Caries and genetic variability of streptococcus mutans / Caries y variabilidad genética de streptococcus mutans

In the last two decades, the increase in population genetics studies has contributed to elucidating important questions about the evolution of the pathogenesis of bacteria of clinical interest. The objective of this study is to revise and update the knowledge of the last fifteen years regarding the genetic variability of Streptococcus mutans and their association with dental caries. Streptococcus mutans, one of the most widely distributed bacteria in the world, are heavily associated with this condition. This research shows the results of numerous studies carried out in various countries that, using molecular and biochemical methods, revealed associations between different serotypes and caries activity. In addition, it is reported that the population genetics structure of Streptococcus mutans in Argentina is highly recombinant, which reflects the largest waves of human immigration that occurred in the 19th and 20th centuries. On the other hand, demographic analysis suggests that these bacteria experienced a population expansion that coincided with the beginning of agricultural development.

En las últimas dos décadas el incremento de los estudios de genética de poblaciones ha contribuido a dilucidar cuestiones importantes sobre la evolución de la patogénesis de bacterias de interés clínico. El objetivo de este trabajo es realizar una actualización sobre los conocimientos de los últimos quince años referidos a la variabilidad genética de Streptococcus mutans y su relación con la caries dental. Streptococcus mutans, de amplia distribución mundial, es una de las bacterias más fuertemente asociada a dicha enfermedad. En este trabajo se muestran resultados de numerosos estudios realizados en diferentes países que utilizando métodos moleculares y bioquímicos revelaron asociaciones entre diferentes serotipos y la actividad de caries. Además, se reporta que la estructura genética poblacional de Streptococcus mutans de Argentina es de alto nivel recombinante, lo que reflejaría las grandes oleadas inmigratorias humanas ocurridas en los siglos 19thy 20th. Por otra parte, los análisis demográficos sugieren que esta bacteria experimentó una expansión poblacional coincidente con el comienzo del desarrollo de la agricultura

Initial acquisition and genetic identity of Streptococcus mutans of mother-child Pairs.

PURPOSE: This study's purpose was to investigate the transmission and genetic identity of Streptococcus mutans strains in mother-child pairs from Cordoba, Argentina in order to establish whether the mother was the main source of infection of the child. METHODS: Seventeen mother-child pairs were analyzed, with samples taken of whole nonstimulated saliva and dental plaque when each child was 18 months old. The mothers gave their written, informed consent to participate in the study. The Streptococcus mutans strains were genotyped by the arbitrarily primed polymerase chain reaction (AP-PCR) technique using primers OPA-02, OPA-05, and OPA-13. Three statistical analyses were used to determine genetic identity (1) Dice similarity index, (2) principal coordinates analysis/minimum spanning tree (PCoA/MST) analysis, and (3) Neighbor-joining consensus tree. RESULTS: The AP-PCR technique showed high genetic polymorphism in the S mutans strains. According to the Dice index, 10 of the 17 pairs presented genetic identity. Results from the PCoA/MST analysis and the Neighbor-joining consensus tree showed that 7 pairs presented high similarity and the other 3 showed moderate levels of similarity CONCLUSIONS: According to the results obtained with 3 primers and with 3 different statistical methods, we could determine that the mothers are an important source of infection for the child at an early age.

Early acquisition of Streptococcus mutans for children.

Existing evidence reveals that in Early Oral Infection the main route of transmission of Streptococcus mutans is mother-child saliva contacts and that initial acquisition takes place during a specific period of time denominated "Window of Infectivity" that lapses between 6 and 30 months of the child's life, with a higher risk between 18 and 30 months of age. The aim of the present study was to analyze Early Oral Infection. The levels of Streptococcus mutans in saliva and bacterial plaque in the binomial mother-child 6 to 18 months after childbirth were evaluated. Twenty-four mother-child binomials that attended the University Hospital of Maternity and Neonatology of Córdoba participated in the study. Samples of saliva and dental plaque were taken from mother and child and seeded in selective Agar Mitis Salivarius Bacitracin medium (0.28 mg/ml) and cultured for 48 hours at 37 degrees C and in 5% CO2 to allow for the growth of Streptococcus mutans. The colonies were identified morphologically and biochemically. At 6 months after childbirth: 58.33% of the samples of the mother's saliva were positive, while the presence of the microorganism was not detected in 100% of the samples of the infants' saliva. At 18 months of after childbirth: 79.16% of the samples of saliva and 100% of the samples of the mothers' dental plaque were positive, whereas the samples of saliva and dental plaque of the infants were positive for Streptococcus mutans in 20.83% and 70.83% of the cases respectively. The initial acquisition of Streptococcus mutans would have occurred in 20.8% of the children at the age of 18 months. Eruption of primary molars occurs at this age.