Determination of Antibiotic Sensitivity of Bacteroid fragilis Isolated from Patients and Healthy Individuals in Imam Reza Center of Medical Teaching and Treatment-Tabriz

Background:: Bacteroides fragilis are among the most important anaerobic bacteria behind most of the anaerobic infections. They have acquired resistance to essential treatment antibiotics of anaerobic infections, more than other anaerobic bacteria. Objectives: The goal of this study is to determine the resistance of isolated B. fragilis against common anaerobic infections treatment antibiotics. Patients and Methods:: A total of 188 fecal samples including 59 samples from hospitalized patients, 84 samples from outpatients, and 45 samples from healthy individuals were collected. The samples were cultured in Bacteroides- Bile- Esculine agar and Kanamycin-Vancomycin-Laked Blood media and were incubated in anaerobic atmosphere at 37°C for at least 48 hours. Suspected one millimeter sized colonies with black surroundings, were selected and further studied using MID8, as well as biochemical tests. For MIC determination of antibiotics against isolated B. fragilis, Etest was used. Results:: There wasn’t any difference between antibiotic resistance patterns of isolated B. fragilis from hospitalized patients or outpatients, including diarrheal and non-diarrheal cases, and resistant pattern of isolates from healthy individuals. All or most of isolated B. fragilis were susceptible to imipenem (100%), metronidazole (95%), rifampin (100%) and piperacillin/tazobactam (95%). On the contrary, they exhibited resistance to other antibiotics such as clindamycin (90%), and chloramphenicol (55%). Conclusions:: In the present study, we have figured out that a number of the important anaerobic infections treatment antibiotics have lost partly or totally their effectiveness on B. fragilis.