Seasonal effects on the aerobic bacterial and fungal conjunctival flora of normal thoroughbred brood mares in Florida

Equine ulcerative keratitis in the Netherlands (2012-2021): Bacterial and fungal isolates and antibiotic susceptibility

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.

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

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.

The conjunctival fungal microflora of horses in a North Queensland tropical environment and their in vitro susceptibilities to antifungal agents

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.

Antimicrobial Activity of Plasma Rich in Platelets (PRP) on the Ocular Microbiota of Healthy Horses from Minas Gerais: In Vitro Study

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.

Corynebacterium conjunctivae: A New Corynebacterium Species Isolated from the Ocular Surface of Healthy Horses

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 2385/12^T, which was the closest phylogenetically related species. The DNA G+C content was 58.4 mol%. The major fatty acids were C_15:0, C_16:0, C_17:1ω8c and C_18:1ω9c, while the predominant mycolic acids consisted of C_30:0, C_32:0 and C_34:0. 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 ICM19-01138^T (DSM 109759^T = CCUG 73728^T).

In vitro antifungal susceptibility of Fusarium species and Aspergillus fumigatus cultured from eleven horses with fungal keratitis

PURPOSE

To examine the relationship between Minimum Inhibitory Concentration (MICs) and response to therapy of 6 Fusarium spp. and 5 Aspergillus fumigatus isolated from equine ulcerative keratitis cases.

PROCEDURE

Fungi were identified by morphology and Internal Transcribed Spacer (ITS) polymerase chain reaction (PCR) with sequencing and evaluated at the University of Texas Fungal Testing Laboratory for susceptibility to three azole antifungals (miconazole, voriconazole, posaconazole), natamycin, and two echinocandins (anidulafungin, caspofungin). A Mann-Whitney rank sum test was used for the comparison of time to heal between infections of different fungal genera and in vitro susceptibility to the drug administered.

RESULTS

Fusarium spp. were resistant to azole antifungals in 6/6 cases (100%). Fusarium spp. were susceptible to echinocandins and natamycin in all cases. A. fumigatus was resistant to anidulafungin in 1/5 cases (20%) and posaconazole in 1/5 cases (20%) The remainder of A. fumigatus isolates were susceptible to all antifungal agents tested. Fusarium isolates were treated with antifungals to which they were not susceptible; however, all cases of A. fumigatus were treated with antifungals to which they were susceptible. All Fusarium cases and A. fumigatus cases experienced clinical resolution, regardless of surgical intervention. There was no statistical correlation between fungal genus and time to heal (p < .082).

CONCLUSIONS

The in vitro susceptibility indicated that all cases of Fusarium spp. were resistant to azole antifungal drugs which were used as treatment. Clinical outcomes, however, showed that all cases healed despite resistance to antifungals.

Ocular Microbiome in a Group of Clinically Healthy Horses

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.

Equine ulcerative keratitis in Belgium: Associated bacterial isolates and in vitro antimicrobial resistance in 200 eyes

PURPOSE

To describe bacterial isolates and associated antibiotic resistance from horses with ulcerative keratitis in Belgium.

METHODS

Medical records from horses with ulcerative keratitis presented to the ophthalmology service of the Veterinary teaching hospital of Liege, Belgium, between 2014 and 2021 were evaluated. Bacterial isolates were identified and VITEK^® 2 (Biomérieux) provided antimicrobial susceptibility testing and resistance detection.

RESULTS

Two hundred eyes of 196 horses were sampled. Ninety-seven eyes had a positive bacterial culture (48.5%) and 139 bacterial isolates were identified. Staphylococcus (63/139: 45.3%) and Streptococcus (33/139: 23.7%) were the most frequent genus isolated. Staphylococcus aureus (21/139: 15.1%) was the most frequent species isolated of which half were methicillin-resistant (MRS). Streptococcus equi subsp. zooepidemicus (19/139: 13.7%) was the second most identified bacterial isolate. Only two Pseudomonas species were isolated (2/139: 1.4%). The overall resistance of all bacterial isolates against chloramphenicol (12.4%) and fluoroquinolones (14.3%) was low. Resistance against tobramycin, polymyxin B, gentamicin, fusidic acid, tetracycline, and neomycin ranged from 40.8% to 58.6%. When separating the MRS from the other staphylococci, a significant difference was noted in percentage of resistance to gentamicin (p = .00026) and tetracycline (p = .00015). MRS were highly resistant to gentamicin (75%) and tetracycline (100%), whereas the remaining staphylococci were significantly less resistant to gentamicin (17%) and tetracycline (40.4%).

CONCLUSION

Although Pseudomonas species has been rarely cultured, our results are roughly consistent with previous studies. Multiple drug resistance was high and resistance to first-choice antibiotics in ulcerative keratitis was noted. These results warrant continued monitoring of susceptibility profile.

Aerobic Commensal Conjunctival Microflora in Healthy Donkeys

Simple Summary

The mucosa of the conjunctival sac in mammals is colonized by a group of bacteria, and their interdependence is referred to as commensalism—the coexistence of two different species populations benefiting at least one of the partners. The presence of conjunctival bacterial commensal flora is very important for the capacity of the non-specific immune response. Some of the bacteria are described as conditionally pathogenic, meaning that in the case of breaking down protective barriers, they may act as pathogens. Knowledge of the commensal flora of healthy individuals is of great clinical importance in the diagnosis of pathological conditions. The aim of this study is to assess the presence and the composition of normal ocular microflora of healthy donkeys. To the best of the authors’ knowledge, this is the first report that provides knowledge about commensal microflora in the conjunctival sac of donkeys bred in Central Europe.

