Prevalence, serotypes and virulence genes of Streptococcus agalactiae isolated from pregnant women with 35-37 weeks of gestation.

BACKGROUND: In pregnant women Streptococcus agalactiae (GBS) can be transmitted to newborn causing severe infections. It is classified into 10 serotypes (Ia, Ib, II-IX). The severity of neonatal disease is determined by the capsular serotype and virulence factors such as the polysaccharide capsule, encoded by the cps gene, protein C, which includes the Cα surface proteins (bca gene), Rib (rib gene) and Cß (bac gene); the proteins Lmb (lmb gene), FbsB (fbsB gene), FbsA (fbsA gene), the cyl operon encoding a ß-hemolysin (hylB gene), the CAMP factor (cfb gene) and the C5a peptidase (scpB gene). The aim of this work was to determine the degree of GBS colonization in pregnant women, the serotypes distribution and to investigate virulence-associated genes. METHODS: We worked with 3480 samples of vagino-rectal swabs of women with 35-37 weeks of gestation. The identification of the strains was carried out using conventional biochemical tests and group confirmatory serology using a commercial latex particle agglutination kit. Two hundred GBS strains were selected. Their serotype was determined by agglutination tests. The monoplex PCR technique was used to investigate nine virulence-associated genes (cps, bca, rib, bac, lmb, fbsB, fbsA, hylB and scpB). RESULTS: The maternal colonization was 9.09%. The serotypes found were: Ia (33.50%), III (19.00%), Ib (15.50%), II (14.00%), V (7.00%) and IX (5.50%). 5.50% of strains were found to be non-serotypeable (NT). The nine virulence genes investigated were detected simultaneously in 36.50% of the strains. The genes that were most frequently detected were scpB (100.00%), fbsA (100.00%), fbsB (100.00%), cylB (95.00%), lmb (94.00%) and bca (87.50%). We found associations between serotype and genes bac (p = 0.003), cylB (p = 0.02), rib (p = 0.01) and lmb (p < 0.001). CONCLUSIONS: The frequency of vaginal-rectal colonization, serotypes distribution and associated virulence genes, varies widely among geographical areas. Therefore, epidemiological surveillance is necessary to provide data to guide decision-making and planning of prevention and control strategies.

Isolation and selection of endophytic spore-forming bacteria with plant growth promoting properties isolated from Ilex paraguariensis St. Hil. (yerba mate).

Yerba mate (Ilex paraguariensis St. Hil.) is a species native to the subtropical regions of South America. Despite being an important crop for the region, there are few studies on the use of microorganisms to improve the growth of seedlings in the nursery stage. The objective of this study was to isolate spore-forming endophytic bacteria with plant growth promoting properties associated with yerba mate seedlings and determine their phytobeneficial effect under controlled laboratory conditions. Isolates were selected based on their sporulation capacity and evaluated for in vitro plant growth promoting properties (nitrogen fixation, phosphate solubilization, production of siderophores and synthesis of indolic compounds). Yerba mate seedlings were inoculated with the most promising isolates, which were identified via analyses of the sequence of their 16S rDNA gene as Bacillus circulans (12RS3) and Bacillus altitudinis (19RS3, T5S-T4). After 120 days plants showed higher root dry weight when inoculated with isolate 19RS3 and higher shoot dry weight with 19RS3 and T5S-T4. In conclusion, further studies to determine the ability of these isolates to adapt to the climatic conditions and to survive amidst the native soil microflora in yerba mate cultivated native soils, will be crucial for developing such strains as biofertilizer.