[Bacterial keratitis. Current diagnostic aspects].

Keratitis remains the third most common etiology for blindness worldwide. Whereas bacteria still predominate as causative organisms in temperate climates, fungal and mixed infections are more common in tropical and semitropical areas. In recent years, a shift in the causative organisms, as well as predisposing factors, has been reported. Risk factors that may have gained in importance, such as wearing contact lenses and corneal surgery, have been identified. Microorganisms, especially Pseudomonas spp. and mycobacteria have been frequently isolated in these patients. A changing pattern in microorganism infection has been observed that might be caused by inappropriate use of potent antimicrobial agents. Because of the sight threatening nature of bacterial keratitis, proper diagnosis and antibiotic selection are required. Management should be guided by the appropriate diagnosis, severity of clinical symptoms and underlying risk factors. Molecular techniques, such as polymerase chain reaction, have increased our diagnostic options, even when they cannot replace established procedures. This article reviews the current data and procedures available for the diagnosis of bacterial keratitis.