Comparison of electrochemiluminescence and ELISA methods in the detection of blood borne pathogens in Gabon

A method to alleviate false-positive results of the Elecsys HIV combi PT assay

To explore the effects of urea dissociation on reducing false-positive results of  the Elecsys HIV combi PT assay. A retrospective analysis was used to evaluate the false-positive rate of the Elecsys HIV combi PT assay. Six false-positive sera, six positive sera and six sera from patients with early HIV infection were collected. Dissociation was performed using 1 mol/L, 2 mol/L, 4 mol/L, 6 mol/L, or 8 mol/L urea, and HIV screening assay were then detected to select the appropriate concentration of urea dissociation. Next, 55 false-positive sera and 15 sera from early HIV infection were used to verify the best concentration of urea to achieve dissociation. Retrospective analysis showed that the COI of the Elecsys HIV combi PT assay in false-positive sera ranged from 1.0 to 200.0, and approximately 97.01%(227/234) of false-positive sera were in the range of 1.0-15.0. The avidity index (AI) in positive and false-positive sera decreased as the urea dissociation concentration increased. When the dissociation concentration was 6 mol/L, the AI of false-positive serum was between 0.0234 and 0.2567, and the AI of early HIV infection sera was between 0.4325 and 0.5017. The difference in AI between false-positive and positive samples was significant. When negativity was defined as an AI of less than 0.3970, the sensitivity and specificity were 100.0% and 100.0%, respectively. Urea-mediated dissociation could significantly reduce the false-positive rate of the Elecsys HIV combi PT assay with a low COI. Our findings provided a reference for distinguishing positive and false-positive of the Elecsys HIV combi PT assay.

Head-to-head comparison of Enzyme Linked Immunosorbent Assay (ELISA) and Enhanced Chemiluminescence Immunoassay (ECLIA) for the detection of Transfusion Transmitted Disease (TTD) Markers; HIV, HCV and HBV in blood donors, in India

Safe blood transfusion being the cornerstone of any Blood Transfusion Services requires meticulous testing for Transfusion Transmitted Disease (TTD) markers in donated blood. We performed head-to-head comparison of ELISA and ECLIA for detection of TTD markers for Human Immunodeficiency Virus (HIV), Hepatitis C Virus (HCV) and Hepatitis B Virus (HBV) in 10,164 Indian blood donors. All concordant reactive, discordant reactive and concordant non-reactive samples were re-confirmed using Individual Donor-Nucleic Acid Amplification Test (ID-NAT) as the 'gold standard' test. 223 samples were found reactive; out of which 93 (four HIV, 34 HCV and 55 HBV) samples were concordant reactive and tested positive by both methods while 130 discordant reactive samples were reactive either by ELISA or ECLIA. Out of 130 discordant reactive samples ELISA-reactive and ECLIA-non-reactive samples for HIV, HCV and HBV were 15, eight, and 29 respectively while ECLIA-reactive ELISA-non-reactive samples for HIV, HCV and HBV were 39, 36 and three respectively. Sensitivity of ECLIA and ELISA was 100 % for all three TTD markers, while specificity was 99.62 % and 99.85 % for HIV; 99.64 % and 99.84 % for HCV and 99.97 % and 99.70 % for HBV respectively. Strength of agreement and Kappa Statistics for ECLIA and ELISA compared to the gold standard test was poor and fair for HIV (k = 0.169 and 0.347), moderate and good for HCV (k = 0.539 and 0.763), and very good and good for HBV (k = 0.973 and 0.783). According to this study, it can be concluded both the testing techniques; ELISA and ECLIA have 100 % sensitivity for the detection for HBV, HCV and HIV in blood donors and therefore, either can be used for TTD screening in blood banks in India.

A novel HCV electrochemical biosensor based on a polyaniline@Ni-MOF nanocomposite

A novel label-free electrochemical biosensor constructed using a polyaniline@nickel metal–organic framework (Ni-MOF) nanocomposite for direct detection of HCV-RNA.

Assessment of rapid diagnostic tests and fourth-generation Enzyme-Linked Immunosorbent Assays in the screening of Human Immunodeficiency and Hepatitis B virus infections among first-time blood donors in Libreville (Gabon)

BACKGROUND

Blood transfusion is a pathway for the transmission of blood-borne pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV) from donors to recipients in most countries in sub-Saharan Africa, including Gabon. The study aimed to compare the performance of four rapid diagnostic tests (RDTs: Alere DETERMINE, BIOSYNEX Exacto Pro HIV, MEDIFF HIV 1&2, and BIOSYNEX IMMUNOQUICK HBsAg) with results of 4th-generation immunoenzymatic assays COBAS 6000 e601 and EVOLIS BioRad for the detection of HIV and hepatitis B surface antigen (HBsAg) in blood donors in Libreville, Gabon.

METHODS

Reactive and nonreactive blood samples for HIV and HBsAg were selected using fourth-generation ELISA COBAS 6000 e601 and EVOLIS BioRad. The sensitivities of RDTs were calculated using Epi Info version 6.04dfr (CDC, Atlanta, USA).

RESULTS

Sensitivities for the detection of HIV in blood donors were 90.9% for Alere DETERMINE, 81.8% for BIOSYNEX Exacto Pro HIV, and 81.8% for MEDIFF HIV 1&2 Serum/sang Total Cassette compared with COBAS 6000 e601. The sensitivity of Alere DETERMINE compared to the semi-automated ELISA Bio-Rad for HIV detection was 65.6%. The sensitivity of BIOSYNEX IMMUNOQUICK HBsAg compared to ELISA tests for the detection of HBsAg was 78.0%. The specificity of all RDTs for the detection of HIV and HBsAg was 100%.

CONCLUSION

Alere DETERMINE HIV-1/2, MEDIFF HIV 1&2 Serum/sang Total Cassette, BIOSYNEX Exacto Pro HIV, and BIOSYNEX IMMUNOQUICK HBsAg are not recommended for determining whether donors qualify to donate blood because of their low sensitivity for the detection of HIV antibodies and HBsAg in blood donors in Gabon.

Detection methods for Pseudomonas aeruginosa: history and future perspective

The current review summarized and analyzed the development of detection techniques forPseudomonas aeruginosaover the past 50 years.