Detection of pneumolysin in sputum

J Med Microbiol. 1999 Sep;48(9):863-866. doi: 10.1099/00222615-48-9-863.


Western blot detection of the species-specific pneumococcal product, pneumolysin (SPN), was shown to be almost as sensitive as PCR for the non-cultural detection of pneumococci in 27 Streptococcus pneumoniae culture-positive sputa from patients stated to have chest infections. Both techniques were considerably more sensitive than counter-current immuno-electrophoresis for pneumococcal capsular polysaccharide antigens (CPS-CIE) on the same specimens. Sensitivities for PCR, SPN-immunoblotting and CPS-CIE were 100%, 85% and 67%, respectively. In 11 S. pneumoniae culture-negative sputa taken from patients receiving antibiotics, but with proven recent pneumococcal infection, PCR and SPN-blot were positive in six (in two of which CPS-CIE was also positive), PCR alone was positive in one and SPN-blot alone was positive in one. In 11 S. pneumoniae culture-negative samples from patients not receiving antibiotics, all three tests were negative in eight, PCR was positive in three (in one of which CPS-CIE was also positive), but SPN-blot was negative in all 11. In 16 S. pneumoniae culture-negative samples from patients receiving antibiotics and with no known recent pneumococcal infections, one or more non-cultural test was positive in 11. Although further evaluation is required to assess the significance of pneumolysin detection in relation to carriage and infection and to devise a more suitable test format, these preliminary studies suggest that pneumolysin detection is a promising new approach to the non-cultural diagnosis of pneumococcal chest infection.

MeSH terms

  • Antigens, Bacterial / analysis
  • Bacterial Proteins
  • Blotting, Western / methods
  • Counterimmunoelectrophoresis
  • Humans
  • Pneumococcal Infections / diagnosis*
  • Pneumococcal Infections / microbiology
  • Polymerase Chain Reaction / methods
  • Polysaccharides, Bacterial / analysis
  • Respiratory Tract Infections / diagnosis*
  • Respiratory Tract Infections / microbiology
  • Sensitivity and Specificity
  • Sputum / chemistry*
  • Sputum / microbiology
  • Streptococcus pneumoniae / isolation & purification*
  • Streptococcus pneumoniae / metabolism
  • Streptolysins / analysis*


  • Antigens, Bacterial
  • Bacterial Proteins
  • Polysaccharides, Bacterial
  • Streptolysins
  • plY protein, Streptococcus pneumoniae