Bacterial infections of the skin are among the most common skin problems. Impetigo, a highly contagious type of bacterial skin infection, is one of the most frequently diagnosed. While it is most common in children, no age group is exempt, and it is particularly contagious within the family. There are two types of impetigo. First, impetigo contagiosa, which presents with honey colored crusts (scabs) and superficial erosions, often found on the face but can present on any part of the body. The second, but less common, is bullous impetigo, which presents with solitary fragile blisters which rupture easily, leaving raw, weeping, denuded areas which spread peripherally. New blisters sprout in the surrounding area. Prompt antibiotic therapy is rapidly curative.
Bacterial infections involving hair follicles are extremely common, particularly in shaved areas such as the beard, scalp and legs, but can occur in any hairy area. They may present as folliculitis superficial pustules (whitehead with a hair in the center), a furuncle green-black necrotic plug (core) that is tenaciously embedded. Little pus is present. When the infection is deep in the follicle at the hair bulb level, the surrounding subcutaneous tissue is involved, usually opening in one draining sinus exuding pus. This is a boil. When a much larger area is involved with multiple draining openings, we refer to it as a carbuncle. If pus is localized, it should be drained surgically and then appropriate antibiotic therapy instituted. Antibiotic therapy without surgical draining will often be ineffective.
Bacterial paronychial (around the cuticle) infections are common particularly in nail biters, nurses, and after a manicure. These are exquisitely painful and present redness, swelling and accumulated pus under the cuticle or lateral nail fold of a finger. It is very important these be treated early with drainage and antibiotics. If neglected, a felon may develop (a deep bacterial infection in the tendon spaces of the hand) which can prove extremely destructive with significant morbidity and loss of function.
Most bacterial infections are pustules, but this is more of a guideline than a rule. The picture on the left may look like a bacterial infection, but it is actually fire ant bites.