Dynamics of Streptococcus agalactiae Colonization in Women during and after Pregnancy and in Their Infants

Abstract

The population dynamics of Streptococcus agalactiae (group B streptococci [GBS]) colonization of the vagina and anorectal area was investigated in a cohort of 77 Danish women during and after their pregnancy by a new sensitive method. The mean carriage rate among individual observations was 36%, and the cumulative carriage rate over the entire observation period was 54%. Examination of more than 1,500 GBS isolates by pulsed-field gel electrophoresis demonstrated that the GBS population was remarkably homogeneous and stable in each carrier. Virtually all carriers were colonized by a single GBS clone on all occasions spanning up to 2 years. Repeated detection of the same clone even in women who were recorded as intermittent carriers suggests that the actual carrier rate exceeds 50% but that fluctuations in the GBS proportions of the flora occasionally preclude their detection. Newborns and young infants usually carried the same GBS clone as their mothers. However, only twice were identical clones of GBS detected in different women in contrast to the observed clonal relationships of clinical isolates. These observations strongly suggest differences in the properties and epidemiology of virulent GBS clones compared to clones commonly carried by healthy individuals.Infection by Streptococcus agalactiae (group B streptococci [GBS]) is still a common cause of neonatal diseases such as pneumonia, septicemia, and meningitis, although the incidence has declined in some countries as a result of active prevention efforts. The overall incidence of early-onset disease in 1998 to 2000 was 0.5 to 0.6 cases per 1,000 live births (12,25,30,32), although there are geographical and racial differences (11). An incidence of 0.24 per 1,000 live births of proven GBS infections in neonates and young infants has been reported for Denmark in the past (8). It is generally accepted that bacterial colonization of the child during its passage through the birth canal is the main cause of early-onset infections among children aged less than 7 days. Intrapartum chemoprophylaxis offered to pregnant carriers is, therefore, the strategy now recommended by the Centers for Disease Control to reduce neonatal GBS infection (13). GBS also causes invasive infections in nonpregnant and pregnant adults (6, 35), although the incidences are lower than for newborns.The carriage rates of GBS among pregnant and nonpregnant women and the rate of neonatal acquisition of GBS has been examined in the past (for reviews, see references 4, 13, and 33). However, relatively little is known about the kinetics of GBS colonization among individual carriers.The main purpose of the present longitudinal study was to evaluate the prevalence of GBS colonization among pregnant and nonpregnant women by using a new sensitive differential agar medium (mixed blood [MB] agar) (19) and to examine the complexity and stability of the GBS population in individual women and their newborns. This was achieved by determination of the carriage and the clonal diversity of GBS defined by pulsed...

Prevalence and risk factors for group B streptococcal colonization in pregnant women in northern India

“…4,5 GBS colonization during pregnancy can be transient, intermittent, or persistent. 6 The gastrointestinal tract serves as the primary reservoir for GBS and is the likely source of vaginal colonization. Heavy colonization, defined as culture of GBS from direct plating rather than from selective broth only, is associated with higher risk for early-onset disease in newborns.…”

Molecular typing of colonizing Streptococcus agalactiae strains by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) in a Chennai based hospital

“…Common clinical manifestations of S. agalactiae include puerperal sepsis, meningitis, and pneumonia in neonates and urinogenital infections and colonization in pregnant and non-pregnant adults [6,7,8]. The incidence of GBS infections varies with the geographical regions with a lower colonization rate in Indian women and infants [15,18].…”

Méningite néonatale à streptocoque du groupe B

“…Le mode de transmission et la physiopathologie du syndrome tardif demeurent en revanche méconnus, bien qu'une transmission mère-enfant soit également suspectée. Une colonisation intestinale précoce suivie d'une translocation digestive permettant l'accès de la bactérie à la circulation sanguine constitue un scénario hautement probable [3,4]. Les données épidémiologiques collectées par le Centre national de référence des streptocoques indiquent qu'une proportion importante de syndromes précoces et la majorité des syndromes tardifs sont associés à un sérotype capsulaire particulier de streptocoque du groupe B, le sérotype III [5].…”