This Article  • Full text  • PDF  • Reply to article  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Contact me when this article is cited  Related Content  • Similar articles in this journal  Topic Collections  • Bacterial Infections  • Middle/ External Ear Disorders  • Infectious Diseases  • Alert me on articles by topic

Effect of Pneumococcal Proteins

Patricia Schachern, BS; Vladimir Tsuprun, PhD; Sebahattin Cureoglu, MD; Patricia Ferrieri, MD; David Briles, PhD; Michael Paparella, MD; Steven Juhn, MD

Arch Otolaryngol Head Neck Surg. 2008;134(6):658-662.

Objective  To determine whether mutants of Streptococcus pneumoniae that are deficient in pneumococcal surface protein A (PspA), pneumococcal surface antigen A (PsaA), or pneumolysin (Ply) are less virulent and less likely to penetrate the round window membrane (RWM).

Design  Histopathologic comparison of wild-type S pneumoniae and its mutants deficient in PspA, PsaA, and Ply.

Setting  Otopathology Laboratory, Department of Otolaryngology, University of Minnesota Medical School, Minneapolis.

Participants  Forty young chinchillas (weight, 250-350 g) with normal external auditory canals and tympanic membranes.

Intervention  Animals were divided into 3 groups and bullae inoculated with wild-type S pneumoniae serotype 2, strain D39, or its mutants deficient in PspA, PsaA, or Ply. Two days after inoculation, bullae were processed for light microscopy and transmission electron microscopy.

Main Outcome Measures  Comparison of inflammatory cell infiltration and penetration of bacteria into the round window membrane and adjacent scala tympani.

Results  Histopathologic findings using wild-type S pneumoniae and Ply^– mutant were similar and included otitis media and the presence of inflammatory cells and damage to and passage of bacteria through the RWM. Although otitis media was seen with the PspA^– and PsaA^– mutants, we observed no passage of bacteria through the RWM.

Conclusions  Both PspA and PsaA affect the ability of S pneumoniae to penetrate the RWM. Understanding the role of S pneumoniae virulence proteins in the pathogenesis of the middle ear, RWM, and inner ear will provide new strategies for the prevention and treatment of otitis media and its complications.

Author Affiliations: Departments of Otolaryngology (Ms Schachern and Drs Tsuprun, Cureoglu, Paparella, and Juhn) and Pediatrics and Laboratory Medicine and Pathology (Dr Ferrieri), University of Minnesota Medical School, and Paparella Ear Head and Neck Institute (Dr Paparella), Minneapolis, Minnesota; and Department of Microbiology, University of Alabama at Birmingham (Dr Briles).