Performance of parallel screening of Brazilian blood donors with two human immunodeficiency virus immunoassays: implications for sequential immunoassay testing algorithms in other countries.

BACKGROUND: In Brazil it is mandatory to screen donors for human immunodeficiency virus (HIV) antibodies using two immunoassays (IAs) in parallel. Confirmatory testing is performed only on reactive donors who return for counseling. The goal of this analysis was to determine if concordant IA reactivity accurately predicts infection and can be used for HIV incidence and/or prevalence analyses. STUDY DESIGN AND METHODS: We reviewed HIV screening and confirmatory results obtained for 307,407 donations in the first year of the REDS-II study in Brazil (2007) and for 2,304,755 donations collected from 1996 to 2006 in one of the REDS-II sites (São Paulo, Brazil). RESULTS: In the São Paulo site, 11,410 (0.50%) HIV IA-reactive donations were discarded, but only 2095 (0.09%) were reactive to both IAs. Western blot was positive on 1002 (48%) dual-IA-reactive donors who returned for counseling. Only four HIV-infected donors were detected who had been missed at screening by one of the IAs; all occurred before 2002. The positive predictive value (PPV) of dual-IA reactivity varied from 45.8 to 100%, with 80% to 90% PPVs when using IAs from different manufacturers. If both assays yielded signal-to-cutoff (S/C) values of 3.0 or more, PPVs ranged from 91% to 99%, with approximately 99% sensitivity for true HIV seropositivity. CONCLUSION: Parallel testing of all donations has limited efficacy when highly sensitive IAs are used. Reactivity by two sequential IAs is useful for prevalence studies if the assays are from different manufacturers and especially if high S/C values are considered.

Enhanced classification of Chagas serologic results and epidemiologic characteristics of seropositive donors at three large blood centers in Brazil.

BACKGROUND: A major problem in Chagas disease donor screening is the high frequency of samples with inconclusive results. The objective of this study was to describe patterns of serologic results among donors to the three Brazilian REDS-II blood centers and correlate with epidemiologic characteristics. STUDY DESIGN AND METHODS: The centers screened donor samples with one Trypanosoma cruzi lysate enzyme immunoassay (EIA). EIA-reactive samples were tested with a second lysate EIA, a recombinant-antigen based EIA, and an immunfluorescence assay. Based on the serologic results, samples were classified as confirmed positive (CP), probable positive (PP), possible other parasitic infection (POPI), and false positive (FP). RESULTS: In 2007 to 2008, a total of 877 of 615,433 donations were discarded due to Chagas assay reactivity. The prevalences (95% confidence intervals [CIs]) among first-time donors for CP, PP, POPI, and FP patterns were 114 (99-129), 26 (19-34), 10 (5-14), and 96 (82-110) per 100,000 donations, respectively. CP and PP had similar patterns of prevalence when analyzed by age, sex, education, and location, suggesting that PP cases represent true T. cruzi infections; in contrast the demographics of donors with POPI were distinct and likely unrelated to Chagas disease. No CP cases were detected among 218,514 repeat donors followed for a total of 718,187 person-years. CONCLUSION: We have proposed a classification algorithm that may have practical importance for donor counseling and epidemiologic analyses of T. cruzi-seroreactive donors. The absence of incident T. cruzi infections is reassuring with respect to risk of window phase infections within Brazil and travel-related infections in nonendemic countries such as the United States.

Rapid detection of resistance against rifampicin in isolates of Mycobacterium tuberculosis from Brazilian patients using a reverse-phase hybridization assay.

The main objective of this study was to evaluate INNO-LiPA Rif.TB and to determine the frequency of mutations in rpoB in rifampicin-resistant Mycobacterium tuberculosis isolates of Brazilian tuberculosis patients. We used the reverse hybridization assay on 113 resistant and 15 sensitive clinical isolates of M. tuberculosis and on reference strains belonging to 37 different species. All MTB complex strains and none of the other strains reacted with the MTB complex-specific probe, meaning that the assay is 100% specific and 100% sensitive for detection of strains of the MTB complex. In 80 resistant strains, mutations causing S531L (n=55), H526Y (n=9), H526D (n=12) or D516V (n=9) were detected while in 30 strains, mutations were present but their exact nature was not determined by the assay (DeltaS patterns). All sensitive strains had the sensitive genotype while among resistant isolates, a sensitive genotype was obtained in three due to the absence of mutations in the hot spot region, demonstrating an assay accuracy of 97.6% for detection of drug susceptibility. In 10 resistant cultures, two or more mutations were detected and in five, mixed sensitive and resistant genotypes were observed. The sensitivity of the assay for detection of resistant organisms in a mixture with sensitive ones were 2% and 70%, respectively, considering the appearance and disappearance of the R2 and S2 bands. The sensitivity to detect heteroresistance is similar to that of the proportion method when a specific probe for the mutation is present but the performance of the assay in the patient population will depend on the frequency of mutation distribution.

