Effect of probiotic colonization on oral hygiene and ventilator-associated pneumonia in ICU patients: a triple-blind randomized controlled trial

Mechanically ventilated patients are highly susceptible to poor oral hygiene and ventilator-associated pneumonia, mainly due to pathogenic bacterial colonization in the oral cavity. While antiseptic mouthwashes are commonly used, they may disrupt natural oral microbiota. Probiotics offer a potential alternative by promoting beneficial microbial colonization, enhancing oral hygiene, and reducing the risk of infection. This study aimed to evaluate the effect of probiotic colonization on oral hygiene and the incidence of ventilator-associated pneumonia in mechanically ventilated patients. This triple-blind randomized controlled trial was conducted in the intensive care units (ICUs) of Shohada-ye Ashayer Hospital, Khorramabad, Iran. Eighty mechanically ventilated patients admitted to the ICU were randomly assigned to either an intervention or a control group using a simple randomization method. The intervention group received two daily doses of 250 mg of Streptococcus salivarius probiotic solution, administered orally for five consecutive days, while the control group received a placebo. Data collection tools included a demographic and clinical characteristics questionnaire, the Beck Oral Assessment Scale, and the Clinical Pulmonary Infection Score. Assessments were performed at baseline and on day six after the intervention. Data were analyzed using SPSS version 26, employing generalized linear models for comparative analysis of outcomes. Baseline demographic and clinical characteristics were comparable (p > 0.05), except for a lower Glasgow coma scale in the intervention arm (5.5 ± 1.3 vs. 6.4 ± 1.3, p = 0.003), which was adjusted for in subsequent analyses. Oral health status significantly improved in the intervention group compared with deterioration in controls (−1.82 ± 1.57 vs. +1.03 ± 1.66; adjusted F = 55.75, p < 0.001). Likewise, the clinical pulmonary infection score decreased in the intervention group but increased in the control group (−0.67 ± 1.29 vs. +1.35 ± 1.58; adjusted F = 30.27, p < 0.001). The proportion of patients at moderate to high risk of developing ventilator-associated pneumonia increased in the control group from 45% to 70%, whereas it decreased in the intervention group from 60% to 50%. The findings of this randomized trial show that the use of Streptococcus salivarius was associated with improvement in oral hygiene scores and reduction in Clinical Pulmonary Infection Score values among mechanically ventilated ICU patients. These outcomes indicate that probiotic-based oral care may help enhance oral health and reduce the estimated risk of ventilator-associated pneumonia. Further research with broader samples can clarify the clinical impact of this approach. The trial was registered in the Iranian Registry of Clinical Trials (IRCT20241019063429N1) in 2024-11-27.