Evaluation of Methods To Increase the Sensitivity and Timeliness of Detection of
            <i>Streptococcus agalactiae</i>
            in Pregnant Women

Overman, Sue B.; Eley, Douglas D.; Jacobs, Barry E.; Ribes, Julie A.

doi:10.1128/jcm.40.11.4329-4331.2002

Cited by 38 publications

(29 citation statements)

References 17 publications

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“…In the two references cited to support this claim (3,7), it is acknowledged that the batches of Granada agar used were probably spoiled (10). Moreover, the flurry of references (1,2,4,6,8,9,14,15) that support a very good sensitivity of Granada agar to detect GBS are not mentioned.…”

Section: Liquid Granada Medium For Detection Of Group B Streptococcimentioning

confidence: 92%

Liquid Granada Medium for Detection of Group B Streptococci

Rosa-Fraile

Camacho-Muñoz

2005

J Clin Microbiol

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Heelan et al. (5) recently presented data on the sensitivity of a liquid Granada medium (9) (GBS broth) for detection of Streptococcus agalactiae. We have tested this medium, and it contains, as Granada medium, starch, proteose peptone 3, methotrexate, a Good's buffer, serum, glucose, and selective agents. So, we agree with the authors that detection of orangered colonies in GBS broth is 100% specific for the presence of beta-hemolytic group B streptococci (GBS). Nevertheless, some statements in this paper need clarification.The authors claim that sometimes Granada agar lacks sensitivity for GBS detection, but no comparison between GBS broth and Granada agar is reported. In the two references cited to support this claim (3, 7), it is acknowledged that the batches of Granada agar used were probably spoiled (10). Moreover, the flurry of references (1,2,4,6,8,9,14,15) that support a very good sensitivity of Granada agar to detect GBS are not mentioned.Regarding sensitivity of GBS broth, the figures reported are somewhat confusing. One-hundred fifty-eight GBS strains were recovered from 580 swabs, but only in 108 cases were red colonies detected, so GBS broth sensitivity is 68.3% instead of the 87.8% or 90.3% reported. GBS pigment was not observed in 35 tubes that later (after subculture) proved to be positive (25% of all positives), and this figure makes the usefulness of this medium for direct GBS detection doubtful. When (study 1) GBS broth was used as a detection medium, 9 of 75 GBS strains (12%) were completely lost (positive in subculture from LIM broth but negative in subculture from GBS broth). When (study 2) GBS broth was used as a detection and transport medium, 6 of 83 GBS (7%) were also completely lost. This failure to detect (even after subculture) some GBS-positive vaginorectal samples can be an important drawback of GBS broth. Another fact is the dramatic failure of LIM broth to recover GBS (21 of 83 positive samples were lost in study 2) found in Heelan's work. This finding needs further evaluation, as enrichment in LIM broth is an accepted procedure for GBS detection in the Centers for Disease Control and Prevention guidelines (13).Poor performance in detecting GBS could be explained by the fact that when liquid Granada media are kept refrigerated the starch precipitates (retrogradation) (16), producing an opaque white mass, where GBS colonies are sometimes barely noticeable. However, if not kept refrigerated the medium deteriorates in a few days (12). We have observed that when media containing folate antagonists (as methotretaxate) are used as transport media and swabs are kept in these media for several hours before starting incubation, the number of GBS CFU nosedives. This renders the use of such media as transport media unsafe. For these reasons, in our view, the use of liquid selective Granada media as transport media for detection of GBS colonization in pregnant women cannot be recommended.

