Probe capture-based tNGS for microbial detection of dacryocystitis

Dacryocystitis is one of the common infectious diseases in ophthalmology. This study evaluates microbial distribution in lacrimal sac secretions using targeted next-generation sequencing (tNGS) and compares it with traditional culture methods. Conducted at the Zhongshan Ophthalmic Center, 31 patients with confirmed dacryocystitis were enrolled. Lacrimal sac secretions were collected during endoscopic dacryocystorhinostomy and analyzed using both tNGS and conventional bacterial cultures. Microbial diversity was assessed, and antibiotic susceptibility was evaluated for cultured isolates. We compared the positivity rate and the detection of various microorganisms between the two tests, as well as the associated resistance information. tNGS detected a significantly broader range of microorganisms (P = 0.0002). Beyond bacteria and fungi, tNGS revealed substantial viral and parasitic presence: viruses were detected in 22 of 31 patients, with Epstein-Barr virus and human herpesvirus 7 being the most prevalent, while parasitic sequences were identified in six patients, including Acanthamoeba species in four patients. Resistance genes were identified in three patients, suggesting the potential presence of antimicrobial resistance determinants. tNGS provides broader microbial profiling in dacryocystitis and may complement conventional culture by detecting not only bacteria but also fungi, viruses, parasites, and resistance genes. These findings highlight the necessity of managing ocular surface microbiota imbalances across a broad spectrum of microorganisms and emphasize the importance of judicious antibiotic use in clinical practice. Additionally, these observations raise the hypothesis that the lacrimal sac may serve as a potential reservoir for fungi, Acanthamoeba, and viruses on the ocular surface.IMPORTANCEDacryocystitis is one of the most common lacrimal duct obstruction disorders in ophthalmology. Conventional culture detected bacteria in only 38.7% of patients in this study and is unable to detect non-culture-dependent pathogens such as viruses and parasites or provide resistance information. As a critical complement to traditional culture, targeted next-generation sequencing (tNGS) detected microorganisms in 87.1% of cases, covering bacteria, fungi, viruses, and parasites while simultaneously identifying resistance genes-substantially enhancing both detection breadth and depth. Notably, tNGS revealed for the first time substantial levels of viruses, fungi, and Acanthamoeba-a dangerous organism linked to severe corneal infections-in the lacrimal sac, raising the novel hypothesis that the lacrimal sac may serve as an unrecognized reservoir for diverse ocular surface microbes. These findings expand the traditional bacteria-centered view of dacryocystitis and highlight the potential value of tNGS in improving diagnostic evaluation, supporting antibiotic stewardship, and guiding future studies of persistent or recurrent ocular infections.