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Published on: November 23, 2012
Multiplication in human blood and deoxyribonuclease production by group G streptococci isolated from animals and
J C Reitmeyer1, R K Guthrie, J H Steele
1Department of Microbiology, University of Texas Medical Branch, Galveston 77550.
Abstract:
An M protein or an M protein-like substance was found to be present in a large proportion of group G streptococci isolated from animals and humans. Forty-seven percent of the isolates from cat throats and 38% of the isolates from the vagina of cats were able to multiply in human blood. Only 14% of the human isolates of group G isolated from various anatomical sites and sources were able to multiply in fresh human blood. Deoxyribonuclease was produced by 81% of cat vagina isolates, by 80% of cat throat isolates and by only 27% of the group G isolates from humans. Thirty-five percent of the cat isolates but only 5% of the human isolates were able to both grow in blood and produce DNase.
Insights
Group G streptococci from cats show higher potential for human blood survival and DNase production compared to human isolates. This suggests a greater zoonotic risk from animal-derived strains.
Area of Science:
- Microbiology
- Zoonotic Diseases
- Bacterial Pathogenesis
Background:
- Group G streptococci (GGS) are bacteria found in both animals and humans.
- M proteins are virulence factors in streptococci, contributing to bacterial survival and pathogenicity.
- Understanding differences between animal and human GGS isolates is crucial for assessing zoonotic potential.
Purpose of the Study:
- To investigate the presence of M protein or M protein-like substances in animal and human GGS isolates.
- To compare the ability of animal and human GGS isolates to multiply in human blood.
- To assess and compare the deoxyribonuclease (DNase) production capabilities of these isolates.
Main Methods:
- Isolation of group G streptococci from animal (cat) and human sources.
- Culturing of isolates in human blood to assess growth and multiplication.
- Assay for deoxyribonuclease (DNase) production by the isolates.
Main Results:
- A significant proportion of GGS isolates from cats (throat and vagina) possessed M protein or M protein-like substances.
- Cat GGS isolates demonstrated a higher capacity to multiply in human blood (47% throat, 38% vagina) compared to human isolates (14%).
- DNase production was significantly higher in cat isolates (81% vagina, 80% throat) than in human isolates (27%).
- 35% of cat isolates and only 5% of human isolates exhibited both blood-growth and DNase production.
Conclusions:
- Group G streptococci from feline sources exhibit enhanced virulence factors, including M protein-like substances and DNase production.
- The higher capacity of animal-derived GGS to grow in human blood suggests a greater potential for causing human infections.
- These findings highlight the potential zoonotic risk associated with group G streptococci originating from animals.
