Non-ventilator hospital acquired pneumonia (NV-HAP) impacts 1 in 100 hospitalized patients and is a significant patient concern due to its negative clinical outcomes. Many factors play a role in NV-HAP development: oral health, oral care, microaspiration risk, and the oral microbiome. Little is known about how the oral microbiome alters during hospitalization. This study explored changes in the oral microbiome of non-ventilated hospitalized patients over time and analyzed the relationship between the oral microbiome, pre-hospital residence, and NV-HAP. A prospective, observational design was used to recruit 46 non-ventilated adults 65 years and older from a large medical center in central Florida (n=15 nursing home; n=31 home) within 72 hours of admission (baseline). Oral salivary specimens were collected, and an oral assessment was completed using the Oral Health Assessment Tool at four time points: baseline and hospital days 3, 5, and 7. Genomic DNA was extracted from oral samples for microbiome profiling by 16S rRNA sequencing. Taxonomic composition, relative abundance, alpha diversity (Shannon Index), and beta diversity (Bray-Curtis dissimilarity) of bacterial communities were determined. Data were analyzed using descriptive statistics, Chi-squared, independent t-test, repeated measures mixed effects modeling, two-way permutational ANOVA, ANOSIM, and multiple dispersion. Most participants were female (70%) and white (74%) with mean age of 78.7+/-9.1 years. Oral bacteria genera remained consistent across hospitalization: Streptococcus, Rothia, and Prevotella. Mean Shannon Index changed over time (p < .001) and over time by group (p < .01). Relative bacterial abundances were similar between groups; however, several less frequent oral bacteria genera were higher in the nursing home group. Mean baseline Shannon Index was lower in the nursing home group (p < .001). Mean Bray-Curtis dissimilarity at baseline genus (p=.010) and ASV levels (p=.003) were higher in the nursing home group. Two patients developed probable NV-HAP (4%), at the time that Neisseria and Streptococcus increased. Although oral bacteria genera remained consistent, oral bacterial diversity changed across hospitalization and over time between groups. Several oral bacteria genera and oral bacterial diversity significantly differed between groups, emphasizing the importance of an individualized approach to oral care beginning at hospital admission. Specific bacteria genera may be meaningful indicators of NV-HAP development.


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Graduation Date





Sole, Mary Lou


Doctor of Philosophy (Ph.D.)


College of Nursing



Degree Program





CFE0009346; DP0027069





Release Date

December 2023

Length of Campus-only Access

1 year

Access Status

Doctoral Dissertation (Open Access)

Included in

Nursing Commons