This type of infection is usually caused by various species of Gram-positive cocci, (Staphylococcus aureus, Streptococcus pyogenes, and enterococci), Gram-negative rods,  (Escherichia coli, Pseudomonas aeruginosa), and anaerobes, (Bacteroides and Clostridium species). Populations of those affected are typically older with medical comorbidities such as diabetes mellitus, obesity, and immunodeficiency. Usually, trauma is not the cause of such infections. Previous history of abscess infection or gut perforation with bacterial translocation may be elicited. Clostridial infection accounts for 10% of type I infection. Clostridium species involved are Clostridium perfringens, Clostridium septicum, and Clostridium sordellii, which typically cause gas gangrene (also known as myonecrosis). Clostridium perfringens produces two deadly toxins: alpha-toxin and theta-toxin. Alpha-toxin causes excessive platelet aggregation which blocks blood vessels and deprives the vital organs of oxygen supply. This creates an acidic, oxygen-deficient environment for the proliferation of bacteria. When alpha-toxin is absorbed by soft tissues, it can inhibit the migration of white blood cells from blood vessels into the soft tissue, thus impairing phagocyte function. The two toxins together can cause destruction of red blood cells in blood vessels, damage to the integrity of the blood vessels, and suppression of heart function.Clostridium sordellii can also produce two major toxins: all known virulent strains produce the essential virulence factor lethal toxin (TcsL), and a number also produce haemorrhagic toxin (TcsH). TcsL and TcsH are both members of the large clostridial cytotoxin (LCC) family. The key Clostridium septicum virulence factor is a pore-forming toxin called alpha-toxin, though it is unrelated to the Clostridium perfringens alpha-toxin.
Lupoid sycosis is a cutaneous condition that is characterized by a scarring form of deep folliculitis, typically affecting the beard area. See also
Sycosis barbae
List of cutaneous conditions


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