Rapid bedside tests for diagnosis, management, and prevention of nosocomial influenza.

Like other respiratory viruses, influenza is responsible for devastating nosocomial epidemics in nursing homes as well as in conventional wards and emergency departments. Patients, healthcare workers, and visitors may be the source of nosocomial influenza. Despite their limited sensitivity, rapid diagnostic tests for influenza can be of real value; they enable early introduction of measures to prevent spread and early specific antiviral treatment of cases. However, these tests cannot detect oseltamivir resistance, susceptibility testing being carried out only in specialist laboratories. Although resistance is rare, it can emerge during treatment, especially of very young children or immunocompromised patients. In the latter, the shedding of resistant influenza virus can last several weeks. Sporadic instances of nosocomial transmission among immunocompromised patients have been reported. The limitations of bedside tests for influenza make them unsuitable for use as stand-alone diagnostic tools. However, their limitations do not preclude their use for detection and subsequent management of nosocomial influenza, for which they are rapid, easy, and cost-effective. Recent developments in these tests look promising, offering prospects of increased sensitivity, increased specificity, and screening for antiviral susceptibility.