Streptococcus bacteremia

Background

Among all patients with Streptococcus bacteremia, the prevalence of infective endocarditis is about 7%1
- This varies greatly by species, with the highest-risk species being Streptococcus gallolyticus and three Viridans group streptococci, Streptococcus sanguinis, Streptococcus gordonii, and Streptococcus mutans

Group	Species	Risk of IE	Number of BSIs
Group A Streptococcus	Streptococcus pyogenes	1.9%	592
Group B Streptococcus	Streptococcus agalactiae	9.1%	441
Group C Streptococcus	Streptococcus equi	0	<4
Group C or G Streptococcus	Streptococcus dysgalactiae	6.6%	901
VGS, Streptococcus anginosus group	Streptococcus anginosus	4.8%	437
	Streptococcus constellatus	<4%	91
	Streptococcus intermedius	0%	40
VGS, Streptococcus mitis group	Streptococcus mitis or oralis	19.4%	408
	Streptococcus cristatus or sinensis	44%	9
	Streptococcus peroris	0	10
VGS, Streptococcus sanguinis group	Streptococcus gordonii	44.2%	95
	Streptococcus sanguinis	34.6%	133
	Streptococcus parasanguinis	10.3%	107
VGS, Streptococcus salivarius group	Streptococcus salivarius	5.8%	191
	Streptococcus vestibularis	low	26
	Streptococcus thermophilus	<4%	45
VGS, Streptococcus mutans group	Streptococcus mutans	47.9%	48
VGS, Streptococcus mutans group	Streptococcus sobrinus	0	<4
Nutritionally variant streptococci	Granulicatella adiacens	12.2%	41
Nutritionally variant streptococci	Granulicatella elegans	0	5
Streptococcus bovis group	Streptococcus gallolyticus	30.7%	225
	Streptococcus lutetiensis	low	23
	Streptococcus infantarius	low	14
	Streptococcus equinus	low	12
	Streptococcus alactolyticus	0	<4
Other streptococci	Streptococcus pneumoniae	1.2%	2,598
	Streptococcus massiliensis	0	5
	Streptococcus pluranimalium	0	<4
	Streptococcus suis	0	<4

Other risk factors include ≥3 positive BC bottles, prosthetic valve, native valve disease, cardiac device, previous endocarditis, and male sex (in descending order of important)

For non-β-hemolytic streptococci, consider using the HANDOC score to risk stratify for need for echocardiography
- Can effectively exclude the diagnosis of IE without needing imaging
Alternatively, can use an approach based on species, number of positive blood culture bottles, and presence of risk factors (native valve disease, previous IE, prosthetic valve, or cardiac device)1

Risk	Species	<3 Bottles		≥3 Bottles
Risk	Species	No RFs	RFs	No RFs	RFs
low	Streptococcus intermedius	no echo			TTE
	Streptococcus pneumoniae
	Streptococcus pyogenes
moderate	Streptococcus agalactiae	no echo	TTE		TTE+TEE
	Streptococcus anginosus
	Streptococcus constellatus
	Streptococcus dysgalactiae
	Streptococcus salivarius
	Streptococcus thermophilus
high	Granulicatella adiacens	TTE	TTE+TEE
	Streptococcus mitis/oralis
	Streptococcus parasanguinis
very high	Streptococcus gallolyticus	TTE+TEE
	Streptococcus gordonii
	Streptococcus mutans
	Streptococcus sanguinis

a b Sandra Chamat-Hedemand, Anders Dahl, Lauge Østergaard, Magnus Arpi, Emil Fosbøl, Jonas Boel, Louise Bruun Oestergaard, Trine K. Lauridsen, Gunnar Gislason, Christian Torp-Pedersen, Niels Eske Bruun. Prevalence of Infective Endocarditis in Streptococcal Bloodstream Infections Is Dependent on Streptococcal Species. Circulation. 2020;142(8):720-730. doi:10.1161/circulationaha.120.046723.