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Performance characteristics of enzyme linked immunosorbent assay and rapid immunochromatographic test for routine screening of human norovirus

HE Sharaf, SS Morsi, MA Gerges

 

Abstract

Noroviruses (NoV) are identified as the major cause of epidemic and sporadic acute gastroenteritis. Controlling the spread of the disease needs early recognition of NoV. This study investigated the  contribution of norovirus to sporadic cases of pediatric gastroenteritis in Zagazig University Hospitals and studied the performance characteristics of enzyme linked immunosorbent assay(EIA) and  immunochromatographic (ICT) assay for their ability to detect NoV. Two hundred stool specimens were
collected from pediatric patients with acute gastroenteritis. Samples were tested for Norovirus presence by reverse transcription PCR (RT-PCR), ICT kit and EIA. 27% of the samples showed the 338-bp portion of the RNA-dependent RNA polymerase (RdRp) gene of both Norovirus genogroups I and II by RT-PCR. The ICT assay showed high specificity (97.94%) and high sensitivity (85.18%). The EIA  showed high specificity (93.8%) but low sensitivity (64.8%). In conclusion, the high detection rate of NoV as the cause of diarrhea in children reported in this study supports their addition in screenings to  identify sporadic cases of acute gastroenteritis. The ICT and RIA Norovirus kits may be useful for rapid screening of stool samples from patients with acute gastroenteritis. However, RT-PCR should be  considered for negative samples to be confirmed.

Key words: Norovirus, pediatric gastroenteritis, RNA-dependent RNA polymerase (RdRp) gene,  enzyme linked immunosorbent assay, immunochromatographic assay, Sensitivity, Specificity.

Abbreviations: NoV , Noroviruses; EIA, enzyme linked immunosorbent assay; ICT,  immunochromatographic; RT-PCR, reverse transcription PCR; RdRp, RNA-dependent RNA polymerase; ORFs, open reading frames.

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Performance characteristics of enzyme linked immunosorbent assay and rapid immunochromatographic test for routine screening of human norovirus

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COMPARATIVE STUDY ON SPECIFIC AND EARLY DETECTION OF PULMONARY MYCOBACTERIA COMPLEX USING SMEAR AND CULTURE METHOD AND SEROLOGICAL PATHOZYME EIA KITS

CA Enwuru, EO Idigbe, NV Ezeobi, CT Oparaugo, U Udensi Kalu, JI Onyewuche, J Ibiam

 

Abstract

The objective of this study was to compare the sensitivity and specificity of smear and culture methods with rapid serological EIA myco kits manufactured by Omega diagnostics, for the early detection of Mycobacterium tuberculosis (MTB) complex. Sera from various categories of smear and culture results were compared with the result of 38KDa, 16KDa and purified protein for IgA, IgM and IgG antibodies with sensitivity of 4%, 24% and 76%, respectively and with specificity of100% for IgG in Smear and Culture Positive (S+)C+)) category. The sensitivity of the test improved to a level of 80% for IgG + IgA without affecting the specificity. A combination of IgG + IgA and IgM further improved the sensitivity to 88% but reduced the specificity to 91%. Amongst the S–)C+) and S–)C–) 64% and 14.7% were positive for IgG respectively. The predictive value of the kit using S+)C+) subject was 96%. For all culture positivity (n=78), there was 2.6%, 33.3% and 71.8% sensitivity for IgA, IgM and IgG respectively. IgA +IgG and IgA + IgM + IgG combination gave 74.4% and 84.6% sensitivity respectively with the same level of specificity. Fifty-five percent of culture positive subjects were found to be MTB complex positive by routine biochemical tests, while 40% through PATHOZYME TB COMPLEX PLUS kit (high positive (H+)) values). When high positivity is combined with low positivity of the same kit (H+) + L+)), 65% of the isolates were found to be MTB complex. Our study showed 88% sensitivity and 91% specificity for combined IgA + IgM + IgG antibodies recorded for MTB (S+)C+) group) and 85% sensitivity and 91% specificity for all culture positives. Our study has demonstrated that the myco kits and TB complex plus kit produced by Omega Diagnostics are a good tool for specific, early and rapid identification of active tuberculosis for both diagnostic and epidemiological purposes.

Key Words: Tuberculosis, diagnosis, comparative, specificity, sensitivity, culture and serological technique.

Afr. J. Clin. Exper. Microbiol. 2004; 5(2): 182 – 188.