You are reviewing a routine Papanicoloaou smear from a 33 year-old female. She has no complaints and appears healthy. A representative field from her Pap smear is shown here. What organism is the most likely cause of the morphologic changes seen here?
- Chlamydia trachomatis
- Human papillomavirus
- Trichomonas vaginalis
- Gardnerella vaginalis
The diagnosis in this case is Chlamydial infection. Genital infection by Chlamydia trachomatis is the most common sexually transmitted disease in the world. In women, chlamydial infection of the cervix is frequently asymptomatic, as it was in this patient. If untreated, however, the infection can lead to pelvic inflammatory disease, infertility and ectopic pregnancy.
Chlamydia trachomatis is a tiny, gram-negative bacterium that exists in two different forms: the elementary body, which is the infectious form, and the reticulate body, which is the replicative form. While Chlamydial organisms are too small to be visible with a gram stain, large, glassy inclusions containing both reticulate bodies and elementary bodies are occasionally clearly visible within cells, as seen in the squamous epithelial cells in this image (see arrows).
-Kristine Krafts, MD, is an Assistant Professor of Pathology at the University of Minnesota School of Medicine and School of Dentistry and the founder of the educational website Pathology Student.