Assessment of a rapid immunochromatographic test for the diagnosis of norovirus gastroenteritis

Noroviruses are the leading cause of acute gastroenteritis in people of all ages. Since the viruses are highly infectious, rapid and early diagnosis is important to prevent and control the disease. The present study aimed to evaluate the commercial immunochromatographic test RIDA? QUICK Norovirus for the detection of norovirus in stool samples from patients with acute gastroenteritis in Thailand. As compared with reference RT-PCR results, the RIDA? QUICK Norovirus assay provided a sensitivity of 48.2 and 83.3% with a specificity of 87.5%. False positive results were observed in 12.5% of norovirus-negative stool samples. Based on commercial quantitative real-time RT-PCR, the RIDA? QUICK Norovirus assay revealed a highly significant association, p-value <0.001, and good agreement (kappa?=?0.6). The assay could detect norovirus in stool samples ranging from 3.22?×?10(6) to 3.26?×?10(8) copies/ml. False negative results occurred in the stool samples containing 5.9?×?10(6) copies/ml of norovirus GI or 1.85?×?10(4)?-?4.28?×?10(5) copies/ml of GII. The immunochromatographic RIDA? QUICK Norovirus assay may be useful for rapid screening of norovirus infections in patients with acute gastroenteritis in both developed and developing countries where the RT-PCR method has not been established for routine diagnosis.     

One-step quantitative RT-PCR for the detection of rotavirus in acute gastroenteritis

The standard diagnosis of rotavirus gastroenteritis is based on the demonstration of rotavirus antigen in stools using an enzyme immunoassay (EIA). In this study, a one-step quantitative RT-PCR (Q-PCR) was used for sensitive detection of rotavirus in diarrheal stools. The primers and TaqMan probe for the Q-PCR were selected from a highly conserved region of the non-structural protein 3 (NSP3) of rotavirus. After validation, the test was applied to study rotavirus EIA positive (N=25) and EIA negative (N=143) stool specimens from cases of acute gastroenteritis of all degrees of severity in a prospective follow-up cohort of infants from 2 months to 2 years of age. Q-PCR detected all 25 EIA positive rotavirus antigens and seven additional cases that were rotavirus EIA negative, i.e. 28% more rotavirus positive cases than identified by EIA. It is concluded that Q-PCR using primers targeted at NSP3 is a rapid and sensitive method for diagnosing acute rotavirus gastroenteritis.     

Detection ofSalmonella species in faeces by latex agglutination in enrichment broth

A test was developed for the detection ofSalmonella spp. in stool enrichment broths using latex particles coated with polyvalent salmonella H antiserum. The test detected salmonella in 146 of 168 positive specimens and gave a positive result in two of 308 culture negative specimens. There was a positive predictive value of 99.6% and a negative predictive value of 95.4%, with an overall efficiency of 95%. Results were available within 18h of receipt compared to the 48–72h required for conventional methods. A positive result was also available within 4h for 17 of 18 specimens tested from patients with active salmonella gastroenteritis. The latex test was rapid, easy to perform and cost-effective, and would appear to be a useful aid in the rapid diagnosis of salmonella infection and carriage.     

Probabilities in norovirus outbreak diagnosis.

BACKGROUND: Noroviruses are recognized as the most common cause of outbreaks of acute gastroenteritis. Yet, diagnostic testing for norovirus is based mostly on RNA detection by RT-PCR, which is not widely available. While antigen detection tests (ELISAs) are easier to perform, they are in general less sensitive. OBJECTIVES: Our aim was to provide a scientific basis for declaring norovirus as the causative agent of an outbreak of acute gastroenteritis. STUDY DESIGN: Statistical analysis used binomial distribution to determine the minimal number of positive samples, and the probability of detecting the required number of positive samples, for different tests, required to assign norovirus as the causative agent of an outbreak of acute gastroenteritis. RESULTS: For either a standard RT-PCR or a commercially available ELISA, finding only 1 sample positive out of 2, 3 or 4 samples is sufficient to assign norovirus as the causative agent of an outbreak of acute gastroenteritis. However, when ELISA is used, the probability of detecting this required minimum number of positive samples is low when small numbers of samples are tested (57% when 2 samples are tested; 72% when 3 samples are tested). In order to reach a 90% probability of detecting a norovirus outbreak (false negativity at outbreak level <10%), at least 3 samples should be tested using RT-PCR, and 6 samples when using an ELISA. CONCLUSIONS: The sensitivity for NoV outbreak diagnosis will increase from 57% to 92%, or from 84% to 96%, for ELISA or RT-PCR respectively, when sample size increases from 2 to 6. Thus, using ELISA instead of RT-PCR for the detection of norovirus in stool samples will result in considerable numbers of false negative outbreaks unless a minimum of 6 samples are tested per outbreak.     

