Presence of viral nucleic acids in the middle ear: acute otitis media pathogen or bystander?

Abstract

Viruses play an important role in acute otitis media (AOM) pathogenesis, and live viruses may cause AOM in the absence of pathogenic bacteria. Detection of AOM pathogens generally relies on bacterial culture of middle ear fluid. When viral culture is used and live viruses are detected in the middle ear fluid of children with AOM, the viruses are generally accepted as AOM pathogens. Because viral culture is not sensitive and does not detect the comprehensive spectrum of respiratory viruses, polymerase chain reaction assays are commonly used to detect viral nucleic acids in the middle ear fluid. Although polymerase chain reaction assays have greatly increased the viral detection rate, new questions arise on the significance of viral nucleic acids detected in the middle ear because nucleic acids of multiple viruses are detected simultaneously, and nucleic acids of specific viruses are detected repeatedly and in a high proportion of asymptomatic children. This article first reviews the role of live viruses in AOM and presents the point-counterpoint arguments on whether viral nucleic acids in the middle ear represent an AOM pathogen or a bystander status. Although there is evidence to support both directions, helpful information for interpretation of the data and future research direction is outlined.

Figure 1

Microbiology of AOM; bacterial and viral findings of the MEF from children with AOM. Figure 1 A: data compiled from 5 studies (708 children) using bacterial and viral culture and respiratory syncytial virus-Ag detection by enzyme immunoassay (ref. 12). Figure 1B: data from a study of 79 children (with acute ear infection and drainage through existing tympanostomy tubes) using comprehensive microbiologic assays, including conventional and molecular viral diagnostics (ref. 18).

Figure 1

Microbiology of AOM; bacterial and viral findings of the MEF from children with AOM. Figure 1 A: data compiled from 5 studies (708 children) using bacterial and viral culture and respiratory syncytial virus-Ag detection by enzyme immunoassay (ref. 12). Figure 1B: data from a study of 79 children (with acute ear infection and drainage through existing tympanostomy tubes) using comprehensive microbiologic assays, including conventional and molecular viral diagnostics (ref. 18).

Figure 2

Timeline of two siblings ages 4 years (above) and 5 (below). PV, Picornavirus RT-PCR; O, negative test; +, Picornavirus positive; RI, Respiratory illness; Bar, span of reported symptoms, dashed line-connects positive samples to associated illness. Reprinted from J. Med. Virol. 78:644-650, 2006. Picornavirus RNA was detected in 42% of weekly samples of nasopharyngeal secretions.