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Phytomedicines Targeting Antibiotic Resistance through Quorum Sensing and Biofilm Formation Associated with Acne Vulgaris
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
Isa A. Lambrechts, Namrita Lall
In nature, most microorganisms do not exist as planktonic bacteria floating in a suspension but rather as a biofilm. Biofilms form when populations or communities of bacteria arrange in layers, together with their decomposition and metabolic products, and adhere to abiotic and biotic surfaces such as the wall of the pilosebaceous unit. After the bacteria have adhered to surfaces, they start to secrete polysaccharides in which these bacteria are encased. The extracellular polysaccharide is around 70% of the biofilm mass and is essential for biofilm architecture. The biofilm is comprised of four components: water, extracellular DNA (eDNA), extracellular polysaccharides and cellular byproducts. Extracellular DNA is produced due to quorum sensing and plays a role in biofilm formation, gene transfer, biofilm stabilization and bacterial and biofilm attachment to a stratum. The extracellular polysaccharide is a glycocalyx polymer, which functions as a protective layer that prevents effective concentrations of antimicrobials from entering the microenvironment of the bacteria. Compared to planktonic bacteria, bacteria associated with a biofilm have altered growth and gene expression. It has been found that bacteria inside the biofilm is more resistant to antibiotics (50–500 times more) than planktonic bacteria not associated with a biofilm (Montanaro et al., 2011; Burkhart and Burkhart, 2003; Sandasi et al., 2011; Yarwood and Schlievert, 2003).
Immunization
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Michael F. Para, Susan L. Koletar, Carter L. Diggs
The polysaccharide capsules of encapsulated organisms such as pneumococcus, meningococcus, and Haemophilus influenzae are the virulence factors for those microbes. At one time these vaccines were prepared from whole inactivated microbes. The soluble components of the capsules from these bacteria, however, have been shown to evoke type-specific protective responses as strong as those induced by the whole microbe. The polysaccharide capsule vaccines now in use induce antibodies which protect the recipient by enhancing phagocytosis of the organisms. These vaccines are used primarily to protect people in high risk groups, such as the old and the young. A recently developed subunit vaccine consists of a conjugate of Haemophilus influenzae type B polysaccharide with diphtheria toxoid. The protein toxoid serves as a carrier for the Haemophilus capsular polysaccharide, greatly improving its immunogenicity in infants. This vaccine provides good protection against invasive hemophilus infection in young infants who as a group respond poorly to the unconjugated capsular antigen.
Candidiasis
Published in Rebecca A. Cox, Immunology of the Fungal Diseases, 2020
Judith E. Domer, Emily W. Carrow
Mannan is the major cell surface antigen of Candida.126C. albicans isolates can be divided into two highly cross-reactive serotypes, designated A and B on the basis of that polysaccharide.127C. tropicalis contains cross-reacting antigens as well, which result in its being more closely related to C. albicans serotype A than B.128 Serotyping is of little value diagnostically or epidemiologically, but since mannan is a major surface antigen, some effort has gone into defining its structure and determining the epitope responsible for immunologic specificity. There is an excellent summary of these studies by deRepentigny and Reiss.74After that review was published however, Wirz et al.129 presented a study in which they compared activity of a glucomannan-protein complex (MPPS) with other polysaccharides from Candida and Saccharomyces cerevisiae. The MPPS contained a glucose to mannose ratio of 1:8 and Piccolella et al. had reported previously130 that it contained 3% protein. Individuals with systemic candidiasis had the highest titers in an enzyme-linked immunoassay (ELISA), but there was some overlap in titers with individuals having superficial infections, and patients with superficial infections overlapped with normal subjects. As the authors point out,129 large scale trials with MPPS in carefully defined patient groups are necessary before the clinical usefulness of this polysaccharide can be ascertained.
Efficacy, immunogenicity, and evidence for best-timing of pneumococcal vaccination in splenectomized adults: a systematic review
Published in Expert Review of Vaccines, 2022
Emil Lenzing, Omid Rezahosseini, Stefan Kobbelgaard Burgdorf, Susanne Dam Nielsen, Zitta Barrella Harboe
We included 21 articles; 17 non-randomized studies [17–33], and four randomized clinical studies (Figure 1) [34–37]. All randomized studies were on the polysaccharide vaccines. Of the non-randomized studies, eight were on conjugate vaccines, eight on polysaccharide vaccines, and one was on both. Moreover, five of the non-randomized studies included a healthy control group. Mixed population of splenectomized patients (e.g. hematological malignancies, autoimmune diseases) were included in 11 of the 17 non-randomized studies [17–22,24–26,29,31]. β-thalassemia was the underlying condition in four studies [23,27,28,33]. Trauma was the reason for splenectomy in two studies (Table 1) [30,32]. Three out of the four randomized trials were conducted on β-thalassemia patients (Table 2) [35–37].
Exploring Klebsiella pneumoniae capsule polysaccharide proteins to design multiepitope subunit vaccine to fight against pneumonia
Published in Expert Review of Vaccines, 2022
Jyotirmayee Dey, Soumya Ranjan Mahapatra, S Lata, Shubhransu Patro, Namrata Misra, Mrutyunjay Suar
For the removal of Klebsiella from human lungs, effective host defense mechanisms are required where the surface of bacteria plays an important role. The three major components of the bacterial outer wall that are said to be triggering the immunity include lipopolysaccharide proteins, outer membrane proteins, and proteoglycans [4,9]. Particularly, acidic Capsular Polysaccharide (CPS), historically known as K-antigen, produced by the bacterium, is the major determinant of virulence, survival, pathogenesis, and antibiotic resistance in K. pneumoniae. The polysaccharide capsule is the outermost layer of the cell and protects the bacterium from desiccation, phage, protist predation and can block the phagocytosis [10,11]. Therefore, CPS is considered as a potential target for therapeutic intervention against klebsiella. Reports suggest that biosynthesis of CPS or K-antigen occurring via the Wzx/Wzy-dependent pathway that facilitates the surface expression of CPS can also be a good vaccine/drug target [12,13]. As in this study, the two genes play a vital role in the Wzx/Wzy-dependent pathway hence is highly antigenic for inclusion in vaccine construct. However, till date, no study has been reported to identify potential epitopes from CPS protein as vaccine candidates.
Effect of different salivary glucose concentrations on dual-species biofilms of Candida albicans and Streptococcus mutans
Published in Biofouling, 2021
Arella Cristina Muniz Brito, Isis Morais Bezerra, Maria Heloisa de Souza Borges, Yuri Wanderley Cavalcanti, Leopoldina de Fátima Dantas de Almeida
Measurement of extracellular polysaccharides, soluble (S-EPS) and insoluble (I-EPS), and quantification of the wet weight was performed from 0.8 ml of the biofilm suspension (n = 12 per group). The microtubes with the biofilm suspension were centrifuged at 3,000 rpm (1,300 RCF) for 10 min, at room temperature. The supernatant was used to measure S-EPS, whereas the biofilm precipitate was used to determine the wet weight in previously weighed microtubes and subsequent I-EPS dosage. The polysaccharide extraction and dosage methodology was previously described by Aires et al. (2008). Dosage of S-EPS and I-EPS was performed using the phenol-sulfuric method (Dubois et al. 1956). Aliquots were read at 490 nm and the quantity of S-EPS and I-EPS was calculated by a standard glucose curve of known glucose concentrations.