Analysis of cariogenic bacteria in saliva of cancer patients

This study examined salivary flow and salivary pH and the prevalence and levels of cariogenic bacteria in the saliva of oncological patients and healthy controls. Quantitative real-time polymerase chain reaction was used to assess the levels of microbes including Streptococcus mutans, Streptococcus sobrinus, Lactobacillus salivarius, and Lactobacillus acidophilus in the saliva of 41 patients with a solid tumor (SO), 30 patients with a hematologic malignancy (HE), and 40 healthy controls. Salivary flow and pH were lower in oncological patients than in controls. The frequencies of all four cariogenic bacteria were highest in the SO group. S. mutans and L. salivarius were the most commonly detected in all three study groups. Mean numbers of S. sobrinus and L. salivarius in the SO group were significantly higher than in controls (p<0.05). There were no significant differences between patients and controls with respect to mean numbers of S. mutans and L. acidophilus in saliva. However, the proportions of S. mutans, S. sobrinus, and L. salivarius versus total bacteria in the SO group were significantly higher than in controls. Within patients, both mean numbers and the proportions of S. mutans and S. sobrinus were significantly different (p<0.05). In summary, significant differences were found in salivary pH values and the levels of S. mutans, S. sobrinus, and L. salivarius between SO patients and healthy controls.