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

Abstract

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

Automated Detection of Streptococcus pyogenes Pharyngitis by Use of Colorex Strep A CHROMagar and WASPLab Artificial Intelligence Chromogenic Detection Module Software

“…The Colorex Strep A agar also showed much better overall performance (whether read by a technologist or by the software), compared to routine cultures plated on BAPs, with or without the use of a bacitracin disk, to facilitate screening for GAS. Our findings are consistent with a previous study that reported superior performance of chromogenic agar and PCR, compared to routine culture, for recovering group B Streptococcus (13). In addition, our previous study on the Lyra PCR assay detected GAS in an additional 26 specimens that were culture negative (10).…”

Group B streptococcal colonization: Prevalence and impact of smoking in women delivering term or near term neonates in a large tertiary care hospital in the southern United States

“…The lowest rates were observed mainly in some East Asian nations [6,12,13]. The across-country differences may be due to differences in techniques [23][24][25][26][27][28][29][30][31][32][33][34][35]. PCR testing after broth enrichment has been has been shown to be a reliable and is now the standard method for GBS testing [24].…”

“…PCR testing after broth enrichment has been has been shown to be a reliable and is now the standard method for GBS testing [24]. However, testing conducted intrapartum may show somewhat lower prevalence rates as compared to antepartum testing [25]. If this is so, then there may be excessive use of intrapartum prophylactic antibiotics to prevent GBS [25].…”

“…However, testing conducted intrapartum may show somewhat lower prevalence rates as compared to antepartum testing [25]. If this is so, then there may be excessive use of intrapartum prophylactic antibiotics to prevent GBS [25]. In spite of the dramatic drop of early onset neonatal GBS sepsis in the United States, the reasons for the persisting high prevalence rates of GBS colonization during pregnancy throughout the past 4 decades need to be further explored.…”

Microbial burden and inflammasome activation in amniotic fluid of patients with preterm prelabor rupture of membranes

“…Clinically, this delay in obtaining culture results has led to the standard practice of administering broad-spectrum antibiotics to patients presenting with inflammation without knowing the specific microorganisms present [168][169][170][171]. Recently, the use of advanced molecular microbiological PCR-based techniques was proposed as a solution to these problems [23], as such methods can identify a greater number of microorganisms, including those which may be difficult to culture [78, 139-145, 147-154, 172-174], and the results can be rapidly obtained [23,[175][176][177][178][179][180][181]. Molecular microbiological techniques can also rule out false positives obtained by conventional culture likely due to contamination [126].…”