Clonal diversity of Streptococcus mitis biovar 1 isolates from the oral cavity of human neonates

Abstract

The clonal diversity of 101 isolates of the pioneer bacterium Streptococcus mitis biovar 1 obtained from the oral cavities of 40 human neonates 1 to 3 days, 2 weeks, and 1 month postpartum was examined by using rRNA gene restriction patterns. There was a high degree of genetic diversity, with the 101 isolates comprising 93 unique PvuII ribotypes. There were eight identical pairs of ribotype patterns, and seven of the eight pairs were obtained from individual neonates. Only one identical pair comprised isolates obtained from different neonates. In all but two cases, isolates with matching ribotypes were obtained at one visit. Two pairs of isolates with matching ribotype patterns were obtained from neonates on successive visits. The ribotype patterns of the isolates were examined by cluster analysis. The isolates forming each cluster were very similar, yet each cluster was well separated from its neighbors. When several isolates were obtained from individual neonates at a particular visit, in some instances they were contained in a single cluster, whereas in other cases each isolate was contained in a separate cluster. Isolates obtained from individual neonates on successive visits tended to be contained in different clusters. This high degree of diversity, which has been observed in other mucosal commensal bacteria, may serve as a mechanism for avoiding immune elimination of these bacteria.

Macrorestriction Fingerprinting of “Streptococcus milleri” Group Bacteria by Pulsed-Field Gel Electrophoresis

“…In each case strains with identical pulsotypes were isolated between two and three times over a 12-month period. These findings confirm the reported stability of other species within the endogenous oral microflora (6).…”

“…The ability to generate genotypic and hence phenotypic variety within bacterial populations is essential for the colonization or survival of the pathogen within the host and, in fact, is the driving force of microbial evolution (11,28). Moreover, it has been suggested that a high degree of genetic diversity is a useful mechanism for avoidance of immune elimination of such bacteria (6). Although, in theory, a number of genetic events can affect the fingerprint profiles (8,13,22,31), the factors contributing to the heterogeneity of RFLPs revealed by MF have not been studied extensively.…”

Oral colonization by anaerobic bacteria during childhood: role in health and disease

“…The clonal heterogeneity among pioneer commensals, such as Streptococcus mitis biovar 1, seems to be very high (Hohwy and Kilian, 1995;Fitzsimmons et al, 1996). In line with that, among an early colonizing anaerobic commensal species, P. melaninogenica (Könönen et al, 1992a(Könönen et al, , 1999c, 101 different ribotypes were found in 11 mother-child pairs and up to seven simultaneous clones could be recovered from an individual (Könönen et al, 1994b).…”

Identification of oral mitis group streptococci by arbitrarily primed polymerase chain reaction

“…The distribution of those species varies between oral sites. Each may appear at different times in plaque development, and multiple strains may be present in the same mouth (19,20,46,49).…”