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Home / Equine Research Bank / PLoS One / Alterations of the bacterial ocular surface microbiome are f...
PloS one2023; 18(9); e0291028; doi: 10.1371/journal.pone.0291028

Alterations of the bacterial ocular surface microbiome are found in both eyes of horses with unilateral ulcerative keratitis.

Abstract: Next generation sequencing (NGS) studies in healthy equine eyes have shown a more diverse ocular surface microbiota compared to culture-based techniques. This study aimed to compare the bacterial ocular surface microbiota in both eyes of horses with unilateral ulcerative keratitis (UK) with controls free of ocular disease. Conjunctival swabs were obtained from both ulcerated eyes and unaffected eyes of 15 client-owned horses with unilateral UK following informed consent, as well as from one eye of 15 healthy horses. Genomic DNA was extracted from the swabs and sequenced on an Illumina platform using primers that target the V4 region of bacterial 16S rRNA. Data were analyzed using Quantitative Insights Into Molecular Ecology (QIIME2). The ocular surface of ulcerated eyes had significantly decreased species richness compared with unaffected fellow eyes (Chao1 q = 0.045, Observed ASVs p = 0.045) with no differences in evenness of species (Shannon q = 0.135). Bacterial community structure was significantly different between either eye of horses with UK and controls (unweighted UniFrac: control vs. unaffected, p = 0.03; control vs. ulcerated, p = 0.003; unaffected vs. ulcerated, p = 0.016). Relative abundance of the gram-positive taxonomic class, Bacilli, was significantly increased in ulcerated eyes compared with controls (q = 0.004). Relative abundance of the taxonomic family Staphylococcaceae was significantly increased in ulcerated and unaffected eyes compared with controls (q = 0.030). The results suggest the occurrence of dysbiosis in infected eyes and reveal alterations in beta diversity and taxa of unaffected fellow eyes. Further investigations are necessary to better understand the role of the microbiome in the pathophysiology of ocular surface disease.
Copyright: © 2023 Julien et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Publication Date: 2023-09-08 PubMed ID: 37682941PubMed Central: PMC10490969DOI: 10.1371/journal.pone.0291028Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research reveals that horses with a condition known as unilateral ulcerative keratitis, affecting only one eye, exhibit significant changes in the diversity and quantity of bacteria present not only on the surface of the affected eye, but also on the healthy eye.

Objectives of the Research

  • The primary goal was to compare the bacterial ecosystem on the ocular surface in horses affected by unilateral ulcerative keratitis (a damaging eye condition) with those in healthy horses.
  • The research utilized advanced Next Generation Sequencing techniques, which have previously revealed a greater diversity in eye-surface bacteria compared to traditional culture-based studies.

Research Methodology

  • The study took conjunctival swabs, samples from the surface of the eye, from 15 horses with unilateral ulcerative keratitis – from both the affected and unaffected eyes.
  • They also took swabs from one eye of 15 healthy horses to serve as a control group.
  • The samples’ genomic DNA was extracted and sequenced using an Illumina platform, targeting a specific bacterial region in the ribosomal RNA (16S rRNA).
  • The data were then analyzed using the Quantitative Insights Into Molecular Ecology (QIIME2) software.

Key Findings

  • The infected eyes had a significantly reduced species richness, or diversity, compared to the healthy eyes in the same horses.
  • The distribution of these species (sometimes referred to as species evenness) was, however, not significantly different.
  • The structure of bacterial communities differed significantly between the eyes of horses with the disease and those without.
  • The infected eyes had a higher relative abundance of Bacilli (a group of Gram-positive bacteria) and Staphylococcaceae (a family of bacteria which includes many harmful species) compared to healthy eyes, including the unaffected eyes of horses with the disease.

Implications and Future Research

  • The findings indicate that the bacterial ecosystem, or microbiome, on the surface of eyes affected by unilateral ulcerative keratitis is significantly altered.
  • This ‘dysbiosis’ in infected eyes and alterations in the bacterial diversity and abundance in the unaffected eyes complicate our understanding of the disease’s pathophysiology.
  • Further investigation is thus needed to fully understand the role the microbiome plays in this and other ocular conditions.

