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]
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.
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]
References
^Farrow, J. A. E.; Kruze, J.; Phillips, B. A.; Bramley, A. J.; Collins, M. D. (December 1984). "Taxonomic studies on Streptococcus bovis and Streptococcus equinus: Description of Streptococcus alactolyticus sp. nov. and Streptococcus saccharolyticus sp. nov". Systematic and Applied Microbiology. 5 (4): 467–482. Bibcode:1984SyApM...5..467F. doi:10.1016/S0723-2020(84)80004-1.
^Rinkinen, M.-L.; Koort, J.-M.; Ouwehand, A. C.; Westermarck, E.; Björkroth, K. J. (15 January 2004). "Streptococcus alactolyticus is the dominating culturable lactic acid bacterium species in canine jejunum and feces of four fistulated dogs". FEMS Microbiology Letters. 230 (1): 35–39. doi:10.1016/S0378-1097(03)00851-6. PMID14734163.
^Devriese, L. A.; Hommez, J.; Pot, B.; Haesebrouck, F. (July 1994). "Identification and composition of the streptococcal and enterococcal flora of tonsils, intestines and faeces of pigs". Journal of Applied Bacteriology. 77 (1): 31–36. doi:10.1111/j.1365-2672.1994.tb03040.x. PMID7928781.
^Devriese, L. A.; Hommez, J.; Wijfels, R.; Haesebrouck, F. (July 1991). "Composition of the enterococcal and streptococcal intestinal flora of poultry". Journal of Applied Bacteriology. 71 (1): 46–50. doi:10.1111/j.1365-2672.1991.tb04480.x (inactive 20 July 2025). PMID1910033.{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
^Yiu, K. H. (2011). "Native-valve endocarditis due to Streptococcus alactolyticus: Case report and literature review". Clinical Microbiology and Infection. 17 (4): 630–632. doi:10.1111/j.1469-0691.2010.03258.x. PMID20459438.