Direct immunofluorescence assay compared to cell culture for the diagnosis of mucocutaneous herpes simplex virus infections in children.

BACKGROUND: Direct immunofluorescence assay (DFA) is commonly used for the rapid identification of herpes simplex virus (HSV) infection in mucocutaneous lesions, yet little is known about its diagnostic accuracy. OBJECTIVE: To determine the diagnostic yield and accuracy of HSV DFA for the diagnosis of mucocutaneous HSV infection in pediatric patients. STUDY DESIGN: Retrospective cross-sectional study of all patients who underwent HSV DFA testing by the Texas Children's Hospital Diagnostic Virology between January 1, 1995 and December 31, 2005. HSV DFA sensitivity, specificity, positive likelihood ratio (LRs), and negative LRs were estimated using viral culture as the reference standard. RESULTS: 659 specimens were submitted for HSV DFA with concurrent viral cultures. Viral cultures were positive for HSV type 1 in 158 (24%) and HSV type 2 in 2 (0.3%). There were 433 different patients with a median age of 8.6 years. Types of lesions were as follows: 50% ulcerative, 26% vesicular, 8% erythema or purpura, 5% pustular, and 11% missing. Of the 659 specimens submitted for HSV DFA, 160 (24%) were inconclusive due to inadequate cells. Of the 499 adequate specimens, overall HSV DFA test accuracy was: sensitivity 61%, specificity 99%, LR positive 40, and LR negative 0.39. CONCLUSIONS: A quarter of specimens submitted for HSV DFA testing are not adequate for DFA testing. When HSV DFA can be performed, it is specific, but not sensitive, for the identification of mucocutaneous HSV infection in children.

Performance of a new immunochromatographic assay for detection of adenoviruses in children.

BACKGROUND: Adenoviruses are a prominent cause of respiratory, ocular, gastrointestinal, and disseminated diseases in healthy and immunocompromised children. An accurate rapid diagnostic assay may impact clinical decision-making. OBJECTIVES: Evaluate the performance of a new rapid assay for detection of adenoviruses directly in pediatric clinical specimens. STUDY DESIGN: The rapid assay was performed on adenovirus culture-positive original samples and on an equal number of culture-negative samples matched by patient age and specimen type. Discrepant results were resolved using a polymerase chain reaction (PCR) assay. RESULTS: 200 adenovirus culture-positive and 200 adenovirus culture-negative samples were evaluated from 315 different patients. Overall sensitivity was 55% and specificity was 98.9%. The assay was most sensitive in children 5 years old and younger and most specific in respiratory samples. CONCLUSIONS: The rapid assay was highly specific for detecting adenovirus infections in children. However, since this rapid assay had only moderate to low sensitivity, samples with negative rapid assay results should have additional testing for adenovirus performed by either viral culture or PCR.

Rapid assays for the diagnosis of influenza A and B viruses in patients evaluated at a large tertiary care children's hospital during two consecutive winter seasons.

BACKGROUND: The rapid and accurate diagnosis of influenza facilitates antiviral therapy, judicious antibiotic usage, and cohorting patients to decrease nosocomial infection. OBJECTIVE: To determine the utility of rapid influenza tests in a children's hospital. STUDY DESIGN: Two in vitro rapid immunochromatographic assays that detect and distinguish influenza A and B viruses were compared to the reference standard of viral culture. RESULTS: In 9186 patients tested, overall sensitivity of the rapid assays for influenza A was 64.4% and specificity was 98.3%. Sensitivity and specificity were 28% and 99.9%, respectively, for influenza B. Overall sensitivity and specificity for Remel Xpect (2004/2005) were 47.7% and 98.7% for influenza A, and 20.3% and 99.8% for influenza B, respectively. Overall sensitivity and specificity of Binax NOW Flu A&B (2005/2006) were 78.3% and 98% for influenza A, and 35.9% and 99.9% for influenza B, respectively. The results for influenza B with both assays were significantly lower than previously reported and lower than stated in the manufacturer's package insert. CONCLUSIONS: In a contemporary clinical setting, rapid assays for influenza displayed significantly lower sensitivities, especially for influenza B, than prior reports. Differences in pre- and post-licensure performance demonstrate the importance of continuous evaluation of rapid diagnostic tests for influenza.

Performance of a rapid assay (Binax NOW) for detection of respiratory syncytial virus at a children's hospital over a 3-year period.

A rapid assay, Binax NOW RSV, was compared to viral culture for 14,756 pediatric respiratory specimens obtained from 2003 to 2006. There were 794 viral culture-confirmed respiratory syncytial virus infections. Sensitivity was 81%, and specificity was 93.2%. Sensitivity was greatest for neonates (91.1% versus 80.7% [P < 0.01]).

Performance characteristics of a rapid immunochromatographic assay for detection of influenza virus in children during the 2003 to 2004 influenza season.

STUDY OBJECTIVE: We evaluate the performance of a rapid assay (Binax NOW) for the detection of influenza A virus in children. METHODS: The performance of an in vitro rapid immunochromatographic assay for detection of influenza A virus was compared to viral culture in 4,383 consecutive respiratory specimens received during the 2003 to 2004 season, which included an influenza A epidemic in October and November of 2003. RESULTS: The overall test sensitivity was 61.6% (95% confidence interval [CI] 60.3% to 63.2%) and specificity was 95.8% (95% CI 95.1% to 96.3%). In preplanned subset analyses, we found the test more sensitive in infants aged 90 days or younger (sensitivity 70.3%; specificity 96.6%) and less specific during the epidemic (sensitivity 61.7%; specificity 90.4%). CONCLUSION: This rapid assay was highly specific for detecting influenza A in children and thus appears useful for confirming this infection. Because of its limited sensitivity, however, a negative test cannot rule out influenza A.

Frequent detection of polyomaviruses in stool samples from hospitalized children.

BACKGROUND: Infection with BK virus (BKV) generally occurs early during life, but its mode of transmission has not been clearly defined. We tested the hypothesis that polyomavirus shedding in stool may be a source of BKV exposure.METHODS. Pediatric stool and rectal swab samples were tested for the presence of polyomavirus DNA by a polymerase chain reaction (PCR) assay that could detect a conserved region in the large T antigen gene of BKV, JC virus (JCV), and simian virus 40 (SV40). The specific viruses detected by this assay were confirmed by DNA sequence analysis of the PCR amplicons.Results. Of 120 samples collected from 99 patients, 54 (45.0%) were positive for polyomavirus DNA. Of the 99 patients, 46 (46.5%) had at least 1 positive sample, with 38 (38.4%) positive for BKV and 8 (8.1%) positive for SV40. JCV was not detected. There was no association between polyomavirus fecal shedding and age, sex, race/ethnicity, immune status, or symptoms of gastrointestinal disease in the children studied. The BKV strains detected displayed polymorphisms in the T antigen sequence.Conclusions. Polyomaviruses are frequently present in stool samples from hospitalized children. These findings suggest that fecal-oral transmission of BKV may play a role in the ubiquity of infection.