Abstract

From a clinical point of view, knowledge of the commensal microbial flora of the conjunctival sac in healthy individuals proves to be of great importance. The aim of this study was to assess the presence and the composition of normal ocular microflora of healthy donkeys. Fourteen clinically healthy donkeys (Equus asinus) participated in the study. After prior ophthalmological examination, which showed no abnormalities, a conjunctival swab was taken from each donkey from the right and left eye. Species-specific identification was based on a morphological assessment of bacterial colonies stained with the Gram technique, as well as on biochemical properties and the disk-diffusion method. Around 82% of samples were positive for bacteria cultivation; Pantoea agglomerans was the most prevalently detected species, followed by Moraxella lacunata. In conclusion, our study made it possible to determine the commensal flora of the conjunctival sac in donkeys. The obtained results also showed discrepancies in the composition of the conjunctival sac flora of donkeys and horses, despite the geographical proximity of performed studies. Knowledge of the commensal conjunctival flora of donkeys is of great clinical importance due to their greater exposure to corneal damage and infections than horses.

Comparison of conjunctival microbiota of clinically normal Persian cats with and without nasolacrimal duct obstruction

OBJECTIVE

This study was performed to determine the conjunctival microbiota of Persian cats with and without nasolacrimal duct obstruction (NLDO).

ANIMALS STUDIED

Twenty-five Persian cats: 15 with bilateral NLDO (Group A) and 10 with no NLDO (Group B).

PROCEDURES

All fifty eyes were assessed. Sterile swab applicators were used for the collection of specimens, which were cultured. PCR was performed on conjunctival swab and blood samples for the detection of Mycoplasma spp. and feline herpesvirus 1(FHV-1), respectively.

RESULTS

FHV-1 was detected in two cats in Group A. Twelve eyes from Group A and four from Group B were Mycoplasma spp. positive based on the PCR results. Moreover, fungal culture was positive in six eyes from Group A and three eyes from Group B. The dominant fungus isolated was Aspergillus spp. (6 out of 11 fungal isolates). Other isolated fungi were Alternaria spp. and Cladosporidium spp. Twenty-three eyes had positive bacterial culture in Group A, while twelve eyes were positive in Group B. The most commonly isolated bacteria were Staphylococcus epidermidis (15 out of 38 bacterial isolates). β-hemolytic Streptococcus spp., Corynebacterium spp., and Staphylococcus aureus were isolated in similar proportions in both groups. Escherichia coli was also present in both groups.

CONCLUSIONS

Results of this study revealed same isolated fungal and bacterial spp. and in similar proportions in Persian cats with and without NLDO.

Evaluation of the ocular surface mycobiota in clinically normal horses

The eye is host to myriad bacterial, fungal, and viral organisms that likely influence ocular surface physiology in normal and diseased states. The ocular surface mycobiota of horses has not yet been described using NGS techniques. This study aimed to characterize the ocular surface fungal microbiota (mycobiota) in healthy horses in 2 environmental conditions (stalled versus pasture). Conjunctival swabs of both eyes were obtained from 7 adult stallions stabled in an open-air pavilion and 5 adult mares living on pasture. Genomic DNA was extracted from ocular surface swabs and sequenced using primers that target the Internal Transcribed Spacer 1 (ITS1) region of the fungal genome on an Illumina platform. Sequences were processed using Quantitative Insights Into Molecular Ecology (QIIME 2.0) and taxonomy assigned with the Findley et al. 2013 ITS1 database. The most abundant genera identified were Leptosphaerulina (22.7%), unclassified Pleosporaceae (17.3%), Cladosporium (16.2%), Alternaria (9.8%), unclassified Pleosporales (4.4%), unclassified Montagnulaceae (2.9%), Fusarium (2.5%), and Pestalotiopsis (1.4%). Fungal community composition (Jaccard, R = 0.460, p = 0.001) and structure (Bray-Curtis, R = 0.811, p = 0.001) were significantly different between pastured mares and stabled stallions. The ocular surface of pastured mares had significantly increased fungal species richness and diversity compared to stabled stallions (Shannon p = 0.0224, Chao1 p = 0.0118, Observed OTUs p = 0.0241). Relative abundances of Aspergillus (p = 0.005) and Alternaria spp. (p = 0.002) were significantly increased in the mycobiota of pastured mares. This is the first report to describe the mycobiota of the equine ocular surface. Environmental factors such as housing influence the composition, structure, and richness of the equine ocular surface mycobiota.

Characterization of the normal equine conjunctival bacterial community using culture-independent methods

BACKGROUND

The equine conjunctival microbiota has often been reported to be dominated by Gram-positive species such as Staphylococcus sp., Bacillus sp., and Corynebacterium sp. However, traditional culture-based methods can only recover a fraction of the bacterial species present in the sample.

OBJECTIVES

This pilot study aimed at exploring the diversity of the equine conjunctival microbiota using culture-independent methods.

