Alterations to the bovine bacterial ocular surface microbiome in the context of infectious bovine keratoconjunctivitis.

BACKGROUND: Infectious bovine keratoconjunctivitis (IBK) is a common cause of morbidity in cattle, resulting in significant economic losses. This study aimed to characterize the bovine bacterial ocular surface microbiome (OSM) through conjunctival swab samples from Normal eyes and eyes with naturally acquired, active IBK across populations of cattle using a three-part approach, including bacterial culture, relative abundance (RA, 16 S rRNA gene sequencing), and semi-quantitative random forest modeling (real-time polymerase chain reaction (RT-PCR)). RESULTS: Conjunctival swab samples were obtained from eyes individually classified as Normal (n = 376) or IBK (n = 228) based on clinical signs. Cattle unaffected by IBK and the unaffected eye in cattle with contralateral IBK were used to obtain Normal eye samples. Moraxella bovis was cultured from similar proportions of IBK (7/228, 3.07%) and Normal eyes (1/159, 0.63%) (p = 0.1481). Moraxella bovoculi was cultured more frequently (p < 0.0001) in IBK (59/228, 25.88%) than Normal (7/159, 4.40%) eyes. RA (via 16 S rRNA gene sequencing) of Actinobacteriota was significantly higher in Normal eyes (p = 0.0045). Corynebacterium variabile and Corynebacterium stationis (Actinobacteriota) were detected at significantly higher RA (p = 0.0008, p = 0.0025 respectively) in Normal eyes. Rothia nasimurium (Actinobacteriota) was detected at significantly higher RA in IBK eyes (p < 0.0001). Alpha-diversity index was not significantly different between IBK and Normal eyes (p > 0.05). Alpha-diversity indices for geographic location (p < 0.001), age (p < 0.0001), sex (p < 0.05) and breed (p < 0.01) and beta-diversity indices for geographic location (p < 0.001), disease status (p < 0.01), age (p < 0.001), sex (p < 0.001) and breed (p < 0.001) were significantly different between groups. Modeling of RT-PCR values reliably categorized the microbiome of IBK and Normal eyes; primers for Moraxella bovoculi, Moraxella bovis, and Staphylococcus spp. were consistently the most significant canonical variables in these models. CONCLUSIONS: The results provide further evidence that multiple elements of the bovine bacterial OSM are altered in the context of IBK, indicating the involvement of a variety of bacteria in addition to Moraxella bovis, including Moraxella bovoculi and R. nasimurium, among others. Actinobacteriota RA is altered in IBK, providing possible opportunities for novel therapeutic interventions. While RT-PCR modeling provided limited further support for the involvement of Moraxella bovis in IBK, this was not overtly reflected in culture or RA results. Results also highlight the influence of geographic location and breed type (dairy or beef) on the bovine bacterial OSM. RT-PCR modeling reliably categorized samples as IBK or Normal.

Relationship between the bacterial ocular surface microbiota and outcomes for cats with feline herpesvirus type 1 ocular surface disease.

OBJECTIVE: Feline herpesvirus 1 (FHV-1) causes ocular surface disease in domestic cats. The purpose of this study was to assess the relationship between bacterial ocular surface microbiota and outcomes for cats with FHV-1 ocular surface disease. ANIMALS STUDIED: Twenty-two shelter-housed cats with confirmed FHV-1 ocular surface disease. PROCEDURES: Animals were grouped according to FHV-1 shedding and ocular clinical scores following intervention: worsened outcome (WorOut, n = 11) or improved outcome (ImpOut, n = 11). Scoring and conjunctival sampling were completed on Days 1 and 8 of twice daily antiviral treatment. Bacterial DNA was extracted and submitted for 16S rRNA gene sequencing. Real-time polymerase chain reaction was performed for selected bacterial species. Overall DNA concentration between groups was assessed. RESULTS: Bacterial microbiota relative abundance composition was significantly different between ImpOut and WorOut groups (weighted UniFrac p = .006). Alpha diversity was significantly higher in the ImpOut group compared with the WorOut group (Shannon p = .042, Simpson's p = .022, Pielou's p = .037). Differences in the relative abundance of various phyla and species were detected between groups. Total DNA concentration was higher in the WorOut group compared with the ImpOut group (p = .04). Feline GAPDH (p = .001) and Bilophila wadsworthia (p = .024) copy number was significantly higher in the ImpOut group compared with the WorOut group. CONCLUSIONS: The results highlight the important relationship between the bacterial ocular surface microbiota and FHV-1 infection outcomes in cats treated with antiviral medications. Low bacterial species diversity, higher overall DNA (presumed predominantly bacterial) load, and certain bacterial phyla/species were associated with poor outcomes for cats with FHV-1 ocular disease.

Relative and Quantitative Characterization of the Bovine Bacterial Ocular Surface Microbiome in the Context of Suspected Ocular Squamous Cell Carcinoma.

