Active Trachoma Cases in the Solomon Islands Have Varied Polymicrobial Community Structures but Do Not Associate with Individual Non-Chlamydial Pathogens of the Eye

Abstract

BackgroundSeveral non-chlamydial microbial pathogens are associated with clinical signs of active trachoma in trachoma-endemic communities with a low prevalence of ocular Chlamydia trachomatis (Ct) infection. In the Solomon Islands, the prevalence of Ct among children is low despite the prevalence of active trachoma being moderate. Therefore, we set out to investigate whether active trachoma was associated with a common non-chlamydial infection or with a dominant polymicrobial community dysbiosis in the Solomon Islands.MethodsWe studied DNA from conjunctival swabs collected from 257 Solomon Islanders with active trachoma and matched controls. Droplet digital PCR was used to test for pathogens suspected to be able to induce follicular conjunctivitis. Polymicrobial community diversity and composition were studied by sequencing of hypervariable regions of the 16S ribosomal ribonucleic acid gene in a subset of 54 cases and 53 controls.ResultsAlthough Ct was associated with active trachoma, the number of infections was low (cases, 3.9%; controls, 0.4%). Estimated prevalence (cases and controls, respectively) of each non-chlamydial infection was as follows: Staphylococcus aureus: 1.9 and 1.9%, Adenoviridae: 1.2 and 1.2%, coagulase-negative Staphylococcus: 5.8 and 4.3%, Haemophilus influenzae: 7.4 and 11.7%, Moraxella catarrhalis: 2.3 and 4.7%, and Streptococcus pneumoniae: 7.0 and 6.2%. There was no statistically significant association between the clinical signs of trachoma and the presence or load of any of the non-Ct infections that were assayed. Interindividual variations in the conjunctival microbiome were characterized by differences in the levels of Corynebacterium, Propionibacterium, Helicobacter, and Paracoccus, but diversity and relative abundance of these specific genera did not differ significantly between cases and controls.DiscussionIt is unlikely that the prevalent trachoma-like follicular conjunctivitis in this region of the Solomon Islands has a dominant bacterial etiology. Before implementing community-wide azithromycin distribution for trachoma, policy makers should consider that clinical signs of trachoma can be observed in the absence of any detectable azithromycin-susceptible organism.

Identification of A Novel Picorna-Like Virus, Burpengary Virus, that is Negatively Associated with Chlamydial Disease in the Koala

“…This may affect the presence of other organisms in the conjunctiva. Indeed, although conflicting evidence exists, studies of human trachoma have reported that chlamydial disease is associated with a decrease in microbial richness and diversity compared to healthy controls [33,34]. Innate immune responses form a key part of the host response to chlamydial infection and, although only speculation, it is possible that upregulation of these processes at the mucosal surface may inadvertently impact on infection by other organisms such as the novel virus detected in this study [32].…”

The utility of serology for elimination surveillance of trachoma

“…A map which highlights the countries from which data were available is presented in the Supplementary Information (Supplementary Figure 2). Full details of the field and laboratory methodologies, relevant ethical and regulatory board approval are provided elsewhere 14,16,33–35 . A summary of the demography of each population is provided in Supplementary Table 1, and age-specific prevalence curves for TF and sero-positivity to Ct antigens are presented in Fig.…”

A systematic review of historical and contemporary evidence of trachoma endemicity in the Pacific Islands

“…A recent study found no association between severe scarring, classed using the FPC grading system [ 64 , 65 ], and age [ 66 ]. Seroepidemiological analyses also provided little evidence of ongoing intense transmission of infection [ 66 , 67 ]. Other pathogens ( Adenoviridae , coagulase-negative Staphylococcus , Haemophilus influenza , Moraxella catarrhalis , Staphylococcus pneumonia and Staphylococcus aureus ) were sought in these samples using PCR, but none appeared to have significant association with TF.…”

“…Other pathogens ( Adenoviridae , coagulase-negative Staphylococcus , Haemophilus influenza , Moraxella catarrhalis , Staphylococcus pneumonia and Staphylococcus aureus ) were sought in these samples using PCR, but none appeared to have significant association with TF. There was also scant evidence for conjunctival dysbiosis, a characteristic disease-associated disturbance of the microbiological community [ 67 ]. A recent analysis of gene expression in the conjunctival epithelium of Solomon Islander Ct -negative TF cases provided no evidence of an allergic aetiology [ 68 ].…”