Streptococcus alactolyticus

Streptococcus alactolyticus is a species of Gram-positive, facultatively anaerobic cocci that forms chains and belongs to the Streptococcus bovis/equinus complex (SBSEC). It was proposed as a novel species in 1984 when lactose-negative porcine intestinal isolates previously assigned to biotype II of Streptococcus bovis were shown by DNA–DNA hybridization and phenotypic traits to constitute a distinct taxon.^[1]

Streptococcus alactolyticus
Scientific classification
Domain:	Bacteria
Phylum:	Bacillota
Class:	Bacilli
Order:	Lactobacillales
Family:	Streptococcaceae
Genus:	Streptococcus
Species:	S. alactolyticus
Binomial name
Streptococcus alactolyticus Farrow & Collins 1984
Type strain
ATCC 43077 = DSM 20542

Etymology

The specific epithet *alactolyticus* (Latin: *a-* "without", *lactum* "milk", and *lyticus* "able to break down") refers to the species’ inability to hydrolyze or ferment lactose.

Ecology

S. alactolyticus has been isolated from dogs,^[2] pigs,^[3][4] and poultry,^[5] where it is considered part of the normal microbiota.

Clinical relevance

Although uncommon, S. alactolyticus has been implicated in opportunistic human infections. Reported clinical cases include infective endocarditis,^[6] bacteremia, and neonatal sepsis. A 2020 case report described a rare instance of neonatal meningitis caused by this species, confirmed through culture and treated successfully with ampicillin and cefotaxime.^[7]