An abscess is a collection of a pus (collection of cellular debris, death and dying bacteria and neutrophils) which wall off at the sites of inflammation.
An abscess is caused by infection. Pyogenic abscess is caused by infection from anaerobes or coliform bacteria ( bacteriodes spp.) , staphylococcus aureus, enteric bacteria ( E. coli) and streptococcus pyogenes. Cold abscess is caused by tuberculosis infection.
The risk factors for developing abscess may include under perfuse space in the body system, the present of necrotic / dead tissue or foreign material ( embedded hair, a fragment of a tooth or the root, malignant cell, mesh from hernia repair or stents). Immunosuppression and diabetes may also leads to abscess formation.
Patient with abscess typically complains of local signs such as pain ( dolor ), redness ( rubor) , heat ( calor) and swelling ( tumour) as well as loss of function of the affected sides ( function lasea ) . All of the above signs are known as Celsian signs /features of acute inflammation. The patient may also complain of general symptoms or signs such as pyrexia (fever) and feeling unwell.
The Celsian features only present at the sites of abscess. If the abscess is present within an organ ( body cavity, lung and liver ), the Celsian features are absent and the only presenting symptoms are swinging fever /pyrexia ( which is due to the inflammatory mediators and microbes mediators that enter the systemic circulation and initiate the defence mechanism against infection
In terms of pathology, the bacteria will initiate an acute inflammation response which later leads to the formation of the pus due to the failure of the phagocytosis process to kill the bacteria. The abscess is formed by the granulation tissue (consists of fibroblast and macrophages) and fibrinous exudates as well as collagen which forms the wall of the abscess. Cold abscess is formed of a collection of caseating necrosis containing Mycobacterium which is not presented with an acute inflammatory response.
The investigation requires to detect the presence of pus may includes blood tests. The full blood count may reveal an increase in the number of neutrophils in the blood. Imaging techniques such as CT scan, MRI scan or ultrasounds are used to detect the sites and the present of the abscess. Ga67 white cell scanning may also be used in selected cases. Aspiration of the pus may reveal the characteristic of the pus which is acidic and low in glucose. The pus is also cultured to identify the organism and sensitivity of the antibiotics towards the organism that present on the pus.
The treatment includes prevention, general treatment, surgical treatment and interventions radiological treatment.
Preventive treatment may include the introduction of the prophylactic antibiotic before any surgical procedure or at the first stages of the infection. General treatment includes drainage of the pus, removal of the foreign material and prescribing the patient with antibiotics as well as treats and removing any precipitating or predisposing causes. Surgical treatment may include debridement of the cavity followed by insertion of the drains if the abscess is deep within an organ or in case of superficial abscess the treatment involved debridement of the cavity and allow free drainage of the pus from the abscess. Interventional radiology treatment may include a CT scan or ultrasound guidance in detecting and aspirating the pus from the abscess.
The complication of the abscess may include the presence of antibioma or sterile collection as a result of the penetrating antibiotic. Abscess also may lead to systemic sepsis as a result of bacteria. An abscess may also lead to skin infection or cellulitis. The present of pressure on the abscess may lead to slow expansion of the abscess which leads to necrotic pressure of the tissue surrounding the abscess. The present of chronic abscess may lead to the formation of discharging fistula or sinus.
The prognosis is good if properly remove the precipitating and predisposing causes and the abscess is carefully drained. The abscess may point to the nearest epithelial surfaces which later leads to the discharging of the content spontaneously if left untreated. Any causes of chronic deep abscess may leads to dystrophic calcification if left untreated.