Factors Related to the Growth of Oral Bacteria After Surgery: An Observational Study of 54 Patients Undergoing Oncologic or Cardiac Surgery

Introduction Postoperative complications, such as surgical site infection and postoperative pneumonia, may be caused by oral bacteria. This study aimed to clarify the factors related to the bacterial count in the saliva of postoperative patients so as to standardize oral management methods before and after surgery. Methods This prospective observational study enrolled 54 patients who underwent major oncologic or cardiac surgery. The following variables were investigated: age, sex, primary disease, body mass index, performance status, smoking, alcohol consumption, serum creatinine and albumin, operation time, intraoperative blood loss, number of teeth, functional tooth unit, plaque control record (PCR), amount of dental plaque, community periodontal index, eating status the day after surgery, oral wetness, and number of bacteria in the saliva before and after surgery. The relationship between each variable and the number of bacteria in the saliva before and after surgery was analyzed. Results Multiple regression analysis revealed that the PCR was significantly associated with the number of bacteria in the saliva before surgery (p=0.021). On the day after surgery, the number of bacteria in saliva was significantly higher than that before surgery (p<0.001). Multivariate analysis showed that eating status the day after surgery (p=0.046) and oral wetness (p=0.043) were significantly associated with the number of bacteria, but dental plaque did not influence the bacterial count. Conclusions Postoperative salivary bacterial counts increased due to reduced oral self-cleaning, regardless of dental plaque content. Therefore, oral feeding should be started promptly after surgery to reduce the number of bacteria in the saliva.