Study of microflora in stomach cancer and gastritis.

Abstract

e15516 Background: The purpose of the study was to compare the rates of bacterial and fungal colonization of the mucosa in stomach cancer and gastritis. Methods: 59 tumor and healthy tissue samples in stomach cancer and 33 stomach mucosa bioptates in gastritis were studied. DNAs were extracted by the adsorption method. DNAs of Enterobacteriaceae, Staphylococcus spp., Streptococcus spp., Candida spp., Bacteroides spp. were determined by real-time PCR. Results: 40.0% of 30 patients with stomach cancer had adenocarcinoma, 13.3% – signet ring cell carcinoma, 6.7% – undifferentiated cancer, 6.7% – NHL, 3.3% – squamous cell carcinoma, 6.7% – combined signet ring cell carcinoma and neuroendocrine or undifferentiated cancer, 23.3% – combined adenocarcinoma and neuroendocrine, signet ring cell or undifferentiated cancer. The comparison group included 33 patients with morphologically verified superficial gastritis. DNA of Bacteroides spp. was found in tumor and healthy tissues of 80.0% of cancer patients; it was not found in gastritis. DNA of B. fragilis was found in all tumor tissue samples, BFT – in 8.3% of them. The mean amount of Enterobacteriaceae in tumor tissue was 6.7x105 copy/ml, in healthy tissue – 7.0x105 copy/ml, in bioptates in gastritis – 4.0х102 copy/ml; Staphylococcus spp. – 3.4х102 copy/ml, 2.6х102 copy/ml and 8.7х101 copy/ml, Streptococcus spp. – 9.1х105 copy/ml, 1.3х105 copy/ml and 5.1х103 copy/ml, respectively. Thus, the amount of Enterobacteriaceae in tumor tissue in stomach cancer exceeded the value in gastritis by 1675 times, Staphylococcus spp. – by 3.9 times, Streptococcus spp. – by 178 times. Genes of resistance to the penicillin class TEM were found in 50.0% of patients with stomach cancer and in 8.7% of patients with gastritis. DNAs of Candida spp. in stomach cancer were found in 40% of patients in tumor tissue and in 31.0% in healthy tissue, in gastritis – in 8.3% of patients. Conclusions: Enterobacteriaceae and Streptococcus spp., mostly combined, dominate among microflora colonizing gastric mucosa in stomach cancer. The established differences in microbiocenosis in stomach cancer in comparison with gastritis suggest the possible involvement of aerobic and anaerobic microflora in the process of malignant transformation.