Rapid diagnosis of rotavirus gastroenteritis by a commercial latex agglutination test.

The Rotalex test, a commercial latex agglutination test for rotavirus, was compared with direct electron microscopy (EM) and the Rotazyme test I, a commercial enzyme immunoassay, for detection of rotavirus in stools of children and neonates. For initial stool specimens from 265 children (less than 3 years old) with diarrhea, the Rotalex test had a sensitivity of 81.7% and specificity of 99.5% compared with EM results. Positive and negative predictive values were 98 and 94.9%, respectively. The Rotalex test was slightly more sensitive and specific than the Rotazyme test. When daily stool specimens from patients with rotavirus gastroenteritis were examined, the sensitivity of the Rotalex test varied depending on the time of stool collection relative to the onset of symptoms. Sensitivity was 100 (20/20), 96 (23/24), and 54% (7/13) during 1 to 4, 5 to 7, and 8 to 18 days, respectively, after the onset of symptoms. The sensitivity of the Rotazyme test varied similarly with days from onset. We also examined 214 EM-negative stool specimens from asymptomatic newborns. False positivity by the Rotalex test was only 3.3% (7/214) compared with 4.2% (9/215) for the Rotazyme test. The Rotalex test was as sensitive and specific as EM for detection of rotavirus during the acute stage of illness and much faster and cheaper than EM or the Rotazyme test. The test appears to be suitable for routine use in small hospitals, emergency wards, or even the physician's office for rapid diagnosis of rotavirus gastroenteritis.     

Evaluation of immunochromatography and commercial enzyme-linked immunosorbent assay for rapid detection of norovirus antigen in stool samples

The efficiency of immunochromatography and commercial enzyme-linked immunosorbent assay (ELISA) kit (Denka Seiken Co. Ltd., Tokyo, Japan) were evaluated for rapid detection of norovirus (NoV) from stool specimens. A total of 503 stool specimens collected from infants and young children who suffered from acute gastroenteritis were tested for NoV by the NoV-immunochromatography kit, Denka ELISA kit, and by a monoplex RT-PCR method. The NoV-immunochromatography revealed 78.9% sensitivity, 96.4% specificity, and 92.4% efficiency with the monoplex RT-PCR method. The Denka ELISA kit had a sensitivity of 90.4%, specificity of 96.4%, and an efficiency level of 95%. The findings indicate that the newly developed NoV-immunochromatography kit provides the specificity equal to that of the Denka ELISA kit, even through the sensitivity of detection was lower. However, the advantage of the NoV-immunochromatography kit is less time consuming and simpler. The data show that both the Denka ELISA and the NoV-immunochromatography kits may be used as an alternative method for screening of NoV in stool samples.     

