Evaluation of CHROMagar™ StrepB agar, an aerobic chromogenic medium for prepartum vaginal/rectal Group B Streptococcus screening

Poisson, Didier-Marc; Evrard, Marie-Liesse; Freneaux, Claire; Vivès, Marie-isabelle; Mesnard, Louis

doi:10.1016/j.mimet.2011.01.014

Cited by 17 publications

(18 citation statements)

References 10 publications

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“…Further, this is the first reported head-to-head comparison of the 96-well plate format Fast-Track Diagnostics GBS qPCR assay run on a high-volume instrument platform. Our results confirm previous reports of the lower sensitivity of routine culture than either of these newer methods (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). Overall, CDC-compliant nonchromogenic culture medium procedures for genital GBS detection had a sensitivity 3 to 5% lower than that of CM cultures or qPCR.…”

Section: Discussionsupporting

confidence: 86%

“…Overall, CDC-compliant nonchromogenic culture medium procedures for genital GBS detection had a sensitivity 3 to 5% lower than that of CM cultures or qPCR. The abilities of various GBS CMs reportedly vary depending on the commercial supplier and whether or not the vaginal-rectal swab is inoculated directly or after broth enrichment (i.e., Lim broth, Todd-Hewitt broth, or SCB) (16)(17)(18)(19)(20). Craven et al compared the yield of ChromID Strepto B agar (bioMérieux, Inc.) with that of routine culture with Lim broth and neomycin-nalidixic acid agar (NNA) for detection of GBS in 250 prenatal screening swabs (17).…”

Section: Discussionmentioning

confidence: 99%

“…Although CM was more sensitive (87.7%) than NNA alone (79%) without pre-enrichment, Lim broth enrichment prior to inoculation of either chromogenic or routine culture medium increased the sensitivity of both methods to 100%. Poisson et al similarly showed improved GBS detection in 285 vaginal-rectal swabs collected from prepartum women by inoculation of ChromID Strepto B agar after Todd-Hewitt broth enrichment compared to the use of two routine culture media (i.e., blood agar and colimycin-nalidixic acid agar) (18). However, another recent study of GBS culture methods by El Aila et al for prenatal screening of 100 pregnant women near term found that direct plating of rectovaginal swabs onto ChromID Strepto B agar was more sensitive (95%) than direct Granada medium culture (91%) or Lim broth enrichment and subculture onto Columbia CAN agar (77%) (19).…”

Section: Discussionmentioning

confidence: 99%

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Evaluation of StrepB Select Chromogenic Medium and the Fast-Track Diagnostics Group B Streptococcus (GBS) Real-Time PCR Assay Compared to Routine Culture for Detection of GBS during Antepartum Screening

et al. 2017

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Life-threatening infection in neonates due to group B Streptococcus (GBS) is preventable by screening of near-term pregnant women and treatment at delivery. A total of 295 vaginal-rectal swabs were collected from women attending antepartum clinics in Calgary, Alberta, Canada. GBS colonization was detected by the standard culture method (Strep B Carrot Broth subcultured to blood agar with a neomycin disk) and compared to recovery with Strep Group B Broth (Dalynn Biologicals) subcultured to StrepBSelect chromogenic medium (CM; Bio-Rad Laboratories) and the Fast-Track Diagnostics GBS real-time PCR (quantitative PCR [qPCR]) assay (Phoenix Airmid Biomedical Corp.) performed with broth-enriched samples and the Abbott m2000sp/m2000rt system. A total of 62/295 (21%) women were colonized with GBS; 58 (19.7%) cases were detected by standard culture, while CM and qPCR each found 61 (20.7%) cases. The qPCR and CM were similar in performance, with sensitivities, specificities, and positive and negative predictive values of 98.4 and 98.4%, 99.6 and 99.6%, 98.4 and 98.4%, and 99.6 and 99.6%, respectively, compared to routine culture. Both qPCR and CM would allow more rapid reporting of routine GBS screening results than standard culture. Although the cost per test was similar for standard culture and CM, the routine use of qPCR would cost approximately four times as much as culture-based detection. Laboratories worldwide should consider implementing one of the newer methods for primary GBS testing, depending on the cost limitations of different health care jurisdictions.KEYWORDS chromogenic medium, detection, group B streptococcus, real-time PCR, screening G roup B streptococcus (GBS) is the most common cause of early-onset neonatal sepsis in developed countries (1, 2). Early-onset disease (0 to 6 days of life) is acquired intrapartum from mothers with vaginal-rectal colonization with GBS (1-3). Maternal GBS colonization rates range from approximately 10 to 40% in developed countries, with an estimated rate of 20% in near-term pregnant women in our health care region (2, 4, 5). Studies have shown that intrapartum administration of antibiotics reduces neonatal transmission of GBS, thereby preventing early-onset disease (1, 6, 7). Laboratory detection of GBS colonization status in near-term pregnant women is therefore important for the selective prescription of antibiotic prophylaxis at delivery.Guidelines for the prevention of early-onset neonatal GBS disease have previously been published that recommend universal prenatal culture-based screening of all

