Bacteriological findings in radicular cyst and keratocystic odontogenic tumour fluids from asymptomatic patients

Objective In this study the potential presence of bacteria in radicular cyst (RC) and keratocystic odontogenic tumour(KCOT) fluids from clinically asymptomatic patients was investigated. Materials and methods Cyst fluids were collected by needle aspiration from 16 patients with asymptomatic osteolytic lesions (10 RCs and 6 KCOTs) undergoing surgery. All samples were transferred into tubes containing pre-reduced transport medium, delivered to the microbiology laboratory and processed within 1 h. The cysts, surgically enucleated, were sent for standard histopathological examination. Cyst fluid samples were cultured on selective and differential media in anaerobic (for about 2 weeks) and aerobic (for 24–48 h) conditions to detect viable microorganisms. After incubation, the colonies were counted, Gram-stained and identified by biochemical tests. Results Cultures were positive for the presence of bacteria in 15 (9 RCs, 6 KCOTs) out of 16 cases. RCs and KCOTs generally yielded low bacterial counts (102–104 CFU/ml) and were predominantly colonized by obligate anaerobes (64%), whereas less commonly by facultative anaerobes (36%). No significant differences in the detection frequencies of obligate and facultative anaerobes were evidenced between RCs and KCOTs. Propionibacterium acnes was the most common obligate anaerobe recovered both in RC and KCOT fluids. Among facultative anaerobes, Gemella morbillorum was more frequently isolated in KCOTs, whereas Staphylococcus spp. in RCs. Conclusions Bacteria may be present and persist within fluids of clinically asymptomatic jaw cystic lesions. The influence of bacteria and latent bacterial infection within cystic jaw lesions should be reconsidered in odontogenic cyst progression.