Ear infections are among the most common diseases seen in pediatric practice. They have generally been considered bacterial diseases and are therefore usually treated with antibiotics. New research, published in the December 15 issue of Clinical Infectious Diseases and currently available online, provides evidence that viruses are found in a great many ear infection cases and may complicate treatment.

The researchers used a variety of laboratory techniques to identify the pathogen that caused ear infections, known clinically as acute otitis media (AOM), in 79 young children. They found bacteria in 92 percent of the cases, viruses in 70 percent, and both bacteria and viruses in 66 percent.

According to Aino Ruohola, MD, PhD, from the Turku University Hospital in Finland and lead author of the study, "the major finding of the study is that acute otitis media is a coinfection of bacteria and viruses in the great majority of children. This is actually logical since acute otitis media is virtually always connected to viral respiratory infection."

Antibiotics, which are effective against the bacteria that cause AOM, have no effect on the viruses found in AOM infections. Therefore, the standard treatment for AOM--antibiotics--can be, at best, partially effective in the majority of cases. "Based on this and previous research," said Dr. Ruohola, "it is possible that viruses cause a considerable proportion of clinical treatment failures. Thus, in these cases a new antibiotic is not necessarily the best choice although bacteria resistant to common antibiotics are wide-spread."

The good news is that many cases of AOM recover spontaneously without antibiotic treatment, a fact that has led the American Academy of Pediatrics and the American Academy of Family Physicians to recommend withholding antibiotic treatment in mild AOM cases.

In an accompanying editorial, Tasnee Chonmaitree, MD, from the University of Texas Medical Branch, notes that studies of AOM have shown that viruses may impair antibiotic efficacy by several mechanisms. "Further studies," she writes, "are required to determine the effect of combined bacterial and viral infections of the respiratory tract in adults and children." She says that if this joint bacterial/viral infection concept also applies to respiratory diseases such as sinusitis and pneumonia, then the expectation of antibiotic efficacy in these diseases needs to be adjusted.

Founded in 1979, Clinical Infectious Diseases publishes clinical articles twice monthly in a variety of areas of infectious disease, and is one of the most highly regarded journals in this specialty. It is published under the auspices of the Infectious Diseases Society of America (IDSA). Based in Alexandria, Va., IDSA is a professional society representing about 8,000 physicians and scientists who specialize in infectious diseases. For more information, visit http://www.idsociety.org.