Material and Method: A prospective, randomized, open-label controlled trial was conducted in 150 adult hospitalized patients in medical wards who were expected to receive mechanical ventilation for 72 hours or longer. The patients were randomized to the probiotics group or the control group. All patients received regular care for mechanical ventilation. The patients in the probiotics group received 80 ml of Lactobacillus casei (Shirota strain) for oral care after having standard oral care once daily and additional 80 ml of the aforementioned fermented dairy product was given via enteral feeding once daily. The primary outcomes were incidence of VAP and incidence rate of VAP episodes per 1,000 ventilator-days. The secondary outcomes were length of hospital stay, mortality at day 28 and 90, incidence of diarrhea, and presence of resistant bacteria in oropharyngeal and rectal swab samples taken from the patients at baseline, day 7 and day 28 after enrollment.

Results: The baseline characteristics of the patients in the probiotics group (75) and the control group (75) were not significantly different. The patients in the probiotics group were less likely to develop VAP compared with the control group (24% vs. 29.3%, p = 0.46), respectively. The incidence rates of VAP in the probiotics and control groups were 22.64 and 30.22 episodes per 1,000 ventilator-days, respectively (p = 0.37). A trend of lower prevalence of some resistant bacteria cultured from oropharyngeal swabs in the probiotics group than that in the control group was observed. Overall 28- and 90-day mortality and length of hospital stay of the patients in both groups were not significantly different.

Conclusion: Administration of probiotics containing Lactobacillus casei (Shirota strain) has a tendency to reduce the incidence of VAP and colonization with resistant bacteria in oropharyngeal cavity without significant effects on mortality and length of hospital stay.

Keywords: Probiotics, Lactobacillus casei (Shirota strain), Prevention, Ventilator-Associated Pneumonia