STUDY DESIGN

Eight horses were included in this study, and only eyes with normal ophthalmic examination (n = 15 eyes) were sampled.

METHODS

Conjunctival biopsies (culture-independent) were collected, and DNA was extracted from the tissues. Bacterial communities in conjunctival biopsies were characterized by next-generation sequencing of the 16S rRNA genes. Individual reads were ascribed to operational taxonomic units (OTUs) using BLASTn and Greengenes databases. Species richness, evenness, and Good's coverage were determined for each conjunctiva-associated microbial community.

RESULTS

Culture-independent samples produced a total of 329 bacterial OTUs. The main OTUs identified in the study belonged to the Gram-negative species Ralstonia mannitolilytica (88.0%), Nicoletella semolina (3.3%), and Pseudomonas tolaasii (1.5%).

CONCLUSIONS

Contrary to previously published data based on culture-dependent methods, the horse eye microbial community was dominated by Gram-negative bacteria of the phylum Proteobacteria.

Equine infectious keratitis in Finland: Associated microbial isolates and susceptibility profiles

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.

Evaluation of the bacterial ocular surface microbiome in clinically normal horses before and after treatment with topical neomycin-polymyxin-bacitracin

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.

Multi-locus DNA sequence analysis, antifungal agent susceptibility, and fungal keratitis outcome in horses from Southeastern United States

Morphological characterization and multi-locus DNA sequence analysis of fungal isolates obtained from 32 clinical cases of equine fungal keratitis (FK) was performed to identify species and determine associations with antifungal susceptibility, response to therapy and clinical outcome. Two species of Aspergillus (A. flavus and A. fumigatus) and three species of Fusarium (F. falciforme, F. keratoplasticum, and F. proliferatum) were the most common fungi isolated and identified from FK horses. Most (91%) equine FK Fusarium nested within the Fusarium solani species complex (FSSC) with nine genetically diverse strains/lineages, while 83% of equine FK Aspergillus nested within the A. flavus clade with three genetically diverse lineages. Fungal species and evolutionary lineage were not associated with clinical outcome. However, species of equine FK Fusarium were more likely (p = 0.045) to be associated with stromal keratitis. Species of Aspergillus were more susceptible to voriconazole and terbinafine than species of Fusarium, while species of Fusarium were more susceptible to thiabendazole than species of Aspergillus. At the species level, A. fumigatus and A. flavus were more susceptible to voriconazole and terbinafine than F. falciforme. Natamycin susceptibility was higher for F. falciforme and A. fumigatus compared to A. flavus. Furthermore, F. falciforme was more susceptible to thiabendazole than A. flavus and A. fumigatus. These observed associations of antifungal sensitivity to natamycin, terbinafine, and thiabendazole demonstrate the importance of fungal identification to the species rather than genus level. The results of this study suggest that treatment of equine FK with antifungal agents requires accurate fungal species identification.

Conjunctival bacterial and fungal flora and cutaneous fungal flora in healthy domestic rabbits (Oryctolagus cuniculus)

OBJECTIVES

To determine the normal conjunctival bacterial and fungal flora in healthy rabbits, to compare the fungal flora from the conjunctival sac with periocular cutaneous fungal flora and to evaluate potential changes in type of micro-organisms over time.

MATERIALS AND METHODS

Samples from 50 pet rabbits with a normal ophthalmic examination were obtained from conjunctival sacs using sterile cotton swabs and from the interpupillary skin space using a piece of sterile carpet. Samples were collected twice, 4 weeks apart, and cultured to evaluate bacterial and fungal populations.

RESULTS

Bacteria were recovered from 35.9% of conjunctival swabs. Corynebacterium species (32.4%), Staphylococcus species (18.3%), Pasteurella species (9.9%) and Moraxella species (8.5%) were the most frequently isolated organisms. Fungi were recovered from 14.6% of conjunctival swabs. The most common fungal genera were Aspergillus (37%), Scopulariopsis (14.8%) and Penicillium (11.1%). Fungal cultures from periocular integument yielded positive results in 96.3% of samples; the same fungal organism was isolated in both conjunctival and cutaneous culture in nine of 20 rabbits (45%). When comparing results 4 weeks apart in 32 of 50 animals, only three rabbits with a positive bacterial culture and one rabbit with a positive fungal culture had the same result at the subsequent test.

CLINICAL SIGNIFICANCE

Fungi and bacteria isolated from the conjunctival sac of rabbits may represent transient seeding from the environment. To our knowledge, this is the first report of fungal composition of the conjunctival sac of rabbits and evaluation of the potential transient nature of both bacterial and fungal composition of this conjunctival flora.

