Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women (original) (raw)
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Gynecologic and Obstetric Investigation, 2003
Objective: To find the optimum screening method in detecting group B streptococcal (GBS) colonization in both mother and infant, and to identify the risk factors that influence GBS colonization in the infants. Patients and Methods: 1,120 singleton pregnant women were evaluated for GBS colonization by combined lower vaginal-anorectal swabs (LVRS) and urine tests, while their infants were evaluated for colonization with skin, ear and gastric aspirate samples. Results: LVRS swabs were positive in 14.2% of mothers while urine was positive in 7.6%. Among the infants skin, ear and gastric aspirate samples were positive in 7.0, 6.9 and 3.5%, respectively. Prolonged rupture of the membrane was the only significant factor associated with colonization in these infants (p < 0.001). Conclusions: Lower vaginal-anorectal swab is an effective method in detecting colonization in mothers especially when combined with urine culture. Skin or ear swabs are equally effective in detecting colonization...
The Indian journal of medical research, 2003
Group B beta haemolytic streptococcus (GBS) is a frequent colonizer of the maternal genital tract causing peripartum fever, puerperal sepsis, neonatal sepsis and neonatal meningitis. The conventional methods for detection of maternal colonization take 24-48 h. We made an attempt to standardize a rapid enrichment cum antigen detection test to screen pregnant women for GBS colonization in less than 8 h, so as to enable early institution of measures to prevent neonatal sepsis. Vaginal swabs of 100 women >36 wk of gestation were inoculated onto enrichment broth (Todd Hewitt broth with lysed horse blood and antibiotics). After incubation for 1,2,4,6, and 18 h, the broth was cultured on sheep blood agar. In culture positive cases, the enrichment broth was subjected to antigen detection by latex agglutination test (LAT). For further evaluation of the rapid test, another group of 100 pregnant women were screened for GBS carriage by 6 h enrichment broth culture followed by antigen detecti...
Increased recovery of group B streptococcus by the inclusion of rectal culturing and enrichment
Diagnostic Microbiology and Infectious Disease, 1995
Detection of intrapartum carriage of group B streptococcus (GBS) and subsequent antibiotic prophylaxis may prevent GBS infections in neonates. Because the gastrointestinal tract is the primary source of this organism, detection of carrier status requires both rectal and vaginal swabs. Vaginal swabs from 651 obstetric outpatients were plated onto 5% sheep blood agar. A second vaginal and a rectal swab were collected and incubated overnight in an enrichment medium of Todd-Hewitt broth containing antibiotics. By at least one method, 110 (16.9%) patients were positive for GBS. Only 31.8% of these positive patients were detected by direct culture of vaginal swabs. The use of vaginal swabs directly plated onto blood agar identified only three carriers not detected by another method. Inoculation of an enrichment broth with the vaginal swab and subsequent subculture detected 70.9% of the total. The use of both vaginal and rectal swabs with enrichment detected 97.3% of total GBS carriers. A subset of enrichment broths inoculated with vaginal and rectal specimens from 279 patients was tested for GBS by direct latex agglutination (Streptex; Murex Diagnostics, Inc., Norcross, GA, USA). Of the 90 broths that grew GBS on subculture, only 59 (65.6%) were positive by the direct agglutination method. The use of this method, although reducing processing time by 1 day, gave false-negative results for one-third of the GBS-positive broths. An accurate detection of the GBS carrier state can only be achieved by a combination of vaginal and rectal swabs incubated in enrichment broth and subcultured on blood agar.