Delayed-onset infections after impacted lower third molar extraction: involved bacteria and sensitivity profiles to commonly used antibiotics.

OBJECTIVES The objectives of this study were to identify the bacteria involved in delayed-onset infections after lower third molar removal and to determine the most suitable antibiotic for such complication. STUDY DESIGN Bacterial samples were collected from 13 patients who developed delayed-onset infections after lower third molar extraction. After the identification of the bacterial isolates, the in vitro antimicrobial susceptibility of the isolated strains was determined. RESULTS A total of 11 patients (12 samples) were finally included in the study. Up to 7 bacteria genera were identified. Fusobacterium sp. was present in 11 patients, Prevotella sp. in 8 cases, and Peptostreptococcus sp. in 7. Some strains of these bacteria were not susceptible to amoxicillin, amoxicillin/clavulanate, and metronidazol, whereas no resistances were found to clindamycin. CONCLUSIONS Fusobacterium sp., Prevotella sp., and Peptostreptococcus sp. are frequently present in delayed-onset infections after lower third molar removal. Based on the results of the microbial susceptibility tests, clindamycin seems to be the most adequate antibiotic for the treatment of this complication.