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Emerging Diseases
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Background: Streptococci are gram positive cocci (spheres) arranged in chains or in pairs and include many species that are pathogenic. There are several groups of streptococci based on serological reactions to surface antigens according the original work of Lancefield in 1933. These groups include A–H, J, and K. The Group A streptococci (GAS) are commonly found in the throat and on the skin. They may cause no symptoms but may also cause infections that range from mild to severe and even life threatening. The major pathogens are included in groups A and B, and their pathogenicity is associated with certain enzymes and surface proteins including hemolysins, erythrogenic toxins, and M-protein.150 Hemolysins are enzymes capable of breaking or lysing blood cells and when Streptococci are grown on sheep blood agar, the types of hemolysis produced place these organisms into three groups. There are gamma hemolytic strep that produce no hemolysis, alpha hemolytic strep that produce a zone of green discoloration around the colony, and beta hemolytic strep that produce a zone of clear hemolysis around the colony. Beta hemolytic, group A strep are most often associated with strep throat infections. The ability to hemolyse blood cells is associated with powerful hemolysins such as oxygen-sensitive streptolysin O and oxygen stable streptolysin S enzymes. Streptococci may also produce erythrogenic toxins (A, B, and C) that harm blood vessels beneath the skin and appear to be produced in streptococci that carry a provirus with the genetic materials capable of coding for the production of these toxins.150 The streptococci may produce a broad of array of enzymes including neuraminidases, hyaluronidases, streptokinases, ATPases, DNAses, and many others that participate in the destruction and invasion of human tissue.
Efficient production of endotoxin depleted bioactive α-hemolysin of uropathogenic Escherichia coli
Published in Preparative Biochemistry and Biotechnology, 2019
Vivek Verma, Surbhi Gupta, Parveen Kumar, Ankita Rawat, Rakesh Singh Dhanda, Manisha Yadav
The α-hemolysin belongs to repeat in toxin (RTX) family of proteins.[1] The α- hemolysin forms a catalytic pore, which is detected as characteristic halo encircle on blood agar plates.[1–4] Both in-vivo and in-vitro experiments have established that high level of HlyA (α-hemolysin) causes osmotic lysis of host cells, at the same time lower level of HlyA concentrations can regulate survival pathways of host by modulating chemotaxis process of phagocytes.[5–8]
PVA, licorice, and collagen (PLC) based hybrid bio-nano scaffold for wound healing application
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Md Mehedi Hasan, Md Abdus Shahid
A wound is vulnerable to invasion by any bacteria or foreign body. Infection of wounds may take place due to the attack of bacteria and consequently bacterial growth led to prolonging wound healing with some difficulties. Wound dressing with antibacterial properties contributes to rapid wound healing by resisting bacterial attack. Hence, the antibacterial properties of the PLC bio-nano scaffold against the bacteria S. aureus and Psedonomas aeruginosa (P. aeruginosa) have been elucidated in this segment. Antibacterial activity or resistance of bacteria growth was represented by zone of inhibition (ZOI). The developed scaffolds showed different ZOI against the bacteria which have been ascribed by Figure 6. The ZOI was found 7 mm, 7 mm, 7 mm and 8 mm for the samples PLC-1, PLC-2, PLC-3 and PLC-4 respectively. But no ZOI was detected against p. aeruginosa, this may be due to low antibacterial activity of licorice extract against gram negative bacteria. The concentration of licorice extract plays a crucial role in forming zone of inhibition. Sample PLC-1 was low licorice extract concentration whereas PLC-4 was high licorice extract concentration and PLC-2 and PLC-3 contained moderate amount of licorice extract. From the result it has been observed that the sample PLC-4 showed higher ZOI which was 8 mm then other samples because of having a higher amount of licorice extract on the spinning solution. But samples PLC-1, PLC-2, PLC-3 exhibited the same ZOI of 7 mm. Although the bio-nano scaffold was fabricated from the mixture of PVA, collagen, and licorice extract only licorice extract has some groups that performed antibacterial activity. Therefore, amount of licorice extract directly contributed to bacterial resistance. Since the thick cell wall of s. aureus impede the action of the bioactive compound, the antibacterial constituent of licorice disrupts the resistance of the bacteria cell wall and resists bacterial growth followed by thwart forming bacteria colony. Licorice extract contains more than 20 triterpenoids and nearly 300 flavonoids. Among them, glycyrrhizin (GL), 18 β-glycyrrhetinic acid (GA), liquiritigenin (LTG), licochalcone A (LCA), licochalcone E (LCE), and glabridin (GLD) are the main active components which possess antiviral and antimicrobial activities. GA reduced the expression of SaeR and Hla which are two virulence genes of methicillin-resistant S. aureus (MRSA) therefore destroying MRSA and thwarting bacterial growth [45]. On the other hand, LTG plays an important role by stultifying the production of important exotoxin α-hemolysin of S. aureus pathogen and reducing the infection of the skin [46]. In a nutshell, four important flavones are LCA, LCE, LTG, and GLD and one triterpene GA is responsible for the bactericidal performance of licorice. Therefore, these groups prevented the activity of bacteria by disrupting the thick cell wall. Apart from this, the nanostructure of fabricated scaffolds circumvents the intrusion of bacteria due to its mesh structure. Hence, the structure of scaffolds and the action of antibacterial chemical compounds of licorice extract showed a good antibacterial property.