Highly pathogenic beta-hemolytic streptococcal infections in cats from an institutionalized hoarding facility and a multi-species comparison.

Abstract

OBJECTIVES: Two hundred and thirty-four cats removed from an institutionalized hoarding facility (IHF) demonstrated severe, atypical pyogenic infections. The objective of this study was to document the various syndromes and determine the etiology of the infections. METHODS: All cats were evaluated initially after removal from the IHF and on a daily basis for at least 15 months. Samples were collected and sent for culture/susceptibility and histopathology to commercial laboratories or stored at -20(o)C. PCR was performed using universal bacterial primers to amplify the 16S-23S rRNA intergenic spacer region. PCR products were sequenced to determine the identity of the bacteria. RESULTS: Multiple pyogenic syndromes were documented, including abscesses of the paws and carpal/tarsal regions in 82 cats, acute rhinitis with profuse purulent nasal discharge in 68 cats and cervical lymphadenitis with abscessation unassociated with any wounding in 51 cats. Many cats exhibited septic arthritis with total joint destruction, necrotizing fasciitis, meningitis, otitis and septic shock, often leading to death. These infections appeared to be caused by beta-hemolytic streptococci (BHS) based on initial culture results (n = 10), though speciation was unclear and some samples (n = 6) produced no growth. Based on PCR results (n = 26), Streptococcus canis was the only bacterial species or the dominant species identified in each sample, and was the only species present in all the regions associated with the pyogenic infections. CONCLUSIONS AND RELEVANCE: Horizontal gene transfer and loss of the cell wall may account for the discrepancy between the culture and PCR results and the highly pathogenic nature of S canis in this particular population of cats. A large-scale hoarding situation with multiple animal species, overcrowding, stress and mixing of animals from many geographical regions created ideal conditions for these events to occur. The specific virulence factors present may be more useful in predicting the pathophysiology of BHS infections than the species of Streptococcus found in the host per se.