[Topical antimicrobial agents in dermatology]. / Antimicrobianos tópicos en Dermatología.

Topical antimicrobial agents are chemical substances that, directly applied to the skin, inhibit the growth or destroy any microorganism, either fungi, viruses or bacteria. Within this term, we generally refer to those that are active against the latter. They are divided into antiseptics and antibiotics. Antiseptics are directly applied to a living organism to eradicate the existing microorganism on the mucocutaneous surfaces, preventing their proliferation. Topical antibiotics are either produced by living organisms or manufactured through synthesis and are mainly used to fight infections. Topical antimicrobials represent an important option in the prophylaxis and treatment of primary and secondary superficial bacterial infections. Antibiotics for topical use have a lower incidence of systemic toxicity, secondary effects and development of resistance than parenteral antibiotics. The ideal topical antimicrobial must have a broad spectrum of activity, fast and prolonged antibacterial effect, bactericidal activity, easy diffusion through tissues and detritus, with minimal toxicity, very low or null incidence of irritation or allergy and sparse activity against normal skin flora. The approach of this article is the description of the classical and new antimicrobials that are, more important due to their wide use and proven efficacy. We review their pharmacological characteristics, spectrum of activity, possible secondary effects and interactions, as well as the combinations that improve their antimicrobial activity, main indications and possible development of resistance, all this properly documented.

Cutaneous necrosis by cold agglutinins associated with glomeruloid reactive angioendotheliomatosis.

The cold agglutinin syndrome is a haemolytic disorder that can cause skin lesions, mainly on the acral areas, with acrocyanosis being the most frequent manifestation. Cutaneous necrosis due to cold agglutinins is very rare. Reactive angioendotheliomatosis (RAE) is an uncommon condition that exclusively affects the skin, characterized by a hyperplasia of endothelial cells and pericytes that can result in the formation of glomeruloid structures. The association of cold agglutinin syndrome with glomeruloid RAE has not been previously described. We report a 70-year-old man diagnosed as having a B-cell low-grade non-Hodgkin's lymphoma. He had two episodes of cutaneous necrosis in acral areas which were related to exposure to cold and due to IgM anti-I(T) cold agglutinins. Biopsy specimens showed vessel proliferations composed of dilated vascular spaces in the dermis and subcutis. Some vessel lumina were partially occluded by eosinophilic thrombi of fibrin and erythrocytes. Numerous closely packed capillaries were observed within pre-existing dilated vessels. This intravascular proliferation of capillaries displayed a glomeruloid pattern. We emphasize the possible presence of a cold agglutinin syndrome in patients with skin necrosis and findings of RAE with a glomeruloid pattern. Cold agglutinaemia may cause these distinctive histological changes.