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Verdenius CY, Slenter IJM, Hermans H, Broens EM, Djajadiningrat-Laanen SC. Equine ulcerative keratitis in the Netherlands (2012-2021): Bacterial and fungal isolates and antibiotic susceptibility. Equine Vet J 2024. [PMID: 38220439 DOI: 10.1111/evj.14059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/14/2023] [Indexed: 01/16/2024]
Abstract
BACKGROUND Ulcerative keratitis is a common ophthalmic disease in horses which can be complicated by microbial infection and requires immediate, accurate treatment to prevent loss of visual function or the eye. OBJECTIVES To report the results of microbial cultures, antibiotic susceptibility tests and corneal cytology in horses with ulcerative keratitis presented to a referral clinic, to assess agreement between cytology and culture results, to investigate whether previous topical treatment affected microbial culture results and whether the incidence of antimicrobial resistance changed during the study period. STUDY DESIGN Retrospective analysis. METHODS Case characteristics and results of cytology and microbial cultures were retrieved. Statistical analyses included descriptive statistics, χ2 or Fisher's exact test and McNemar test. RESULTS Samples for bacterial culturing (n = 187), fungal culturing (n = 153) and cytology (n = 153) were collected from 178 horses. Bacterial and fungal cultures were positive in 36% (n = 67) and 20% (n = 30), respectively. Staphylococcus (n = 35/67; 48%), Streptococcus (n = 12/67; 16%) and Aspergillus species (n = 22/30; 81%) were most frequently found. Microorganisms were observed in 14% of cytology samples (n = 22/153). Acquired antibiotic resistance was commonly observed amongst Streptococcus and Staphylococcus species. Acquired antibiotic resistance to gentamicin was more common in cases previously treated with gentamicin (p < 0.001). The incidence of acquired antibiotic resistance did not increase significantly between Cohort 2012-2017 and Cohort 2018-2021. Neither bacterial nor fungal culturing results were in agreement with cytology findings (p < 0.001 and p = 0.02, respectively). In 6 of 104 samples that were negative on fungal culturing, cytology revealed fungal elements. MAIN LIMITATIONS Due to the retrospective nature of this study, some case characteristics and test results were unavailable. CONCLUSIONS Acquired resistance was commonly observed amongst Streptococcus and Staphylococcus species, and in bacteria previously exposed to topical gentamicin. The incidence of acquired antibiotic resistance did not increase over time. When fungal cultures prove negative, cytology may have some added benefit in identifying keratomycosis.
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Affiliation(s)
- Clara Y Verdenius
- Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands
| | - Inge J M Slenter
- Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands
| | | | - Els M Broens
- Department of Biomolecular Health Sciences, Infectious Diseases & Immunology, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands
| | - Sylvia C Djajadiningrat-Laanen
- Department of Clinical Sciences, Surgery of Companion Animals, Ophthalmology Section, Utrecht University, Faculty of Veterinary Medicine, Utrecht, The Netherlands
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Julien ME, Shih JB, Correa Lopes B, Vallone LV, Suchodolski JS, Pilla R, Scott EM. Alterations of the bacterial ocular surface microbiome are found in both eyes of horses with unilateral ulcerative keratitis. PLoS One 2023; 18:e0291028. [PMID: 37682941 PMCID: PMC10490969 DOI: 10.1371/journal.pone.0291028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023] Open
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.
