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Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Valentino MD, McGuire AM, Rosch JW, Bispo PJ, Burnham C, Sanfilippo CM, Carter RA, Zegans ME, Beall B, Earl AM, Tuomanen EI, Morris TW, Haas W, Gilmore MS - Nat Commun (2014)

Bottom Line: Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States.These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae.They also possess putative adhesins that have not been described in encapsulated pneumococci.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, 243 Charles Street C703, Boston, Massachusetts 02114, USA [2] Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA [3] The Broad Institute of MIT and Harvard, 320 Charles Street, Cambridge, Massachusetts 02141, USA.

ABSTRACT
Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

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MLST-based phylogenetic relationships among conjunctivitis strainsSNP-based tree based on a concatenation of MLST loci, with prevalence in conjunctivitis for each ST.
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Figure 2: MLST-based phylogenetic relationships among conjunctivitis strainsSNP-based tree based on a concatenation of MLST loci, with prevalence in conjunctivitis for each ST.

Mentions: To determine the diversity of S. pneumoniae causing conjunctivitis, 271 strains5–8 were characterized by MLST16 (Fig. 1, Supplementary Data 1). Sequence type ST44817,18 was found to cause the majority of infections (67.2%). The next most common types caused substantially fewer: ST344 (8.9%), ST1186 (4.8%), ST2315 (4.4%). Together, 10 different sequence types of unencapsulated S. pneumoniae accounted for 90.8% of conjunctivitis cases. A diverse set of strains of S. pneumoniae from other types of infections, for which closed genomes are available in Genbank, were included for comparison (Supplementary Data 2). A distinct, deeply rooted cluster of S. pneumoniae was formed that included 11 unencapsulated MLST types encompassing 89.3% of conjunctivitis isolates (Fig. 2). Only 1 sequence type that is encapsulated, ST199, caused more than 2 cases. This shows that conjunctivitis in the US is mainly caused by a closely related group of unencapsulated S. pneumoniae sequence types, although other strains can cause conjunctivitis, most likely as an extension of upper respiratory infection.


Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Valentino MD, McGuire AM, Rosch JW, Bispo PJ, Burnham C, Sanfilippo CM, Carter RA, Zegans ME, Beall B, Earl AM, Tuomanen EI, Morris TW, Haas W, Gilmore MS - Nat Commun (2014)

MLST-based phylogenetic relationships among conjunctivitis strainsSNP-based tree based on a concatenation of MLST loci, with prevalence in conjunctivitis for each ST.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231546&req=5

Figure 2: MLST-based phylogenetic relationships among conjunctivitis strainsSNP-based tree based on a concatenation of MLST loci, with prevalence in conjunctivitis for each ST.
Mentions: To determine the diversity of S. pneumoniae causing conjunctivitis, 271 strains5–8 were characterized by MLST16 (Fig. 1, Supplementary Data 1). Sequence type ST44817,18 was found to cause the majority of infections (67.2%). The next most common types caused substantially fewer: ST344 (8.9%), ST1186 (4.8%), ST2315 (4.4%). Together, 10 different sequence types of unencapsulated S. pneumoniae accounted for 90.8% of conjunctivitis cases. A diverse set of strains of S. pneumoniae from other types of infections, for which closed genomes are available in Genbank, were included for comparison (Supplementary Data 2). A distinct, deeply rooted cluster of S. pneumoniae was formed that included 11 unencapsulated MLST types encompassing 89.3% of conjunctivitis isolates (Fig. 2). Only 1 sequence type that is encapsulated, ST199, caused more than 2 cases. This shows that conjunctivitis in the US is mainly caused by a closely related group of unencapsulated S. pneumoniae sequence types, although other strains can cause conjunctivitis, most likely as an extension of upper respiratory infection.

Bottom Line: Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States.These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae.They also possess putative adhesins that have not been described in encapsulated pneumococci.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, 243 Charles Street C703, Boston, Massachusetts 02114, USA [2] Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA [3] The Broad Institute of MIT and Harvard, 320 Charles Street, Cambridge, Massachusetts 02141, USA.

ABSTRACT
Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

Show MeSH
Related in: MedlinePlus