Bacterial susceptibility to amoxycillin and potassium clavulanate in advanced periodontitis patients not responding to mechanical therapy

Aim of the study

To evaluate the effects of systemic amoxycillin/potassium clavulanate (AC) on the subgingival flora in patients not responding to mechanical therapy. To test the bacterial susceptibility to these antibiotics before and after treatment.

Materials and methods

In ten periodontitis patients (of whom 8 were smokers) with no subgingival detection of Aa, the predominant subgingival organisms were identified and their susceptibilities to the antibiotics were evaluated.

Results

Porphyromonas gingivalis (Pg), Porphyromonas oralis (Po) were present in 7/10 patients before treatment and absent following it. Fusobacterium nucleatum (Fn) and Peptostreptococcus micros (Pm) were present in 5/10 patients before treatment and in 6/10 and 3/10 respectively after treatment. These bacteria were not targeted by amoxycillin/AC.

Conclusion

The conventional methods of testing the susceptibility of bacteria to antibiotics must be interpreted with caution in the case of plaque related diseases. The use of amoxycillin/AC is not justified for the elimination of Fn and Pm.

Commentaries

This is the first study to compare bacterial susceptibility before and after antibiotic treatment. Many parameters, such as the in vitro and in vivo conditions, render the interpretation of the data difficult.