Técnica de filtragem em membrana para avaliação quantitativa da aglutinação de linhagens de E. Coli em mananoligossacarídeo

Abstract

The objective of this study was to standardize a quantitative technique to evaluate the in vitro capacity of agglutination of different mannanoligosaccharides (MOS) to the strain of Escherichia coli isolated from cases of infantile diarrhea in children from 0 to 5 years of age. The research for the expression of fimbria Type 1 present in the isolates was performed by the microhemoagglutination test. For the oligosaccharide agglutination assays three MOS markers were extracted from S. cerevisae, groups 1, 2 and 3, filtered through a microfilter, later diluted for surface sowing in chromogenic Agar E. coli. For microscopic evaluation of binder capacity of the MOS were subjected to slide agglutination tests. In order to estimate the total bacterial count (CBT), the counts of the three-plate set were calculated. Assumptions of homogeneity of variances and normality of data were validated, respectively, by the Levene and Shapiro-Wilk test. Homozygous variables were compared by analysis of variance in one way (ANOVA one-way), with contrasts by the Tukey method. Heterocedastic variables were compared with one-way ANOVA with application of the Welche contrast contrasts by the Games-Howell method. Correlations between CBTs, Titres hemagglutinants, diameters and areas of the globules were evaluated by the Pearson correlation test. All analyzes were conducted in software R, considering probability of error type 1 = 5% Of the 30 strains tested, 25 (83.3%) expressed hemagglutinating capacity with titers ranging from 1: 4 to 1: 16. The results suggest that the MOS showed effective action on the agglutination of the bacteria, since the estimates of CBTs of the strains treated with MOS were inferior the counts of the pure sample. The degree of agglutination may vary according to the composition of the MOS, since product 1 showed higher CBTs than the others, indicating that the agglutinated beads were not able to retain bacteria in the pores of the filters similarly to products 2 and 3. It was observed significant correlation between mannose-sensitive haemagglutination and MOS agglutination for products 1 and 2, suggesting that the intensity of bacterial agglutination may be related to the expression of type 1 fimbriae. It is concluded that the filtration and culture technique can be used to evaluate different degrees of agglutination of MOS products and the amount of bacteria retained in the filters appears to be more related to the expression of mano-sensitive type 1 fimbriae than to the sizes of the globules produced.