Determination of Salivary Streptococcus mutans Level in a Stable Sucrose-Sulphasomidine-Containing Broth

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Abstract
A method for the determination of the level of Streptococcus mutans in saliva samples was developed. The method was a modification of a previously described technique based on the ability of this microorganism to adhere to the walls of test tubes when growing in a selective sucrose-containing medium. An aliquot of the saliva samples was inoculated into a sucrose-sulphasomidine (Elkosin®)-broth (SEB). The test tube was tilted at a 40° angle and incubated aerobically at 37 °C for 24 h. The broth was removed, the tube rinsed carefully with water after which the amount of the adherent deposits was scored into one of four classes (≤ 103,104, 105 and ≥ 106 S. mutans/ml saliva). The number of S. mutans in 380 paraffin-stimulated whole saliva samples was determined after culturing on Mitis Salivarius Bacitracin agar plates and in SEB. A high correlation was found between the two methods. The level of S. mutans was diagnosed the same in 86% when 137 of the 380 saliva samples were cultured in both freshly prepared and 6-month-old medium. The SEB method is simple and inexpensive and may be used, e.g. in epidemiological studies and in routine practise, for the determination of the level of S. mutans in saliva samples.