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Brazilian Journal of Microbiology
On-line version ISSN 1678-4405
MOREIRA, Mônica; VICENTE, Vânia Aparecida and GLIENKE, Chirlei. Genetic variability of Streptococcus mutans isolated from low-income families, as shown by RAPD markers. Braz. J. Microbiol. [online]. 2007, vol.38, n.4, pp. 729-735. ISSN 1678-4405. http://dx.doi.org/10.1590/S1517-83822007000400026.
The detection of Streptococcus mutans isolates with high genetic variability in different individuals indicates the occurrence of transmissibility. In this context, nine low-income families (40 individuals in total) with similar social conditions were assessed to identify the bioserotypes of S. mutans using both biochemical and RAPD markers and to establish the degree of similarity among the intra-familial isolates. The polymorphism analysis used the coefficient of Jaccard in both a Principal Coordinates Analysis (PCO) and in a UPGMA clustering method. A total of 157 isolates were obtained from salivary samples, using the morphology of colonies recovered using MSB agar as indicators. From those, 64 were characterized biochemically as S. mutans and 10 as S. sombrinus. Genetic variability among isolates based on RAPD markers was not consistent with their intra-familial distribution. In particular, some individuals might have experienced multiple infections given the high genetic variability among their isolates. The occurrence of 4 isolates with 100% genetic similarity is indicative of intra-familial transmission.
Keywords : Streptococcus mutans; genetic variability; RAPD.