Clinical characteristics and <i>ompA</i> serovar correlation in adult inclusion conjunctivitis: a cohort study in China

Background Adult inclusion conjunctivitis (AIC) caused by non-trachomatous Chlamydia trachomatis is often under-recognised due to variable and non-specific clinical features. This study aimed to describe its clinical and laboratory characteristics, ompA serotype distribution, and their association with clinical presentation and outcome. Methods This retrospective cohort study included 22 patients with laboratory-confirmed AIC diagnosed at a tertiary eye centre between February 2023 and January 2026. Clinical signs were graded using a structured conjunctival scoring system. Diagnosis was based on conjunctival cytology, nucleic acid amplification testing and cell culture. C. trachomatis ompA genotyping was performed by PCR and sequencing with phylogenetic analysis. Patients were classified into serovar D and non-D groups, and clinical severity scores and time to resolution were compared using the Mann-Whitney U test. Results Patients presented with subacute or chronic conjunctivitis with variable conjunctival hyperaemia, follicular reaction, papillary hypertrophy and discharge. ompA genotyping revealed a heterogeneous serovar distribution, with serovar D predominating. Overall clinical scores at presentation were higher in patients with non-D serovars than in those with serovar D (p&lt;0.05), while only papillary reaction differed among individual signs. Time to clinical resolution after standard antibiotic therapy varied but did not differ significantly between groups. Conclusion This study provides a clinical and molecular profile of AIC and highlights variability across ompA serotypes. By generating data from a Chinese cohort, it helps address the limited evidence base in this setting and may support improved clinical recognition and future genotype–phenotype research.