Spiramycin resistance in human periodontitis microbiota

The occurrence of in vitro resistance to therapeutic concentrations of spiramycin, amoxicillin, and metronidazole was determined for putative periodontal pathogens isolated in the United States. Subgingival plaque specimens from 37 consecutive adults with untreated severe periodontitis were anaerobically cultured, and isolated putative periodontal pathogens were identified to a species level. In vitro resistance to spiramycin at 4 μg/ml, amoxicillin at 8 μg/ml, and/or metronidazole at 16 μg/ml was noted when putative periodontal pathogen growth was noted on the respective antibiotic-supplemented primary culture plates. A total of 18 (48.7%) subjects yielded antibiotic-resistant putative periodontal pathogens with spiramycin at 4 μg/ml in drug-supplemented primary isolation plates, as compared to 23 (62.2%) subjects with amoxicillin at 8 μg/ml, and 10 (27.0%) subjects with metronidazole at 16 μg/ml. Spiramycin in vitro resistance occurred among species of Fusobacterium nucleatum (44.4% of organism-positive subjects), Prevotella intermedia/nigrescens (11.1%), Parvimonas micra (10.8%), Streptococcus constellatus (10%), Streptococcus intermedius (10%), Porphyromonas gingivalis (6.7%), and Tannerella forsythia (5.3%). Amoxicillin in...Continue Reading