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Infect. Immun., Apr 1996, 1140-1145, Vol 64, No. 4
K Sato, MK Quartey, CL Liebeler, CT Le and GS Giebink
Streptococcus pneumoniae cell wall and pneumolysin are important
contributors to pneumococcal pathogenicity in some animal models. To
further explore these factors in middle ear inflammation caused by
pneumococci, penicillin-induced inflammatory acceleration was studied by
using three closely related pneumococcal strains: a wild-type 3 strain
(WT3), its pneumolysin-negative derivative (P-1), and into
autolysin-negative derivative (A-1). Both middle ears of chinchillas were
inoculated with one of the three pneumococcal strains. During the first 12
h, all three strains grew in vivo at the same rate, and all three strains
induced similar inflammatory cell responses in middle ear fluid (MEF).
Procaine penicillin G was given as 12 h to one-half of the animals in each
group, and all treated chinchillas had sterile MEF at 24 h. Penicillin
significantly accelerated MEF inflammatory cell influx into WT3-and
P-1-infected ears at 18 and 24 h in comparison with the rate for
penicillin-treated A-1-infected ears. Inflammatory cell influx was
slightly, but not significantly, greater after treatment of WT3 infection
than after treatment of P-1 infection. Interleukin (IL)-1beta and IL-6, but
not IL-8, concentrations in MEF at 24 h reflected the penicillin effect on
MEF inflammatory cells; however, differences between treatment groups were
not significant. Results suggest that pneumococcal otitis media
pathogenesis is triggered principally by the inflammatory effects of intact
and lytic cell wall products in the middle ear, with at most a modes
additional pneumolysin effect. Investigation strategies that limit the
release of these products or neutralize them warrant further investigation.
Copyright © 1996, American Society for Microbiology
Roles of autolysin and pneumolysin in middle ear inflammation caused by a type 3 Streptococcus pneumoniae strain in the chinchilla otitis media model
Otitis Media Research Center, Minneapolis, Minnesota, USA.
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