Infections caused by Chlamydia trachomatis (including lymphogranuloma venereum) and Mycoplasma genitalium

Chlamydia trachomatis Cell-to-Cell Spread through Tunneling Nanotubes

Tunneling nanotubes (TNTs) are transient cellular connections that consist of dynamic membrane protrusions. They play an important role in cell-to-cell communication and mediate the intercellular exchanges of molecules and organelles. TNTs can form between different cell types and may contribute to the spread of pathogens by serving as cytoplasmic corridors. We demonstrate that Chlamydia (C.) trachomatis-infected human embryonic kidney (HEK) 293 cells and other cells form TNT-like structures through which reticulate bodies (RBs) pass into uninfected cells. Observed TNTs have a life span of 1 to 5 h and contain microtubules, which are essential for chlamydial transfer. They can bridge distances of up to 50 μm between connecting neighboring cells. Consistent with the biological role for TNTs, we show that C. trachomatis spread also occurs under conditions in which the extracellular route of chlamydial entry into host cells is blocked. Based on our findings, we propose that TNTs play a critical role in the direct, cell-to-cell transmission of chlamydia. IMPORTANCE Intracellular bacterial pathogens often undergo a life cycle in which they parasitize infected host cells in membranous vacuoles. Two pathways have been described by which chlamydia can exit infected host cells: lytic cell destruction or exit via extrusion formation. Whether direct, cell-to-cell contact may also play a role in the spread of infection is unknown. Tunneling nanotubes (TNTs) interconnect the cytoplasm of adjacent cells to mediate efficient communication and the exchange of material between them. We used Chlamydia trachomatis and immortalized cells to analyze whether TNTs mediate bacterial transmission from an infected donor to uninfected acceptor cells. We show that chlamydia-infected cells build TNTs through which the intracellular reticulate bodies (RBs) of the chlamydia can pass into uninfected neighboring cells. Our study contributes to the understanding of the function of TNTs in the cell-to-cell transmission of intracellular pathogens and provides new insights into the strategies by which chlamydia spreads among multicellular tissues.

Lymphogranuloma Venereum-Associated Proctitis Mimicking a Malignant Rectal Neoplasia: Searching for Diagnosis

<b><i>Background:</i></b> <i>Chlamydia trachomatis</i>-lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) and an uncommon cause of proctitis. The diagnosis requires a high index of clinical suspicion, since the clinical, imaging, endoscopic, and histological findings can mimic multiple benign or malignant conditions like inflammatory bowel disease and rectal neoplasms. <b><i>Case Presentation:</i></b> We present the case of a 48-year-old Caucasian male with no significant previous medical history who was admitted due to the suspicion of a rectal neoplasia. He underwent an abdominopelvic computed tomography (CT) scan and pelvic magnetic resonance imaging (MRI) before admission due to complaints of anorectal pain, hematochezia, and constipation over the previous 2 weeks. The examination revealed a circumferential rectal wall thickening, infiltration of the perirectal fat and invasion of the mesorectal fascia, associated with perirectal fat lymphadenopathy. A radiological diagnosis of a rectal malignant neoplasia staged as T4N2MX was stated. Digital rectal examination identified a circumferential rectal tumor. Rectosigmoidoscopy showed an extensive and circumferential ulceration of the rectal mucosa, with elevated geographical borders, exudate, and aphthoid erosions at the proximal limit of the endoscopic mucosal ulceration. Biopsy specimens revealed acute ulcerative proctitis with lymphoplasmocytic inflammatory infiltrate but no evidence of dysplasia or malignancy. A STI screening was positive for HIV-1 (CD4+ 251/mm³; <i>N</i> = 700–1,100) and <i>C. trachomatis</i>, with an elevated IgA-specific antibody titer (52.000; <i>N</i> &#x3c; 5.0), suggesting LGV disease. The diagnosis was confirmed by the identification of <i>C. trachomatis</i> DNA on rectal swab. Other infectious causes of acute proctitis were excluded. When faced with these results, the patient ended up mentioning that he had unprotected anal sex with men. He started treatment with doxycycline 100 mg twice a day for 21 days, with a drastic improvement. Rectosigmoidoscopy was repeated and showed clear signs of progressive resolution of the ulcerative proctitis. <b><i>Discussion:</i></b> LGV-associated proctitis, often undervalued, is a reemerging disease which should always be considered a benign cause of rectal mass, in order to avoid delay in diagnosis and development of complications. Diagnosis becomes more challenging in patients with unknown HIV status. A detailed clinical history, including sexual behaviors, is a vital step to achieve the final diagnosis.