title: The important role of nontypable Streptococcus pneumoniae international clones in acute conjunctivitis.
abstract: BACKGROUND
  In a recent epidemiological study in southern Israel, nontypable Streptococcus pneumoniae isolates were found to be highly associated with sporadic cases of acute conjunctivitis (AC). The purpose of the present study was to evaluate the relative importance in causing AC of the absence of capsule versus genotype properties.
  
  
  METHODS
  DNA typing by pulsed-field gel electrophoresis (PFGE) was performed on 148 nontypable organisms isolated from 3 sites: nasopharynx of healthy children, middle-ear fluid, and conjunctiva.
  
  
  RESULTS
  Analysis of the PFGE patterns revealed the presence of 6 clusters; 2 clusters that included 44% of the isolates (65/148) were associated with AC, and the remaining 4 were frequently isolated from the nasopharynx. Multilocus sequence typing, performed on representative isolates of the 2 major clusters, confirmed that the organisms were pneumococci; one is a single-locus variant of sequence type (ST) 448, and the other is related to ST344. Both types appear to be members of pneumococcal lineages that have lost capsular loci. The nontypable isolates showed high rates of resistance to antimicrobial agents.
  
  
  CONCLUSIONS
  Our data suggest that the absence of the capsule--along with other, yet-unidentified genetic characteristics--provide S. pneumoniae with a selective virulence advantage in conjunctivitis.
authors.affiliation: Pediatric Infectious Disease Unit, Soroka University Medical Center and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84101, Israel. npurat@bgu.ac.il
authors.forename: Nurith
authors.initials: N
authors.lastname: Porat
authors.forename: David
authors.initials: D
authors.lastname: Greenberg
authors.forename: Noga
authors.initials: N
authors.lastname: Givon-Lavi
authors.forename: Dror S
authors.initials: DS
authors.lastname: Shuval
authors.forename: Ronit
authors.initials: R
authors.lastname: Trefler
authors.forename: Orit
authors.initials: O
authors.lastname: Segev
authors.forename: William P
authors.initials: WP
authors.lastname: Hanage
authors.forename: Ron
authors.initials: R
authors.lastname: Dagan
mesh_terms: D015373:Bacterial Typing Techniques; D002648:Child; D003231:Conjunctivitis / Q000145:classification / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007557:Israel; D011008:Pneumococcal Infections / Q000145:classification*; D013296:Streptococcus pneumoniae / Q000145:classification* / Q000302:isolation & purification / Q000472:pathogenicity
chemical_list: D004269:DNA, Bacterial