Darkfield microscopy. An option in the diagnosis of syphilis

Abstract

Introduction: The diagnosis of syphilis by darkfield microscopy, also known as ultra-microscopy, can get ahead in the primary stage up to two weeks compared to a serodiagnostic immunoassay by serological test for syphilis and rapid plasma reagin test, which can result non-reactive. The analysis of the results of the last seven years was the reason for conducting this work. Objective: To characterize the dark field microscopy as an option in the diagnosis of syphilis. Methods: a descriptive, longitudinal and retrospective study was conducted from January 2004 to December 2010. The population consisted of 496 patients who met the inclusion criteria. Results: there were 496 samples of which 354 were negative 71.3%, the overall results of the first and second semesters do not provide differences of epidemiological value. Positive diagnosis reached 28.6%. Conclusions: dark field microscopy allows confirming the presumptive diagnosis at the primary stage, when nontreponemal serological techniques are in an open window period (not reactive). The results show that one in three patients was diagnosed by this technique, leading to the begining of therapy and the implementation of the epidemiological containment of transmission. The negative darkfield does not exclude the possibility of syphilis, the knowledge of the requirements and limitations are essential for a successful diagnosis.