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Cardiology
Published in Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan, Essential Notes for Medical and Surgical Finals, 2021
Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan
Precipitated by group A Streptococcal infection. Diagnosis: based on evidence of Strep. infection (positive throat swab, raised serum anti-streptolysin titre, etc) and on the Revised Jones Criteria which require 2 major, or 1 major + 2 minor criteria to be present for diagnosis.
Inflammation
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
Many bacteria kill phagocytes such as the pathogenic streptococci and staphylococci. In Streptococcus infection the production of streptolysin O destroys the polymorph neutrophil granules by osmotic force. Antiphagocytic substances are also present on bacterial surfaces, such as polysaccharide capsules (pneumococci, Haemophilus influenzae, Klebsiella pneumoniae) or specific proteins (protein A: Staphylococcus aureus; protein M: streptococci). Protein A from S. aureus inhibits phagocytosis and becomes bound to the Fc portion of IgG, hence inhibits binding to the Fc surface receptors of neutrophils.311
Role of Bacteria in Blood Infections
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
Kannan Balaji, Gnanasekaran JebaMercy, K. Balamurugan
In addition to its effect on erythrocytes, extracellular products released by such bacteria are toxic to a variety of cells and cell fractions, including polymorphonuclear leukocytes, platelets, tissue-culture cells, lysosomes, and isolated mammalian and amphibian hearts (Duncan & Schlegel, 1975; Bisno et al., 2003). Streptolysin S is a hemolysin produced by S. pyogenes in the presence of serum or several other substances such as serum albumin, alpha-lipoprotein, and ribonucleic acid. It exists in intracellular, cell-surface-bound, and extracellular forms, and it is one of the most potent cytotoxins known (Sierig et al., 2003; Datta et al., 2005; Sumitomo et al., 2011). Other extracellular antigenically distinct enzymes are DNases A, B, C, and D, which are involved in degradation of DNA, streptokinase, which causes dissolution of clots by catalyzing the conversion of plasminogen to plasmin, streptococcal pyrogenic exotoxin B (speB), a potent protease that cleaves the PMN binding site (Ji et al., 1996; Bisno et al., 2003), streptococcal inhibitor of complement, which inhibits lysis of the bacterium by binding to the insertion site of complement (Fernie-King et al., 2002).
Platelet interaction with bacterial toxins and secreted products
Published in Platelets, 2015
Streptococcus pyogenes produce a pore-forming toxin, Streptolysin O (SLO) that can mediate platelet activation and CD62P-dependent PNC formation [55]. Importantly, the authors demonstrated that SLO decreases local blood flow in an animal model and speculated that PNCs induced by SLO occlude the vasculature. The same authors have also demonstrated that phospholipase C (PLC) produced by Clostridium perfringens stimulates platelet aggregation and platelet–leukocyte complex formation [56]. Furthermore, local administration of PLC decreased blood flow in an animal model and platelet–platelet and platelet–leukocyte aggregates were evident in tissue sections of occluded vessels from the animals [57]. The ability of both SLO and PLC to induce platelet-dependent vessel occlusion may be highly relevant to the pathogenesis of necrotising local tissue infection caused by the toxin-producing organisms.
β-Hemolytic Streptococcus anginosus subsp. anginosus causes streptolysin S-dependent cytotoxicity to human cell culture lines in vitro
Published in Journal of Oral Microbiology, 2019
Atsushi Tabata, Takuya Yamada, Hiromi Ohtani, Kazuto Ohkura, Toshifumi Tomoyasu, Hideaki Nagamune
In S. pyogenes, the SLS produced is known to be a virulence factor similar to the pore-forming protein hemolysin streptolysin O, and much research was reported on this topic in the middle of the 1960’s and from the late 1970’s to the early 1980’s. However, possibly due to the questionable molecular properties of SLS (e.g., low or no antigenicity and difficulty in purification), the research on SLS temporarily stagnated in the 1990’s. After the year 2000, the situation improved due to the discovery of the genes for the biosynthesis of SLS and their secretion [15]. As a result, many investigations were conducted and SLS was recognized as the virulence factor of S. pyogenes. For example, the functions of SLS identified include the inhibition of neutrophil recruitment during the early stages of infection [16,17], translocation across the epithelial barrier [18], contribution of GAS evasion from immune cell killing, local tissue damage, and mortality of mouse [19], promotion of programmed cell death and enhancement of inflammatory signaling in epithelial keratinocytes [20], inhibition of neutrophil recruitment and systemic infection [21], and direct activation of nociceptor neurons and production of pain [22]. In addition, by contribution from the dramatic evolution of next-generation sequencing, the presence of the genes encoding SLS-related peptides in the Gram-positive bacteria besides S. pyogenes was also reported. These include the SLS-related peptide hemolysin secreted from Streptococcus iniae [23], perfringolysin S secreted from Clostridium perfringens [24], and listeriolysin S produced from Listeria monocytogenes [25].
Clinical features and radiological findings of 67 patients with SAPHO syndrome
Published in Modern Rheumatology, 2018
Hiroshi Okuno, Munenori Watanuki, Yoshiyuki Kuwahara, Akira Sekiguchi, Yu Mori, Shin Hitachi, Keiki Miura, Ken Ogura, Mika Watanabe, Masami Hosaka, Masahito Hatori, Eiji Itoi, Katsumi Sato
Laboratory data showed that the mean white blood cell count (WBC), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were 7140/μl (range 2400–11,000), 1.22 mg/dl (0.1–6.6), and 52.0 mm/h (4–150), respectively. The WBC, CRP, and ESR were positive in 10 (16.7%), 36 (60.0%), and 36 patients (72.0%), respectively (Table 2). The 50% hemolytic unit of complement (CH50) was increased in 48 patients (90.6%). Anti-streptolysin O (ASO) was positive in eight patients (18.2%). Anti-nuclear antibody (ANA), rheumatoid factor (RF), and anti-cyclic citrullinated peptide antibody (anti-CCP) were negative except for one patient. Matrix metalloproteinase-3 (MMP-3) was increased in 12 patients (26.1%).