We’re thrilled that our publication was featured as an editorial in Cell Host & Microbe. Read Drs Erin S. Keebaugh and William W. Ja’s excellent editorial here…..
Colonization of Streptococcus pneumoniae within the upper respiratory tract (URT) of elderly individuals is a major concern, as it often results in the development of pneumonia, which can be deadly in this population. A study published by MIRC Masters’ student Netusha Thevaranjan, under the supervision of Dr. Dawn Bowdish, examined how aging can change the composition of the respiratory microbial community and consequently, impact bacterial colonization. Using a mouse model of pneumococcal colonization, the study characterized the composition of the URT microbiota in young, middle-aged, and old mice in both the naïve state, and throughout the course of nasopharyngeal colonization with S. pneumoniae. It was shown that the composition of the URT microbiota differs with age, and that colonization with S. pneumoniae in older mice disrupted pre-existing microbial communities.
Furthermore, the study demonstrated that there were several interspecies interactions between S. pneumoniae and resident microbes. In particular,Streptococcus interacted competitively with Staphylococcus and synergistically with Haemophilus. This work provides insight into how aging influences bacterial colonization, and understanding the relationship between these two factors can help create strategies to protect the elderly from age-associated infections and disease. Read More
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Stearns JC, Davidson CJ, McKeon S, Whelan FJ, Fontes ME, Schryvers AB, Bowdish DM, Kellner JD, Surette MG. Culture and molecular-based profiles show shifts in bacterial communities of the upper respiratory tract that occur with age. ISME J. 2015 May;9(5):1268. doi: 10.1038/ismej.2015.49.
Abstract: The upper respiratory tract (URT) is a crucial site for host defense, as it is home to bacterial communities that both modulate host immune defense and serve as a reservoir of potential pathogens. Young children are at high risk of respiratory illness, yet the composition of their URT microbiota is not well understood. Microbial profiling of the respiratory tract has traditionally focused on culturing common respiratory pathogens, whereas recent culture-independent microbiome profiling can only report the relative abundance of bacterial populations. In the current study, we used both molecular profiling of the bacterial 16S rRNA gene and laboratory culture to examine the bacterial diversity from the oropharynx and nasopharynx of 51 healthy children with a median age of 1.1 years (range 1–4.5 years) along with 19 accompanying parents. The resulting profiles suggest that in young children the nasopharyngeal microbiota, much like the gastrointestinal tract microbiome, changes from an immature state, where it is colonized by a few dominant taxa, to a more diverse state as it matures to resemble the adult microbiota. Importantly, this difference in bacterial diversity between adults and children accompanies a change in bacterial load of three orders of magnitude. This indicates that the bacterial communities in the nasopharynx of young children have a fundamentally different structure from those in adults and suggests that maturation of this community occurs sometime during the first few years of life, a period that includes ages at which children are at the highest risk for respiratory disease.
Verschoor CP, Dorrington MG, Novakowski KE, Kaiser J, Radford K, Nair P, Anipindi V, Kaushic C, Surette MG, Bowdish DME. MicroRNA-155 Is Required for Clearance of Streptococcus pneumoniae from the Nasopharynx. Infect Immun. 2014 Nov;82(11):4824-33. doi: 10.1128/IAI.02251-14.
This paper outlines how microRNA- (miR-)155 regulates the immune response to S. pneumoniae colonization in the nasal passages of mice by stimulating the differentiation of Th17 cells.
Kaiser JC, Verschoor CP, Surette MG, Bowdish DME. Host cytokine responses distinguish invasive from airway isolates of the Streptococcus milleri/anginosis group. BMC Infect Dis. 2014 Sep 11;14:498. doi: 10.1186/1471-2334-14-498.
This paper demonstrates that there are host- and strain- specific responses to isolates of the Streptococcus milleri/anginosis group and that isolates from invasive disease appear to be more immunostimulatory than those from commensal relationships.
Whelan FJ, Verschoor CP, Stearns JC, Rossi L, Luinstra K, Loeb M, Smieja M, Johnstone J, Surette MG, Bowdish DM. The Loss of Topography in the Microbial Communities of the Upper Respiratory Tract in the Elderly. Ann Am Thorac Soc. 2014 Mar 6.
This paper describes how the microbial communities of the anterior nares and nasopharynx change between adults and the elderly.