Comparison of a rapid cytomegalovirus pp65 antigenemia assay revealed by immunofluorescence to an in-house assay revealed by immunoperoxidase for diagnosis in solid organ transplant recipient patients

Cytomegalovirus (CMV) antigenemia is still one of the two major assays available for diagnosis and monitoring of CMV infections. A commercial rapid test recently available in Brazil for quantification of human cytomegalovirus pp65 antigenemia revealed by immunofluorescence technique was compared with the original in-house method revealed by immunoperoxidase in patients receiving solid organ transplants. Of 80 blood samples tested for CMV antigenemia, 34 (42.5 percent) were positive: commercial assay detected 33 (97 percent) and in-house assay detected 20 (58.8 percent) samples. The numbers of positive cells in the two assays were different, with a median of 4.5 and 12 positive cells obtained by in-house and commercial kit, respectively. Discrepancies between assays occurred in 15 specimens from patients with low-grade antigenemia (median 6 positive cells). The assay-time was reduced in approximately 50 percent compared to in-house methodology. In conclusion, besides comparable results obtained for both assays, the commercial antigenemia assay provides more rapid and sensitive results.

Rotavirus infection in children and adult patients attending in a tertiary Hospital of São Paulo, Brazil

During the period of January 2003 to December 2005, 3,768 stool samples were received in the Microbiology Laboratory for rotavirus antigen detection from outpatients and inpatients of Albert Einstein Hospital, SP. Fresh stool samples from children and adults were analyzed by two methodologies: during 2003 and 2004 by latex agglutination (Slidex Rotavirus, Biomerieux) and 2005 by an immunochromatographic assay for the combined detection of rotavirus and adenovirus (Vikia Rota-Adeno, Biomerieux). Rotavirus group A was detected in 755 (20 percent) samples. The annual prevalence was 19.8 percent in 2003, 21.7 percent in 2004, and 18.7 percent in 2005. Rotavirus was detected every month during the period of the study, with peak of positivity between June and August (>35 percent). The prevalence in hospitalized patients was 26.1 percent (352/1,350) and in outpatients was 16.7 percent (403/2,418). For hospitalized patients most of the rotavirus infections were diagnosed in Pediatric setting, age range of 0 to 10 years (prevalence of 55.3 percent, 295/534). Overall positivity was up to 30 percent in patients between six months and five years of age (67 percent of all positive patients), all other age groups had at least 10 percent positive tests. Rotavirus infection is common in Sao Paulo, and besides the expected higher frequency in children it is also frequent in adults.

Avaliação de quatro kits comerciais para detecção rápida de antígenos de Rotavírus em amostras de fezes / Four kits evaluation for Rotavirus rapid antigen detection in stool samples

O Rotavírus é um dos principais agentes causadores de diarréia, sendo desejável o diagnóstico laboratorial de maior rapidez e acurácia para evitar a complicação por essa infecção. Nesse estudo, foram comparados os resultados obtidos por 4 diferentes kits comerciais para pesquisa de antígenos de rotavírus em 42 amostras de fezes: dois kits com metodologia de aglutinação em látexe dois kits de detecção combinada de Rotavírus e Adenovírus por imunocromatografia. A concordância entre os kits testados foi de 88%, sendo 16 amostras positivas e 21 negativas em todos os testes. Nas cinco amostras com resultados discordantes apenas um kit obteve resultado diferente dos demais, sendo estes, repetidos por outro executor. Essa repetição demonstrou interpretação diferenteem duas amostras por um dos testes de aglutinação de látex. As taxas de detecção pelos kits imunocormatográficos foi de 66% (18/42) e para os kits de aglutinação de látex foi de 38-40% (16 e 17/42). Os kits imunocromatográficos demonstraram total concordância coma maioria dos demais kits testados. Conclui-se que, apesar da boa concordância entre os kits avaliados, algumas metodologias podem apresentar problemas na aplicação prática, principalmente com a interpretação da aglutinação de látex.

A total of 42 stool specimens were tested for the presence of antigen rotavirus by two distinct enzyme immunoassays (EIA) and two latex agglutination tests (LAT). Overall concordance was 88%, with 16 positive and 21 negative results by all tests. Discordant results occurred when one test differed from the others and was repeated by other technician. These procedures change the interpretation of latex agglutination. Detection rate for two immunocromatographic tests were 66% (18/42) and two latex agglutination tests were 40% and 38% (17 and 16/42). The results show that each of the commercial assays evaluated could accurately detect rotavirus in the stools specimens. Comparative results demonstrate that sensitivity of latex agglutination tests was lower than immunocromatographic tests. In conclusion, those rapid tests could be detect differently antigen rotavirus, the latex agglutination methodology could be difficult interpretation and immunochromatographic technique do not require specialized equipment, showed higher sensitivity and was rapid and easy to perform in the routine clinical laboratory.