Detection of Bacteria Within Oral Squamous Cell Carcinoma Tissue

Introduction: There is increasing interest in the relationship between bacteria and the different stages of cancer development, yet the association of bacteria with cancer of the oral cavity has yet to be adequately examined. Objective: To identify whether bacteria are present within oral squamous cell carcinoma (OSCC) tissue by a combination of standard culture and molecular techniques. Methods: At the time of surgery, a 1cm³ portion of tissue was harvested from deep within the tumour mass using fresh blades for each cut. Whenever possible, “superficial” portions from the mucosa overlying the tumour and non-tumourous control specimens from at least 5cm away from the primary tumour site were also obtained. Surface contamination was eliminated by immersion in Betadine® and washing with PBS. Half of each specimen was macerated under aseptic conditions, suspended in PBS and cultured on non-selective media under both aerobic and anaerobic conditions. PCR using Bacteria-specific 16S rDNA primers was undertaken on DNA extracted from the remainder of each specimen. The products were singularised by TA cloning and sequenced. Results: Twenty deep tissue specimens, 19 corresponding superficial tissues and 12 control tissues, were studied. Negative results from prolonged cultural and 16S rRNA PCR analysis of surface washes indicated that surface decontamination was successful. A diversity of bacterial species was isolated and the detailed findings will be presented and discussed. On average 6 different species were isolated from each specimen. Potentially significant species detected include Atopobium parvulum, Capnocytophaga gingivalis, Fusobacterium nucleatum, Granulicatella adiacens, Propionibacterium acnes, Ralstonia insidiosa, Streptococcus anginosus, and an unnamed Prevotella species. Conclusions: For the first time viable bacteria have been isolated from within OSCC tumour tissue. A diversity of bacterial species was detected and a degree of restriction in comparison to control sites demonstrated. The significance of these bacteria within the tumour tissue warrants further study.