Cite This Article

APA
Julien ME, Shih JB, Correa Lopes B, Vallone LV, Suchodolski JS, Pilla R, Scott EM. (2023). Alterations of the bacterial ocular surface microbiome are found in both eyes of horses with unilateral ulcerative keratitis. PLoS One, 18(9), e0291028. https://doi.org/10.1371/journal.pone.0291028

Publication

PloS one
ISSN: 1932-6203
NlmUniqueID: 101285081
Country: United States
Language: English
Volume: 18
Issue: 9
Pages: e0291028

Researcher Affiliations

Julien, Martha E
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Shih, Johnathan B
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Correa Lopes, Bruna
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Vallone, Lucien V
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Suchodolski, Jan S
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Pilla, Rachel
  • Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America.
Scott, Erin M
  • Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America.

MeSH Terms

  • Horses
  • Animals
  • Corneal Ulcer / veterinary
  • RNA, Ribosomal, 16S / genetics
  • Keratitis
  • Eye
  • Face

Conflict of Interest Statement

The authors have declared that no competing interests exist.

References

This article includes 52 references
  1. Kugadas A, Gadjeva M. Impact of microbiome on ocular health. Ocul Surf 2016; 14(3):342–349.
    doi: 10.1016/j.jtos.2016.04.004pmc: PMC5082109pubmed: 27189865google scholar: lookup
  2. Zegans ME, Van Gelder RN. Considerations in understanding the ocular surface microbiome. Am J Ophthalmol 2014; 158(3): 420–422.
    doi: 10.1016/j.ajo.2014.06.014pmc: PMC4497523pubmed: 25132249google scholar: lookup
  3. Weese SJ, Nichols J, Jalali M, Litster A. The oral and conjunctival microbiotas in cats with and without feline immunodeficiency virus infection. Vet Res 2015; 46:21.
    doi: 10.1186/s13567-014-0140-5pmc: PMC4348098pubmed: 25879465google scholar: lookup
  4. Darden JE, Scott EM, Arnold C, Scallan EM, Simon BT, Suchodolski JS. Evaluation of the bacterial ocular surface microbiome in clinically normal cats before and after treatment with topical erythromycin. PLoS ONE 2019; 14(10): e0223859.
    doi: 10.1371/journal.pone.0223859pmc: PMC6788832pubmed: 31603921google scholar: lookup
  5. Scott EM, Arnold C, Dowell S, Suchodolski JS. Evaluation of the bacterial ocular surface microbiome in clinically normal horses before and after treatment with topical neomycin-polymyxin-bacitracin. PLoS ONE 2019; 14(4).
    doi: 10.1371/journal.pone.0214877pmc: PMC6447178pubmed: 30943258google scholar: lookup
  6. Walsh ML, Meason-Smith C, Arnold C, Suchodolski JS, Scott EM. Evaluation of the ocular surface mycobiota in clinically normal horses. PLoS ONE 2021; 16(2): e0246537.
    doi: 10.1371/journal.pone.0246537pmc: PMC7861450pubmed: 33539431google scholar: lookup
  7. Martin de Bustamante M, Gomez D, MacNicol J, Hamor R, Plummer C. The Fecal Bacterial Microbiota in Horses with Equine Recurrent Uveitis. Animals (Basel) 2021. Mar 9;11(3):745.
    doi: 10.3390/ani11030745pmc: PMC7998804pubmed: 33803123google scholar: lookup
  8. Leis ML, Costa MO. Initial description of the core ocular surface microbiome in dogs: Bacterial community diversity and composition in a defined canine population. Vet Ophthalmol 2018.
    doi: 10.1111/vop.12599pubmed: 30095241google scholar: lookup
  9. Rogers CM, Scott EM, Sarawichitr B, Arnold C, Suchodolski JS. Evaluation of the bacterial ocular surface microbiome in ophthalmologically normal dogs prior to and following treatment with topical neomycin- polymyxin-bacitracin. PLoS ONE 2020; 15(6): e0234313.