The ocular surface microbiome is altered in certain disease states. The aim of this study was to characterize the bovine bacterial ocular surface microbiome (BBOSM) in the context of ocular squamous cell carcinoma (OSCC). The conjunctiva of normal (n = 28) and OSCC (n = 10) eyes of cows aged 2 to 13 years from two farms in Louisiana and Wyoming were sampled using individual sterile swabs. DNA extraction followed by 16S ribosomal ribonucleic acid (rRNA) gene sequencing and real-time polymerase chain reaction (RT-PCR) were performed to, respectively, assess the relative and absolute BBOSM. Discriminant analysis (DA) was performed using RT-PCR data, and relative abundance analysis was performed using 16S rRNA gene sequencing data. The 11 most abundant phyla in both normal and OSCC-affected cows were identified using 16S rRNA gene sequencing analysis. The relative abundance of Euryarchaeota was found to be significantly lower (p = 0.0372) in OSCC eyes compared to normal eyes. Relative abundance differences within and between geographic locations were also identified. Quadratic DA categorized samples as OSCC or normal with 100% sensitivity and 83.3-100% specificity. Relative abundance analysis identified relative BBOSM phylum alterations in OSCC. Quadratic DA can be used to accurately categorize BBOSM from normal and OSCC ocular surface samples.

An Update on the Ocular Surface Bacterial Microbiota in Small Animals.

High-throughput sequencing (HTS) techniques have revolutionized the way we understand microbial communities in both research and clinical settings and are bringing new insights into what constitutes a healthy ocular surface (and a diseased one). As more diagnostic laboratories incorporate HTS into their technique repertoire, practitioners can expect this technology to become increasingly accessible for clinical practice, potentially becoming the new standard. However, particularly regarding ophthalmic microbiota, considerable research remains to render HTS accessible and applicable.

Glaucoma Associated with Anterior Segment Dysgenesis in Dogs and Cats.

Reports of glaucoma associated with anterior segment dysgenesis in dogs and cats are rare. Anterior segment dysgenesis is a sporadic, congenital syndrome with a range of anterior segment anomalies that may or may not result in congenital or developmental glaucoma within the first years of life. Specifically, the anterior segment anomalies that put the neonatal or juvenile dog or cat at high risk for the development of glaucoma are filtration angle and anterior uveal hypoplasia, elongated ciliary processes, and microphakia.

Streptococcus canis sequence type 43 may be associated with treatment failure in dogs with corneal ulceration.

OBJECTIVE: To profile Streptococcus canis isolates obtained from corneal ulcers in dogs. ANIMALS: 10 dogs. PROCEDURES: Medical records were searched to identify dogs diagnosed with ulcerative keratitis by a veterinary ophthalmologist and having a positive corneal culture for S canis during the year 2020. For each case, clinical findings and outcome were determined, antimicrobial resistance and sensitivity panels were summarized, whole genome sequencing was performed, and isolates were typed using multi-locus sequence typing and genome-based proteome phylogenetic analysis. RESULTS: 10 S canis isolates were included from dogs diagnosed with ulcerative keratitis. Dogs were either treated surgically via keratectomy and conjunctival grafting (n = 6) or treated medically (4). Three of 10 corneas failed to heal and required enucleation (2/6 conjunctival grafts and 1/4 medically managed corneal ulcers). All three corneal ulcers that failed to heal were associated with S canis sequence type (ST) 43. Sequence types identified from successfully treated cases included ST8 (n = 1), ST50 (1), ST2 (2), ST27 (1), and ST15 (1). One ST43 isolate was obtained from a dog that healed following a conjunctival graft, however this was the only dog that received an oral antibiotic in addition to topical antibiotics. CLINICAL RELEVANCE: Based on this small dataset, S canis ST43 may be associated with increased virulence and contribute to conjunctival graft failure and progressive corneal collagenolysis. The postoperative administration of an oral antimicrobial may protect against conjunctival graft rejection in dogs specifically due to S canis ST43.

Comparison of the effect of sedation and general anesthesia on pattern and flash visual evoked potentials in normal dogs.

BACKGROUND: Visual evoked potentials (VEPs) can provide objective functional assessment of the post-retinal visual pathway. This study compared the effects of sedation (butorphanol and dexmedetomidine) and general anesthesia (propofol and sevoflurane) on pattern and flash VEPs. Dogs (n = 13) underwent sedation or anesthesia and VEPs were obtained from 3 subcutaneous recording electrodes placed on the head (O1, Oz, O2). RESULTS: Pattern VEPs could only be recorded under sedation and a maximum of 3 peaks were identified (N75, P100, N135). Flash VEPs could be recorded under both sedation and anesthesia and a maximum of 5 peaks were identified (N1, P1, N2, P2, N3). The latency of the N1 peak and the baseline-N1 amplitude were significantly longer under general anesthesia. CONCLUSION: Visual evoked potentials should be preferentially recorded in dogs sedated with dexmedetomidine and butorphanol, regardless of the stimulus.