Accident and Emergency
Nagi Giumma Barakat in Get Through, 2006
There are six serotypes of polysaccharide on the bacterial capsule. There are other non-typable forms, which are responsible for neonatal infections and some infections in immunocompromised patients. Hib is responsible for 70% of meningitis and 10% of epiglotitis and cellulitus. Osteomyelitis and joint infections are less frequent. Third-generation cephalosporins are the most effective antibiotics, but sensitivity should always be determined when a culture is positive. A polymerase chain reaction can be performed if antibiotics are started or cultures are negative. The vaccination almost eradicates the infection if it is type b. There is a small group (<5%), who are not immune either because of poor technique or because the vaccine has not been updated. Other groups show low levels of antibodies and may require a booster. A new vaccine is available that will cover most serotypes. Answer: D
Campylobacter
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
Precisely what can be learned about C. jejuni infection using this model is probably limited in its scope. The first uses of this model were published by Champion et al.81 and by Senior et al.80 After testing a variety of C. jejuni strains and deletion mutants, the mutants showing the largest attenuation in the insect model were those in O-methyl phosphoramidate capsule modification, with mutants defective in the MeOPN capsule modification gene cj1416 being largely nonvirulent.82 This observation was supported by further studies by van Alphen et al.70 An additional study by Gundogdu et al. assessed how a mutant in an oxidative stress regulatory protein (cj1556) fared in the insect host, and found them to be much less virulent.83 Together, these previous studies suggest that assessing bacterial capsule function as well as susceptibility to stresses may be the most effective use of the C. jejuni insect model.
Preservatives and Preservation
Philip A. Geis in Cosmetic Microbiology, 2020
Specific, purpose-added ingredients inadequate as preservatives are known to facilitate effective preservation. The chelator EDTA is very effective as preservative adjunct. Although it does not possess stand-alone efficacy, EDTA adds significantly to the efficacy of preservative systems and can be found in many cosmetic products. In this context, it is presumed not only to sequester divalent cations necessary for microbial stability and metabolism, but also to destabilize bacterial capsules and biofilm, allowing better access of the preservative to the biological active (17,109,110). Other chelators such as phytic acid (hinokitol) and gluconolactone presumably offer similar effect (111,112) though the literature offers no compelling data regarding impact on efficacy. Similarly, the efficacy of pyrithione antimicrobials is at least in part associated with divalent cation sequestration (113). In addition to chelators, ingredient such as anisic and levulinic acids, ethyl hexyl glycerine, essential oils, and low levels of ethanol are used as preservative adjuncts (76,114,115,116). General formulation elements contributing to mitigated microbiological risks are also detailed in the relevant ISO guideline (117).
Abundant production of exopolysaccharide by EAEC strains enhances the formation of bacterial biofilms in contaminated sprouts
Published in Gut Microbes, 2018
Quintin Borgersen, David T. Bolick, Glynis L. Kolling, Matthew Aijuka, Fernando Ruiz-Perez, Richard L. Guerrant, James P. Nataro, Araceli E. Santiago
Virulence factors associated with EAEC strains include the AraC family regulator AggR9 and its regulon,10-13 serine protease autotransporters (Pic, SepA and SigA)14-17 and, potentially extracellular polysaccharides.18-22E. coli extracellular polysaccharides are mainly found in the bacterial capsule (K antigens),23-25 released as slime into the medium (exopolysaccharide [EPS]),26,27 or attached to the lipopolysaccharide (O antigen)28-31 of E. coli strains. Four loci have been implicated in EAEC 042 polysaccharide synthesis32: wzzB-wza (Ec042_2270 – Ec042_2299), kpsF-kpsM (Ec042_3230 – Ec042_3240), and two copies of the shf locus, which encodes a homolog of IcaB protein of Staphylococcus epidermidis and it is implicated in adhesion and LPS modification (Ec042_4769 – Ec042_4772 and Ec042_pAA021 – Ec042_pAA023).
Development of Lactobacillus kimchicus DCY51T-mediated gold nanoparticles for delivery of ginsenoside compound K: in vitro photothermal effects and apoptosis detection in cancer cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Yeon-Ju Kim, Haribalan Perumalsamy, Josua Markus, Sri Renukadevi Balusamy, Chao Wang, Seong Ho Kang, Seungah Lee, Sang Yong Park, Sung Kim, Verónica Castro-Aceituno, Seung Hyun Kim, Deok Chun Yang
In summary, this study highlights the development of ginsenoside CK-gold nanocarriers (DCY51T-AuCKNps) via an intracellular membrane-bound mechanism by lactic acid-producing Lactobacillus kimchicus DCY51T. Ginsenoside CK was effectively loaded onto the surface of gold nanoparticles by non-covalent conjugation such as, electrostatic forces, hydrogen bonding, hydrophobic forces and van der Waals interactions. Upon further investigation by HR-TEM, the particles were formed in the bacterial capsule and cell wall than on the cytoplasmic membrane, possibly due to reduction of the metal ions by enzymes and EPSs present in the cell wall and slime layer. The drug loading efficiency was determined to be ∼11.03%. The FTIR spectra of DCY51T-AuCKNps demonstrated the presence of alkane (C–H) bending and ether (C–O) stretching of ginsenoside CK, further confirming the direct complexation of ginsenoside to the surface of nanoparticles. The in vitro stability of DCY51T-AuNps and DCY51T-AuCKNps demonstrated their resistance to aggregation and dissociation caused by pH variation or a high ionic strength environment. Although DCY51T-AuCKNps demonstrated greater cell inhibition in RAW264.7 cells at 10–20 µM of equivalent ginsenoside CK concentration compared to A549 and HT29 cells at the same concentrations, preferential cytotoxicity of DCY51T-AuCKNps against A549 cells and HT29 compared to free ginsenoside CK was demonstrated by MTT assays. Increased apoptosis of DCY51T-AuCKNps in cancer cells compared to cell apoptosis count in RAW264.7 cells and DCY51T-AuNps-treated cells at sublethal concentrations was confirmed by Hoechst staining with excitations by laser. These results suggest that DCY51T-AuCKNps are promising drug delivery platforms for cancer therapy as novel photothermal and chemotherapeutic agents.
Promoter orientation of the immunomodulatory Bacteroides fragilis capsular polysaccharide A (PSA) is off in individuals with inflammatory bowel disease (IBD)
Published in Gut Microbes, 2019
Lucy E. Blandford, Emma L. Johnston, Jeremy D. Sanderson, William G. Wade, Alistair J. Lax
Bacterial capsules are extracellular structures, typically comprised of polysaccharide, outside the cell envelope. Capsule possession appears to be part of a strategy to evade the host immune system, for example, by preventing the formation of a complement attack complex, and to avoid engulfment by phagocytosis.5 They also have roles in adhesion and colonization and for these reasons can be considered virulence factors; in addition, capsular mutants are often avirulent.6
Related Knowledge Centers
- Bacteria
- Bacterial Outer Membrane
- Cell Envelope
- Glycocalyx
- Lipopolysaccharide
- Polysaccharide
- Slime Layer
- Lipoprotein
- Gram-Negative Bacteria
- Gram-Positive Bacteria