Gram-Negative Oral Colonization in Intensive Care Unit Patients: A Non-Randomized Comparative Study of Three Oral Hygiene Protocols

The oral cavity may serve as a reservoir for Gram-negative bacteria in critically ill patients. This study compared short-term oral hygiene protocols and explored factors associated with subsequent Gram-negative oral colonization. In this prospective, single-center, non-randomized comparative interventional study, 90 ICU patients were enrolled, of whom 86 received mechanical oral cleaning alone, mechanical cleaning with 0.2% chlorhexidine, or mechanical cleaning with hexetidine according to a predefined cyclic allocation sequence. Saliva samples were collected at ICU admission and on day 3. Multivariable logistic regression analyses were exploratory. Oral hygiene protocol was not significantly associated with day-3 g-negative bacterial growth after adjustment (overall p = 0.479). Baseline Gram-negative colonization (adjusted OR = 2256.88, 95% CI: 21.80–233,657.01) and visible dental plaque (adjusted OR = 41.18, 95% CI: 2.42–701.66) were associated with day-3 growth, but estimates were imprecise and potentially affected by sparse-data bias and overfitting. No statistically significant association between oral hygiene protocol and short-term Gram-negative colonization was detected. Equivalence cannot be inferred. Associations with baseline colonization and visible plaque require confirmation in larger studies.