Oral Colonization with Actinomyces Species in Infants by Two Years of Age

Abstract

In early childhood, the human mouth is already colonized by actinomycetes. Due to recent taxonomic changes within the genus Actinomyces, up-to-date data are warranted on the time and succession of different Actinomyces species in the oral cavity. By using a longitudinal study design and culture techniques, we examined the age-related occurrence of Actinomyces species in saliva from 39 healthy infants at 2, 6, 12, 18, and 24 months of age. Altogether 428 Actinomyces isolates were available for this study. Identification was based on biochemical tests and gas chromatographic demonstration of metabolic end-products, and when needed, cellular fatty acid profiles were determined. The frequency of the total actinomycetal flora increased from 31% to 97% within 2 years. A. odontolyticus was the most prominent Actinomyces colonizer at all five sampling occasions. A. naeslundii was the second most common Actinomyces sp. but was not detected before the age of 1 year. As a novel observation, we found A. graevenitzii in the oral cavity. The number of A. graevenitzii isolates indicates that this species is not just occasionally present in infants' mouths. We also found A. viscosus, A. gerencseriae, A. israelii, and A. georgiae. Based on the present results, we suggest that A. odontolyticus is the main primary Actinomyces species on oral mucosal surfaces in infants up to 2 years of age.

Dental Caries: A Microbiological Approach

“…Actinomyces odontolyticus colonizes infants before eruption of teeth [45]. Some root caries lesions are dominated by Actinomyces naeslundii, A. israelii and A. gerencseriae [46][47][48][49][50]. The other significant species involved in caries includes Streptococcus mitis, Bifidobacterium and Actinomyces, a group of 'low pH' aciduric isolates which have been isolated from white spot lesions in humans [6,46,51].…”

“…Phenotypic adaptation and stress response mechanisms such as tolerance of acid, starvation, oxygen, fluoride and expression of urease [44,[46][47][48][49]52,[54][55][56][57]. that are common among strains of a species can be regarded as support of bacteria to survive stresses common to their habitats due to 'stress proteins' [58][59][60][61].…”

Molecular Analysis of Bacterial Species Associated with Childhood Caries

“…The SD was large, and the bacteria were not present in all subjects (data not shown); however, in 18 out of 29 samples from white spot lesions, the bacteria were present at greater than 3 ϫ 10 8 cells, making them the most numerous bacteria measured in these lesions. A. gerencseriae is a common inhabitant of the oral cavity of children once teeth have erupted (32), and closely related Actinomyces species have been shown to produce lactic acid (40). A. gerencseriae has been isolated from root caries (4) but has not been associated with caries in children.…”

Phenotypic Identification of Actinomyces and Related Species Isolated from Human Sources

“…3813, 2000). Actinomyces odontolyticus, Actinomyces naeslundii, and Actinomyces viscosus are the primary Actinomyces species in infants' mouths (21) as well as in early dental plaque (13,17). Actinomyces georgiae, Actinomyces gerensceriae, and Actinomyces meyeri have been isolated from gingival crevices of periodontally healthy individuals (3,10).…”

“…Actinomyces georgiae, Actinomyces gerensceriae, and Actinomyces meyeri have been isolated from gingival crevices of periodontally healthy individuals (3,10). Two new Actinomyces species of oral origin have been described recently: Actinomyces radicidentis from infected root canals (4) and Actinomyces graevenitzii from respiratory tract secretions (19) and infants' saliva (21). During the past few years, several other new species from nonoral sources have been included in the genus Actinomyces (6,7,12,16,27) and some former Actinomyces species have been moved to the closely related genera Arcanobacterium and Actinobaculum (11,18).…”