    doi: 10.1371/journal.pone.0234313pmc: PMC7282667pubmed: 32516320google scholar: lookup
  10. Seyer LD, Wills R, Scott EM, Betbeze C. Description of non-brachycephalic canine conjunctival microbiome before and after application of an antiseptic preparation. Vet Ophthalmol 2022;25:297–306.
    doi: 10.1111/vop.12992pubmed: 35526224google scholar: lookup
  11. Banks KC, Giuliano EA, Busi SB, Reinero CR, Ericsson AC. Evaluation of Healthy Canine Conjunctival, Periocular Haired Skin, and Nasal Microbiota Compared to Conjunctival Culture. Front Vet Sci 2020;7:558.
    doi: 10.3389/fvets.2020.00558pmc: PMC7481369pubmed: 33195492google scholar: lookup
  12. Whitley RD, Burgess EC, Moore CP. Microbial isolates of the normal equine eye. Equine Vet J 1983;2: 138–140.
  13. Santibáñez R, Lara F, Barros TM, Mardones E, Cuadra F, Thomson P. Ocular microbiome in a group of clinically healthy horses. Animals 2022;12,943.
    doi: 10.3390/ani12080943pmc: PMC9028004pubmed: 35454190google scholar: lookup
  14. Andrew SE, Nguyen A, Jones GL, Brooks DE. Seasonal effects on the aerobic bacterial and fungal conjunctival flora of normal thoroughbred brood mares in Florida. Vet Ophthalmol 2003;6(1): 45–50.
    doi: 10.1046/j.1463-5224.2003.00265.xpubmed: 12641842google scholar: lookup
  15. Gemensky-Metzler AJ, Wilkie DA, Kowalski JJ, Schmall LM, Willis AM, Yamagata M. Changes in bacterial and fungal ocular flora of clinically normal horses following experimental application of topical antimicrobial or antimicrobial-corticosteroid ophthalmic preparations. Am J Vet Res 2005;66: 800–811.
    doi: 10.2460/ajvr.2005.66.800pubmed: 15934607google scholar: lookup
  16. Johns IC, Baxter K, Booler H, Hicks C, Menzies-Gow N. Conjunctival bacterial and fungal flora in healthy horses in the UK. Vet Ophthalmol 2001;14(3): 195–199.
    pubmed: 21521444
  17. Hampson ECGM, Gibson JS, Barot M, Shapter FM, Greer RM. Identification of bacterial and fungi samples from the conjunctival surface of normal horses in south-east queensland, australia. Vet Ophthalmol 2019;22(3):265–275.
    doi: 10.1111/vop.12587pubmed: 29963751google scholar: lookup
  18. Moore CP, Heller N, Majors LJ, Whitley RD, Burgess EC, Weber J. Prevalence of ocular microorganisms in hospitalized and stabled horses. Am J Vet Res 1988;49(6): 773–777.
    pubmed: 3400913
  19. Whitley RD, Moore CP. Microbiology of the equine eye in health and disease. Vet Clin North Am Large Anim Pract 1984;6(3): 451–466.
    doi: 10.1016/s0196-9846(17)30003-4pubmed: 6393541google scholar: lookup
  20. Moore CP, Collins BK, Fales WH. Antibacterial susceptibility patterns for microbial isolates associated with infectious keratitis in horses: 63 cases (1986–1994). Am J Vet Med Assoc 1995;7: 928–933.
    pubmed: 7559027
  21. Moore CP, Fales WH, Whittington P, Bauer L. Bacterial and fungal isolates from equidae with ulcerative keratitis. J Am Vet Med Assoc 1983;6: 600–603.
    pubmed: 6833103
  22. Mustikka MP, Grönthal TSC, Pietilä EM. Equine infectious keratitis in finland: associated microbial isolates and susceptibility profiles. Vet Ophthalmol 2020;23:148–159.
    doi: 10.1111/vop.12701pmc: PMC7004187pubmed: 31364808google scholar: lookup
  23. Keller RL, Hendrix DV. Bacterial isolates and antimicrobial susceptibilities in equine bacterial ulcerative keratitis (1993–2004). Equine Veterinary Journal 2005; 37: 207–211.
    doi: 10.2746/0425164054530731pubmed: 15892227google scholar: lookup
  24. da Silva Curiel JM, Murphy CJ, Jang SS, Bellhorn RW. Nutritionally variant streptococci associated with corneal ulcers in horses: 35 cases (1982–1988). J Am Vet Med Assoc 1990. Sep 1;197(5):624–6.