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Affiliation(s)
- Martha E. Julien
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Johnathan B. Shih
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Bruna Correa Lopes
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Lucien V. Vallone
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Jan S. Suchodolski
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Rachel Pilla
- Department of Small Animal Clinical Sciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Erin M. Scott
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
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Mo PM, Picard J, Gummow B. The conjunctival fungal microflora of horses in a North Queensland tropical environment and their in vitro susceptibilities to antifungal agents. Vet Res Commun 2023; 47:1641-1651. [PMID: 37022654 PMCID: PMC10485094 DOI: 10.1007/s11259-023-10119-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 03/30/2023] [Indexed: 04/07/2023]
Abstract
Fungi are ubiquitous in the environment and part of the commensal microflora on the conjunctiva of equine eyes. North Queensland, being tropical, presents an ideal environment for fungi growth. When the cornea is injured, fungi can invade the corneal stroma, resulting in keratomycosis. The objectives of this study were to determine the fungal species specific to the eyes of horses in the Townsville region; to investigate the potential risk factors associated with the presence of fungi; and to test their susceptibility to antifungals to create an empirical guide for treatment. The eyes of forty ophthalmologically normal horses from James Cook University were sampled throughout the summer months of December 2017, January 2018, and January and February 2020. Cultured fungi were identified morphologically, and their identity confirmed by comparing partial 18sRNA DNA sequences with the NCBI nucleotide database. Minimum inhibitory concentration testing of common antifungal medications was performed. Sixty-one out of eighty conjunctival samples grew fungi, and 21 different fungi genera were isolated. The most common genera were Aspergillus (18%, 26/141), Curvularia (14%,20/141), Rhodotorula (12%,17/141) and Penicillium (12%,17/141). No significant association was found between age or environmental factors and fungal culture status. Most fungi were highly susceptible to voriconazole and ketoconazole but resistant to fluconazole and amphotericin B. This adds to the body of evidence on which species of fungi are present as normal ocular microflora of horses living in tropical regions of Australia, and an avenue for treating them.
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Affiliation(s)
- Phu Mo Mo
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Queensland, Australia.
| | - Jacqueline Picard
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Queensland, Australia
| | - Bruce Gummow
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Queensland, Australia
- Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
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4
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Torres LEC, Florez CO, Oliveira JG, Vieira GD, Ribeiro IS, Keller KM, Leme FOP, Fantini P, Maranhão RPA. Antimicrobial Activity of Plasma Rich in Platelets (PRP) on the Ocular Microbiota of Healthy Horses from Minas Gerais: In Vitro Study. Vet Med Int 2023; 2023:2407768. [PMID: 37622165 PMCID: PMC10447163 DOI: 10.1155/2023/2407768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 02/28/2023] [Accepted: 04/20/2023] [Indexed: 08/26/2023] Open
Abstract
In equine ophthalmology, ulcerative keratitis is among the most common conditions and, in general, arises as a consequence of some trauma suffered. Secondarily, subsequent contamination by pathogenic or resident bacteria of the horse's ocular microbiota may have undesirable consequences. Under physiological conditions, the normal microbiota coexists with the immune status of the host, serving as a barrier, ensuring the health of the ocular surface, and inhibiting the proliferation of pathogens. However, in the imbalance of immune barriers, the normal microbiota can become pathogenic and lead to infection, acting as an opportunistic agent. The present study aims to demonstrate the antimicrobial effect of platelet-rich plasma (PRP), its time of action, and its correlation with the concentration of its same components in vitro on Staphylococcus sciuri, a bacterium with high prevalence in the normal ocular microbiota of horses in the municipality of Minas Gerais. For the preparation of the PRP, eight adult Quarter Horse (QH) horses were used. The individual PRP was prepared by the double centrifugation protocol, and then, the PRPs were added to a pool, followed by testing their interaction in culture with Brain Heart Infusion (BHI) broth at different dilutions against five strains collected from different animals. After 3, 6, 12, and 18 hours, the colony formation units (CFU) count on a 5% horse blood agar plate was evaluated for each time point. Our study showed that Staphylococcus sciuri, the resident microorganism of the ocular conjunctival microbiota of horses, is more susceptible when compared to the standard strain "American Type Culture Collection" (ATCC-29213) Staphylococcus aureus, a pathogenic microorganism, which was used for the validation of our study. The antibacterial effect shown in this study was bacteriostatic for up to 6 hours. The most concentrated PRP dilutions, 1 : 1 and 1 : 2, were also most effective, suggesting that the antibacterial effect is volume dependent.
