Application of the appropriate molecular biology-based method significantly increases the sensitivity of group B streptococcus detection results

Abstract

Background: Streptococcus agalactiae (group B streptococcus: GBS) is a leading cause of early-and late-onset diseases in neonates. Reliable results of GBS carriage investigation among pregnant women may decrease the incidence of neonatal infection and mortality. Aim: To compare the results of conventional culture investigation with those of the US Food and Drug Administration-approved nucleic acid amplification test (BD Max GBS (Becton Dickinson)), and to establish our own protocols of standard polymerase chain reaction (PCR). Methods: A total of 250 vaginalerectal swabs from three different hospitals in Bydgoszcz, Poland, were used to evaluate GBS carriage. Standard laboratory technique (overnight culture in broth enrichment media) results were compared with those of BD Max GBS assay (Becton Dickinson) and two standard PCR protocols, established to detect the cfb and 16S rRNA S. agalactiae genes, from the overnight cultures of the samples in the liquid enrichment media. Findings: The overall GBS carriage was estimated as 16.4e23.2%, depending on the applied detection method. The highest percentage of positive results, from each laboratory was obtained with the application of BD Max GBS assay. The differences in the number of positive results obtained with this particular method were statistically significant. Overall, 27 discrepancies were noted for the results obtained with the application of the methods compared. Conclusions: The methods applied for GBS detection differ in sensitivity. A culture technique, though very specific, appears to be less sensitive at detecting S. agalactiae compared with the commercially available BD Max GBS assay or in-house PCR protocols established for this purpose.

An Application of Real-Time PCR and CDC Protocol May Significantly Reduce the Incidence of Streptococcus agalactiae Infections among Neonates

“…They usually involve real-time PCR, either "in house" assays, dedicated to a number of PCR devices or molecular platforms. All of them differ in sensitivity and specificity of the results [1,[31][32][33][34][35][36][37][38][39][40][41][42][43].…”

“…Moreover, due to abundance of other growing bacteria, beta hemolysis of the blood-supplemented medium may not be noticeable, which can additionally lead to false negative results [21]. Other reasons for a limited culture method sensitivity might be the low number of streptococcal cells in the swab, due to an improper sample collection, a reduced viability of the GBS and inappropriate sampling or material transporting [39]. Surprisingly, the differences in a prevalence of a GBS carriage may also result from the manner of swab collection.…”

Analysis of molecular characteristics of CAMP-negative Streptococcus agalactiae strains

“…Research indicates that approximately 11 to 35% of pregnant women are colonized by GBS in the vagina or rectum. ( Russell et al, 2017 ; Bogiel et al, 2021 ). GBS is the primary pathogen responsible for neonatal infections, with mother-to-child transmission being the predominant mode of infection.…”