Metagenomic Shotgun Sequencing Analysis of Canalicular Concretions in Lacrimal Canaliculitis Cases.

Yukinobu Okajima,Kotaro Aoki,Yoshikazu Ishii,Kazuhiro Tateda,Yuka Suzuki,Satoshi Goto,Sho Ishikawa,Takashi Suzuki,Chika Miyazaki,Yuichi Hori

doi:10.3390/cimb43020049

Abstract

Lacrimal canaliculitis is a rare infection of the lacrimal canaliculi with canalicular concretions formed by aggregation of organisms. Metagenomic shotgun sequencing analysis using next-generation sequencing has been used to detect pathogens directly from clinical samples. Using this technology, we report cases of successful pathogen detection of canalicular concretions in lacrimal canaliculitis cases. We investigated patients with primary lacrimal canaliculitis examined in the eye clinics of four hospitals from February 2015 to July 2017. Eighteen canalicular concretion specimens collected from 18 eyes of 17 patients were analyzed by shotgun metagenomics sequencing using the MiSeq platform (Illumina). Taxonomic classification was performed using the GenBank NT database. The canalicular concretion diversity was characterized using the Shannon diversity index. This study included 18 eyes (17 patients, 77.1 ± 6.1 years): 82.4% were women with lacrimal canaliculitis; canalicular concretions were obtained from 12 eyes using lacrimal endoscopy and six eyes using canaliculotomy with curettage. Sequencing analysis detected bacteria in all samples (Shannon diversity index, 0.05–1.47). The following genera of anaerobic bacteria (>1% abundance) were identified: Actinomyces spp. in 15 eyes, Propionibacterium spp., Parvimonas spp. in 11 eyes, Prevotella spp. in 9 eyes, Fusobacterium spp. in 6 eyes, Selenomonas spp. in 5 eyes, Aggregatibacter spp. in 3 eyes, facultative and aerobic bacteria such as Streptococcus spp. in 13 eyes, Campylobacter spp. in 6 eyes, and Haemophilus spp. in 3 eyes. The most common combinations were Actinomyces spp. and Streptococcus spp. and Parvinomonas spp. and Streptococcus spp., found in 10 cases. Pathogens were identified successfully using metagenomic shotgun sequencing analysis in patients with canalicular concretions. Canalicular concretions are polymicrobial with anaerobic and facultative, aerobic bacteria.

Highlights

Lacrimal canaliculitis, an infectious inflammation of the lacrimal canaliculus, often remains undiagnosed for extended periods as a result of its rarity and variety
We describe the results of using next-generation sequencing (NGS) for metagenomic shotgun sequencing analysis of canalicular concretion samples from primary lacrimal canaliculitis; this is the first report to clarify the composition of the canalicular concretions
We investigated patients with primary lacrimal canaliculitis who were examined in Toho University Omori Medical Center Hospital, Amagasaki Medical Center Hospital, Jikei University Hospital, Saitama Medical Center Hospital from February 2015 to July 2017

Summary

Introduction

An infectious inflammation of the lacrimal canaliculus, often remains undiagnosed for extended periods as a result of its rarity and variety. Patients with lacrimal canaliculitis typically present with red eye, epiphora, and punctal discharge. Lacrimal canaliculitis can be primary or secondary. In 1854, Von Graefe first reported primary canaliculitis, which leads to concretions with lacrimal canaliculus, and in 1878, Israel, who described human Actinomycosis, considered it to be often associated with. Secondary canaliculitis is often a complication of punctal or intercanalicular plug insertion for treating dry eye [1]. The presence of concretions may shield the bacteria from the antibiotics [2], promoting resistance and an inadequate treatment response. Many studies have summarized the clinical characteristics and treatment of primary canaliculitis, but few have investigated primary canaliculitis with concretions

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