Evaluation of a new chromogenic agar medium for isolation and identification of Group B streptococci

Perry, John D.; Oliver, Michelle; Nicholson, A.; Wright, Joyce; Gould, F.K.

doi:10.1111/j.1472-765x.2006.02023.x

Cited by 17 publications

(9 citation statements)

References 5 publications

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“…We compared i) rectovaginal, vaginal and rectal sampling, and ii) culture on Columbia CNA agar (CNA), on group B streptococcus differential agar (GBSDA) and on Chromogenic Strepto B ID Agar (CA), iii) directly and after Lim broth enrichment. Other groups studying chromogenic agar did so only for vaginal samples [18-20,22], whereas we also included the CDC recommended rectovaginal sampling method, or they did not compare to Granada agar and used miscellaneous samples [23]. …”

Section: Discussionmentioning

confidence: 99%

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Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women

et al. 2010

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BackgroundStreptococcus agalactiae (group B streptococcus; GBS) is a significant cause of perinatal and neonatal infections worldwide. To detect GBS colonization in pregnant women, the CDC recommends isolation of the bacterium from vaginal and anorectal swab samples by growth in a selective enrichment medium, such as Lim broth (Todd-Hewitt broth supplemented with selective antibiotics), followed by subculture on sheep blood agar. However, this procedure may require 48 h to complete. We compared different sampling and culture techniques for the detection of GBS.MethodsA total of 300 swabs was taken from 100 pregnant women at 35-37 weeks of gestation. For each subject, one rectovaginal, one vaginal and one rectal ESwab were collected. Plating onto Columbia CNA agar (CNA), group B streptococcus differential agar (GBSDA) (Granada Medium) and chromID Strepto B agar (CA), with and without Lim broth enrichment, were compared. The isolates were confirmed as S. agalactiae using the CAMP test on blood agar and by molecular identification with tDNA-PCR or by 16S rRNA gene sequence determination.ResultsThe overall GBS colonization rate was 22%. GBS positivity for rectovaginal sampling (100%) was significantly higher than detection on the basis of vaginal sampling (50%), but not significantly higher than for rectal sampling (82%). Direct plating of the rectovaginal swab on CNA, GBSDA and CA resulted in detection of 59, 91 and 95% of the carriers, respectively, whereas subculturing of Lim broth yielded 77, 95 and 100% positivity, respectively. Lim broth enrichment enabled the detection of only one additional GBS positive subject. There was no significant difference between GBSDA and CA, whereas both were more sensitive than CNA. Direct culture onto GBSDA or CA (91 and 95%) detected more carriers than Lim broth enrichment and subculture onto CNA (77%). One false negative isolate was observed on GBSDA, and three false positives on CA.ConclusionsIn conclusion, rectovaginal sampling increased the number GBS positive women detected, compared to vaginal and/or rectal sampling. Direct plating on CA and/or GBSDA provided rapid detection of GBS that was at least as sensitive and specific as the CDC recommended method of Lim broth subcultured onto non chromogenic agar.

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Section: Discussionmentioning

confidence: 99%

“…Most other bacterial species are either inhibited or the colonies produced have a different colour (e.g. violet, blue, colourless) [18-20]. …”

Section: Introductionmentioning

confidence: 99%

Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women

et al. 2010

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“…GBS culture in the microbiology laboratory GBS detection by culture was carried out by inoculating in Todd-Hewitt broth supplemented with antibiotics (TODD H-T, BioMérieux, Marcy l'Etoile, France) and then subculture on selective chromogenic agar (ChromID Strepto B Agar, BioMérieux) at 35°C for 24 h [25]. Identification of suspect colonies was further confirmed by a streptococcal agglutination test (Slidex strepto Plus, BioMérieux) to ensure specific identification of GBS.…”

Section: Sample Collectionmentioning

confidence: 99%

Intrapartum Group B streptococcus detection by rapid polymerase chain reaction assay for the prevention of neonatal sepsis

Tejada

Pfister

Renzi

et al. 2011

Clinical Microbiology and Infection

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Group B streptococcus (GBS) is a leading cause of infectious neonatal morbidity and mortality. Timely and accurate identification of colonized mothers is imperative so that antibioprophylaxis can be implemented during labour to reduce the risk of neonatal sepsis. We planned our study to analyse the diagnostic accuracy of an intrapartum PCR assay to identify GBS-colonized women and to allow the implementation of correct (i.e. at least 4 h) intrapartum antibiotic prophylaxis based on the PCR results. We included 695 women in labour who were tested for rectovaginal GBS carriage by culture and PCR. Women were also screened at 35-37 weeks of gestation. Intrapartum GBS colonization was 19.3%. Assay sensitivity was 81.0% for antenatal culture and 85.0% for intrapartum PCR; p 0.72. GBS colonization (n = 107) was known at least 4 h before delivery in 68 (64%) and 73 (68%) women based on antenatal culture and intrapartum PCR, respectively. Among 43 women delivering preterm, correct status was known at least 4 h before delivery in 10 (23%) and 32 (74%) women according to antenatal culture and intrapartum PCR, respectively. These results support the concept that GBS screening can be performed routinely during labour in a clinical setting. The intrapartum approach is at least as accurate as the antenatal screening, with the additional advantage of identifying women delivering preterm or not followed during pregnancy.

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“…1). In a study with 134 vaginal swabs Strepto B ID was shown to have a higher specificity and sensitivity than blood agar for detection of S. agalactiae (Perry et al. 2006).…”

Section: Detection Of Streptococcus Agalactiaementioning

confidence: 99%

The application of chromogenic media in clinical microbiology

Perry

Freydière

2007

Journal of Applied Microbiology

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105

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Summary Since 1990, a wide range of chromogenic culture media has been made commercially available providing useful tools for diagnostic clinical microbiology. By the inclusion of chromogenic enzyme substrates targeting microbial enzymes, such media are able to target pathogens with high specificity. Examples of target pathogens include Staphylococcus aureus, Streptococcus agalactiae, Salmonella spp. and Candida spp. The inclusion of multiple chromogenic substrates into culture media facilitates the differentiation of polymicrobial cultures, thus allowing for the development of improved media for diagnosis of urinary tract infections and media for the enhanced discrimination of yeasts. The purpose of this review is to provide some insight into how such media work and appraise their utility in routine clinical diagnostics, in comparison with conventional media.

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Evaluation of a new chromogenic agar medium for isolation and identification of Group B streptococci

Cited by 17 publications

References 5 publications

Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women

Comparison of different sampling techniques and of different culture methods for detection of group B streptococcus carriage in pregnant women

Intrapartum Group B streptococcus detection by rapid polymerase chain reaction assay for the prevention of neonatal sepsis

The application of chromogenic media in clinical microbiology

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