IDENTIFICATION AND ANTIBIOTIC-SENSITIVITY OF BACTERIA ISOLATED FROM PERIAPICAL LESIONS

Periradicular tissues from 28 refractory endodontic cases requiring su rgical intervention were submitted for histological diagnosis and micr obiological culture. Bacteria isolated from these lesions were identif ied and then tested for their antibiotic sensitivity to a panel of com mon antibiotics. The periapical tissue specimens of 22 out of 28 lesio ns (79%) contained microorganisms. Of the 22 cases showing positive gr owth cultures, 15 were polymicrobial and 7 were single species isolate s. Fifty-three different species were recovered: 29 anaerobes, 19 facu ltative anaerobes, and 5 aerobes. Microbes were observed under light m icroscopy in only one case. The most common organisms isolated were Pr opionibacterium acnes, Staphylococcus epidermidis, Streptococcus inter medius, Wolinella recta, Fusobacterium species, and Clostridium specie s. Antibiotic susceptibility results showed no clear cut evidence of s ignificant antibiotic resistance among the species tested. The results of this study seem to corroborate earlier studies regarding the micro bial population of periapical lesions refractory to nonsurgical endodo ntics.