Susceptibility of endodontic pathogens to antibiotics in patients with symptomatic apical periodontitis

The aim of this study was to evaluate susceptibility of predominant endodontic pathogens isolated from teeth with symptomatic apical periodontitis to most commonly prescribed antibiotics.

Among 58 patients with symptomatic apical periodontitis, 47 and 11 cases were caused by primary and secondary root canal infection, respectively. The microbial samples were taken either from the root canals (35 cases) or by aspiration from apical abscesses (23 cases). Culture methods were used to identify the microorganisms present in the samples. Antibiotic susceptibilities of all isolates were evaluated by using the E-test method.

Microorganisms were isolated from 49 of the 58 samples studied and included facultative and obligate anaerobes. Streptococci and obligate anaerobes were the predominant microorganisms in cases of primary infection. Enterococcus faecalis dominated in cases of secondary infection. All tested microorganisms were highly sensitive to penicillin G, amoxicillin, and ampicillin. Susceptibilities to clindamycin and erythromycin were 73.8% and 54.7%, respectively. About 40% of the isolates were resistant to tetracycline. More than 50% of all anaerobes were resistant to metronidazole. All E. faecalis isolates were resistant to clindamycin.

Based on the study results, penicillin and amoxicillin are suitable antibiotics for treatment of endodontic infection when conventional root canal treatment alone is insufficient. Clindamycin could be advised for penicillin-allergic patients with primary endodontic infections.