Evaluation of the bacterial ocular surface microbiome in clinically normal cats before and after treatment with topical erythromycin

The ocular surface microbiome of veterinary species has not been thoroughly characterized using next generation sequencing. Furthermore, alterations in the feline ocular surface microbiome over time or following topical antibiotic treatment are unknown. Aims of this study were to further characterize the ocular surface microbiome of healthy cats and to identify whether there are microbial community changes over time and following topical antibiotic use. Twenty-four eyes from twelve adult, research-bred, female spayed domestic shorthaired cats were evaluated. Erythromycin ophthalmic ointment (0.5%) was applied to the ocular surface of one randomly assigned eye per cat three times daily for 7 days, while the fellow eye served as an untreated control. The ocular surface was sampled by swabbing the inferior conjunctival fornix of both eyes 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 the swabs and sequenced using primers that target the V4 region of bacterial 16S rRNA genes. At baseline, the most common bacterial phyla identified were Proteobacteria (42.4%), Firmicutes (30.0%), Actinobacteria (15.6%), and Bacteroidetes (8.1%). The most abundant bacterial families sequenced were Corynebacteriaceae (7.8%), Helicobacteraceae (7.5%), Moraxellaceae (6.1%), and Comamonadaceae (5.6%). Alpha and beta diversity measurements were largely unchanged in both treatment and control eyes over time. However, univariate and linear discriminant analyses revealed significant and similar changes in the abundance of some bacterial taxa over time in both treatment and control eyes. Overall, the feline ocular surface microbiome remained stable over time and following topical antibiotic therapy.

EVALUATION OF CONJUNCTIVAL MICROBIOTA IN CLINICALLY NORMAL PERSIAN SQUIRRELS ( SCIURUS ANOMALUS)

This study aimed to evaluate the bacterial flora in the conjunctival fornix of clinically normal Persian squirrels ( Sciurus anomalus). Forty healthy Persian squirrels of equal gender distribution with similar ages (approximately 2 yr) were used for this study. A total of 80 conjunctival swabs were taken from both the right and left eyes of each squirrel for aerobic and anaerobic bacterial identification. A slit-lamp examination was conducted and no external ocular disease was identified. From 80 normal eyes, Staphylococcus spp. comprised the most frequently isolated organism (83%), while Corynebacterium spp. were the second most frequently isolated bacteria (56%), followed by Streptococcus spp. (53%), Chlamydia spp. (33%). Mycoplasma spp. (30%), Pseudomonas spp. (23%), Escherichia coli spp. (12.5%), Enterococcus spp. (7%), and Micrococcus spp. (4%) were also isolated. The most frequently isolated bacteria from the conjunctival fornix of healthy Persian squirrels were Staphylococcus spp. followed by Corynebacterium spp.

Conjunctival aerobic bacterial flora in healthy Silesian foals and adult horses in Poland

Background

Commensal bacterial and fungal flora of the conjunctival sac has been described in horses and other animals. The identification of commensal flora of the conjunctival sac may aid in the diagnosis of ocular inflammatory diseases, such as conjunctivitis or more severe ulcerative keratitis, common in horses. Moreover, damage of ocular protective barriers may lead to an opportunistic infection. The study was carried out in Silesian horses kept at a single breeding center in South-western Poland, in order to limit any breed-dependant and climate-dependant variables affecting the results. Following an ophthalmic examination that revealed no abnormalities, sterile swabs were collected from conjunctival sac in 26 adult horses and 11 foals. The obtained swabs were subjected to bacterial culture testing. In case of Staphylococcus spp. isolation, susceptibility to methicillin was evaluated.

Results

Forty- three bacterial isolates, representing eleven genera of bacteria were cultured from 30 (81%) horses. Gram-positive bacteria were the dominant isolates (72%) (p < 0.001). The most commonly isolated Gram-positive bacteria were Staphylococcus spp., while Moraxella spp. were the most frequently isolated Gram-negative bacteria. There was no significant influence of sex and age on the frequency and type of microbial isolates.

Conclusions

Commensal flora is present in the conjunctival sac of healthy horses in Poland. Age does not affect the abundance and type of microbial isolates.

Identification of bacteria and fungi sampled from the conjunctival surface of normal horses in South-East Queensland, Australia

OBJECTIVE

To identify bacteria and fungi found on the conjunctival surface of normal horse eyes; to investigate potential risk factors for these microflora; and to determine their susceptibility to common topical ophthalmic antimicrobials.

ANIMALS STUDIED

A total of 95 client-owned horses were studied.

PROCEDURES

Horses within sub-tropical Australia (South-East Queensland) were sampled once between April 2012 and March 2013. A conjunctival swab was taken from each eye and cultured for aerobic bacteria and fungi. Organisms were identified by colony morphology and phenotype. Antimicrobial disk diffusion susceptibility testing for commonly used antimicrobials was performed.

RESULTS

Positive bacterial cultures were returned from 187/190 (98.4%) eyes from 94/95 (98.9%) horses. The most common species included Staphylococcus spp. (25.2% of total bacterial isolates), Bacillus cereus (17.4%), Bacillus spp. (14.1%), and Corynebacterium spp. (8.9%). Most bacterial isolates were susceptible to neomycin and fluoroquinolones. Positive fungal cultures were returned from 111/190 (58.4%) eyes from 73 (76.8%) horses. The most common species identified included: Penicillium spp. (16.7% of fungal isolates), Aspergillus spp. (15.4%), and Scopulariopsis spp. (10.3%). Most (≥90%) molds were susceptible to ketoconazole, voriconazole, itraconazole, and miconazole. Yeasts were most susceptible to ketoconazole. There was no significant effect of breed, age, sex, purpose, or housing of the horse or climatic conditions on bacterial or fungal culture status.

