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Staphylococcus
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Although S. aureus is phylogenetically identical to coagulase negative staphylococci (CoNS), it appears to be more virulent than CoNS. S. aureus colonies often produce golden color on solid media. S. aureus cell wall is a tough protective coat of about 20–40 nm in thickness. Peptidoglycan is composed of 50% of cell mass [23]. The peptidoglycan of S. aureus may act like endotoxin that is involved in the release of cytokines via complement activation, macrophages, and platelets aggregation [4]. A group of phosphate-containing polymers known as teichoic acids (cell wall techoic acid and cell membrane–associated lipoteichoic acid), bound covalently to the peptidoglycan or inserted in the lipid membrane, constitute 40% of S. aureus cell mass, and the remaining 10% is composed of surface proteins, exoproteins, and autolysins [23]. Teichoic acid carries a negative charge and plays a part in the process of biofilm formation [25] as well as acquisition and localization of metal ions and activation of autolytic enzymes. The capsular polysaccharide is possessed by more than 90% of clinical S. aureus strains [23].
Phosphonic Acids And Phosphonates As Antimetabolites
Published in Richard L. Hilderbrand, The Role of Phosphonates in Living Systems, 2018
The material (21) has also been noted to be active in the inhibition of growth of strains of Bacillus subtilis.126,127 Here it is noted, in similarity to E. coli, that phosphatidylglycerol synthesis is inhibited, but also that (21) is incorporated into the cell wall. With strain 168, containing polyglycerolphosphate cell wall teichoic acid, (21) is bacteriostatic; with strain W23, containing polyribitol cell wall teichoic acid, (21) is bactericidal.
Microbial ecology of the vulva
Published in Miranda A. Farage, Howard I. Maibach, The Vulva, 2017
Catherine C. Davis, Ronald W. Berg
The ability of a microorganism to colonize a surface is generally proportional to the ability of the organism to adhere to that surface. This specific binding results from the interaction between the surface and specific cell receptors and provides an ecological advantage by ensuring that organisms can successfully colonize a surface that allows them to thrive. It has been suggested that fimbriae in Gram-positive bacteria and pili in Gram-negative bacteria may be involved in binding organisms to surfaces (15) and that teichoic acid is a major adhesin of S. aureus to epithelial cells (16). Human epithelial cells have been shown to bind specifically with P. aeruginosa, Staphylococcus epidermidis, S. aureus, S. pyogenes, and diphtheroids, but not with viridans streptococci and Candida albicans (4). Microbial adhesion to the vulva per se has not been studied satisfactorily, in part because this environment contains several cell types and is therefore ecologically complex. However, some microbial adherence properties of the labia majora and minora have been studied and the results demonstrate that labia majora cells generally are more amenable to microbial adherence than are labia minora cells (17).
Untargeted lipidomic differences between clinical strains of methicillin-sensitive and methicillin-resistant Staphylococcus aureus
Published in Infectious Diseases, 2022
Philip Nikolic, Poonam Mudgil, David G. Harman, John Whitehall
Due to the presence of teichoic acids in the cell wall, the overall surface charge in Gram-positive bacteria is negative. Bacterial cell surface charge is known to affect susceptibility to positively charged antimicrobial agents [24]. The cytochrome c assay used in this study showed that the negative charge did not vary significantly between the ten strains. The difference in cell surface charge between the MSSA group and MRSA group was also not significant. The lack of a difference may have been due to the lack of antibiotic challenge or that alterations to cell surface charge may not assist in methicillin resistance and so was not developed in MRSA strains. This second hypothesis is supported by methicillin being a non-charged molecule. Future experiments involving a charged antimicrobial can identify if exposure to sublethal concentrations can induce changes in the whole-cell surface charge and affect resistance.
Aflatoxin M1 in milk and dairy products: global occurrence and potential decontamination strategies
Published in Toxin Reviews, 2022
Khurram Muaz, Muhammad Riaz, Carlos Augusto Fernandes de Oliveira, Saeed Akhtar, Shinawar Waseem Ali, Habibullah Nadeem, Sungkwon Park, Balamuralikrishnan Balasubramanian
It has been proposed that the binding of aflatoxins to bacterial cell occur through non-covalent interactions (Bovo et al. 2013). Although the binding mechanism of these strains is not fully understood yet, some authors have proposed the polysaccharides and peptidoglycans of the bacterial cell wall to be the major binding sites. These propositions were made as a result of lack in binding abilities after treatment of bacterial cells with periodate and pronase E which had nonspecific degradation impact on both carbohydrates and proteins, respectively (Lahtinen et al. 2004). The involvement of teichoic acids present in the cell wall of the bacterial strains in binding of AFB1 was also proposed by Hernandez‐Mendoza et al. (2009). The possibility of toxin degradation only metabolically had, however, been eliminated as the heat and acid treated nonviable strains reduced the aflatoxin even more effectively as compared to the viable ones in some cases (Abdelmotilib et al. 2018).
Cerebrospinal fluid culture-positive bacterial meningitis increases the risk for neurologic damage among neonates
Published in Annals of Medicine, 2021
CSF culture-positive neonates also demonstrated significantly high levels of CSF protein, which reflects an ongoing inflammatory response. During the acute phase of NBM, increased interstitial vascular permeability allows pathogens to cross the blood-brain barrier. These pathogens release inflammatory mediators, such as teichoic acid and endotoxins, which, in turn, incite an immune response. The increase in inflammatory mediators, such as polymorphonuclear leukocytes, interleukins, and cytokines, in the CSF presents an increased CSF protein count on CSF analysis. However, the same immune response also results in the formation of reactive oxygen species. These free radicals are highly unstable and may produce harmful proteins, lipids, and nucleic acids. High lipid levels in the setting of low cerebral antioxidant levels are harmful to the central nervous system [19,20]. As such, while the inflammatory cascade in NBM aims to protect the central nervous system, it is also the cause behind neurologic morbidity.