Streptococcus (strep?to-kok'us) [ strepto- + coccus],
A genus of gram-positive, facultatively anaerobic cocci of the family Streptococcaceae, in which the cells tend to form chains or pairs. Many species are saprophytes, but others are virulent pathogens. They may be classified as alpha (a), beta (ß), and gamma (?) on the basis of their growth on blood agar plates and the hemolysis produced. Alpha-hemolytic streptococci produce partial hemolysis and create a greenish coloration around the colonies. Beta-hemolytic types completely hemolyze blood and form clear zones round colonies; those of the gamma type are nonhemolytic and do not change the color of the medium. Streptococci are also classified into several immunological groups (Lancefield groups) designated by the letters A through H, and K through O. Most human infections are caused by groups A, B, D, F, G, H, K, and O. Approximately 100 types of group A beta-hemolytic streptococci have been identified. See: rheumatic fever
; scarlet fever
Synonym: Streptococcus, Group B
A group B ß-hemolytic species found in raw milk that is the leading cause of bacterial sepsis and meningitis in newborns and a major cause of endometritis and fever in postpartum women.
Infected infants develop early-onset symptoms in the first 5 days of life, including lethargy, jaundice, respiratory distress, shock, pneumonia, and anorexia. The fatality rate is 50% for very low birth weight neonates and 2% to 8% in term infants.
Infected postpartum women develop late-onset symptoms 7 days to several months after giving birth. Symptoms include sepsis, meningitis, seizures, and psychomotor retardation. Neonatal infection may be prevented by detecting colonization by these bacteria in pregnant women and by administering antibiotics prior to birth.
A species that causes abscesses. It was formerly known as S. milleri.
The former name of a species now known as S. gallolyticus.
Streptococcus dysgalactiae subsp. equisimilis
A species that causes skin infections, such as erysipelas, as well as puerperal sepsis, osteomyelitis, pneumonia, bacteremia, and endocarditis.
The former name of a species now known as S. dysgalactiae subsp. equisimilis .
The former name of Enterococcus faecalis.
A species that causes bloodborne infections, esp. in patients with diseases of the large bowel, e.g. colon cancer.
Streptococcus, Group BStreptococcus agalactiae.
A species pathogenic to fish that may cause cellulitis in people who handle affected fish and have skin abrasions.
A species that has been implicated in initiation of dental caries and bacterial endocarditis.
A species that occurs in pairs with capsules and may be part of the transient flora of the upper respiratory tract. Based on capsular chemistry, more than 80 serological types have been identified. It is the causative agent of certain types of pneumonia, esp. lobar pneumonia, and is associated with other infectious diseases such as meningitis, conjunctivitis, endocarditis, periodontitis, septic arthritis, osteomyelitis, otitis media, septicemia, spontaneous bacterial peritonitis, and, rarely, urinary tract infections. About 40,000 people die of pneumococcal disease each year in the U.S., more than from any other vaccine-preventable illness. Synonym: pneumococcus
Any of the group A ß-hemolytic streptococci causing suppurative infections. These streptococci are the causative agents of scarlet fever, erysipelas, bacterial pharyngitis, puerperal sepsis, and necrotizing fasciitis.