Histological findings in corneal stromal abscesses of 11 horses: correlation with cultures and cytology.
Abstract: Histopathology was compared to culture results and cytology from horses with corneal stromal abscess at the Auburn University and the Ohio State University Veterinary Teaching Hospitals. Significant bacteria were not isolated in culture or seen on histopathology in any of the horses. Although most bacteria infecting equine corneas can be isolated with blood and MacConkey's agars, failure to detect bacterial growth may not rule out infection because anaerobic or intracellular bacteria would not be isolated. The inability to visualise bacterial organisms on histological sections did not rule out their presence in the tissue, because there is often destruction of bacteria by neutrophils, macrophages and antibiotic therapy greatly reducing their numbers. Fungal keratitis was diagnosed by histopathology in 4 of 11 eyes (36%) and keratitis with no aetiological agent in 7 of 11 eyes (64%). Nine of 11 horses (82%) had a prominent neutrophilic stromal infiltrate and 2 (18%) had a predominantly pyogranulomatous reaction. Two of the 4 lesions that showed histological evidence of fungal infection were positive for identifiable fungi on culture and cytology. Fungal cultures of the other 2 cases with histological evidence of mycotic keratitis were negative or grew unidentifiable fungi which were considered pathogenic because, on histopathological sections, fungal hyphae were found deep in the corneal stroma surrounded by an inflammatory reaction. In 3 of 6 cases where fungi were recovered on culture, they were considered contaminants based on lack of evidence of organisms in histopathological sections. Histopathology and the use of special stains were important in the interpretation of culture and cytology results.
Publication Date: 1994-11-01 PubMed ID: 7889917DOI: 10.1111/j.2042-3306.1994.tb04048.xGoogle Scholar: Lookup
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- Journal Article
Summary
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The research involves a comparative study of histopathology, culture results, and cytology from horses diagnosed with corneal stromal abscess, with the objective to understand potential discrepancies between these tests and uncover the real extent of microbial infection in these conditions.
Methods and Sample Population
- The study was conducted in two veterinary teaching hospitals – Auburn University and Ohio State University.
- It involved 11 horses that were diagnosed with corneal stromal abscess.
Findings
- No bacteria were isolated in the culture or seen on histopathology in any of the horses, suggesting that routine testing methods may fail to detect certain bacterial infections.
- The absence of visible bacterial organisms in the histological sections doesn’t necessarily mean they aren’t present. This could be a result of destruction of bacteria by neutrophils, macrophages, and antibiotic therapy reducing their numbers.
- Out of the 11 horses, 4 (36%) were diagnosed with fungal keratitis via histopathology, while 7 (64%) exhibited keratitis without any known causative agent.
- Corneal stroma of 9 horses (82%) had a dense infiltration of neutrophils, and 2 (18%) showed a primarily pyogranulomatous reaction.
Inferences
- Out of the 4 horses that showed histological signs of fungal infection, only 2 were positive for identifiable fungi on culture and cytology. This indicates that traditional culture techniques can sometimes fail to identify an existing fungal infection.
- The other 2 horses, despite testing negative for fungal culture, were still considered pathogenic because fungal hyphae were observed in the deeper layers of the corneal stroma surrounded by an inflammation, providing histological evidence of mycotic keratitis.
- In 3 out of 6 cases where fungi were recovered on culture, they were considered contaminants due to lack of evidence in the histopathological sections, suggesting the importance of a diagnostic combination for accuracy.
Conclusions
- The study emphasizes the role of histopathology and application of special stains in interpreting culture and cytology results.
- This holistic approach can greatly enhance the accuracy of diagnosis in cases of corneal stromal abscess in horses.
Cite This Article
APA
Hamilton HI, McLaughlin SA, Whitley EM, Gilger BC, Whitley RD.
(1994).
Histological findings in corneal stromal abscesses of 11 horses: correlation with cultures and cytology.
Equine Vet J, 26(6), 448-453.
https://doi.org/10.1111/j.2042-3306.1994.tb04048.x Publication
Researcher Affiliations
- Department of Small Animal Surgery and Medicine, College of Veterinary Medicine, Auburn University, Alabama 36849-5523.
MeSH Terms
- Abscess / microbiology
- Abscess / pathology
- Abscess / veterinary
- Animals
- Corneal Stroma / microbiology
- Corneal Stroma / pathology
- Female
- Gram-Positive Cocci / isolation & purification
- Horse Diseases / microbiology
- Horse Diseases / pathology
- Horses
- Keratitis / microbiology
- Keratitis / pathology
- Keratitis / veterinary
- Male
- Mitosporic Fungi / isolation & purification
- Retrospective Studies
Citations
This article has been cited 3 times.- Flores MM, Del Piero F, Habecker PL, Langohr IM. A retrospective histologic study of 140 cases of clinically significant equine ocular disorders. J Vet Diagn Invest 2020 May;32(3):382-388.
- Mustikka MP, Grönthal TSC, Pietilä EM. Equine infectious keratitis in Finland: Associated microbial isolates and susceptibility profiles. Vet Ophthalmol 2020 Jan;23(1):148-159.
- Reed Z, Thomasy SM, Good KL, Maggs DJ, Magdesian KG, Pusterla N, Hollingsworth SR. Equine keratomycoses in California from 1987 to 2010 (47 cases). Equine Vet J 2013 May;45(3):361-6.
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