Streptococcus ferus

Streptococcus viridans blood agar culture

Overview

Streptococcus ferus is a facultatively anaerobic, gram-positive species of the Streptococcus genus.^[1] The species is a member of the Viridans streptococci group ^[2] which are a large mixed-group of mostly alpha-hemolytic streptococci.^[3] The alpha-hemolytic bacteria are ones that exhibit a partial hemolysis with green coloration when grown on sheep blood agar^[4] (see image.)

Ecology

S. ferus was originally isolated from the oral cavity wild rats who were living in sugar cane fields and eating a high sucrose diet ^[5] The species name ferus, meaning wild, refers to their association with these animals.^[5] More recently the strain has also been isolated from the nasal and oral cavities of pigs.^[1] The species has not been identified in any other host organisms.

Morphology

S. ferus are gram positive lanceolate coccobacillus^[1] Non-motile and approximately 0.5 micrometers in diameter.^[6] They are non-sporulating and catalase-negative^[1] The majority of specimens test positive for the production of acetoin (Vogues-Proskauer reaction).^[5] They occur singly, in pairs or in short chains.^[5]

Pathogenicity

S. ferus is commensal in wild rats and pigs and demonstrates a relatively weak cariogenic potential compared to other streptococcus species such as S. mutans^[7] S. ferus has not had any reported pathogenic instances in humans.^[6]

History

S. ferus was originally proposed as a species in 1977 ^[5]

References