Isolation of Moraxella spp. strains in horses.

Overview

• This study isolated and identified two species of Moraxella bacteria from horses showing symptoms of eye and nasal infections.
• The research aimed to better understand the role of these bacteria in equine conjunctivitis and rhinitis, highlighting their identification and antibiotic sensitivity.

Introduction and Purpose

• The research focused on Moraxella spp., a genus of bacteria commonly found as commensals but sometimes involved in infections.
• Two symptomatic horses displaying conjunctivitis (eye inflammation) and rhinitis (nasal inflammation) were studied to isolate and identify bacterial species causing these conditions.
• There is limited knowledge on the pathogenic role and identification of Moraxella species in horses, motivating this study.

Methods

• Swabs were collected from affected sites (eyes and nose) of the two horses showing clinical signs.
• Bacterial isolates were identified using Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF), a rapid and precise bacterial identification method based on protein fingerprinting.
• Species identification was supported by BLAST sequence analysis (a genomic sequence comparison tool) to confirm high similarity to known Moraxella species.
• Antimicrobial susceptibility testing was performed using the minimum inhibitory concentration (MIC) method to determine which antibiotics the isolates were sensitive or resistant to.

Results

• Two different Moraxella species were identified:
  • Moraxella osloensis from one horse
  • Moraxella equi from the other horse
• Identification scores from MALDI-TOF indicated reliable genus-level and probable species-level identifications.
• BLAST analysis confirmed the identification of Moraxella osloensis with 99% sequence homology.
• Both bacterial strains showed sensitivity to all tested antimicrobial drugs, indicating they could be effectively treated with standard antibiotics.
• The applied therapeutic protocols led to positive clinical outcomes with no recurrence of symptoms.

Discussion and Implications

• Moraxella spp. are normally commensal bacteria, making it challenging to determine their direct role in causing disease.
• Despite this difficulty, the bacteria should be considered in differential diagnoses of equine conjunctivitis and rhinitis, especially when common pathogens are not identified.
• The study highlights the importance of accurate bacterial identification techniques such as MALDI-TOF and genomic sequencing to better understand the epidemiology of these infections.
• Reporting such clinical cases contributes to expanding veterinary knowledge about Moraxella species infections and their treatment in horses.

Conclusion

• The study successfully isolated and identified two Moraxella species from horses with conjunctivitis and rhinitis.
• Both isolates were sensitive to antibiotics and responded well to treatment.
• The findings emphasize the need to include Moraxella species as potential etiologic agents in ocular and respiratory infections in horses despite their commensal status.
• Further reports and studies are encouraged to enhance understanding and clinical management of Moraxella-related diseases in veterinary medicine.