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Evaluation of StrepB Select Chromogenic Medium and the Fast-Track Diagnostics Group B Streptococcus (GBS) Real-Time PCR Assay Compared to Routine Culture for Detection of GBS during Antepartum Screening

et al. 2017

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“…On successive days the cervicovaginal vault of each mouse was swabbed with ultrafine calcium alginate-tipped swabs and the recovered bacteria enumerated by serial dilution plating. WT GBS was identified by orange/red pigmentation of colonies on THB medium or on CHROMagar StrepB agar (DRG International Inc.) (35). Duplicate plating of samples on THB medium supplemented with 5% sheep blood allowed further identification of GBS by the presence of beta-hemolysis.…”

Section: Methodsmentioning

confidence: 99%

Serine-Rich Repeat Proteins and Pili Promote Streptococcus agalactiae Colonization of the Vaginal Tract

et al. 2011

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Streptococcus agalactiae (group B streptococcus [GBS]) is a Gram-positive bacterium found in the female rectovaginal tract and is capable of producing severe disease in susceptible hosts, including newborns and pregnant women. The vaginal tract is considered a major reservoir for GBS, and maternal vaginal colonization poses a significant risk to the newborn; however, little is known about the specific bacterial factors that promote GBS colonization and persistence in the female reproductive tract. We have developed in vitro models of GBS interaction with the human female cervicovaginal tract using human vaginal and cervical epithelial cell lines. Analysis of isogenic mutant GBS strains deficient in cell surface organelles such as pili and serine-rich repeat (Srr) proteins shows that these factors contribute to host cell attachment. As Srr proteins are heavily glycosylated, we confirmed that carbohydrate moieties contribute to the effective interaction of Srr-1 with vaginal epithelial cells. Antibody inhibition assays identified keratin 4 as a possible host receptor for Srr-1. Our findings were further substantiated in an in vivo mouse model of GBS vaginal colonization, where mice inoculated with an Srr-1-deficient mutant exhibited decreased GBS vaginal persistence compared to those inoculated with the wild-type (WT) parental strain. Furthermore, competition experiments in mice showed that WT GBS exhibited a significant survival advantage over the ⌬pilA or ⌬srr-1 mutant in the vaginal tract. Our results suggest that these GBS surface proteins contribute to vaginal colonization and may offer new insights into the mechanisms of vaginal niche establishment.Group B streptococcus (GBS) is the leading cause of neonatal meningitis and sepsis in the developed world and also causes serious invasive infections in certain adult populations (54). GBS can be isolated from the rectovaginal tracts of up to 30% of women (16,38), and it can be transmitted to infants during birth through the aspiration of vaginal fluids or cross the placental barrier in utero (7,18). GBS neonatal infection is divided into two categories, early-onset (Ͻ7 days old) and late-onset (7 to 90 days old) disease. Due to the serious nature of GBS infection, pregnant women in the United States are routinely screened for GBS vaginal colonization late in the third trimester of pregnancy; a positive test results in the administration of antibiotics during birth to reduce the risk of GBS transfer to the newborn. Despite this intervention, the incidence of early-onset GBS infection in the United States remains at 1 in 3,000 live births, corresponding to approximately 1,200 infected infants per year (54). There is also evidence that infection rates are much higher among some ethnic groups and in infants delivered at Ͻ37 weeks of gestation (42,43,54,62). Additionally, antibiotic prophylaxis does not prevent late-onset disease.Most women are intermittently asymptomatically colonized by GBS in the genitourinary tract (19); however, colonization poses a significant r...

