Caries experience and quantification of Streptococcus mutans and Streptococcus sobrinus in saliva of Sudanese schoolchildren.

Streptococcus mutans and Streptococcus sobrinus are among the most commonly isolated bacterial species implicated as etiological agents of dental caries. Details of the composition of the oral microflora related to dental caries should aid in assessing the prevalence and risk of disease at an individual level. The aim of the present study was to determine the presence and relative amounts of S. mutans and S. sobrinus in the saliva samples obtained from schoolchildren in Khartoum State, the Sudan, and to study the association of the amounts of S. mutans and S. sobrinus with caries experience, socioeconomic status and sugar-sweetened snacks in this population. 140 samples, 30 of which were from individuals with caries experience, were examined using quantitative real-time polymerase chain reaction (qRT-PCR) with specific oligonucleotide primers. The mean ratio of fold differences of S. mutans to S. sobrinus was 0.77 (SD 5.4) and 2.29 (SD 6.0) for samples obtained from caries-free and caries-active individuals, respectively. This suggested that the proportion of S. sobrinus was higher than S.mutans in the caries-active group when compared to the caries-free group. An association was found between children with caries-active lesions and the frequent consumption of sticky desserts and higher socioeconomic status. S. sobrinus seems to be associated with caries experience in the studied population. A proposal of caries screening programs designed to test for S. sobrinus in this population may be developed.