CONCLUSIONS

Bacteria and fungi were commonly isolated from the eyes of healthy horses. The antibiotic and antifungal susceptibilities identified can be used as a guide for empirical therapy after cytology in the treatment of corneal ulceration in horses.

Occurrence and molecular composition of methicillin-resistant Staphylococcus aureus isolated from ocular surfaces of horses presented with ophthalmologic disease

Severe infections due to methicillin-resistant Staphylococcus aureus (MRSA) have been increasingly recognized in virtually all fields of veterinary medicine. Our objective was to study the occurrence, phylogenetic relationships and antimicrobial resistance properties of MRSA isolated from ocular surfaces of horses prior to invasive procedures. Within a 49-week sampling period, ocular swabs obtained from 46 eyes of 44 horses, including eyes with clinical signs of conjunctivitis/blepharitis, keratitis or uveitis were screened for the presence of S. aureus. As a result, seven samples were positive for S. aureus (15.2%), with six of them being classified as MRSA (13%). In addition, all isolates were resistant or showed reduced susceptibility to tetracyclines, the aminoglycosides gentamicin and kanamycin, fluoroquinolones, and the combination sulfamethoxazole/trimethoprim. Since a very close relationship between the MRSA isolates was assumed after pulsed-field gel electrophoresis employing the restriction endonuclease ApaI, whole genome sequencing (WGS) was used to shed more light on the phylogenetic relationships and the molecular composition of all MRSA isolates. Analysis of WGS data revealed closely related MRSA belonging to sequence type 398, spa type t011 and dru type dt10q, harboring an SCCmec IV element and the Staphylococcus aureus pathogenicity island SaPIbov5. Moreover, all MRSA were positive for a beta-hemolysin converting phage carrying genes of the immune evasion cluster (IEC). Since cases of eye infections due to MRSA were often associated with fatal outcomes, more research is needed with respect to the origin of MRSA isolated from ocular surfaces to implement sufficient barrier and infection control measures.

Corneal abrasion and microbial contamination in horses following general anaesthesia for non-ocular surgery

OBJECTIVE

To evaluate the incidence of corneal abrasions/ulceration and microbial contamination in horses undergoing general anaesthesia.

STUDY DESIGN

Prospective, observational, clinical study.

ANIMALS

A total of 40 client-owned healthy horses scheduled for elective non-ophthalmic procedures.

METHODS

Conjunctival sac swabs were taken, fluorescein dye applied and digital images recorded from both eyes of the horses after preanaesthetic medication and 24 hours after recovery from general anaesthesia. A paraffin-based bland ophthalmic ointment was applied on the ocular surface intraoperatively following collection of a sample into a sterile container. All samples underwent aerobic, anaerobic and fungal culture. Subject demographics, chronology of ophthalmic ointment use, anaesthesia duration, recumbency after induction, during surgery and recovery, fluorescein uptake and culture results were recorded. Descriptive statistics were performed.

RESULTS

Complete data were collected from 34 horses; six (17.6%) developed mild unilateral generalized fluorescein uptake consistent with corneal abrasions. Recumbency on the operating table was the only risk factor significantly associated with corneal abrasions. A total of 11 bacterial species were identified; Staphylococcus spp. (15 eyes) and Micrococcus spp. (eight eyes) were the most frequently isolated bacteria. Two fungal species were isolated postoperatively (Aspergillus spp., Saccharomyces spp.) in two eyes. Ointment contamination was recorded in two cases (5%) but cross-contamination was not recognized.

CONCLUSIONSAND CLINICAL RELEVANCE

Incidence of corneal abrasion/ulceration in horses undergoing general anaesthesia and contamination rate of ophthalmic solutions are similar to those previously reported in dogs.

Antifungal Therapy in Equine Ocular Mycotic Infections

Fungi are clinically important causes of ocular infections in the horse. Keratomycosis is the most common; however, a diverse range of mycotic infections, affecting numerous ocular tissues, may be encountered. Many equine mycoses are diagnostic and therapeutic challenges. Prompt and appropriate treatment is essential to minimize morbidity and reduce the likelihood of vision loss. Knowledge of the characteristics and properties of equine ophthalmology antifungal medications is essential to selecting an optimal treatment strategy, including selection of appropriate medication and effective administration route. Newer delivery methods and devices are available and can contribute to an improved outcome in select situations.

The eye of the Barbary sheep or aoudad (Ammotragus lervia): reference values for selected ophthalmic diagnostic tests, morphologic and biometric observations

The purpose of this study was to describe the normal ocular anatomy and establish reference values for ophthalmic tests in the Barbary sheep or aoudad (Ammotragus lervia). Aoudad eyes are large and laterally positioned in the head with several specialized anatomic features attributed to evolutionary adaptations for grazing. Normal values for commonly used ophthalmic tests were established, Schirmer tear test (STT) - 27.22 ± 3.6 mm/min; Predominant ocular surface bacterial microbiota - Staphylococcus sp.; Corneal esthesiometry- 1.3 ± 0.4 cm; Intraocular pressure by rebound tonometry- 19.47 ± 3.9 mmHg; Corneal thickness- 630.07 ± 20.67 µm, B-mode ultrasonography of the globe-axial eye globe length 29.94 ± 0.96 mm, anterior chamber depth 5.03 ± 0.17 mm, lens thickness 9.4 ± 0.33 mm, vitreous chamber depth 14.1 ± 0.53 mm; Corneal diameter-horizontal corneal diameter 25.05 ± 2.18 mm, vertical corneal diameter 17.95 ± 1.68 mm; Horizontal palpebral fissure length- 34.8 ± 3.12 mm. Knowledge of these normal anatomic variations, biometric findings and normal parameters for ocular diagnostic tests may assist veterinary ophthalmologists in the diagnosis of ocular diseases in this and other similar species.