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Affiliation(s)
- Luis E. C. Torres
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Camilo O. Florez
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Jéssica G. Oliveira
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Giovanna D. Vieira
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Ilza S. Ribeiro
- Grupo UnieduK, Centro Universitário de Jaguariúna-UNIFAJ, Jaguariúna, São Paulo 13918-110, Brazil
| | - Kelly M. Keller
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Fabíola O. P. Leme
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Priscila Fantini
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
| | - Renata P. A. Maranhão
- Escola de Veterinária, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901, Brazil
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Fernández-Garayzábal JF, LaFrentz S, Casamayor A, Abarca E, Mohammed HH, Cuming RS, Arias CR, Domínguez L, Vela AI. Corynebacterium conjunctivae: A New Corynebacterium Species Isolated from the Ocular Surface of Healthy Horses. Animals (Basel) 2022; 12:ani12141827. [PMID: 35883374 PMCID: PMC9312174 DOI: 10.3390/ani12141827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 11/19/2022] Open
Abstract
Simple Summary The identification of commensal bacteria in normal eyes is relevant because they contribute to ocular defense mechanisms. Studies focused on identifying the normal ocular flora in horses confirm that Gram-positive bacteria are predominant, with the genus Corynebacterium being among the most frequently identified. However, identification at the species level is uncommon, which limits precise knowledge about the diversity of the corynebacterial species in equine eyes. The purpose of this study was to characterize some commensal Corynebacterium-like organisms recovered from the conjunctival sac of healthy adult horses using phenotypic, chemotaxonomic and molecular genetic methodologies. Based on the results obtained, we propose a new Corynebacterium species, Corynebacterium conjunctivae, as a commensal organism of the horse eye. Abstract Twenty-two unidentified Gram-positive, rod-shaped organisms were recovered from the conjunctival surface of apparently healthy horses and subjected to a polyphasic taxonomic analysis. Based on cellular morphology and biochemical criteria, the isolates were tentatively assigned to the genus Corynebacterium, although they did not match any recognized species. Comparative 16S rRNA gene sequencing studies demonstrated that all of the isolates were phylogenetically members of the genus Corynebacterium. The isolates shared 99.4 to 100% 16S rRNA gene sequence similarity among the strains and 96.5% similarity with Corynebacterium tapiri 2385/12T, which was the closest phylogenetically related species. The DNA G+C content was 58.4 mol%. The major fatty acids were C15:0, C16:0, C17:1ω8c and C18:1ω9c, while the predominant mycolic acids consisted of C30:0, C32:0 and C34:0. The isolates were distinguished from related Corynebacterium species by a number of phenotypic properties. On the basis of phenotypic and phylogenetic evidence, it is proposed that the unknown isolates from horses be classified in the genus Corynebacterium as Corynebacterium conjunctivae sp. nov. The type strain of C. conjunctivae is ICM19-01138T (DSM 109759T = CCUG 73728T).
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Affiliation(s)
- José F. Fernández-Garayzábal
- Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, 28040 Madrid, Spain; (J.F.F.-G.); (A.C.); (L.D.)
- Department of Animal Health, Veterinary School, Complutense University, 28040 Madrid, Spain
| | - Stacey LaFrentz
- Department of Biological Sciences, Auburn University, Auburn, AL 36894, USA;
| | - Almudena Casamayor
- Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, 28040 Madrid, Spain; (J.F.F.-G.); (A.C.); (L.D.)
| | - Eva Abarca
- Servei d’Oftalmologia, ARS Veterinaria, 08034 Barcelona, Spain;
| | - Haitham H. Mohammed
- Department of Aquatic Animal Medicine and Management, Faculty of Veterinary Medicine, Assiut University, Assiut 71526, Egypt;
| | | | - Cova R. Arias
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL 36894, USA
| | - Lucas Domínguez
- Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, 28040 Madrid, Spain; (J.F.F.-G.); (A.C.); (L.D.)
- Department of Animal Health, Veterinary School, Complutense University, 28040 Madrid, Spain
| | - Ana I. Vela
- Centro de Vigilancia Sanitaria Veterinaria (VISAVET), Universidad Complutense, 28040 Madrid, Spain; (J.F.F.-G.); (A.C.); (L.D.)
