Streptococci
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Overview
- Cause suppurative infections in many different animals
- Cause mastitis, metritis, polyarthritis, meningitis
Characteristics
- Gram positive cocci forming chains
- Catalase negative, facultative anaerobes
- Fastitidious - require enriched media such as blood or serum
- Small haemolytic, translucent colonies
- Catalase negative
- Susceptible to desiccation
- Commensals on mucous membranes of upper respiratory and lower urogenital tract
Identification
- Beta haemolysis (complete with clear zones surrounding colonies)
- Alpha haemolysis (partial with green zones surrounding colonies)
- Lancefield grouping - serology based on group-specific polysaccharide in cell wall
- Biochemical testing
Pathogenicity
Clinical infections
Diagnosis
Treatment
Control
- Haemolytic streptococci of Lancefield group C are common inhabitants of the equine nasopharynx
- Streptococcus zooepidemicus and S. equisimilis are usually non-pathogenic
- S. equi is more pathogenic and is the cause of strangles with rhinitis, pharyngitis, lymphadenitis, myositis
- S. equi may be involved in cutaneous lesions
- S. zooepidemicus can cause similar signs to strangles in horses, may accompany COPD
- May cause sinusitis in horses
- Can cause vascular fragility, leading to haemorrhagic disease.
- Secondary invadors after Equine influenza
- S. suis in pneumonia of pigs
- In pyothorax
- In osteomyelitis
- In infectious arthritis of sheep, arthritis in calves, arthritis in horses and arthritis in pigs
- In horses sometimes purpura haemorrhagica follows, especially during recovery from strangles
- In catarrhal stomatitis
- In deep pyoderma and subcutaneous abscesses