    pubmed: 2211314
  25. Wada S, Hobo S, Niwa H. Ulcerative keratitis in thoroughbred racehorses in Japan from 1997 to 2008. Vet Ophthalmol 2010; 13: 99–100.
    doi: 10.1111/j.1463-5224.2010.00767.xpubmed: 20447028google scholar: lookup
  26. Vercruysse EM, Narinx FP, Rives AC, Sauvage AC, Grauwels MF, Monclin SJ. Equine ulcerative keratitis in belgium: Associated bacterial isolates and in vitro antimicrobial resistance in 200 eyes. Vet Ophthalmol 2022;25:326–337.
    doi: 10.1111/vop.12985pubmed: 35343046google scholar: lookup
  27. Lu LJ, Liu J. Human microbiota and ophthalmic disease. Yale J Biol Med 2016;89: 325–330.
    pmc: PMC5045141pubmed: 27698616
  28. Tuzhikov A, Pnachin A, Thanathanee O, Shalabi N, Nelson D, Akileswaran L. Keratitis-induced changes to the homeostatic microbiome at the human cornea. Invest Ophthalmol Vis Sci 2013;54:2891.
  29. Segata N, Izard J, Waldron L, Gevers D, Miropolsky L, Garrett WS. Metagenomic biomarker discovery and explanation. Genome Biol 2011;12(6).
    doi: 10.1186/gb-2011-12-6-r60pmc: PMC3218848pubmed: 21702898google scholar: lookup
  30. Schlemmer SN, Scott EM, Vallone LV, Johnson MC, Guo F, Zhu G. What is your diagnosis? corneal scrape from a dog. Vet Clin Pathol 2018. Jun;47(2):315–316.
    doi: 10.1111/vcp.12587pubmed: 29406606google scholar: lookup
  31. Husted, JR. Bacterial and fungal organisms in the vagina of normal cows and cows with vaginitis. Master’s thesis, Texas A&M University. Texas A&M University. 2003 [Cited 24 December 2022]. Available from: https://hdl.handle.net/1969.1/1310.
  32. Parada AE, Needham DM, Fuhrman JA. Every base matters: assessing small subunit rRNA primers for marine microbiomes with mock communities, time series and global field samples. Environ Microbiol 2016;18(5): p. 1403–14.
    doi: 10.1111/1462-2920.13023pubmed: 26271760google scholar: lookup
  33. Apprill A, McNally SP, Parsons R, Weber L. Minor revision to V4 region SSU rRNA 806R gene primer greatly increases detection of SAR11 bacterioplankton. Aquatic Microbial Ecology 2015;75(2):129–137.
  34. Bolyen E, Rideout JR, Dillon MR, Bokulich NA, Abnet CC, GA Al-Ghalith. Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2. Nat Biotechnol 2019;37(8):852–857.
    doi: 10.1038/s41587-019-0209-9pmc: PMC7015180pubmed: 31341288google scholar: lookup
  35. Callahan BJ, MCMurdie PJ, Rosen MJ, Han AW, Johnson AJA, Holmes SP. DADA2: High-resolution sample inference from Illumina amplicon data. Nat Methods 2016; 13(7):581–583.
    doi: 10.1038/nmeth.3869pmc: PMC4927377pubmed: 27214047google scholar: lookup
  36. Davis NM, Proctor DM, Holmes SP, Relman DA, Callahn BJ. Simple statistical identification and removal of contaminant sequences in marker-gene and metagenomics data. Microbiome 2018;6(1):226.
    doi: 10.1186/s40168-018-0605-2pmc: PMC6298009pubmed: 30558668google scholar: lookup
  37. Lozupone C, Knight R. UniFrac: a new phylogenetic method for comparing microbial communities. Applied and environmental microbiology 2005;71(12):8228–8235.
    doi: 10.1128/AEM.71.12.8228-8235.2005pmc: PMC1317376pubmed: 16332807google scholar: lookup
  38. Benjamini Y, Hochberg Y. Controlling the false discovery rate: a practical and powerful approach to multiple testing. Journal of the royal statistical society. Series B (Methodological) 1995: 289–300.
  39. Dong Q, Brulc JM, Iovieno A, Bates B, Garoutte A, Miller D. Diversity of bacteria at healthy human conjunctiva. Invest Ophthalmol Vis Sci 2011;52(8): 5408–5413.
    doi: 10.1167/iovs.10-6939pmc: PMC3176057pubmed: 21571682google scholar: lookup
