Pulmonary Disease Potentially Associated with Nicoletella semolina in 3 Young Horses

A 10-month-old, 200-kg, Arabian filly presented to the University of Georgia Veterinary Teaching Hospital for evaluation of cough, nasal discharge, and fever of 24 hours duration. Before referral to UGA, the filly had never traveled off the farm. The filly was vaccinated against EEE/WEE viruses, EHV-1, EIV, WNV, tetanus, and Streptococcus equi subsp. equi at 8 months of age. Deworming with ivermectin was performed 1 week before presentation. Several horses on the farm had a suspected viral upper respiratory tract infection 2–3 weeks before the filly became ill. On examination, the filly was quiet, alert, and responsive. Heart rate was 60 beats per minute, respiratory rate was 20 breaths per minute, and rectal temperature was 101.3°F. There was bilateral mucopurulent nasal discharge and an intermittent spontaneous cough, and tracheal palpation elicited coughing. Pulmonary auscultation revealed normal lung sounds bilaterally at rest and during rebreathing examination. No other abnormalities were noted on physical examination. CBC was within reference range. Percutaneous transtracheal aspirate (TTA) yielded a grossly turbid fluid classified as septic, suppurative inflammation with nondegenerate neutrophils and rare intracellular bacterial rods. PCR for the R. equi virulence associated proteinA (vap-A) gene and 16S rRNA on the fluid was negative. Nasopharyngeal lavage was negative for S. equi subspecies equi by PCR. Nasal swabs were PCR negative for EHV-1 and EIV viruses, as was whole blood buffy coat EHV-1 PCR. Thoracic radiographs revealed a moderate caudoventral interstitial-alveolar pattern. Transthoracic ultrasonography revealed mild bilateral cranioventral pleural roughening. Initial treatment for presumptive bacterial bronchopneumonia consisted of broad-spectrum antimicrobial treatment with potassium penicillin G (22,000 U/kg IV q6 h) and gentamicin (6.6 mg/kg IV q 24 h), and antiinflammatory treatment with flunixin meglumine (0.25 mg/kg IV q8 h). Within 72 hours, the filly’s fever and nasal discharge resolved and her cough improved. Aerobic bacterial culture of TTA fluid yielded heavy growth of S. equi subsp. zooepidemicus and heavy growth of a slow-growing nonreactive nonfermenting gram-negative rod with colony morphology consistent with the recently characterized Pasteurellaceae organism Nicoletella semolina (Fig 1), both with broad sensitivity profiles. This organism was cultured on a chocolate-agar plate incubated in carbon dioxide and