Wir überwinden Grenzen

Scientists at the University Medical Center Freiburg and colleagues from Regensburg are investigating how resistance develops through oral disinfectants / Around 660,000 euros in funding from the German Research Foundation (DFG)

Antibiotic resistance has been widely studied and publicly discussed over the last two decades. However, resistance to antiseptics, locally acting disinfectants, has received much less attention. Scientists from the Department of Dental Conservation and Periodontology at the University Medical Center Freiburg and the University of Regensburg are now investigating how such resistance develops in the caries pathogen Streptococcus mutans, among others, and why it can also lead to antibiotic resistance. Using selected bacterial species and patient samples, they are investigating how microorganisms in the oral flora change as a result of treatment with chlorhexidine, the most important oral antiseptic. The researchers will receive joint funding of 664,000 euros from the German Research Foundation for the next three years.

"Our aim is to understand the development of resistance of oral bacteria to chlorhexidine, both at the genetic level and in relation to changes in bacterial metabolism," says Prof. Dr. Ali Al-Ahmad, Head of the "Oral Microbiology" Department at the Clinic for Restorative Dentistry and Periodontology at the Freiburg University Medical Center. He is leading the project together with PD Dr. Fabian Cieplik, Senior Physician at the Polyclinic for Tooth Preservation and Periodontology at the University of Regensburg. Chlorhexidine is considered the most important antiseptic in dentistry and is widely used there. The antiseptic is also used intensively in other medical fields. "One of the project's questions is whether freely available chlorhexidine-based mouthwashes can also contribute to the development of resistance," says Cieplik.

Is antibiotic resistance the result of the frequent use of chlorhexidine?

The two research groups will use different methods to investigate whether resistance to chlorhexidine goes hand in hand with resistance to antibiotics, known as cross-resistance. "In future, we could decide specifically when a broad-spectrum antiseptic needs to be used and when alternative preparations are sufficient," explains Al-Ahmad.

Examination of samples from intensively treated patients

In addition, a special genetic analysis, the shotgun metagenome analysis, is used to check whether the composition of the entire bacterial oral flora changes in relation to chlorhexidine in patients who have to use the antiseptic over a longer period of time due to oral surgery.

Caption: The main cause of tooth decay, Streptococcus mutans, can also develop resistance to the antiseptic chlorhexidine.
Image source: Freiburg University Medical Center

Contact: 
Prof. Dr. Ali Al-Ahmad
Head of the "Oral Microbiology" department
Clinic for Dental Preservation and Periodontology
University Medical Center Freiburg
Phone: 0761 270-48940
ali.al-ahmad@uniklinik-freiburg.de