- Department of Animal Health, Veterinary School, Complutense University, 28040 Madrid, Spain
- Correspondence:
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Santibáñez R, Lara F, Barros TM, Mardones E, Cuadra F, Thomson P. Ocular Microbiome in a Group of Clinically Healthy Horses. Animals (Basel) 2022; 12:ani12080943. [PMID: 35454190 PMCID: PMC9028004 DOI: 10.3390/ani12080943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/22/2022] [Accepted: 03/31/2022] [Indexed: 02/01/2023] Open
Abstract
The ocular microbiome in horses is poorly described compared to other species, and most of the information available in the literature is based on traditional techniques, which has limited the depth of the knowledge on the subject. The objective of this study was to characterize and predict the metabolic pathways of the ocular microbiome of a group of healthy horses. Conjunctival swabs were obtained from both eyes of 14 horses, and DNA extraction was performed from the swabs, followed by next generation sequencing and bioinformatics analyses employing DADA2 and PICRUSt2. A total of 17 phyla were identified, of which Pseudomonadota (Proteobacteria) was the most abundant (59.88%), followed by Actinomycetota (Actinobacteria) (22.44%) and Bacteroidota (Bacteroidetes) (16.39%), totaling an average of 98.72% of the communities. Similarly, of the 278 genera identified, Massilia, Pedobacter, Pseudomonas, Sphingomonas, Suttonella and Verticia were present in more than 5% of the samples analyzed. Both Actinobacteria and Bacteroides showed great heterogeneity within the samples. The most abundant inferred metabolic functions were related to vital functions for bacteria such as aerobic respiration, amino acid, and lipid biosynthesis.
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Affiliation(s)
- Rodrigo Santibáñez
- Departamento de Ingeniería Química y Bioprocesos, Facultad de Ingeniería, Pontificia Universidad Católica, Santiago 8940000, Chile;
| | - Felipe Lara
- Unidad de Cirugía y Medicina Equina, Hospital Clínico Veterinario, Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370134, Chile;
| | - Teresa M. Barros
- Department of Clinical Science, College of Veterinary Medicine Specialty Ophthalmology Intern, Vaughan Large Animal Teaching Hospital, Auburn, AL 36832, USA;
| | - Elizabeth Mardones
- Laboratorio de Microbiología Clínica y Microbioma, Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370134, Chile; (E.M.); (F.C.)
| | - Françoise Cuadra
- Laboratorio de Microbiología Clínica y Microbioma, Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370134, Chile; (E.M.); (F.C.)
| | - Pamela Thomson
- Laboratorio de Microbiología Clínica y Microbioma, Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago 8370134, Chile; (E.M.); (F.C.)
- Correspondence: ; Tel.: +56-227-703-688
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Chalder RH, Knott T, Rushton JO, Nikolic-Pollard D. Changes in antimicrobial resistance patterns of ocular surface bacteria isolated from horses in the UK: An eight-year surveillance study (2012-2019). Vet Ophthalmol 2020; 23:950-956. [PMID: 32961021 DOI: 10.1111/vop.12827] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/27/2020] [Accepted: 09/07/2020] [Indexed: 11/29/2022]
Abstract
PURPOSE To identify temporal changes in antimicrobial resistance of ocular surface bacteria isolated from clinically symptomatic equine eyes in the South West of the UK. STUDY DESIGN Retrospective. METHODS Clinical and laboratory records of horses treated for suspected bacterial ocular surface disease (ulcerative and non-ulcerative) at a single facility between January 2011 and December 2019 were reviewed. Cases were included if they underwent ocular surface sampling, aerobic bacterial culture, and antimicrobial susceptibility testing. Cases were split into two time periods based on when sampling occurred: "early" (2012-2015) and "late" (2016-2019) to enable identification of temporal trends in resistance to chloramphenicol, gentamicin, fusidic acid, neomycin, cloxacillin, ofloxacin, and polymyxin B. RESULTS A total of 125 samples from 110 horses were included in analyses. Culture-positive isolates were identified in 76/110 (60.8%) samples. Principal isolates included Staphylococci spp. (n = 45; 64.3%), Streptococci spp. (n = 14; 20%), and Enterobacter spp. (n = 11; 15.7%). There was a significant increase in resistance to chloramphenicol over time (P = .007) and a decrease in resistance to ofloxacin that approached significance (P = .059). Chloramphenicol (100%) and gentamicin (85.7%) had the highest overall in-vitro efficacy during the early and late periods, respectively. There was no significant difference in the type of bacteria isolated across the two time periods. CONCLUSIONS These results suggest a potential increase in resistance to chloramphenicol among bacteria isolated from the ocular surface of horses in the South West UK, reinforcing the value of surveillance to guide the empirical use of antimicrobials.
