Antimicrobial profiles of periodontal pathogens from The Netherlands and Spain

Objectives: Microbial resistance in the periodontal microflora has been found more frequently in Spanish patients than in Dutch patients. The aim of the present study was to compare antimicrobial susceptibility profiles of 5 periodontal bacteria isolated from periodontitis patients in Spain and in The Netherlands. Methods: Subgingival plaque samples (Spain=54, Netherlands=26) from adult patients with periodontitis were cultured on selective and non-selective plates. Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn) and Peptostreptococcus micros (Pm) were isolated and used for minimal inhibitory concentration tests using the Epsilometer (E-test) technique. Eight different antibiotics were tested on all bacterial isolates. MIC90 values for each antibiotic and each species were determined and the percentage of resistant strains was calculated. Results: Significantly higher MIC values were noted in Spanish strains: Fn for penicillin and ciprofloxacin, Pi for penicillin, amoxicillin and tetracycline, Pm for tetracycline, amoxicillin and azithromycin, and Pg for tetracycline and ciprofloxacin. Based on breakpoint concentrations, a higher number of resistant strains in Spain were found in Fn for penicillin, amoxicillin and metronidazole, in Pi for tetracycline and amoxicillin, and in Aa for amoxicillin and azithromycin. Pg resistance was not observed for any of the antibiotics tested both in Spain and The Netherlands. Conclusions: Differences exist in the susceptibility profiles of periodontal pathogens isolated from periodontitis patients in Spain and in The Netherlands. Clinical studies with antibiotics should take these differences into account. The information from the present study indicates that it may not be possible to develop uniform protocols for usage of antibiotics in the treatment of severe periodontitis in the European union.