Streptococcus thoraltensis

Streptococcus thoraltensis is a species of Gram-positive, facultatively anaerobic bacteria in the genus Streptococcus. It was first described in 1997 after isolation from the genital tract of sows in Belgium.^[1] The species is part of the viridans streptococci group and is primarily associated with animals, particularly pigs. Although rare in clinical contexts, it has been occasionally reported as an opportunistic pathogen in humans.^[2]

Streptococcus thoraltensis
Scientific classification
Domain:	Bacteria
Kingdom:	Bacillati
Phylum:	Bacillota
Class:	Bacilli
Order:	Lactobacillales
Family:	Streptococcaceae
Genus:	Streptococcus
Species:	S. thoraltensis
Binomial name
Streptococcus thoraltensis Devriese et al., 1997
Type strain
S69 (DSM 12221)

Taxonomy

Streptococcus thoraltensis was described in 1997 based on isolates from healthy sows.^[1] It belongs to the family Streptococcaceae, order Lactobacillales, and phylum Bacillota. The species name refers to Torhout, Belgium (Latin: Thoraltum), where it was first discovered. The type strain is S69, also catalogued as DSM 12221.^[3]

Ecology

Streptococcus thoraltensis has been isolated from the gastrointestinal and genital tracts of pigs and rabbits.^[4] It has also been found in raw cow's milk, likely through environmental contamination.^[5] Its presence in humans is rare, but it has been recovered from subgingival plaque,^[6] nasopharyngeal swabs,^[7] and the respiratory tract, particularly in individuals with animal contact or compromised immunity.^{[citation needed]}

Clinical relevance

The bacterium is generally considered nonpathogenic in animals, though it may act as a commensal.^[1] In humans, a small number of opportunistic infections have been reported, including cases of bacteremia,^[2] pneumonia,^[8] endocarditis,^[9] and maternal-neonatal infection.^[10] A 2019 case documented postpartum pneumonia and sepsis caused by S. thoraltensis,^[8] and another in 2020 reported vancomycin-resistant endocarditis in a patient with a prosthetic heart valve.^[9]

Most clinical isolates have been susceptible to beta-lactams and vancomycin, though some environmental strains harbor antimicrobial resistance genes such as vanA and optrA, raising concern over emerging multidrug resistance.^[5]