By Amy Trevor1,4; Tom Maier1,2, PhD; and Curtis A. Machida1,3, PhDDepartments of 1Integrative Biosciences, 2Oral Pathology and Radiology, and 3Pediatric Dentistry, and 4Academic DMD Program, Oregon Health & Science University School of DentistryFor more information, read “OSHU School of Dentistry examines antimicrobial drug interactions in periodontology” on DentistryIQ.com. Looking to improve the prognosis for patients requiring scaling and root planing (SRP) treatment, many clinicians are turning to adjunct therapies such as the use of the antibiotic minocycline hydrochloride. Minocycline hydrochloride encapsulated into slow-release bioresorbable microspheres can be introduced directly into the periodontal pocket. This modality has proven to be an effective adjunctive therapy when combined with conventional SRP. Given the growing use of minocycline hydrochloride in periodontitis applications, we wanted to explore and identify potential interactions that might occur between minocycline hydrochloride and other drugs commonly used during SRP and in the treatment of periodontal disease.
1 Our study used recombinant strains of oral streptococci in order to evaluate the antibacterial activity of minocycline hydrochloride when used alone or in combination with the anesthetic lidocaine/prilocaine or with the antiseptic chlorhexidine. As all three of these products are commonly applied to the same periodontal sulcus and/or in the oral cavity in a relatively short period of time, the probability of interactions seems possible.Of the many different strains of oral microorganisms commonly associated with periodontal disease, isolates of
Streptococcus mutans were used as models in this study because they tend to be among the most common colonizers in early plaque biofilm that would be reforming following treatment with SRP. In order to monitor the growth of oral bacteria rapidly and accurately,
S. mutans isolates were genetically modified with bioluminescence genes from
Photorhabdus luminescens. By using bioluminescence-generating bacterial cells, changes in the metabolic activity of bacteria could be detected before changes in cell mass occur, thereby increasing the sensitivity of the tests and giving results in real time.Bioluminescence is a naturally occurring trait in a number of organisms, including the firefly. Long fascinated by this phenomenon, scientists quickly sought to discover the mechanism that enabled these organisms to produce light. Experimentation revealed that bioluminescence-generating organisms convert the energy molecule adenosine triphosphate (ATP) into visible light through the use of enzymes. These types of enzymes are referred to as luciferases. The applications of bioluminescence in science are now widespread. Many industries have adopted testing methods involving bioluminescence in order to monitor microbial contaminations in everything from historical documents to pharmaceuticals and the food and sanitation industries. In medicine, bioluminescence can be utilized as a marker for cancer cells, thus monitoring their growth and response to chemotherapy drugs or as a reporter for assessing gene expression. The applications of bioluminescence in dentistry are just beginning to be explored. In this study, the use of bioluminescent bacterial recombinants as biosensors proved to be an excellent method of assessing the metabolic activity of bacteria and was useful for evaluating microbial agents alone or in combination with other drugs. This research is the first time that bioluminescent genetic recombinants have been used for dental applications.In addition, using a different type of bioluminescence assay, or ATP-driven bioluminescence, oral bacteria can be enumerated in dental plaque.
2 ATP-driven bioluminescence determinations can be performed at chairside to serve as additional tools to access caries risk, to track the effectiveness of a patient’s home-care regimen, and to determine the unique effectiveness of prescribed antimicrobial therapies in individual patients. For the study recently published in
Periodontitis: Symptoms, Treatment and Prevention (Nova Science Publishers),
S. mutans recombinants were subjected to different concentrations of minocycline hydrochloride, lidocaine/prilocaine or chlorhexidine, used alone or in combination. The results of this study have important implications for periodontists who are considering using the minocycline hydrochloride antibiotic as an adjunct therapy for SRP with concurrent treatment with prilocaine/lidocaine anesthetic or followed by treatment with chlorhexidine antiseptic. It appears that there are no contraindicative effects to using these products in combination. The use of prilocaine/lidocaine as an anesthetic during SRP, or the use of chlorhexidine antiseptic, does not appear to have a negative effect on the bacteriostatic effects of minocycline hydrochloride. In fact, using these products in combination seems to have an additive antimicrobial effect that may provide additional benefit.
