Background Respiratory infections are a leading cause of pediatric hospitalizations. This study investigated whether virus–virus or virus–Bordetella co-infections are more frequent or more severe than previously recognized. Methods This is a 3-year prospective study of children younger than 24 months hospitalized with a febrile respiratory illness. Viral pathogens were detected using multiplex polymerase chain reaction (PCR), enzyme-linked immunoassays, and/or viral cultures from nasopharyngeal samples. Bordetella infections were detected by PCR. Results A total of 201 patients were enrolled. Respiratory viruses were detected in 187 (93%) patients, with 52 (28%) multipathogen infections. The most common viruses detected were respiratory syncytial virus and rhinovirus/enterovirus. There were no differences in illness severity when comparing patients infected with one pathogen and those with multipathogen infection. Conclusion Virus co-infection in young children hospitalized with an acute febrile respiratory infection is common but does not appear to be associated with illness severity.

The performance of a new rapid lateral-flow chromatographic membrane immunoassay test kit for detection of influenza virus was evaluated and compared to that of viral culture in respiratory secretions collected from 400 adults and children seen at three large university hospitals during the recent 2003 influenza season. The rapid test provided results in 15 min, with excellent overall performance statistics (sensitivity, 94.4%; specificity, 100%; positive predictive value, 100%; negative predictive value, 97.5%). Both influenza A and B type viruses were reliably detected, with no significant difference in performance statistics noted by influenza virus type or by the center performing the test.Influenza virus is a major cause of respiratory infection in both adults and children and is a common cause of hospitalization, especially in young children, elderly adults, and persons with chronic diseases (17,20). Influenza epidemics also account for over 47,000 deaths annually in the United States. Furthermore, three global pandemics during the 20th century caused over 50 million deaths (22). Readily available, rapid, and accurate detection methods for influenza virus allow for prompt administration of appropriate antiviral therapy and judicious use of antibiotics, assist in isolation of patients in hospitals and emergency centers to reduce health care-associated spread of infection, and identify local epidemics of influenza in a timely manner (10, 13-15, 19, 21, 22). Rapid detection of influenza virus also is currently important because of increased concern for pandemic influenza caused by either naturally occurring strains, such as avian H5N1, or altered strains that may be used in an act of bioterrorism (7,8,18). Also, the diagnosis of influenza based on clinical grounds alone may be inaccurate, because the presenting symptoms of influenza are similar to those caused by other infectious agents (13). Furthermore, the rapid and accurate determination that a severe respiratory or flu-like illness is caused by influenza virus rather than severe acute respiratory syndrome-associated coronavirus or a bioterrorism agent, such as smallpox or tularemia, is helpful not only to the individual patient but also from the public health perspective (6).Currently, there are at least seven different test kits approved by the Food and Drug Administration for detection of influenza virus in respiratory samples (2-4, 9, 12, 16, 21, 23). However, not all available methods distinguish the type of influenza virus present in the sample, and those that do distinguish type A and B influenza viruses have not shown consistently reliable performance for both types of virus (3,4,9,12). This recent multicenter study documented promising performance of a new rapid lateral-flow chromatographic immunoassay for both detection and differentiation of influenza A and B type viruses in respiratory samples. . Most (239 of 400, or 59.75%) specimens were nasal washes, 122 of 400 (30.5%) were nasopharyngeal swabs, 30 of 400 (7.5%) were throat swabs, 4 of 400 ...

Respiratory viruses were detected frequently in nasopharyngeal samples from febrile neutropenic patients with negative bacterial cultures, thus providing an impetus to determine the relationship between virus detection, infection, and pathology in this unique patient population.

The MicroTrak Chlamydia trachomatis Direct Specimen Test (MT; Syva Co., Palo Alto, Calif.) was compared with cell culture in two patient populations. The sensitivity of the MT for a low-prevalence group was significantly lower (59.6%) than that for a high-prevalence group (84.4%). The results underscored the need to run the MT in parallel with culture initially if the prevalence of chlamydial infections is unknown and questioned the usefulness of the MT as a screening test for chlamydia in low-prevalence populations.

The rapid diagnosis of influenza A and B infections is beneficial for the proper management of patients with acute respiratory illness. The authors evaluated a shell vial centrifugation method to detect these viruses 16-18 hours postinoculation and compared it with conventional tube cell culture. Rhesus monkey kidney cells were used in both methods. Conventional culture of 334 respiratory specimens recovered 64 influenza isolates; the average time to positivity was 4.1 days. Low-speed shell vial centrifugation with polyclonal immunofluorescent staining 16-18 hours postinoculation was performed on 96 fresh specimens and on an additional 38 frozen specimens. These 134 specimens contained 49 of the 64 total influenza-positive specimens. The shell vial method yielded a sensitivity of 90.9% and 87.5% for fresh and frozen specimens, respectively, as compared with conventional tube cell culture. The authors conclude that the shell vial method is an important adjunct to conventional culture for the rapid detection of influenza A and B in clinical specimens.