Contribution of pneumolysin and autolysin to the pathogenesis of experimental pneumococcal endophthalmitis.
OBJECTIVE
To determine the contribution of pneumolysin and autolysin, two putative pneumococcal virulence proteins, to the pathogenesis of Streptococcus pneumoniae endophthalmitis.


METHODS
Endophthalmitis was established in Lewis rats by intravitreal injection of pneumococcal strains at an inoculum of 10 organisms. The virulence of three closely related type 2 S. pneumoniae strains were compared: a pneumolysin-deficient derivative (PLN-A), an autolysin-deficient derivative (AL-6), and their isogenic wild-type parent (D 39). Clinical and histologic inflammation scores were compared 24 hours and 48 hours after inoculation.


RESULTS
Eyes infected with PLN-A and AL-6 strains showed less anterior segment inflammation clinically at 24 hours than did eyes infected with the wild-type strain. Histologic examination at 24 hours showed significantly less corneal infiltration and vitritis and more relative preservation of retinal tissue in eyes infected with PLN-A and AL-6 strains than in eyes infected with the wild-type strain. At 48 hours, no observable differences between PLN-A and wild-type strains were present clinically or histologically. Histologically, however, the AL-6 strain caused less retinal damage than did the wild-type strain.


CONCLUSIONS
Intraocular infection with pneumolysin-deficient S. pneumoniae results in less severe tissue damage in the first 24 hours of disease compared with infection with pneumolysin-producing S. pneumoniae. Autolysin-deficient S. pneumoniae shows a similar degree of attenuated virulence. Pneumolysin and autolysin may contribute to the early pathogenesis of pneumococcal endophthalmitis.
Ng
Eugene W M
EW
The Wilmer Ophthalmological Institute, and The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
Costa
J Ricardo
JR
Samiy
Nasrollah
N
Ruoff
Kathryn L
KL
Connolly
Edward
E
Cousins
Felecia V
FV
D'Amico
Donald J
DJ
D000818:Animals; D001426:Bacterial Proteins; D003603:Cytotoxins / Q000633:toxicity*; D009877:Endophthalmitis / Q000382:microbiology* / Q000473:pathology; D015818:Eye Infections, Bacterial / Q000382:microbiology* / Q000473:pathology; D008297:Male; D009238:N-Acetylmuramoyl-L-alanine Amidase / Q000633:toxicity*; D011008:Pneumococcal Infections / Q000382:microbiology* / Q000473:pathology; D051381:Rats; D011917:Rats, Inbred Lew; D013296:Streptococcus pneumoniae / Q000472:pathogenicity*; D013301:Streptolysins / Q000633:toxicity*; D014774:Virulence
D001426:Bacterial Proteins; D003603:Cytotoxins; D013301:Streptolysins; C032290:plY protein, Streptococcus pneumoniae; D009238:N-Acetylmuramoyl-L-alanine Amidase