Antibacterial susceptibility patterns for microbial isolates associated with infectious keratitis in horses: 63 cases (1986-1994).
Abstract: Seventy-three aerobic bacterial isolates were cultured from 64 eyes of 63 horses with infectious keratitis. Forty-two (58%) of the organisms isolated initially were gram-positive (g+, 10 genera) and 31 (42%) were gram-negative (g-, 5 genera). After local antimicrobial treatment, repeat cultures from samples obtained from 15 eyes of hospitalized horses yielded 21 secondary bacterial isolates. Staphylococci spp and Streptococci spp were the most common g(+) isolates and accounted for 79% of g(+) organisms isolated initially. Antibiograms revealed ticarcillin to be the most efficacious antibiotic tested on g(+) organisms, with 28 of 30 (93%) being susceptible. Of commercially available topical ophthalmic antibiotics tested on g(+) organisms, erythromycin was the most efficacious, with 32 of 35 (91%) isolates being susceptible. Pseudomonas spp, Escherichia coli, and Acinetobacter spp accounted for 68% of g(-) organisms isolated initially. Gentamicin, tobramycin, polymyxin B, and neomycin were highly effective in vitro against initial g(-) isolates. Chloramphenicol was ineffective against g(+) and g(-) organisms isolated initially. A significantly (P < 0.05) higher frequency of g(-) organisms was noticed on repeat cultures after intensive topical antimicrobial treatments as compared to organisms isolated at initial examination. Pseudomonas organisms isolated from second cultures were resistant to gentamicin, but susceptible to ciprofloxacin. Overall, secondary g(-) isolates were more susceptible to ciprofloxacin, neomycin, tobramycin, or amikacin than to gentamicin. Fungi were isolated in 24 of 63 (38%) horses in the study. Twenty-five filamentous fungi and 2 yeasts were identified from 24 eyes.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1995-10-01 PubMed ID: 7559027
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- Journal Article
Summary
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This research study investigates the antibacterial susceptibility of bacteria associated with infectious keratitis in horses. The study reveals specific patterns of antibiotic resistance and susceptibility, helpful for treatment strategies.
Overview of the Study
- The investigation focused on 63 horses that had infectious keratitis. For these horses, a total of 73 aerobic bacterial isolates were cultured from 64 eyes.
- The majority (58%) of the first organisms isolated were gram-positive, while the rest (42%) were gram-negative.
- After initial antimicrobial treatment, additional samples from 15 horses yielded 21 new bacterial isolates.
Findings for Gram-positive Organisms
- Among gram-positive isolates, the most common were Staphylococci spp and Streptococci spp, contributing to 79% of the total gram-positive bacteria initially isolated.
- From the antibiograms, ticarcillin showed the most efficacy on gram-positive organisms. Of the organisms tested, 93% reacted positively to ticarcillin treatment.
- Among the commercially available, topical ophthalmic antibiotics tested on gram-positive organisms, erythromycin indicated high efficacy. Around 91% showed susceptibility.
Findings for Gram-negative Organisms
- Pseudomonas spp, Escherichia coli, and Acinetobacter spp made up 68% of the initial gram-negative isolates.
- Gentamicin, tobramycin, polymyxin B, and neomycin demonstrated high effectiveness in vitro against initial gram-negative isolates.
- Chloramphenicol showed no effectiveness against both gram-positive and gram-negative organisms.
- On repeat cultures taken after intensive antimicrobial treatments, a significantly higher frequency of gram-negative organisms was noticed.
Findings for Repeat Cultures
- Pseudomonas organisms from second cultures demonstrated resistance to gentamicin, but susceptibility to ciprofloxacin.
- Overall, secondary gram-negative isolates showed more positive treatment response to ciprofloxacin, neomycin, tobramycin, or amikacin compared to gentamicin.
Findings for Fungal Isolates
- The study also discovered fungi in approximately 38% of horses. A total of 25 filamentous fungi and 2 yeasts were detected from 24 eyes.
The results from this study could assist in infoed decision making when selecting the most potent antibiotics to use against specific bacterial isolates associated with infectious keratitis in horses.
