact

Klebsiella pneumoniae (K. pneumoniae) is a common nosocomial pathogen causing respiratory tract (pneumoniae) and blood stream infections. Multidrug-resistant (MDR) isolates of K. pneumoniae infections are difficult to treat in patients in health care settings. Aim of the present study was to determine the impact of Mr. Trivedi’s biofield treatment on four MDR clinical lab isolates (LS) of K. pneumoniae (LS 2, LS 6, LS 7, and LS 14). Samples were divided into two groups i.e. control and biofield treated. Control and treated groups were analyzed for antimicrobial susceptibility pattern, minimum inhibitory concentration (MIC), biochemical study and biotype number using MicroScan Walk-Away® system. The analysis was done on day 10 after biofield treatment as compared with control group. Antimicrobial sensitivity assay showed that there was 46.42% alteration in sensitivity of tested antimicrobials in treated group of MDR K. pneumonia isolates. MIC results showed an alteration in 30% of tested antimicrobials out of thirty after biofield treatment in clinical isolates of K. pneumoniae. An increase in antimicrobial sensitivity and decrease in MIC value was reported (in LS 6) in case of piperacillin/tazobactam and piperacillin. Biochemical study showed a 15.15% change in biochemical reactions as compared to control. A significant change in biotype numbers were reported in all four clinical isolates of MDR K. pneumoniae after biofield treatment as compared to control group. On the basis of changed biotype number after biofield treatment, new organism was identified as Enterobacter aerogenes in LS 2 and LS 14. These results suggest that biofield treatment has a significant effect on altering the antimicrobial sensitivity, MIC values, biochemical reactions and biotype number of multidrug-resistant isolates of K. pneumoniae.

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.

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