Conjunctival flora of healthy and diseased eyes of grey seals (Halichoerus grypus): implications for treatment

Ocular pathology is relatively common in stranded seals admitted to wildlife rehabilitation hospitals. Some have pre-existing problems, while others develop eye problems in captivity, and in particular ulcerative keratitis, due to factors such as large prominent eyes, suboptimal water quality, trauma and infighting. Despite treatment, corneal ulcerations can rapidly progress to 'melting' ulcers with subsequent rupture of the globe. In this case series, 32 grey seals (Halichoerus grypus) had conjunctival swabs taken on admission to a UK wildlife hospital to identify ocular bacterial flora and nine had subsequent swabs taken after four weeks to see if this changed in captivity. Additionally, nine seals with ocular pathology were also swabbed. Although a wide range of bacteria were cultured on admission, the most common isolates were Gemella haemolysans, Escherichia coli and Clostridium perfringens All 'melting' ulcers were associated with Pseudomonas aeruginosa, which suggests this bacterial species may be significant in the pathogenesis of progressive stromal ulceration in grey seals.

Baseline assessment of ophthalmic parameters in the greater one-horned rhinoceros (Rhinoceros unicornis)

Five healthy captive greater one-horned rhinoceroses (Rhinoceros unicornis) were evaluated with standing sedation (detomidine hydrochloride 20-30 mg and butorphanol tartrate 50-60 mg per animal) to determine baseline values for tear production, intraocular pressure (IOP), conjunctival flora, and ocular anatomy using brightness mode transpalpebral ultrasonography with a 4- to 7-MHz broadband curvilinear transducer. The mean Schirmer tear test I value was 18.2 ± 3.49 mm/min. The mean IOP measured using applantation tonometry was 31.2 ± 6.62 mm Hg. Ocular biometry measurements were the following: axial length 2.61 ± 0.11 cm; corneal thickness 0.13 ± 0.01 cm; anterior segment depth 0.28 ± 0.06 cm; lens depth 0.70 ± 0.11 cm; and posterior segment depth 1.46 ± 0.13 cm. These values indicate that the globe is smaller than that of the domestic horse. All eight conjunctival swabs cultured bacterial and fungal microorganisms, with the most common being Staphylococcus spp. (57%). All bacterial isolates were considered to be commensal organisms due to the presence of mixed bacterial populations and lack of clinical signs of ocular disease. The data collected in this study should provide veterinarians with baseline information to assist in the diagnosis of ophthalmic conditions in the greater one-horned rhinoceros.

Conjunctival bacterial and fungal flora in clinically normal sheep

Objectives

The aim was to identify conjunctival bacterial and fungal flora in clinically normal sheep.

Design

Prospective study.

Setting

Tuscany.

Participants

100 eyes from 50 adult Massese female sheep were examined. The sheep included in the study were considered free of anterior ophthalmic abnormalities.

Primary and secondary outcome measures

Bacteria were identified by morphological assessment, Gram staining, biochemical tests. Identification of filamentous fungi was achieved at the genus level, and Aspergillus species were identified based on keys provided by other authors. Yeast colonies were highlighted, but not identified.

Results

Positive cultures were obtained from 100/100 eyes for bacteria, and from 86/100 eyes for fungi. A total of 14 types of bacteria and 5 types of fungi were isolated. Yeasts were isolated from 13/100 eyes. The most frequent fungal isolates were saprophytic fungi.

Conclusions

Conjunctival bacterial and fungal flora of clinically normal eyes were reported in sheep. The positivity obtained for conjunctival bacteria was higher compared to findings in the literature by other authors in the same species (100 per cent v 40 per cent), while our results were in line with a recent work performed on mouflons (Ovis Musimon) with a 100 per cent positivity for bacterial conjunctival fornix. In our survey, Gram-positive species were prevalent, as reported by other authors in different species. Few data are available in the literature regarding conjunctival fungal flora in healthy small ruminants. The prevalence of conjunctival fungal flora in this study was higher than findings reported in mouflons (86 per cent v 45 per cent). Differences in fungal prevalence may be due to different methods of managing herds, though further studies are required to verify this hypothesis. The similarities in bacterial and fungal isolates between sheep and mouflons suggest a genera pattern of conjunctival colonisation by bacteria and fungi.

Ocular fungal flora from healthy horses in Iran

OBJECTIVE

This study was carried out in order to isolate and identify the normal conjunctival fungal flora from Caspian miniature, Thoroughbred, Turkmen and Persian Arab breeds in Tehran, Iran.

MATERIALS AND METHODS

A total of seventy-two adult healthy horses were studied. Ocular samples were collected from right and left eyes by using sterile cotton swabs; samples were cultured on Sabouraud dextrose agar and incubated at 30°C for 7-10 days. Molds and yeasts were identified using macro and micro-morphological and physiological characteristics.

