UCLA Oral Microbiology Laboratory
School of Dentistry, 10833 Le Conte Avenue, UCLA, Los Angeles, CA 90095-1668
Salivary Streptococcus mutans : Protocol for Testing and Follow-Up
The science: dental caries is a S. mutans associated bacterial infectious disease
Although several local environmental factors including dietary pattern, fluoride level and salivary flow contribute to the development of dental caries, cariogenic bacteria are ultimately responsible for the disease. These bacteria have the ability to make a gel-like plaque from sucrose in the diet, and then to create an acid environment deep in the gel-plaque whenever sugars are eaten. The acid dissolves the crystalline structure of the tooth to create a cavity. Among the cariogenic bacteria, Streptococcus mutans is the principal bacterium responsible for the initiation and progression of human dental caries. Previous clinical studies have established a close relationship between salivary S. mutans level and the risk of developing caries. Similar relationships also exist with disease activity state. These data strongly indicate that salivary S. mutans can serve as an index of both the state of activity and the risk or susceptibility of developing caries. Salivary S. mutans counts can be used as an aid to patient motivation and compliance to reduce caries risk or activity, to help check that patients remain at low risk after treatment, and as an aid in assisting parents and infants in delaying or avoiding initial S. mutans infection.
The technology: monoclonal antibody based methods for detecting S. mutans
Monoclonal antibody based bacterial detection methods have been recognized as an excellent diagnostic tool. UCLA recently developed highly species-specific monoclonal antibodies against S. mutans . In conjunction with fluorescent microscopy and flow cytometric techniques, the antibodies allow quick, low-cost assays that detect salivary S. mutans with nearly 100% sensitivity and specificity and which count the number of bacteria with great accuracy. The new technique was described in Hybridoma (17:365-371, 1998; Shi, Jewett and Hume) and granted US Patent No. 6,231,857 B1. This new technology is now available to you conveniently and at low cost and by mailing samples to the Oral Microbiology Laboratory at UCLA School of Dentistry.
The Testing Protocol
1. The testing kit includes a disposable cup, a pipette, and a tube with fixing solution. You can request the testing kits by e-mail: wenyuan@ucla.edu ; fax: 310-794-7109; or phone 310-825-8356. Please address your request to Dr. Wenyuan Shi at the UCLA Oral Microbiology Laboratory. Please include your name, mailing address, phone/fax number, e-mail address (optional).
2. At your chair side, ask your patient to spit normal (unstimulated) saliva into the cup. Use the pipette to transfer 0.5 ml of saliva into the tube with fixing solution, then mix the saliva with fixing solution for 5 seconds by shaking. For children less than 2 years old, use the pipette to collect saliva directly from the floor of child's mouth, then transfer the collected saliva into the cup. After enough saliva is collected, transfer 0.5 ml of saliva into the tube with fixing solution, and mix.
Warning: Do not re-introduce the pipette into the mouth if it has touched the fixing solution. The pipette is single use only and should be disposed after usage.
3. Label each tube with the unique identifier for your office and the individual patient using a fine point, permanent marker pen. To protect patient confidentiality please do not include the patient's name or related medical information in any material sent to our laboratory.
4. Please make a record on whether the patient has consumed food within 2 hours of collection. Salivary S. mutans may increase 2-4 fold in the hours immediately after food intake. You may consider this information when you examine the report.
5. The fixed saliva samples can be stored at room temperature for up to three weeks. Unless you require results more quickly, we recommend that you mail one week's samples together in a padded or bubble cushioned envelope. Please mail the saliva samples to Dr. Wenyuan Shi, Oral Microbiology Laboratory, UCLA School of Dentistry, 10833 Le Conte Avenue, Los Angeles, CA 90095-1668. Please include a cover letter stating your contact information (name, address, phone/fax number and e-mail address), a list of saliva samples using each patient's identifying code only.
Test Results
UCLA Oral Microbiology Laboratory will use the monoclonal antibody based detection method to determine the number of S. mutans cells in per milliliter (ml) of saliva. The results will be reported to you through either fax or e-mail, 2-3 days after we receive the saliva samples. Figure 1 shows the distribution of salivary S. mutans counts within a human population. Individuals with less than 100,000 (10 5 ) S. mutans cells/ml of saliva are considered low caries risk or activity; 100,000 to 500,000 (10 5 to 5X10 5 ) S. mutans cells/ml are medium, and 500,000 (5X10 5 ) or above cells/ml are high risk or activity.
Health Education and Follow-up
Bringing about biochemical and behavioral change to prevent and cure caries relies on the development of a therapeutic alliance between the dental professional, the patient and any caregiver. We recommend using one or more of the following at your discretion to treat patients who either have high salivary S. mutans indicated by salivary bacterial count, or who you know from other signs (continually progressing lesions, low stimulated salivary flow) to have active caries or high risk:
1. Provide oral health education for better and more frequent brushing and flossing.
2. Change the dietary pattern through sugar reduction and reduction in the frequency of eating.
3. For individuals younger than 6 years advise the use of a fluoride-containing dentifrice formulated for children. For individuals over 6 years of age advise the use of a toothpaste that contains both fluoride and an anti-bacterial compound.
4. Provide frequent in-office prophylaxis, fluoride treatment (liquid or varnish) and counseling.
5. Advise the use of a high-fluoride home treatment of your choice (e.g., over-the-counter fluoride rinse, or a tray or stent with pH-neutral fluoride gel).
6. For individuals with very high initial counts, prescribe chlorhexidine (Peridex) 0.2% as a daily rinse for 2 weeks at a time several hours removed from any fluoride rinse.
Using salivary S. mutans counts as an index of caries risk and activity is much more beneficial to the patient than waiting for signs of cavity development and is a service for which appropriate professional fees should be charged.
The Testing Cost and Payment
The salivary S. mutans test costs $10/per test including the testing kit. Please include the payment check (payable to the Regents of the University of California) when sending back the saliva for testing. A volume discount will be applied if you purchase over 100 test kits.
The Contact Information
If you have any further questions, please contact us at:
Dr. Wenyuan Shi, Director
Oral Microbiology Laboratory
UCLA School of Dentistry
10833 Le Conte Avenue
Los Angeles, CA 90096-1668
Tel: 310-825-8356
Fax: 310-794-7109
E-mail: wenyuan@ucla.edu |