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Section: Liquid Granada Medium For Detection Of Group B Streptococcimentioning

confidence: 92%

Liquid Granada Medium for Detection of Group B Streptococci

Rosa-Fraile

Camacho-Muñoz

2005

J Clin Microbiol

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“…Granada medium has long been used in Europe to detect GBS in pregnant women. Strains of beta-hemolytic GBS produce a carotenoid pigment, visible as an orange color, in this medium, usually within 24 h. Variable results on the sensitivity of this medium have been reported, with some investigators considering it to be unacceptably low (4,5). A new, improved enrichment broth, modified from the original Granada medium, called GBS broth, is now also available (7).…”

mentioning

confidence: 99%

Evaluation of a New Selective Enrichment Broth for Detection of Group B Streptococci in Pregnant Women

et al. 2005

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Studies at two Brown Medical School-affiliated hospitals were undertaken to evaluate a new selective broth medium (GBS broth) and to compare it to the LIM broth currently used to culture for group B streptococci. Beta-hemolytic group B streptococci produce a carotenoid pigment that turns GBS broth an orange color. From a total of 580 pregnant women, duplicate vaginal-rectal swabs were collected at 35 to 37 weeks of gestation and cultured for group B streptococci, using either LIM broth (a selective broth containing antibiotics) or GBS broth for enrichment. Specimens were either transported to the laboratory or immediately placed in the respective enrichment broths and delivered to the laboratory. GBS broth medium had sensitivity, specificity, and positive and negative predictive values of 87.8, 100, 100, and 95.1% when planted in the laboratory and 90.3, 100, 100 and 97.6%, respectively, when inoculated at bedside. Use of GBS broth would satisfy Centers for Disease Control and Prevention requirements and would provide faster, more-sensitive, and cost-effective detection of group B streptococci in pregnant women.Group B streptococci (GBS) cause serious, life-threatening infections in the newborn. Mortality of GBS sepsis in neonates may exceed 50%, and preterm infants are especially at risk. Intrapartum prophylaxis for pregnant women colonized with GBS has been recommended for several years, since clinical trials showed that the administration of antibiotics to women in labor had a drastic effect in reducing early-onset invasive GBS infection in the neonate (1). Centers for Disease Control and Prevention guidelines issued in 2002 (2, 3) recommend that all pregnant women be screened for vaginal-rectal colonization with GBS at 35 to 37 weeks of gestation. These new guidelines for predelivery testing of pregnant women may have a significant impact on clinical microbiology laboratories, which may expect to see an increase in the volume of test requests for GBS screening for pregnant women. The recommended method for detecting carriage of GBS in pregnant women is to use a selective enrichment broth medium with subsequent subculture on a sheep blood agar plate (BAP) (3). Some laboratories inoculate a BAP before placing the swab in the enrichment broth. The enrichment broth is subcultured only if the primary BAP is negative. A more rapid, less labor-intensive, and more cost-effective method than the traditional culture is needed to screen patients for GBS colonization. Granada medium has long been used in Europe to detect GBS in pregnant women. Strains of beta-hemolytic GBS produce a carotenoid pigment, visible as an orange color, in this medium, usually within 24 h. Variable results on the sensitivity of this medium have been reported, with some investigators considering it to be unacceptably low (4, 5). A new, improved enrichment broth, modified from the original Granada medium, called GBS broth, is now also available (7). This medium has the advantage of reducing both incubation and technical time. Our studies were un...

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“…In their recent article Overman et al (5) present data on the sensitivity of Granada agar (7). These data are similar to those presented by the same authors in a poster with the same title (D. D. Eley, S. B. Overman, B. E. Jacobs, and J.…”

Section: Granada Agar Sensitivity and Detection Of Group B Streptococcusmentioning

confidence: 99%

Granada Agar Sensitivity and Detection of Group B Streptococcus

Rosa-Fraile

2003

J Clin Microbiol

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Evaluation of Methods To Increase the Sensitivity and Timeliness of Detection of Streptococcus agalactiae in Pregnant Women

Cited by 38 publications

References 17 publications

Liquid Granada Medium for Detection of Group B Streptococci

Liquid Granada Medium for Detection of Group B Streptococci

Evaluation of a New Selective Enrichment Broth for Detection of Group B Streptococci in Pregnant Women

Granada Agar Sensitivity and Detection of Group B Streptococcus

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