IADR Abstract Archives
Evaluation of Antimicrobial Susceptibility of Fusobacterium Nucleatum to Different Antibiotics
Objectives: The purpose of this study was to evaluate the susceptibility of anaerobe Gram negative species Fusobacterium nucleatum, isolated from root canal with pulpal necrosis and periapical lesion to different antibiotics prescribed in Endodontics.
Methods: One Fusobacterium nucletum isolate from root canal with pulpal necrosis and periapical lesion and your ATCC strain (25586) were tested against the following antibiotics: amoxicillin, amoxicillin-clavulanic acid, ampicillin, azithromycin, clindamycin, erythromycin and metronidazole. Minimal inhibitory concentrations (MICs) of the antimicrobial agents were determined using the E-test System. The inoculum was made from colonies transferred to liquid medium, agitated and standardized until turbidity equivalent to McFarland scale #1. It was inoculated in Reinforced Clostridial medium (RCM) agar plates supplemented with 5% defibrinated sheep blood. After drying the E-test strips were placed over the bacteria. The plates were incubated at 37ºC in an anaerobic atmosphere for up to 48 hour. All tests were performed in triplicate.
Results: F. nucleatum isolate was resistant to most antibiotics showing sensitivity only to metronidazole (MIC = 0,064µg/mL) and erythromycin (MIC = 4,0µg/mL). Its susceptibility to metronidazole was decreased, however it was similar to erythromycin, when comparing to the standard strain ATCC. The results of the E-test showed that the most effective tested antibiotics against Fusobacterium nucleatum standard strain were metronidazole, amoxicillin, amoxicillin -clavulanic acid and clindamycin with similar results (MIC = 0,016μg/ml). Erythromycin was the least effective antibiotic (MIC = 4.0μg/ml).
Conclusions: The strain of Fusobacterium nucleatum isolated clinically showed to be much more resistant than the standard strain, being inhibited by only two of the tested antibiotics and requiring higher concentrations of them.
Methods: One Fusobacterium nucletum isolate from root canal with pulpal necrosis and periapical lesion and your ATCC strain (25586) were tested against the following antibiotics: amoxicillin, amoxicillin-clavulanic acid, ampicillin, azithromycin, clindamycin, erythromycin and metronidazole. Minimal inhibitory concentrations (MICs) of the antimicrobial agents were determined using the E-test System. The inoculum was made from colonies transferred to liquid medium, agitated and standardized until turbidity equivalent to McFarland scale #1. It was inoculated in Reinforced Clostridial medium (RCM) agar plates supplemented with 5% defibrinated sheep blood. After drying the E-test strips were placed over the bacteria. The plates were incubated at 37ºC in an anaerobic atmosphere for up to 48 hour. All tests were performed in triplicate.
Results: F. nucleatum isolate was resistant to most antibiotics showing sensitivity only to metronidazole (MIC = 0,064µg/mL) and erythromycin (MIC = 4,0µg/mL). Its susceptibility to metronidazole was decreased, however it was similar to erythromycin, when comparing to the standard strain ATCC. The results of the E-test showed that the most effective tested antibiotics against Fusobacterium nucleatum standard strain were metronidazole, amoxicillin, amoxicillin -clavulanic acid and clindamycin with similar results (MIC = 0,016μg/ml). Erythromycin was the least effective antibiotic (MIC = 4.0μg/ml).
Conclusions: The strain of Fusobacterium nucleatum isolated clinically showed to be much more resistant than the standard strain, being inhibited by only two of the tested antibiotics and requiring higher concentrations of them.