Final answer:
Treponema pallidum causes syphilis, diagnosed via darkfield microscopy and serological tests like VDRL, RPR, and treponemal tests. The spirochete's ability to evade the immune system contributes to the persistence and spread of this STI.
Step-by-step explanation:
Syphilis and its Diagnostic Methods
The bacterium Treponema pallidum is responsible for the sexually transmitted infection syphilis, which is a significant health concern with nearly 75,000 new cases reported in the United States in 2015. T. pallidum is classified as a spirochete due to its spiral shape and is known to evade the immune system while causing tissue damage. Diagnosing syphilis involves using darkfield microscopy to observe live, unstained spirochetes, as well as serological tests like the nontreponemal VDRL and RPR tests for screening, and the treponemal tests such as TP-PA, FTA-ABS, and EIA for confirmation. These diagnostic methods are crucial since T. pallidum cannot be cultured in the lab on an artificial medium.
In addition to syphilis, there are other subspecies of T. pallidum that cause tropical diseases, and a comprehensive understanding of these bacteria is vital for proper diagnosis and treatment. The information provided on microscopy and serologic testing offers a detailed overview of how healthcare professionals detect T. pallidum infections.