  40. Huang Y, Yang B, Li W. Defining the normal core microbiome of conjunctival microbial communities. Clin Microbiol Infect 2016; 22(7): 643.e7–643.e12.
    doi: 10.1016/j.cmi.2016.04.008pubmed: 27102141google scholar: lookup
  41. Ozkan J, Nielsen S, Diez-Vives C, Coroneo M, Thomas T, Willcox M. Temporal stability and composition of the ocular surface microbiome. Nature Sci Rep 2017.
    doi: 10.1038/s41598-017-10494-9pmc: PMC5575025pubmed: 28852195google scholar: lookup
  42. Qi Y, Wan Y, Li T, Zhang M, Song Y, Hu Y. Comparison of the ocular microbiomes of dry eye patients with and without autoimmune disease. Front Cell Infect Microbiol 2021. Sep 22;11:716867.
    doi: 10.3389/fcimb.2021.716867pmc: PMC8493086pubmed: 34631599google scholar: lookup
  43. Kang Y, Zhang H, Hu M, Ma Y, Chen P, Zhao Z. Alterations in the ocular surface microbiome in traumatic corneal ulcer patients. Invest Ophthalmol Vis Sci 2020. Jun 3;61(6):35.
    doi: 10.1167/iovs.61.6.35pmc: PMC7415308pubmed: 32543662google scholar: lookup
  44. Wang C, Schaefer L, Bian F, Yu Z, Pflugfelder SC, Britton RA. Dysbiosis modulates ocular surface inflammatory response to liposaccharide. Invest Ophthalmol Vis Sci 2019. Oct 1;60(13):4224–4233.
    doi: 10.1167/iovs.19-27939pmc: PMC6795342pubmed: 31618426google scholar: lookup
  45. Song HY, Qiu BF, Liu C, Zhu SX, Wang SC, Miao J. Identification of causative pathogens in mouse eyes with bacterial keratitis by sequence analysis of 16S rDNA libraries. Exp Anim 2015;64(1):49–56.
    doi: 10.1538/expanim.14-0046pmc: PMC4329515pubmed: 25312507google scholar: lookup
  46. Tyler AD, Smith MI, Silverberg MS. Analyzing the human microbiome: a “how to” guide for physicians. Am J Gastroenterol 2014;109:983–993.
    doi: 10.1038/ajg.2014.73pubmed: 24751579google scholar: lookup
  47. Huang X, Ye Z, Cao Q, Su G, Wang Q, Deng J. Gut microbiota composition and fecal metabolic phenotype in patients with acute anterior uveitis. Investig Ophthalmol Vis Sci 2018;59:1523–1531.
    doi: 10.1167/iovs.17-22677pubmed: 29625474google scholar: lookup
  48. Ehling-Schulz M, Lereclus D, Koehler TM. The Bacillus cereus group: Bacillus species with pathogenic potential. Microbiol Spectr 2019. May;7(3):10.1128/microbiolspec.GPP3-0032-2018.
    doi: 10.1128/microbiolspec.GPP3-0032-2018pmc: PMC6530592pubmed: 31111815google scholar: lookup
  49. Matysiak A, Kabza M, Karolak JA, Jaworska MM, Rydzanicz M, Ploski R. Characterization of ocular surface microbial profiles revealed discrepancies between conjunctival and corneal microbiota. Pathogens 2021. Mar 30;10(4):405.
    doi: 10.3390/pathogens10040405pmc: PMC8067172pubmed: 33808469google scholar: lookup
  50. Leis ML, Madruga GM, Costa MO. The porcine corneal surface bacterial microbiome: A distinctive niche within the ocular surface. PLoS One 2021. Feb 19;16(2):e0247392.
    doi: 10.1371/journal.pone.0247392pmc: PMC7895408pubmed: 33606829google scholar: lookup
  51. Auten CR, Urbanz JL, Dees DD. Comparison of bacterial culture results collected via direct corneal ulcer vs conjunctival fornix sampling in canine eyes with presumed bacterial ulcerative keratitis. Vet Ophthalmol 2020. Jan;23(1):135–140.
    doi: 10.1111/vop.12698pubmed: 31328879google scholar: lookup
  52. Selway CA, Eisenhofer R, Weyrich LS. Microbiome applications for pathology: challenges of low microbial biomass samples during diagnostic testing. J Pathol Clin Res 2020. Apr;6(2):97–106.
    doi: 10.1002/cjp2.151pmc: PMC7164373pubmed: 31944633google scholar: lookup
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