An abscess is the body walling off an infection, and the wall backfires
When bacteria invade tissue, the body floods the spot with white blood cells and then seals the resulting pus inside a capsule of healthy cells. That barrier protects neighbouring tissue, but it also shields the germs from the very immune cells sent to kill them, which is why draining usually matters more than drugs.
The process begins when microbes or foreign material kill local cells, which release signalling molecules called cytokines. Those trigger inflammation, drawing crowds of white blood cells and boosting blood flow. Pus accumulates, and surrounding healthy cells build a wall around it. Staphylococcus aureus is the usual culprit in skin abscesses, with some studies finding it behind more than 90 per cent of cultured cases; parasites are a rare cause, more often seen in the developing world. Boils and the larger carbuncles are both forms of abscess, whereas a cyst holds something other than pus inside a clearly defined wall.
Skin abscesses are common and may be growing more so. In 2005 some 3.2 million Americans went to emergency departments with one, and around 13,000 Australians were admitted to hospital with the condition in 2008. Injecting drug use is a major risk factor, with rates as high as 65 per cent reported among users. Internal abscesses, in organs such as the lungs, brain or kidneys, are harder to spot and more serious.
Cutting the abscess open and draining it is the standard approach for uncomplicated skin cases, echoing the old Latin maxim ubi pus, ibi evacua, 'where there is pus, drain it'. The value of adding antibiotics is genuinely mixed in the literature: some evidence suggests modest benefit, while other guidance holds that most uncomplicated cases gain nothing. Traditional North American practice of stuffing the cavity with gauze has also been challenged; emergency medicine studies report that packing hurts without speeding healing or preventing recurrence, and one paediatric study of 143 cases found a failure rate of 1.4 per cent with a looped drain against 10.5 per cent with packing.
Outcomes depend heavily on location. Skin abscesses rarely kill, because they tend to break through to the surface on their own. Brain abscesses can be fatal untreated, and even with treatment mortality runs at 5 to 10 per cent.
Source: Abscess
