Observation of a cytopathogenic effect on cell lines used for routine viral cultures led to the diagnosis of lymphogranuloma venereum.

Objectives This article reports the fortuitous recovery of nine Chlamydia trachomatis serovar L strains in cell cultures (Vero and LLC-MK2 cell line) designed for viral culture. Methods Nine ano-genital swabs were inoculated on confluent Vero, MRC5 and LLC-MK2 cell cultures. They were collected from HIV-positive patients who were primarily men who have sex with men (MSM) presenting ulcerations that mimicked herpes simplex infections. Results A cytopathogenic effect was observed on Vero and LLC-MK2 cells on day 14. The presence of C trachomatis serovar L in the cell lines was confirmed by Real Time-PCR. ConclusionsC trachomatis serovar L can grow on Vero and LLC-MK2 cell lines designed for viral cultures. Lymphogranuloma venereum must be considered as a differential diagnosis for herpes-like lesions, particularly in MSM with high-risk behaviours.