beta-hemolytic streptococci

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Related to beta-hemolytic streptococci: streptococcal

β-he·mo·lyt·ic strep·to·coc·ci

those that produce active hemolysins (O and S) that cause a zone of clear hemolysis on the blood agar medium in the area of the colony; β-hemolytic streptococci are divided into groups (A-O) on the basis of cell wall C carbohydrate (see Lancefield classification); Group A (in the strains pathogenic in humans) comprises more than 50 types (designated by Arabic numerals) determined by cell wall M protein, which seems to be associated closely with virulence and is produced chiefly by strains with matt or mucoid colonies, in contrast to nonvirulent, glossy colony-producing strains; other surface protein antigens such as R and T (substance T), and the nucleoprotein fraction (substance P) seem to be of less importance. The more than 20 extracellular substances elaborated by strains of β-hemolytic streptococci include erythrogenic toxin (elaborated only by lysogenic strains), deoxyribonuclease (streptodornase), hemolysins (streptolysins O and S), hyaluronidase, and streptokinase.
Farlex Partner Medical Dictionary © Farlex 2012


(strep?to-kok'us) (-kok'si?) plural.streptococci [ strepto- + coccus]
An organism of the genus Streptococcus. See: bacteria for illus streptococcic, adjective

a-hemolytic streptococci

Streptococci that, when grown on blood-agar, produce a zone of partial hemolysis around each colony and often impart a greenish appearance to the agar. Included are S. pneumoniae and viridans group streptococci.

ß-hemolytic streptococci

group B streptococci

group A streptococci

Beta-hemolytic streptococci (esp. Streptococcus pyogenes) that produce human diseases, including pharyngitis, cellulitis, erysipelas, impetigo, otitis media, pneumonia, scarlet fever, necrotizing fasciitis, sepsis, sinusitis, and tonsillitis. In addition, group A streptococcus infection may have immunologic sequelae such as rheumatic fever and acute glomerulonephritis.

group B streptococci

Streptococci that, when grown on blood-agar, produce complete hemolysis around each colony, indicated by a yellowish zone. Included are S. pyogenes and S. agalactiae.These streptococci are a leading cause of early-onset neonatal infections and late-onset postpartal infections. In women, this is marked by urinary tract infection, chorioamnionitis, postpartum endometritis, bacteremia, and wound infections complicating cesarean section. Eradication of this organism during labor decreases the chances for neonatal sepsis. Performance of cervical-rectal screening cultures at 35 to 37 weeks’ gestation (and intrapartum treatment with penicillin if cultures are positive) prevents the development of neonatal sepsis.
Synonym: ß-hemolytic streptococci

group D streptococci

Any Streptococcus species, including S. bovis and S. equinus, that is not destroyed by bile or exposure to heat. These strains can be destroyed in a laboratory by a 6.5% concentration of sodium chloride. Many Group D streptococci have been reclassified and placed in the genus Enterococcus (including S. faecalis, S. faecium, S. durans, and S. avium). For example S. faecalis is now E. faecalis. The remaining strains of nonenterococcal Group D streptococci include S. bovis and S. equinus.

nutritionally variant streptococcus

Abbreviation: NVS
The obsolete name for bacteria of the genera Abiotrophia or Granulicatella.
Medical Dictionary, © 2009 Farlex and Partners
References in periodicals archive ?
Out of 11 beta-hemolytic streptococci, 45.4% (4/11) showed intermediate susceptibility to penicillin.
Beta-hemolytic streptococci (BHS) are well-known causative agents of cutaneous, oropharyngeal, and invasive infections (1).
We diagnosed guttate psoriasis in this patient based on her history and physical exam, a throat culture that was positive for group A beta-hemolytic streptococci, and blood work that showed an elevated antistreptolysin O titer.
Today, the most common causative agents are beta-hemolytic streptococci. (1) Other bacteria that cause supraglottitis include staphylococci, pneumococci, Pasteurella spp, and Fusobacterium spp.
The aerobic culture grew few alpha-hemolytic streptococci, occasional beta-hemolytic streptococci (not group A or B), rare Staphylococcus aureus, and rare Candida albicans.
In vitro protection of group A beta-hemolytic streptococci from penicillin and cephalothin by Bacteroides fragilis.
Prevalence of beta-hemolytic streptococci carrier rate among schoolchildren in Salem.
Beta-hemolytic streptococci were isolated from 12 of the daycare workers (19.05%), S aureus from 9 (14.29%), and M catarrhalis from 2 (3.17%) (table 3).

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