Evaluation of 4 immunochromatographic tests for rapid detection of norovirus in faecal samples

BackgroundThe rapid detection of noroviruses is essential to implement measures to reduce the rapid spread of gastroenteritis infections they cause, notably in institutions.ObjectivesTo evaluate 4 rapid immunochromatographic tests: RIDA^®QUICK Norovirus, ImmunoCardSTAT!^® Norovirus, NOROTOP^® and SD BIOLINE NOROVIRUS by determining their sensitivity and specificity on a large panel of samples representing 11 genotypes of norovirus genogroup I and 14 of genogroup II, and their cross-reactivity with other enteric viruses.Study designThawed stool samples containing norovirus genogroup I or II or other enteric viruses, and negative samples, were tested by the 4 assays and compared to the reference standard RT-PCR. Fresh stool samples were also tested by RIDA^®QUICK.ResultsThe sensitivity of RIDA^®QUICK, ImmunoCardSTAT!^®, NOROTOP^® and SD BIOLINE for the detection of norovirus genogroup I on thawed samples was 17%, 26%, 52% and 23%, respectively. For genogroup II, the sensitivity was 64%, 39%, 50% and 54%, respectively. For GII.4, the main circulating genotype, the sensitivity was 78%, 59%, 61% and 67%, respectively. For all tests, the specificity was 100% and no cross-reactivity with other enteric viruses was observed. The sensitivity of RIDA^®QUICK on fresh stool samples positive for GII.4 was 71%.ConclusionsKnowing that most gastroenteritis cases are due to GII.4, the immunochromatographic tests may be useful for preliminary screening, notably in outbreaks. However, negative samples need to be tested using RT-PCR methods.     

Enzyme linked immunosorbent assay for detecting adenoviruses in stool specimens: comparison with electron microscopy and isolation.

A commercial enzyme linked immunosorbent assay (ELISA) for detection of adenoviruses in stool samples was compared with the use of electron microscopy and isolation in Graham 293 cells. Although specific, the ELISA was less sensitive than both electron microscopy and isolation. The ELISA had an overall sensitivity of 78% and a specificity of 100%. The sensitivity was related to the amount of virus particles present in the stool sample, increasing to 90% with about 10(7) viral particles/ml of stool. The ELISA was easy to perform, requiring no instrumentation, and is a useful first line test for detection of adenoviruses in stool samples, especially in laboratories without access to an electron microscope. Wider use of ELISAs should help in evaluating the role of adenoviruses in viral gastroenteritis.     

Evaluation of the immunochromatographic CORIS Giardia-Strip test for rapid diagnosis of Giardia lamblia

The aim of this study was to evaluate the performance of the CORIS Giardia-Strip test (CORIS Bioconcept, Gembloux, Belgium) as a rapid initial method for the routine diagnosis of giardiasis. Compared to a commercial ELISA-coproantigen test (ProSpect Giardia-ELISA-microplate assay; Remel, Lenexa, KS, USA), the commercial strip test had a sensitivity of 58%, a specificity of 99%, a positive predictive value of 93% and a negative predictive value of 93% (n=158). These results are comparable to those obtained using microscopy of direct wet-mounted stool. Since the CORIS Giardia-Strip test is simpler to perform, it can replace direct wet-mounted stool microscopy for the rapid diagnosis of giardiasis; however, its sensitivity is inferior to that of other immunochromatographic antigen detection tests and fresh stool samples are required for its use. Nevertheless, the results suggest that a positive CORIS Giardia-Strip test outcome does not need confirmation, while samples with negative results should be re-examined using another, more sensitive, test.     

Comparative evaluation of a commercial enzyme-linked immunoassay and solid-phase immune electron microscopy for rotavirus detection in stool specimens.

Using solid-phase immune electron microscopy (SPIEM) as a reference test, we examined 151 stool specimens from infants and young children with acute gastroenteritis for rotavirus detection by a one-step commercial enzyme-linked immunosorbent assay (ELISA) with labeled monoclonal antibody. Of the 83 samples determined to be positive for rotavirus by SPIEM, 82 were detected as positive by the monoclonal antibody ELISA (sensitivity, 98.7%), while 67 of the 68 specimens determined to be negative by SPIEM were correctly detected as negative by the ELISA (specificity, 98.5%). The diagnostic accuracy of the ELISA kit was 98.6%. Thus, the one-step monoclonal antibody ELISA, which can be completed in less than 90 min, appears to be highly suitable for the rapid and reliable detection of rotavirus in stools.