RESULTS AND CONCLUSION

Number of fungal colonies per eye varied between 0 and 123 colony forming units (CFUs). The most predominant fungal isolates were Aspergillus (19.9%), Rhizopus (15.9%) and Penicillium (15.1%). No significant differences were observed between types of eye fungal floras in different breeds. Caspian miniature horses had significantly the highest number of fungal isolates in compare with other breeds (P<0.001), however no significant difference was observed among other breeds under study. The fungal isolates were almost the same as with studies performed in other countries, although differences in species isolated could be related to geographic and climate difference.

Conjunctival and cutaneous fungal flora in clinically normal dogs in southern France

The objectives of the present study were to describe the fungal flora of the conjunctiva in clinically normal dogs in southern France and to compare the fungal flora from the conjunctiva and that from adjacent skin areas (medial canthus and nose). Fifty dogs aged from 5 months to 13 years were investigated for conjunctival fungal flora. Specimens were obtained from both conjunctivae and the skin of the medial canthus and from the surface of the nose using sterile cotton-wool swabs and a piece of sterile carpet, respectively. Identification of fungal colonies was achieved recording the genus level on the basis of macro- and microscopic features. Fourteen fungal genera (most frequently Alternaria, Cladosporium, Penicillium and Aspergillus) were isolated from the conjunctival fornix of 7 dogs (14%). There was no significant effect of sex or age on frequency of fungal isolation. Eleven dogs (22%) had a positive mycological culture from at least one eye. Fungi found in the conjunctival fornix of dogs might represent transient seeding from the environment, as suspected in other animal species. The presence of conjunctival fungal organisms was correlated to the presence of fungi on the skin.

O olho da coruja-orelhuda: observações morfológicas, biométricas e valores de referência para testes de diagnóstico oftálmico

Objetivou-se relatar características morfológicas do bulbo ocular e determinar valores de referência para testes oftálmicos selecionados em corujas-orelhudas (Asio clamator). Foram estudados 32 olhos de 16 corujas (Asio clamator), adultas e jovens, machos e fêmeas, de vida livre. Sendo compilados dados referentes a observações morfológicas do crânio, bulbo ocular e anexos, além de mensuração de testes oftálmicos, incluindo, Teste Lacrimal de Schirmer (TLS), cultura da microbiota normal da conjuntiva, estesiometria, pressão intraocular (PIO), espessura de córnea central (ECC), diâmetro horizontal da rima palpebral, diâmetro horizontal da córnea e oftalmoscopia indireta. Vinte e dois tipos de bactérias foram identificados em 12 corujas havendo predominância de microrganismos Gram-positivos. A média encontrada para o TLS foi de 5,03±3,28mm/min, para o diâmetro horizontal da rima palpebral em 16 corujas foi 21,24±1,17mm, e 15,7±2,74mm para o diâmetro horizontal da córnea. O valor médio para o teste de estesiometria foi de 0,80±0,59cm, a PIO média de 13,81±5,62mmHg e ECC média de 0,28±0,03cm. O estudo contribuiu para a caracterização da morfologia ocular e para o estabelecimento de valores de referências de testes diagnósticos oftálmicos em corujas-orelhudas, sendo necessário ainda o desenvolvimento de estudos complementares sobre histologia ocular desta espécie.

Evaluation of the conjunctival fungal flora and its susceptibility to antifungal agents in healthy horses in Switzerland

OBJECTIVE

To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland.

PROCEDURE

Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detected in samples from eyes with keratomycosis in Switzerland. Minimal inhibitory concentrations (MICs) for voriconazole, fluconazole, itraconazole, amphotericin B, and miconazole were recorded.

RESULTS

Fifty-nine of the horses were tested positive for fungal growth from at least one eye (92%). Eleven genera of fungi were identified. The most common fungal genera were Alternaria, Eurotium, Rhizopus, and Cladosporium. Aspergillus spp. and Penicillium spp. were isolated frequently, while no Fusarium spp. was found. In only 2 cases, yeasts were identified as Candida guilliermondii. For certain fungal species, the type of bedding and housing appeared to influence their prevalence. Susceptibility testing of A. fumigatus showed lowest MICs for voriconazole, E. amstelodami for voriconazole and itraconazole. High MICs for fluconazole were detected for all tested fungi while MICs for amphotericin B and miconazole were variable.

CONCLUSIONS

A large range of fungal mold species was identified including A. fumigatus and E. amstelodami, which have been causative agents of keratomycosis in Switzerland. Best in vitro susceptibility results for these two species were obtained for voriconazole.

Periocular anterior adnexal anatomy and clinical adnexal examination of the adult Asian elephant (Elephas maximus)

Formalin preserved ocular-associated anterior adnexa tissues from five necropsied Asian elephants (Elephas maximus) were dissected with attention to the palpebrae, conjunctiva, nictitating membranes, nasolacrimal ducts, and periocular glandular tissues. Gross and histologic examination revealed that lacrimal and tarsal glands were not present. Evidence of the lacrimal drainage apparatus, including lacrimal punctae or any remnant of lacrimal sacs, was also absent. In contrast, well-developed sebaceous glands associated with accessory hairs along the palpebrae were exceptionally abundant. Mixed-secreting accessory lacrimal glands were noted in the deep stroma posterior to the tarsus of both palpebrae and the gland of the nictitating membrane. Apparently, the Asian elephant has developed a novel tear system in the absence of lacrimal and tarsal (meibomian) glands. Clinical examinations and bacterial cultures of the visible periocular tissues were performed on eight living adult Asian elephants to confirm the postmortem anatomic findings and provide guidance to the clinician during examination of the elephant conjunctiva.

