ABSTRACT
OBJECTIVE: The aim of the present study was to analyze in vitro the combinatorial effects of the antibiotic combination of amoxicillin plus metronidazole on subgingival bacterial isolates. DESIGN: Aggregatibacter (Actinobacillus) actinomycetemcomitans, Prevotella intermedia/nigrescens, Fusobacterium nucleatum and Eikenella corrodens from our strain collection and subgingival bacteria isolated from patients with periodontitis were tested for their susceptibility to amoxicillin and metronidazole using the Etest. The fractional inhibitory concentration index (FICI), which is commonly used to describe drug interactions, was calculated. RESULTS: Synergy, i.e. FICI values ≤ 0.5, between amoxicillin and metronidazole was shown for two A. actinomycetemcomitans (FICI: 0.3), two F. nucleatum (FICI: 0.3 and 0.5, respectively) and one E. corrodens (FICI: 0.4) isolates. Indifference, i.e. FIC indices of >0.5 but ≤4, occurred for other isolates and the 14 P. intermedia/nigrescens strains tested. Microorganisms resistant to either amoxicillin or metronidazole were detected in all samples by Etest. CONCLUSION: Combinatorial effects occur between amoxicillin and metronidazole on some strains of A. actinomycetemcomitans, F. nucleatum and E. corrodens. Synergy was shown for a few strains only.
Subject(s)
Amoxicillin/pharmacology , Anti-Bacterial Agents/pharmacology , Dental Plaque/microbiology , Metronidazole/pharmacology , Periodontitis/microbiology , Aggregatibacter actinomycetemcomitans/drug effects , Drug Resistance, Bacterial , Drug Synergism , Eikenella corrodens/drug effects , Fusobacterium nucleatum/drug effects , Humans , In Vitro Techniques , Microbial Sensitivity Tests , Prevotella nigrescens/drug effectsABSTRACT
In dentistry, antibiotics are prescribed both for prophylactic and therapeutic purposes. Their unwarranted use, however, may lead to the selection of resistant microorganisms. The aim of this study was to evaluate the indications and the extent of antibiotic prescription by dentists in Switzerland. A questionnaire was sent to 800 dentists during the winter of 2008/2009. Responses to the questionnaire were received from 20% of them. Many respondents indicated that they tried to prescribe antibiotics in a selective and cautious manner. Nevertheless, uncertainties existed regarding the indications. For example, the frequency of prescribing an antibiotic when it was not absolutely necessary was related to the respondents' uncertainty regarding the correct diagnosis and therapy. Not surprisingly, two-thirds of the respondents would prefer to have precise guidelines for the use of these drugs.
