The Role of Bacterial Enzymes in Inducing Inflammation in the Middle Ear Cavity

Abstract

Current knowledge of the pathophysiology of bacterial infections is elementary. The initial events leading to the invasion of host tissues are a matter of conjecture for many bacterial organisms. This is particularly true for pneumococci, the most frequent causative organisms of acute otitis media. Bacterial enzymes may account for the initial disruption of host tissues, and this study explored their role in the infectious process. As a first step, pneumococcal cultures were analyzed, and significant levels of the enzymes lipase and hyaluronidase were demonstrated. Secondly, the presence of these enzymes in middle ear effusions was explored in an animal model of acute otitis media. The enzymes reached peak levels at seven days. The third and most important portion of the study examined the significance of these enzymes in producing inflammation and alterations in the middle ear cavity of normal experimental animals. This portion was a histologic comparison of temporal bone specimens and demonstrated that marked acute and chronic changes can be induced by placing solutions of these enzymes in the middle ear cavity. This study concludes that bacterial enzymes play an important role in the induction of acute otitis media.

Virulence of enterococci

“…Unsworth (222) observed hyaluronidase-producing Streptococcus milleri strains from abscesses more frequently (83%) than strains that were part of the normal flora (25%). Pneumococcal hyaluronidase appeared to play a role in one animal model of middle ear inflammation (150). In addition, it has been described as a spreading factor for Ancylostoma duodenale (hookworm) in cutaneous larva migrans (108) and as important for the dissemination of Treponema pallidum (74).…”

Purification and Properties of Streptococcus pneumoniae Neuraminidase

“…Bacterial en zymes released by microorganisms in the middle ear cavity could play a significant role in inducing inflammation [4,5], Neur aminidase has been shown to be present in MEE from patients with both acute and chronic OME [4,6,7]. In each of these stud ies, the finding of neuraminidase activity has been highly correlated with the presence of Streptococcus pneumoniae, one of the most commonly observed pathogens in OME [8], This organism is a rich source of a variety of extracellular glycosidases, including neur aminidase, ß-galactosidase, and hexosamini dase, all of which are capable of removing sugar residues from glycoproteins and glycolipids lining the middle ear mucosae.…”

Protease inhibitors α1‐antitrypsin and ilomastat are not ototoxic in the chinchilla

“…Human and bacterial proteases have long been known to play a role in the pathogenesis of otitis media 23,24 . Leukocyte‐derived proteases help to eradicate bacterial infection 25 .…”