Patterns of multiple human papillomavirus clearance during 5-aminolevulinic acid-based photodynamic therapy in patients with genital warts

Multiple human papillomavirus infections are commonly encountered in genital warts. Infection can be eliminated using 5-aminolevulinic acid-based photodynamic therapy. The aim of this study was to identify the preponderant genotypes and patterns of human papillomavirus co-infection clearance during photodynamic therapy in patients with genital warts. We conducted a retrospective study between January 2020 and February 2021 at two hospitals in Guangzhou, China. Human papillomavirus typing and quantitative detection were performed before starting treatment and after each session of photodynamic therapy. A total of 97 patients participated in the study. Co-infections with low-risk and high-risk types were common in genital warts. Types 6 was the most common type detected, followed by types 52, 11, 58, 51 and 56. Patients with multiple infections were more likely to have high-risk human papillomavirus infection. The viral load of high-risk human papillomavirus before treatment was significantly lower than that of low-risk human papillomavirus, and decreased faster during therapy. In addition, high-risk types were cleared more readily than low-risk types, and 51.4% of high-risk types were eliminated after three rounds of therapy. A transient increase in viral load, especially low-risk types, was observed after two sessions of therapy. Low-risk human papillomavirus was preponderant in patients co-infected with low-risk and high-risk types. Photodynamic therapy effectively eliminated multiple human papillomavirus infections. The response to photodynamic therapy was mainly determined by the low-risk types in patients infected with combinations of low-risk and high-risk types.