Probiotics are hypothesized to moderate the microbiome of the aerodigestive tract, decrease colonization with pathogenic organisms, and therein protect patients from aspirating the organisms that lead to hospital-acquired pneumonia. Many studies have been conducted to test this hypothesis but most have been small, variably blinded, single-center assessments with discrepant results. A recent meta-analysis of 13 randomized trials with 1,969 adults and children did report a significant association between probiotics and lower VAP rates (RR: 0.73; 95% CI: 0.60–0.89) but no difference in duration of mechanical ventilation, ICU length of stay, or mortality. Notably, the meta-analysis did report near-significant trends toward lower mortality rates (RR: 0.84; 95% CI: 0.70–1.02; p = 0.09) and shorter duration of mechanical ventilation (−3.32 days, 95% CI: −6.74 to +0.09, p = 0.06) in patients randomized to probiotics, so future studies may reveal clearer evidence of net benefit. There is a large multicenter randomized trial of this intervention underway that may be helpful in this regard.
Note that there is some risk associated with probiotics. There are multiple case reports of bloodstream infections with probiotic strains following exposure to these agents.[104–106] Probiotics are therefore contraindicated in patients with impaired immunity, severe pancreatitis, and short-gut syndrome. There have also been reports of airborne transmission of probiotic strains within intensive care units.[107,108]
Semin Respir Crit Care Med. 2019;40(4):548-557. © 2019 Thieme Medical Publishers