[The discarding of blood units and the prevalence of infectious diseases in donors at the Pro-Blood Foundation/Blood Center of São Paulo, São Paulo, Brazil]. / Descarte de bolsas de sangue e prevalência de doenças infecciosas em doadores de sangue da Fundação Pró-Sangue/Hemocentro de São Paulo.

OBJECTIVES: To analyze the changes in the proportion of blood units discarded from 1991 through 2001 at the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo), which is the largest blood bank in Latin America, and to determine the prevalence of infectious diseases among donors at the Blood Center in November 2001. METHODS: We compiled data concerning the discarding of blood units due to the presence of serological markers for communicable diseases at the Blood Center during the period from 1991 through 2001. To determine the prevalence of infectious diseases, 9 942 screened samples were analyzed in November 2001; all reactive samples underwent confirmatory tests. RESULTS: Over the study period there was a significant decrease in the percentage of units discarded, from 20% in 1991 to 9% in 2001. In November 2001 the prevalence of infectious diseases among donors was: 0.04% for human immunodeficiency virus (HIV), 0.21% for hepatitis C virus (HCV), 0.06% for human T-lymphotropic virus (HTLV), 0.14% for Chagas' disease, and 1.10% for syphilis. For hepatitis B virus, the prevalences found were: 0.14% for anti-HBc and HBsAg, 1.68% for anti-HBc and anti-HBs, and 1.67% for isolated anti-HBc. CONCLUSIONS: The decrease in the discarding of blood units and in infectious diseases among donors at the Blood Center of São Paulo reflects the increase in the Center's percentage of repeat donors.

Evaluation of the concomitant use of two different EIA tests for HIV screening in blood banks.

OBJECTIVE: In 1998, the Brazilian Ministry of Health made it mandatory for all blood banks in the country to screen donated blood for human immunodeficiency virus (HIV) concomitantly using two different enzyme immunoassay (EIA) tests. Concerned with the best use of available resources, our objective with this study was to evaluate the usefulness of conducting two EIA screening tests instead of just one. METHODS: We analyzed data from 1999 through 2001 obtained by testing 698 191 units of donated blood using two EIA HIV screening tests concomitantly at the Pro-Blood Foundation/Blood Center of São Paulo (Fundação Pró-Sangue/Hemocentro de São Paulo), which is a major blood center in the city of São Paulo, Brazil. All samples reactive in at least one of the two EIA tests were submitted for confirmation by a Western blot (WB) test, and the persons who had donated those samples were also asked to return and provide a follow-up sample. RESULTS: Out of the 698 191 blood units that were donated, 2 718 of them (0.4%) had to be discarded because they were reactive to at least one of the EIA tests. There were two WB-positive donation samples that were reactive in only one HIV EIA screening test. On their follow-up samples, both donors tested WB-negative. These cases were considered false positive results at screening. Of the 2 718 donors who were asked to return and provide a follow-up sample, 1 576 of them (58%) did so. From these 1 576 persons, we found that there were two individuals who had been reactive to only one of the two EIA screening tests and who had also been negative on the WB at screening but who were fully seroconverted on the follow-up sample. We thus estimated that, in comparison to the use of a single EIA screening test, the use of two EIA screening tests would detect only one extra sample out of 410 700 units of blood. CONCLUSIONS: Our data do not support the use of two different, concomitant EIA screening tests for HIV. The great majority of HIV-positive donors have already seroconverted and will be detected using only a single EIA screening test. Only persons who are going through the process of seroconversion may be missed by using a single EIA test and detected using two EIAs for screening. To screen out these individuals and decrease the residual risk of HIV transmission from the blood donated in our center, the use of other techniques, such as nucleic acid testing (NAT) or a p24 antigen assay, would be more effective.

