Abscess

It is defined as localized collection of pus in the living solid tissue that is caused by acute inflammation such as a result of pyogenic organism or chemical irritants .

Pyogenic organism responsible for formation of abscess …..

i)                    Some cocci like streptococcus haemolyticus , Staphyococcus aureus , Pneumococcus , Gonococcus , anaerobic coccus etc .

ii)                  Some bacilli like Escherichia colui , proteus group , pseudomonas group etc .

 Type of disease …..

a)      Acute abscess – which may healed up by the process of fibrosis after evacuation or may be healed up as a cosed cavity by inspissation with fibrosis or may be rupture and develop sinus or fistula or may enter into  chronic abscess .

b)      Chronic abscess .

 Mechanism of formation of abscess …..

i)                    Presence of infection is not essential for th formation of abscess which will form sterile abscess . If there is any infective organism there  develops inflammatory condition in the tissue . Due to inflammationm , there will be vasoconstriction , vasodilation , celluar infiltration , exudation and tissue change at the site .

ii)                  If the boby resistance is low , there will be coagulative necrosis at the central part of the affected site .

iii)                The necrosed area ultimately will be liquefied by the lysosomal stimulation of the infiltrating neutrophils which are degenerated . Protein , fat , and carbohydrate will be broken down by proteolytic , lipolytic and saccharolytic  ferments . This liquid necrosed tissue is further enforced by serious exudates of inflammation . The liquefied necrosed  tissue will form pus which is a thick liquid , yellowish in colour , composed of pus cells and causative oirgganism  which may be dead or living .

iv)                The peripheral zone of the inflamed area shows the presence of fibrin barrier . Thhe zone is crowded with polymorphs and macrophages . From there , pus cells will be discharged into abscess cavity , so this azone is called pyogenic membrane .

v)                  If the virulence of the organism is low , there will be formation of small abscess cavity known as Micro-abscess . If the virulence of the organism is high , the micro-abscess may unite to form big abscess cavity .

vi)                The wall of the abscess cavity is composed of thick fibrocolagen band and internally by granulation tissue . The cavity is transversed by fibrous stands and thick walled vesssels . Degenerated leucocytes , pus cell and pyogenic organism can be identified .