Oral/Dental Considerations The oral mucosa and tooth surfaces of children who are beyond infancy are populated by a variety of pathogenic and Baltimore et al Infective Endocarditis in Childhood: 2015 Update 1491 nonpathogenic bacteria, which are representative of hun- dreds of strains of aerobic and anaerobic species.,35,36 This oral flora, in both health and disease, is different from adults and less diverse, but it becomes more like that of adults as the child ages, including increases in the percentage of VGS ( -hemolytic streptococci), Prevotella, and Actinomyces spe- In health, the child s oral flora has a variety of VGS, Neisseria species, Haemophilus species, and Staphylococcus species. In older children, species responsible for periodontal diseases (eg, Capnocytophaga) can be found along with oth- ers known to cause IE (eg, Aggregatibacter actinomycetem- This is particularly relevant with regard to the formation of plaque on the teeth of children at risk for IE. Dental plaque biofilm formation begins soon after a tooth surface is cleaned, and in the absence of oral hygiene, this bio- film thickens and evolves to include a more pathogenic bacte- rial flora largely isolated from the immune system. In contrast to plaque in adults, plaque bacteria on the visible surfaces of the teeth (supragingival) in children are similar to those in the gingival crevice (subgingival space), where there are more Gram-negative and anaerobic species than other sites in the oral The host response to plaque is gingival inflammation and enlargement (gingivitis). Gingivitis can result in an increased depth to this shallow gingival crevice between the tooth surface and the gingival crevicular mucosa that is more difficult to clean with a toothbrush and floss. In the absence of disease, the cre- vicular mucosa serves as a barrier to bacterial invasion. 