Cite This Article
APA
Moore CP, Collins BK, Fales WH.
(1995).
Antibacterial susceptibility patterns for microbial isolates associated with infectious keratitis in horses: 63 cases (1986-1994).
J Am Vet Med Assoc, 207(7), 928-933.
Publication
Researcher Affiliations
- Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211, USA.
MeSH Terms
- Animals
- Anti-Bacterial Agents
- Anti-Infective Agents / pharmacology
- Bacteria / drug effects
- Breeding
- Eye Infections, Bacterial / drug therapy
- Eye Infections, Bacterial / microbiology
- Eye Infections, Bacterial / veterinary
- Eye Infections, Fungal / drug therapy
- Eye Infections, Fungal / microbiology
- Eye Infections, Fungal / veterinary
- Female
- Fungi / drug effects
- Horse Diseases / drug therapy
- Horse Diseases / microbiology
- Horses
- Keratitis / drug therapy
- Keratitis / microbiology
- Keratitis / veterinary
- Male
- Microbial Sensitivity Tests / veterinary
Citations
This article has been cited 14 times.- 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(9):e0291028.
- Foote BC, Smith JS, Bowden AC, Allbaugh RA, Sebbag L. Case Report: Successful Management of Refractory Keratomycosis in an Alpaca Using Penetrating Keratoplasty and Combination Antifungal Therapy (Caspofungin 0.5% and Terbinafine 1%).. Front Vet Sci 2021;8:644074.
- Walsh ML, Meason-Smith C, Arnold C, Suchodolski JS, Scott EM. Evaluation of the ocular surface mycobiota in clinically normal horses.. PLoS One 2021;16(2):e0246537.
- Tahoun A, Elnafarawy HK, Elmahallawy EK, Abdelhady A, Rizk AM, El-Sharkawy H, Youssef MA, El-Khodery S, Ibrahim HMM. Epidemiological and Molecular Investigation of Ocular Fungal Infection in Equine from Egypt.. Vet Sci 2020 Sep 8;7(3).
- 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.
- Scott EM, Arnold C, Dowell S, Suchodolski JS. Evaluation of the bacterial ocular surface microbiome in clinically normal horses before and after treatment with topical neomycin-polymyxin-bacitracin.. PLoS One 2019;14(4):e0214877.
- Leigue L, Montiani-Ferreira F, Moore BA. Antimicrobial susceptibility and minimal inhibitory concentration of Pseudomonas aeruginosa isolated from septic ocular surface disease in different animal species.. Open Vet J 2016;6(3):215-222.
- Hidaka S, Kobayashi M, Ando K, Fujii Y. Efficacy and safety of lomefloxacin on bacterial extraocular disease in the horse.. J Vet Med Sci 2015 Jul;77(7):829-35.
- Hellander-Edman A, Makdoumi K, Mortensen J, Ekesten B. Corneal cross-linking in 9 horses with ulcerative keratitis.. BMC Vet Res 2013 Jun 26;9:128.
- Czerwinski SL, Lyon AW, Skorobohach B, Léguillette R. Pharmacokinetic analysis of topical tobramycin in equine tears by automated immunoassay.. BMC Vet Res 2012 Aug 21;8:141.
- Clark C, Greenwood S, Boison JO, Chirino-Trejo M, Dowling PM. Bacterial isolates from equine infections in western Canada (1998-2003).. Can Vet J 2008 Feb;49(2):153-60.
- Cullen CL, Grahn BH. Diagnostic ophthalmology. Corneal ulcer with severe secondary anterior uveitis in a pony.. Can Vet J 2000 Nov;41(11):887-9.
- Vaneechoutte M, Devriese LA, Dijkshoorn L, Lamote B, Deprez P, Verschraegen G, Haesebrouck F. Acinetobacter baumannii-infected vascular catheters collected from horses in an equine clinic.. J Clin Microbiol 2000 Nov;38(11):4280-1.
- Dowling PM, Grahn BH. Antimicrobial therapy of ocular infections.. Can Vet J 1998 Feb;39(2):121-4.
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