Fungal polymerase chain reaction testing in equine ulcerative keratitis

OBJECTIVE

To assess the diagnostic utility of fungal polymerase chain reaction (PCR) in forty-three horses with naturally acquired corneal ulcers presenting to a private practice.

METHODS

Routine evaluation of cytologic, histologic, and microbiologic samples was performed. Two PCR approaches were compared - generic and specific fungal nested PCR followed by sequencing and quantitative PCR (qPCR). PCRs were applied to pure control fungal cultures, corneal tissue from ulcerated eyes and in a subset of 9 horses, to swabs from contralateral normal eyes.

RESULTS

The expected fungus was identified by nested PCR and qPCR in all control fungal cultures. In all fungal culture-positive affected eyes (10/43), one or more fungi were identified by nested PCR and 4/10 were positive by qPCR. In 6/10 animals, the same fungus was identified by nested PCR and culture. Of these 6, only three were positive by qPCR. Fungal agents were identified by morphology in 8/10 horses. Diagnosis of fungal keratitis was reserved for only those cases in which the same fungus could be identified by PCR, culture, and morphology (5 horses). In 33/43 culture-negative affected eyes and in 6/9 unaffected eyes, one or more fungi were identified by nested PCR in 26 samples and by qPCR in 2 samples. Apart from Aspergillus spp, similar fungi were identified in affected and control eyes. Most eyes harbored mixed bacterial and fungal agents.

CONCLUSIONS

Nested PCR results confirmed all cytologically positive cases of fungal keratitis. Nested PCR identified a greater spectrum of agents than either culture or qPCR.

Equine keratomycoses in California from 1987 to 2010 (47 cases)

REASONS FOR PERFORMING STUDY

Equine keratomycosis in the western USA has received little study, probably owing to its low prevalence.

OBJECTIVES

To determine clinical features, predominant fungal isolates, treatment modalities and outcomes of horses with keratomycosis in California and compare these with results from different geographic regions.

METHODS

Records of horses presented to the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) with confirmed keratomycosis between 1987 and 2010 were reviewed for this retrospective study. Information retrieved from the record included background, ophthalmic examination findings, treatment prior to and following presentation, visual outcome, and ocular survival.

RESULTS

A total of 48 eyes in 47 horses met the inclusion criteria and comprised 2% of cases presented to the UCD-VMTH ophthalmology service. Prior to presentation, 20 horses (43%) received at least one topically administered anti-inflammatory medication. Keratomycosis was confirmed by fungal culture in 38 horses (81%), by histopathology in 2 horses (4%) and by cytology in 7 horses (15%). Forty-four isolates were identified in the 38 horses cultured; Aspergillus was the most common isolate (64%) and a novel isolate, Papulospora, was identified in 2 horses. Treatment consisted of medication only (73%), medical and surgical treatment (25%), or immediate enucleation (2%). Globe retention was 77% and vision retention was 53%. Corneal perforation was significantly associated with loss of vision (P<0.001).

CONCLUSIONS

Keratomycosis is relatively uncommon in horses presented for ophthalmic conditions at UCD-VMTH. Corneal perforation was a negative prognostic indicator for vision in this population of northern Californian horses.

Optimal management of equine keratomycosis

Keratomycosis in the horse exists in several unique clinical forms. This paper discusses the diagnosis and clinical management of keratomycosis in the horse associated with tear film instability, epithelial keratopathy, subepithelial infiltrates, superficial and deep ulcers, plaques, melting ulcers, descemetoceles, iris prolapse, and stromal abscesses. Prompt diagnosis and aggressive treatment of equine keratomycosis can make a major difference in the maintenance of a cosmetic and visual eye.

Mortierella wolfii keratomycosis in a horse

PURPOSE

To describe a case of superficial keratomycosis caused by Mortierella wolfii (M. wolfii) in a horse.

METHODS

A thoroughbred filly was presented with painful right eye of 2 days' duration. A superficial corneal ulcer was observed ventrally together with multifocal punctuate opacities axially. Samples were collected by swabbing and scraping the ulcerated lesion and submitted for microbiologic and cytologic examination.

RESULTS

Microscopic evaluation of debrided corneal tissue revealed the presence of nonseptate fungal hyphae, and culture of a corneal swab yielded fungal growth. Medical treatment with topical antifungal, antibiotic and autogenous serum and systemic anti-inflammatory resolved the problem within 2 weeks.

CONCLUSIONS

Cytologic evaluation of a corneal scraping was useful to make a clinical diagnosis of keratomycosis. Based on the mycological characteristics, the fungus isolated from the corneal lesion was identified as M. wolfii. To the authors' knowledge, this is the first case report of equine keratomycosis associated with this fungus, although the organism is known to infect various organs of cattle.