Identification of a Highly Encapsulated, Genetically Related Group of Invasive Type III Group B Streptococci

Abstract

Type III group B streptococci (GBS) isolated from Tokyo and Salt Lake City were classified according to the similarity of HindIII and Sse83871 restriction digest patterns (RDPs) of bacterial DNA. The bacteria were clustered into three RDP types, with excellent correlation between subtyping based on the two enzymes. The majority (91%) of invasive isolates obtained from neonates were RDP type III-3. The mean sialic acid content of the III-3 strains was higher than that of other type III strains. Closely related isolates were concordant for expression of the bacterial enzyme C5a-ase, but invasive strains were no more likely to be C5a-ase positive than were strains isolated from the genitourinary tract of pregnant women. These data indicate that a group of genetically related organisms with increased capsule production causes the majority of invasive type III GBS disease. Group B streptococci (GBS) 3) causes most serotype III neonatal sepsis, suggesting the RDP typing. DNA was extracted from GBS suspended in agarose existence of a genetically related subgroup of serotype III GBS gel plugs (InCert; FMC BioProducts, Rockland, ME) according to that are intrinsically more virulent than other serotype III strains the manufacturer's instructions except that mutanolysin and SDS con- [4]. The purpose of these studies was to determine whether taining proteinase K were used for digestion of the bacteria. DNA in invasive serotype III isolates from Salt Lake City, as well as the agarose gel plugs was digested with HindIII, extracted from the more recently isolated clinical isolates from Japan, are also agarose with phenol, and redigested with HindIII. The DNA sample RDP III-3. We also validated the HindIII typing by typing the was then subjected to electrophoresis in a conventional ethidium bromide-agarose gel. The similarity between densitometric RDPs from individual strains was expressed as a Pearson product moment correlation coefficient (PPMCC) and clustered by the unweighted

A unique serine-rich repeat protein (Srr-2) and novel surface antigen (ε) associated with a virulent lineage of serotype III Streptococcus agalactiae

“…Strains DL797, DL769, DL771, DL686, DL775, DL1104, DL785 and DL700 were clinical isolates kindly provided by Dr Daniel Lim from the University of South Florida, Tampa, FL, USA. GBS strains representing RDP III types 1-4 were isolated from vaginal swabs, blood or cerebrospinal fluid, as described previously (Takahashi et al, 1998). Strains COH1 and COH1-13 were kindly provided by Dr Craig Rubens of the University of Washington and Children's Hospital and Regional Medical Center, Seattle, WA, USA.…”

“…In addition to antigenic differences, serotype III GBS strains also have been classified into four distinct lineages, designated RDP types III-1, -2, -3 and -4, based on HindIII and Sse83871 restriction digest patterns (RDPs) of chromosomal DNA (Takahashi et al, 1998). A multilocus sequence typing (MLST) system has also been developed that categorizes GBS strains based on the combination of alleles of seven housekeeping genes (Jones et al, 2003).…”

“…Comparison of these two typing methods has shown that RDP III-3 strains correspond to the ST-17 clonal complex lineage. Over 90 % of serotype III invasive neonatal isolates have been identified as RDP III-3, suggesting that this may represent a more virulent lineage (Takahashi et al, 1998). Several investigators have now also reported that ST-17 lineage strains are significantly associated with invasive disease in neonates (Jones et al, 2003;Luan et al, 2005;Bisharat et al, 2004).…”

Genetic diversity of Streptococcus agalactiae strains and density of vaginal carriage

“…Prevention of severe neonatal meningitis, pneumonia and sepsis associated with S. agalactiae requires detection of vaginal carriage in pregnant women, followed by penicillin treatment preceding delivery. Various methods, mostly involving culture, are used for the detection of vaginal carriage (Jones et al, 2003;Musser et al, 1989;Rallu et al, 2006;Schrag et al, 2002;Takahashi et al, 1998).…”

Induction of cyclooxygenase-2 by human monocytes exposed to group B streptococci

“…GBS were isolated and heat-killed organisms prepared as previously described [9,32]. Briefly, the bacteria were grown overnight in Todd-Hewitt broth (Difco Laboratories, Inc., Detroit, MI) for 18 h at 37°C.…”