Influence of capsular neuraminic acid on properties of streptococci of serological group B

Abstract

~Neuraminic acid is thought to be a critical virulence factor of group B streptococci. The present study was designed to further characterize a previously described type I11 group B streptococcus and its transposon-mutagenized asialo capsular mutant. The wild-type group B streptococcus grew as short chains with a uniform turbidity and had diffuse colonies in soft agar media. In contrast, the asialo mutant grew in fluid media as a granular sediment, formed significantly longer chains and had compact colonies in soft agar. These differences, possibly related to the surface charge of the bacteria, could also be demonstrated in salt aggregation tests and hexadecane adherence studies. The wild-type group B streptococcus showed hydrophilic, and the asialo mutant hydrophobic surface properties. Removal of neuraminic acid from the wild-type strain changed the surface properties from hydrophilic to hydrophobic. A similar masking effect of capsular neuraminic acid could be observed in adherence and phagocytosis experiments. In contrast to the wild-type strain, the asialo mutant adhered significantly more to buccal epithelial cells and was phagocytosed more by polymorphonuclear leucocytes. These altered properties might possibly be of importance for group B streptococcal pathogenicity.

Chemistry, biochemistry and biology of sialic acids

“…These cells adhered better to a layer of desialylated gangliosides than to the native, negatively charged, species, or after desialylation of the cells. In contrast to the wild-type strain, an asialo mutant obtained by the transposon method showed stronger cell adherence, probably due to the more hydrophobic surface resulting from the lack of sialic acid [915]. After the removal of sialic acids by sialidase, erythrocytes were found to aggregate readily, either without the influence of other compounds or under the influence of immunoglobulins and fibrinogen, respectively.…”

Pheno- and genotypic properties of streptococci of serological group B of canine and feline origin

“…In parallel the bacteria were determined for biochemical properties, for colony morphology in soft agar media [30,21], for pigmentation in GBS Islam agar (Oxoid, Wesel, Germany) supplemented with 50 ml l 31 sterile horse serum [31], for hemagglutinating properties [32], for CAMP reactivity on sheep blood agar in the presence of a L toxin producing S. aureus, for antibiotic resistancies [31], and for hyaluronidase enzyme activity with a decapsulation test using a mucoid growing Staphylococcus equi subsp. zooepdemicus strain [29].…”

“…All these properties had been described for di¡erentiation of human and bovine isolates of this species [1,6,11,13,14,31,39^41]. The relation between the occurrence of polysaccharide or protein antigens and growth properties of the bacteria in £uid medium and soft agar had been investigated with a capsular free group B streptococcal mutant [30] and with group B-streptococcal phase variants [42]. A hemagglutinating adhesin had been described for bovine but not for human group B streptococci [32].…”

Biochemical characterization of different types of adherence of Vibrio species to fish epithelial cells

“…Thus, at least two possible adherence characteristics were observed in our Vibrio isolates. It is possible that vibrios have evolved to possess many types of adhesins to maintain their niche in interacting with the host, as seen in V. cholerae (Sperandio et al, 1995 ;Manning, 1997) and other bacteria such as E. coli (DeGraaf, 1990 ;Hacker, 1990) and group B streptococci (Teti et al, 1987 ;Wibawan et al, 1991Wibawan et al, , 1992. Expression of different adherences may be dependent on the different environmental conditions as well as the host-cell receptors.…”