Identification of a high-virulence clone of type III Streptococcus agalactiae (group B Streptococcus) causing invasive neonatal disease.

Abstract

Of the 44 isolates of type III from invasive episodes, 24 were cultured from blood, 18 were recovered from cerebrospinal fluid (CSF), and 1 each was grown from joint fluid and pulmonary secretions collected by tracheal aspiration. The 19 isolates from asymptomatic neonates were collected from the umbilicus (16 isolates), rectum (2 isolates), and throat (1 isolate). The sample also included isolates of types I (n = 8), lb (n = 16), Ic (n = 14), Ic/Il (n = 6), and II (n = 11) collected during disease episodes in 15 states, primarily from blood or cerebrospinal fluid. In addition, nine isolates from cases of bovine mastitis in France were examined: types Ia (n = 2), lb (n = 2), Ic (n = 4), and II (n = 1).The actual frequencies of recovery of the various serotypes from invasive episodes are not accurately reflected by the numbers of isolates in the collection studied. Non-type-Ill isolates were greatly overrepresented among the invasive isolates, strictly for purposes of genetic comparison. The human isolates were obtained from collections previously characterized for neuraminidase production and other phenotypes (13)(14)(15)(16)(17)(18)(19)(20)(21)(22). No non-type-Ill carrier isolates were analyzed.Many of the type III isolates obtained from humans were coded by S.J.M. for blind analysis in the laboratory ofR.K.S.Abbreviation: ET, electrophoretic type. 4731The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Hyaluronan Binding and Degradation byStreptococcus agalactiae Hyaluronate Lyase

“…One third of HA in a human body is overturned every day (37). The pathogenic strains of S. agalactiae that cause meningitis and septicemia and other serious diseases in humans, especially neonates, usually secrete more hyaluronate lyase to degrade HA and CS, two major kinds of polysaccharide components of the extracellular matrix (5). Mammals use endogenous hyaluronidases, a group of hydrolases, to accomplish the task of HA degradation.…”

“…High levels of hyaluronate lyase (SagHL) were found in the extracellular cultures of the disease-causing strains of serotype III GBS (4 -6). Clinical studies indicated that strains of type III GBS that produce more extracellular hyaluronate lyase (division I S. agalactiae) are apparently more virulent than those strains producing less (division II S. agalactiae) (5,6). Division I S. agalactiae usually causes invasive infections, whereas division II bacteria cause diseases much less frequently and are usually found in asymptotically colonized infants.…”

Physiological impact of transposable elements encoding DDE transposases in the environmental adaptation of Streptococcus agalactiae

“…Nevertheless, high HylB levels or the presence of an intact hylB gene were also reported in isolates of S. agalactiae causing invasive disease. These contradictory reports point out that the exact involvement of HylB in systemic infections needs further investigations (Bohnsack et al, 2001;Musser et al, 1989;Rojo et al, 2008). IS1548 possesses another preferential insertion target just upstream of the lmb gene encoding a bifunctional laminin-binding protein/zinc-binding protein (Granlund et al, 1998(Granlund et al, , 2001; Fig.…”

Hyperinvasive Neonatal Group B Streptococcus Has Arisen from a Bovine Ancestor

“…A single homogeneous clone of capsular serotype III GBS (sequence type [ST] 17 ) was found to be significantly associated with cases of invasive neonatal disease (22). In the 1980s, Musser and colleagues (27) had also concluded that a single virulent clone was responsible for many cases of neonatal disease. Their work, based on multilocus enzyme electrophoresis, showed that a proportion of invasive neonatal GBS strains were genetically related and possessed capsular serotype III.…”