Adenovirus infection encompasses an array of clinical syndromes that can be caused by adenoviruses, ranging from benign and self-limiting upper respiratory illness to life-threatening conjunctival infection in neonates, hemorrhagic cystitis and severe disseminated infection of various tissues. Microbiological testing is pivotal in order to make the diagnosis, primarily through methods that are able to detect viral deoxyribonucleic acid (DNA) in patient samples.
Adenoviruses, belonging to the group of double-stranded positive (+) sense DNA viruses, are a large group of pathogens responsible for numerous types of human disease  . They are divided into six subgroups (A, B, C, D, E, and F) and more than 60 different serotypes have been described in the literature   . Common modes of transmission include the fecal-oral, direct contact with infected secretions, and respiratory spread, suggesting that the virus is able to cause local outbreaks  . As the pediatric population is the age group where adenovirus infections are most prevalent, kindergartens, summer or college camps and schools are the main sites of outbreaks . In addition, hospital-based (nosocomial) and severe, sometimes even life-threatening outbreaks have known to occur . Adenovirus infection is seen across all ages and gender, although immunocompromised hosts seem to be at an increased risk compared to the immunocompetent . The clinical presentation of adenovirus infection depends on the organ or tissue affected. Keratoconjunctivitis ( the principal form of the disease that causes outbreaks) manifests with fever, vomiting, diarrhea, muscle pain and malaise, usually after an incubation period of 1-14 days, whereas rhinitis, fever, and cervical lymphadenopathy are typical for pharyngoconjunctival fever (PCF) . Other notable infections caused by adenovirus are those of the respiratory tract (both lower and upper), gastroenteritis, central nervous system infection (CNS), and hemorrhagic cystitis . Neonatal adenovirus infection, despite being rare, is a frequently fatal disease characterized by severe forms of conjunctivitis (as a result of viral transmission from the mother), cyanosis, respiratory failure, fever and a rash in neonates .
Despite the nonspecific signs and symptoms of an adenovirus infection, the physician must perform a thorough physical examination and obtain a detailed patient history. Patients (or parents of the infected children) should be asked about similar symptoms in people with whom they were in contact (schools, kindergartens, camps, other crowded areas), as it may provide valuable clues toward the diagnosis. To confirm adenovirus infection, a comprehensive microbiological investigation is necessary. It must be pointed out that detection of adenoviruses readily occurs in asymptomatic individuals, and thus the term adenovirus infection does not always imply to a disease state . In the presence of symptoms, however, the identification of this virus is highly suggestive that it is responsible for their onset. Direct methods in the form of isolation of virus in cultures or antigen/viral DNA detection from patient samples are recommended diagnostic tests, but since up to 3 weeks are necessary for viral cultures to yield conclusive results, the focus of diagnostics is turned to the latter method  . Polymerase chain reaction (PCR) is the gold standard for both screening and diagnostic purposes  . Based on the clinical and microbiological criteria, an adenovirus infection may be probable (absence of histologic criteria in the presence of typical symptoms) or proven (both microbiological and corresponding clinical confirmation), which can be further divided into local (when the virus is isolated from local specimens and not peripheral blood) or systemic (detection of virus in peripheral blood along with clinical manifestation) .