Descarte de bolsas de sangue e prevalência de doenças infecciosas em doadores de sangue da Fundação Pró-Sangue/Hemocentro de São Paulo / The discarding of blood units and the prevalence of infectious diseases in donors at the Pro-Blood Foundation/Blood Center of Säo Paulo, Säo Paulo, Brazil

OBJETIVO: Analisar a evoluçäo, de 1991 a 2001, do descarte sorológico na Fundaçäo Pró-Sangue/Hemocentro de Säo Paulo, o maior banco de sangue da América Latina, e verificar a prevalência de doenças infecciosas entre doadores dessa instituiçäo no ano de 2001. MÉTODOS: Foram compilados os dados de descarte sorológico relativos aos anos de 1991 a 2001. Para determinar a prevalência de doenças infecciosas, foram analisadas 9 942 amostras triadas em novembro de 2001, sendo as amostras reativas submetidas a testes confirmatórios. RESULTADOS: Foi encontrada uma diminuiçäo percentual significativa de descarte, de 20 por cento em 1991 para 9 por cento em 2001. A prevalência de doenças infecciosas entre doadores em 2001 foi de 0,04 por cento para vírus da imunodeficiência humana (VIH); 0,21 por cento para vírus da hepatite C (VHC); 0,06 por cento para vírus T-linfotrópico humano (HTLV); para vírus da hepatite B (VHB), as prevalências foram de 0,14 por cento para anti-HBc + HBsAg, 1,68 por cento para anti-HBc + anti-HBs e 1,67 por cento para anti-HBc isolado; 1,10 por cento para sífilis; e 0,14 por cento para doença de Chagas. CONCLUSÄO: A diminuiçäo no descarte e a prevalência de doenças infecciosas entre doadores da Fundaçäo Pró-Sangue/Hemocentro de Säo Paulo em 2001 refletem o aumento na porcentagem de doadores de repetiçäo nesse banco de sangue

Evaluation of the concomitant use of two different EIA tests for HIV screening in blood banks

OBJECTIVE: In 1998, the Brazilian Ministry of Health made it mandatory for all blood banks in the country to screen donated blood for human immunodeficiency virus (HIV) concomitantly using two different enzyme immunoassay (EIA) tests. Concerned with the best use of available resources, our objective with this study was to evaluate the usefulness of conducting two EIA screening tests instead of just one. METHODS: We analyzed data from 1999 through 2001 obtained by testing 698 191 units of donated blood using two EIA HIV screening tests concomitantly at the Pro-Blood Foundation/Blood Center of Säo Paulo (Fundaçäo Pró-Sangue/Hemocentro de Säo Paulo), which is a major blood center in the city of Säo Paulo, Brazil. All samples reactive in at least one of the two EIA tests were submitted for confirmation by a Western blot (WB) test, and the persons who had donated those samples were also asked to return and provide a follow-up sample. RESULTS: Out of the 698 191 blood units that were donated, 2 718 of them (0.4 percent) had to be discarded because they were reactive to at least one of the EIA tests. There were two WB-positive donation samples that were reactive in only one HIV EIA screening test. On their follow-up samples, both donors tested WB-negative. These cases were considered false positive results at screening. Of the 2 718 donors who were asked to return and provide a follow-up sample, 1 576 of them (58 percent) did so. From these 1 576 persons, we found that there were two individuals who had been reactive to only one of the two EIA screening tests and who had also been negative on the WB at screening but who were fully seroconverted on the follow-up sample. We thus estimated that, in comparison to the use of a single EIA screening test, the use of two EIA screening tests would detect only one extra sample out of 410 700 units of blood. CONCLUSIONS: Our data do not support the use of two different, concomitant EIA screening tests for HIV. The great majority of HIV-positive donors have already seroconverted and will be detected using only a single EIA screening test. Only persons who are going through the process of seroconversion may be missed by using a single EIA test and detected using two EIAs for screening. To screen out these individuals and decrease the residual risk of HIV transmission from the blood donated in our center, the use of other techniques, such as nucleic acid testing (NAT) or a p24 antigen assay, would be more effective

Identificaçäo de microbactérias de interesse clínico por cromatografia em camada delgada de micobactina e de ácidos micólicos / Thin-layer chromatography of micobactns and mycolic acids for the identification of clinical mycobacteria

Resumo: Quarenta e sete amostras de micobactérias (12 de referência e 35 isolados de espécimes clínicos) foram analisadas quanto à produçäo de micobactinas e ácidos micólicos, pela técnica de cromatografia em camada delgada (CCD). Diferentes condiçöes de crescimento pouco ou nada afetaram o perfil de separaçäo das micobactinas. Foi verificada a reprodutibilidade nos valores de Rf das micobactinas das diferentes espécies analisadas. Os perfis de ácidos micólicos foram comparados aqueles de amostras padröes. Todaas as amostras da mesma espécie, isoladas de espécimes clínicos, mostraram os mesmos perfis. O uso combinado dos 2 métodos químicos permitiu a identificaçäo das micobactérias patogênicas ou oportunistas cultiváveis. Para o exame de rotina, a análise de micobactinas e de micolatos provêe um meio simples e adequado de caracterizaçäo e identificaçäo de microbactérias (au)