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

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 US. 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.

Mutations in Pneumococcal cpsE Generated via In Vitro Serial Passaging Reveal a Potential Mechanism of Reduced Encapsulation Utilized by a Conjunctival Isolate

“…S. pneumoniae TIGR4 and its unencapsulated derivative AC4421 were from our laboratory stocks. For indicated experiments, encapsulated and unencapsulated conjunctival isolates (serotype 19A) were utilized (43).…”

A novel streptococcal cell–cell communication peptide promotes pneumococcal virulence and biofilm formation

“…Epidemiologic studies reveal that infection with multiple pneumococcal strains occur in an estimated 20-40% of infections (Everett et al, 2012;Rodrigues et al, 2013;Saha et al, 2015). Furthermore, multiple streptococcal species, such as S. mitis and S. oralis, commonly colonize the human nasopharynx, and there are many examples of DNA exchange between pneumococcus and these species (Dowson et al, 1993;Chi et al, 2007;Croucher et al, 2012;Johnston et al, 2013;Valentino et al, 2014;Eutsey et al, 2015). We have analyzed the distribution of vp1 across pneumococci and related species: vp1 is widely distributed in pneumococcal strains (Fig.…”

N -Acetyl- l -Cysteine and Cysteamine as New Strategies against Mixed Biofilms of Nonencapsulated Streptococcus pneumoniae and Nontypeable Haemophilus influenzae

“…The widespread use of pneumococcal conjugate vaccines, which target the capsular polysaccharide (CPS), has led to decreased nasopharyngeal carriage of vaccine serotypes but a concomitant increase in the carriage of nonvaccine serotypes and nonencapsulated (NE) S. pneumoniae. NE S. pneumoniae, which was once considered to be avirulent (with some exceptions, e.g., strains causing conjunctivitis) (9), is currently recognized as playing important roles in AOM pathogenesis (10). Indeed, NE S. pneumoniae accounts for up to 8% of AOM pneumococcal isolates, the majority of which are resistant to one or more antibiotics (11), although values near 17% have been reported in some populations (12).…”