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Mustikka MP, Grönthal TSC, Pietilä EM. Equine infectious keratitis in Finland: Associated microbial isolates and susceptibility profiles. Vet Ophthalmol 2019; 23:148-159. [PMID: 31364808 PMCID: PMC7004187 DOI: 10.1111/vop.12701] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/05/2019] [Accepted: 06/27/2019] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To retrospectively describe laboratory findings, treatment, and outcome associated with equine infectious keratitis in Finland. ANIMALS AND PROCEDURES Medical records of horses diagnosed with infectious keratitis in University of Helsinki Equine Hospital from January 2007 to June 2018 were reviewed. RESULTS Forty-seven cases were included. Keratomycosis was diagnosed in 27 eyes and bacterial keratitis in 20 eyes. Aspergillus flavus was the most frequent fungal isolate (9/17, 53%), followed by Cylindrocarpon sp. (3/17, 18%) and Aspergillus fumigatus (2/17, 12%). Susceptibility was tested for 10/11 Aspergillus sp. isolates; all were susceptible to voriconazole while only two were susceptible to amphotericin B. Cylindrocarpon sp. isolates were resistant to both agents. Streptococcus equi subsp. zooepidemicus was the most frequent bacterial isolate (9/19, 47%), followed by other streptococci (4/19, 21%). All 13 Streptococcus sp. isolates were susceptible to penicillin, and all tested isolates (n = 11) were also susceptible to chloramphenicol. Mean duration of medical treatment was longer in fungal keratitis (38 days) than in bacterial keratitis (25 days) (P < .001). Twenty-six of the eyes underwent globe-sparing surgery in addition to medical therapy. Recovery was achieved in 66% (31/47) of all cases and in 59% (16/27) and 75% (15/20) (P = .264) of cases with keratomycosis and bacterial keratitis, respectively. CONCLUSIONS Although Aspergillus sp. and S zooepidemicus were the most frequently encountered isolates, cytology, culture, and susceptibility testing are essential to differentiate bacterial and fungal keratitis and guide the clinician to choose the most efficient treatment.
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Affiliation(s)
- Minna P Mustikka
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Thomas S C Grönthal
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
| | - Elina M Pietilä
- Department of Equine and Small Animal Medicine, University of Helsinki, Helsinki, Finland
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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:e0214877. [PMID: 30943258 PMCID: PMC6447178 DOI: 10.1371/journal.pone.0214877] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 03/21/2019] [Indexed: 12/22/2022] Open
Abstract
Next generation sequencing (NGS) studies have demonstrated a rich and diverse ocular surface-associated microbiota in people that was previously undetected by traditional culture-based methods. The ocular surface microbiome of horses has yet to be investigated using NGS techniques. This study aimed to determine the bacterial composition of the ocular surface microbiome in healthy horses, and to identify whether there are microbial community changes over time and following topical antibiotic use. One eye of 12 horses was treated 3 times daily for 1 week with neomycin-polymyxin-bacitracin ophthalmic ointment. Contralateral eyes served as untreated controls. The inferior conjunctival fornix of both eyes was sampled at baseline prior to initiating treatment (day 0), after 1 week of treatment (day 7), and 4 weeks after concluding treatment (day 35). Genomic DNA was extracted from ocular surface swabs and sequenced using primers that target the V4 region of bacterial 16S rRNA. At baseline, the most abundant phyla identified were Proteobacteria (46.1%), Firmicutes (24.6%), Actinobacteria (12.6%), and Bacteroidetes (11.2%). The most abundant families included Pasteurellaceae (13.7%), Sphingomonadaceae (7.9%), an unclassified Order of Cardiobacteriales (7.7%), and Moraxellaceae (4.8%). Alpha and beta diversity measurements were unchanged in both treatment and control eyes over time. Overall, the major bacterial taxa on the equine ocular surface remained stable over time and following topical antibiotic therapy.
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Affiliation(s)
- Erin M. Scott
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| | - Carolyn Arnold
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Samantha Dowell
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
| | - Jan S. Suchodolski
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas, United States of America
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