CHARACTERIZATION AND TRANSMISSION OF
GROUP B STREPTOCOCCI BY MOLECULAR BIOLOGIC METHODS
Shen AD, Si Y, Yang Y H
Department of Microbiology, Beijing Children¡¯s
Hospital, China
Objective: To investigate the
characteristics of GBS infection in Beijing, to explore the transmission of
GBS infection in neonates.
Materials and methods: Experiments
were carried out to characterize GBS strains by randomly amplified
polymorphic DNA analysis (RAPD) and to Study on transmission of GBS
infection in neonates by serotyping, RAPD, hybridization which have been
performed on using as probes representing the genes scpB, glnA, scaA, alpha (bca), beta (bac). 109 GBS strains
were analyzed by two primers, named OPS11 and OPS16; 85 and 14 GBS strains
isolated from vaginas of pregnant women in Beijing and St. Petersburg of
Russia, respectively. 10 GBS strains were isolated from invasive GBS
infection patients in Orebro of Sweden. 7of 85 Strains were mother-baby
pairs with early and late onset infection.
Results: Type ability of RAPD was
100 %, discrimination index was 93.7% and 96.7%, respectively. Dendrogram
analysis created 5 clusters. All strains isolated in infected patient in
Beijing were clustered in A group, which was composed of a & b lineage.
The Sweden invasive GBS strains were clustered in C and A group. The
carrier strains are clustered in a lineage and in B, D, E group. In the two
cases, the strains of each mother-baby pair produced identical serotype
(III/R). Genes (including alpha and beta genes negative, scaA 2kb, glnA 6.5kb, scpB 2.6kb)
in the case of early-onset infection, the strains of mother-baby pair have
the identical. In the late-onset infection, the strains of mother-baby pair
produced different RAPD pattern, GBS strains isolated from blood and CSF of
the same patient have the identical RAPD pattern.
Conclusion: The result showed that
RAPD genotyping is suitable for studies on epidemiological of GBS infection
with high type ability, discrimination power, rapidness, simplicity. It is
suspected that the cluster A, especially b lineage is a high virulence
clone in Beijing region, and C group is an additional virulence clone in
Orebro, Sweden. These data also exhibit the mother-baby vertical
transmission in early-onset and cross transmission in late-onset.