Affiliation:
1. Division of Infectious Diseases Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
2. Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts, USA
3. Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
4. Department of Medicine, Colitis and Crohn’s Disease Center, University of California, San Francisco, California, USA
Abstract
ABSTRACT
The nose and throat are important sites of pathogen colonization, yet the microbiota of both is relatively unexplored by culture-independent approaches. We examined the bacterial microbiota of the nostril and posterior wall of the oropharynx from seven healthy adults using two culture-independent methods, a 16S rRNA gene microarray (PhyloChip) and 16S rRNA gene clone libraries. While the bacterial microbiota of the oropharynx was richer than that of the nostril, the oropharyngeal microbiota varied less among participants than did nostril microbiota. A few phyla accounted for the majority of the bacteria detected at each site:
Firmicutes
and
Actinobacteria
in the nostril and
Firmicutes
,
Proteobacteria
, and
Bacteroidetes
in the oropharynx. Compared to culture-independent surveys of microbiota from other body sites, the microbiota of the nostril and oropharynx show distinct phylum-level distribution patterns, supporting niche-specific colonization at discrete anatomical sites. In the nostril, the distribution of
Actinobacteria
and
Firmicutes
was reminiscent of that of skin, though
Proteobacteria
were much less prevalent. The distribution of
Firmicutes
,
Proteobacteria
, and
Bacteroidetes
in the oropharynx was most similar to that in saliva, with more
Proteobacteria
than in the distal esophagus or mouth. While
Firmicutes
were prevalent at both sites, distinct families within this phylum dominated numerically in each. At both sites there was an inverse correlation between the prevalences of
Firmicutes
and another phylum: in the oropharynx,
Firmicutes
and
Proteobacteria
, and in the nostril,
Firmicutes
and
Actinobacteria
. In the nostril, this inverse correlation existed between the
Firmicutes
family
Staphylococcaceae
and
Actinobacteria
families, suggesting potential antagonism between these groups.
IMPORTANCE
The human nose and throat, though connected, contain distinct niches that are important sites of colonization by pathogenic bacteria. For many of these pathogens, colonization increases the risk of infection. Most research on the microbiota of nose and throat habitats has focused on carriage of one or a few pathogens. We hypothesized that increased knowledge of the composition of the complex bacterial communities in which these pathogens reside would provide new insights into why some individuals become colonized with pathogens, while others do not. Indeed, in the nostril microbiota of participants, there was an inverse correlation between the prevalences of the
Staphylococcaceae
family (
Firmicutes
), whose members include important pathogens, and the
Corynebacteriaceae
and
Propionibacteriaceae
families (both
Actinobacteria
), whose members are more commonly benign commensals. An improved understanding of competitive bacterial colonization will increase our ability to define predispositions to pathogen carriage at these sites and the subsequent risk of infection.
Publisher
American Society for Microbiology