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“…Considering methods to decrease the GBS detection time, studies have shown that direct plating on colistin-nalidixic agar (CNA) is a low-cost alternative for GBS recovery, albeit with a lower sensitivity that has ranged from 59% to 83% (17-19). In recent years, several commercial chromogenic media, such as Granada medium, CHROMagar StrepB (CA), and chromID Strepto B agar, have been tested for their suitability for detecting GBS (18,20). CA is a commercially available selective chromogenic medium that inhibits most saprophytic bacteria and yeasts and produces mauve-colored GBS colonies under aerobic conditions irrespective of their hemolytic properties, allowing direct visual identification.…”

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confidence: 99%

Evaluation of Trans-Vag Broth, Colistin-Nalidixic Agar, and CHROMagar StrepB for Detection of Group B Streptococcus in Vaginal and Rectal Swabs from Pregnant Women in South Africa

et al. 2013

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d Maternal vaginal colonization with group B streptococcus (GBS) is a major risk factor for invasive GBS infection in newborns.The CDC-recommended method for detecting GBS colonization is to culture vaginal and rectal swabs in a selective broth followed by subculture on blood agar or a selective medium. A high incidence of antimicrobial resistance in the fecal microflora can compromise the recovery of GBS from the selective broth. Here, we compared CHROMagar StrepB (CA), Columbia colistinnalidixic agar (CNA), and Trans-Vag selective broth enrichment for the isolation of GBS from 130 vaginal and 130 rectal swabs from pregnant women. The swabs were randomized for plating first on either CA or CNA, and they then were inoculated in Trans-Vag broth. GBS was cultured from 37.7% of the vaginal swabs and 33.1% of the rectal swabs. There were no differences in the detection rates for the vaginal swabs between CA (31.5%), CNA (26.2%), and the selective broth (30.0%). The sensitivities in relation to a composite score were 83.7%, 69.4%, and 79.6%, respectively. However, recovery of GBS from the rectal swabs was significantly higher from CA (29.2%; P < 0.0001) and CNA (23.8%; P ‫؍‬ 0.002) than from the selective broth (9.2%). The sensitivities were 88.4%, 72.1%, and 27.9%, respectively. The order of plating on the solid medium was significant (P ‫؍‬ 0.003), with GBS detection rates of 30.8% and 24.6% when swabs were plated first and second, respectively. These findings show that a selective broth is not suitable for the recovery of GBS from rectal swabs in settings such as ours, due to masking of the GBS colonies by persistent microflora. Infection by group B streptococcus (GBS) is one of the most common infections in newborns (1). Maternal colonization has been found to be a major risk factor for invasive GBS disease within 6 days of birth. Approximately 10 to 40% of pregnant women are colonized with GBS in either the vagina, the rectum, or both areas (2). The rate of peripartum transmission of GBS to newborns of colonized women is approximately 50%, after which 1 to 2% of these newborns develop invasive GBS infection in the first week of life (3, 4). The Centers for Disease Control and Prevention (CDC) has recommended that all pregnant women be screened for rectovaginal carriage of GBS at 35 to 37 weeks' gestation to identify women who should receive intrapartum antimicrobial prophylaxis (IAP). When successfully implemented, IAP targeted at GBS-colonized pregnant women has reduced the incidence of invasive GBS disease by 86 to 89% (5-7). The sensitivities of screening methods for the identification of maternal carriage of GBS depends on the timing of specimen collection, the source of the specimen, and the culture technique used. Optimally, specimens should be collected as close to delivery as possible. The use of vaginal and rectal swab specimens has been shown to yield higher GBS culture-positivity rates than vaginal swabs alone or cervical specimens (8-10). The current CDC recommendation for the isolation of GBS from v...

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Evaluation of CHROMagar™ StrepB agar, an aerobic chromogenic medium for prepartum vaginal/rectal Group B Streptococcus screening

Cited by 17 publications

References 10 publications

Evaluation of StrepB Select Chromogenic Medium and the Fast-Track Diagnostics Group B Streptococcus (GBS) Real-Time PCR Assay Compared to Routine Culture for Detection of GBS during Antepartum Screening

Evaluation of StrepB Select Chromogenic Medium and the Fast-Track Diagnostics Group B Streptococcus (GBS) Real-Time PCR Assay Compared to Routine Culture for Detection of GBS during Antepartum Screening

Serine-Rich Repeat Proteins and Pili Promote Streptococcus agalactiae Colonization of the Vaginal Tract

Evaluation of Trans-Vag Broth, Colistin-Nalidixic Agar, and CHROMagar StrepB for Detection of Group B Streptococcus in Vaginal and Rectal Swabs from Pregnant Women in South Africa

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