Abstract: BACKGROUND AND AIM: To explore the correlation of staphylococcus aureus L-form infection and mutation of k-ras in ovarian carcinomas. MATERIALS AND METHODS: Gram staining and PCR-FLRP were used for detection of bacterial L-forms in paraffin-embeded tissues of 97 ovarian papillary carcinomas and 23 benign tumors. RESULTS: The positive rate of L-forms in ovarian carcinomas was 25.8％(25/97)，and in this group, the mutation rate of k-ras at codon 12 was 45.5％.However the positive rate of L-forms in ovarian benign tumors was only 13.0％(3/23)，and in this group, the mutation rate of k-ras at codon 12 was only 8.7％.With Spearman analysis, the malignant group was r=0.504 7(P<0.05);and the benign group was r=-0.119 5(P>0.05). CONCLUSION: Infection of L-forms had a positive correlation with point mutation of k-ras in malignant tumors but not in benign tumors.

Key words: ovarian neoplasms, staphylococcus aureus L-forms, polymerase chain reaction, restriction fragment length polymorphism