Streptococcus hillyeri isolated from septic pleuritis in a horse.

The research study pertains to a case where Streptococcus hillyeri was isolated from a horse suffering from septic pleuritis. This bacterium’s presence was confirmed through various tests and analyses, raising potential implications regarding its role in causing disease in horses.

Case Background and Symptom Observations

• The preliminary part of the paper describes the case of a 17-year-old Hungarian Sport Horse mare that was brought to the University of Veterinary Medicine in Budapest, Hungary with suspected pleuritis (inflammation of the membrane enveloping the lungs).
• Upon examination, the horse was found to have high fever, tachycardia (abnormally fast heart rate), severe difficulty in inspiration, and tachypnea (excessively fast breathing).
• Further diagnostics carried out using thoracic ultrasonography indicated that the horse suffered from severe pleural effusion (fluid accumulation around the lungs) and lung consolidation (a condition where a part or the whole lung becomes solid due to inflammation or damage).

Diagnostic Tests and Treatments

• Following the clinical examinations, both sides (hemithoraces) of the horse’s chest were sampled and 66 liters of cloudy fluid indicative of an infection was extracted.
• The horse was diagnosed with septic pleuritis and immediately put on broad-spectrum antibiotics, NSAIDs (Non-Steroidal Anti-Inflammatory Drugs), anticoagulants, and intravenous fluids as a course of treatment.
• Despite these intensive measures, the horse’s condition worsened, leading to euthanasia after six days.

Postmortem Analysis

• The horse’s fluid sample confirmed the diagnosis of septic pleuritis, with the presence of coccoid bacteria (spherical, oval, or generally roundish bacteria).
• An anaerobic culture (a culture devoid of oxygen), revealed Gram-positive cocci (spherical-shaped bacteria classified by their positive reaction to the Gram stain test) in almost pure culture, in samples from both hemithoraces.
• Application of 16S rDNA and whole genome analyses identified the bacteria as Streptococcus hillyeri, confirming its presence in the horse’s thoracic sample.

Additional Findings

• This study also identified four prior unclassified Streptococcus species sequences as Streptococcus hillyeri. These sequences were derived from aborted equine fetuses and a donkey suffering from mastitis (inflammation of the breast or udder), highlighting a possibility that Streptococcus hillyeri may be a pathogen in these species.