Kit Lots Research Articles

Evaluation de la qualité des principales trousses de dépistage de l'antigène HBs utilisées dans les centres français de transfusion sanguine

The aim of this study is the evaluation of the main kits used for the HBs Ag screening in French blood donors. Eight ELISA or RIA kits were evaluated. The specificity was assessed by testing samples from unselected blood donors. Repeatedly reactive sera were confirmed by a neutralisation test using an anti-HBs polyclonal antibody. The specificity expressed by the false positive reactions was lower than 0.1% for the ELISA and RIA kits. Sensitivity was assessed by the study of a panel of 16 HBs Ag specimens (ad and ay subtypes) with titres ranging from 0.05 to 1.80 ng/ml; all were tested in duplicate. Differences in sensitivity were observed according to the kits and procedures used. Some kits have a better sensitivity than RIA which is no longer the most sensitive technique. Such a study and a permanent control of each lot of HBs Ag commercial kit allow an improvement of reagents quality.

Mycobacterium gordonae pseudoinfection associated with a contaminated antimicrobial solution

At Yale-New Haven Hospital, 46 specimens submitted for mycobacterial culture during an 8-week period in 1989 were positive for Mycobacterium gordonae, a nontuberculous acid-fast bacterium (AFB) of low pathogenicity. The specimens were submitted from 34 patients who came from various inpatient and outpatient services. Four patients were begun on antimycobacterial therapy on the basis of an AFB isolate which was later identified as M. gordonae. Isolation of M. gordonae was associated with use of the BACTEC TB system (BACTEC TB; Becton Dickinson Diagnostic Instrument Systems, Towson, Md.) and an antimicrobial solution, BACTEC PANTA PLUS (PANTA; Becton Dickinson Diagnostic Instrument Systems). The manufacturer reported that two lots (B9K1 and C9K1) of PANTA kits containing a single production lot (N8C1) of PANTA, which had been shipped to 173 laboratories, had been contaminated with M. gordonae. A survey of mycobacteriology laboratories in the United States revealed that, during April to July 1989, the M. gordonae isolation rate was 5.8/1,000 AFB specimens processed at laboratories that did not use BACTEC TB, 11.4/1,000 AFB specimens at laboratories that used BACTEC TB but not the implicated lot of PANTA, and 23.5/1,000 AFB specimens at laboratories that used BACTEC TB and the lot of implicated PANTA. Intrinsic contamination of PANTA was attributed to ineffective sterilization of water used in the manufacturing process and was not detected prior to product shipment because cultures for AFB were not part of the quality control regimen. This episode emphasizes that clinical laboratories can detect pseudoepidemics promptly if they are alert to abrupt increases in isolation rates, especially of unusual or generally nonpathogenic organisms.

Frequency of Indeterminate Western Blot Tests in Healthy Adults at Low Risk for Human Immunodeficiency Virus Infection

As part of a phase 1 trial of a candidate AIDS vaccine, blood specimens were collected from 168 healthy adult volunteers at minimal or no risk for becoming infected with human immunodeficiency virus type 1 (HIV-1). These specimens were screened for evidence of HIV-1 infection by enzyme immunoassay (EIA) and the Biotech/Du Pont Western blot (n = 168), culture (n = 122), and polymerase chain reaction assay (n = 20). None of the subjects had a positive test result by any of these assays, but 32% had indeterminate Western blot tests, most of which demonstrated a single band of low intensity. The most common bands were p24 (47%), p55 (34%), and p66 (36%); envelope bands were unusual (gp41, 2%; gp120, 2%). No serum specimen collected after 2-11 months from individuals with indeterminate Western blot results was positive by EIA or Western blot. There was 91% agreement in the test results of the first and second serum samples when the same lot of Western blot kit was used but only 36% agreement when different lots were used. The Biotech/Du Pont Western blot kit thus frequently yields indeterminate test results in the absence of HIV-1 infection, the reproducibility of which is subject to lot-to-lot variability.

Development of quality control procedures for the human immunodeficiency virus type 1 antibody enzyme-linked immunosorbent assay.

A standardized pool of human sera that was positive for human immunodeficiency virus type 1 (HIV-1) antibody was developed. This positive control serum was used to analyze test differences among eight laboratories, among the HIV-1 antibody test kits of three different manufacturers, among different lots of the same test kit, and among pipetting devices and techniques. The standardized pool of human sera was tested 327 times by the different laboratories. In terms of positive tests, a reproducibility of 99.69% was achieved; however, significant test variance among laboratories, among test kit lots, and among pipetting devices and techniques could be demonstrated if the tests were compared on the basis of the net positive optical density (OD) value. This value was calculated by subtracting the cutoff OD value (i.e., the value below which an OD value was considered negative for HIV-1 antibody) from the observed OD value of the standardized pool of human sera. The results obtained suggest that this strategy can be used for proficiency testing, for monitoring the quality of HIV-1 antibody enzyme-linked immunosorbent assay reagents, and for evaluating pipetting devices and techniques.

Quality control of radioimmunoassay for TSH, LH, FSH, C-peptide, prolactin based on NIH-computer program

As there has been no data available on the variation of RIA through a year, we assessed within kit and component of between assay variation of TSH, LH, FSH, C-peptide and PRL kit through a year (more than 12 sequential assays). The average of within kit variation was 6.9% (ranged from 4.7 to 9.8%) and that of component of between assay variation was 11.2% (ranged from 8.9 to 14.5%). These values were almost similar to those obtained for the within kit variation and component of between assay variation employing single lot of kit. These results warrant that quality of kits produced by manufacturers was homogeneous throughout the observation period.

Comparison of Microchromatography and Electrophoresis with Elution for Hemoglobin A2(Hb A2) Quantitation

Microcolumns prepared in the authors' laboratory, two commercial microchromatography kits, and electrophoresis with elution were compared for Hb A2 quantitation. Day-to-day imprecision of microchromatographic methods was similar (CV 4.7--6.6%) and somewhat less than electrophoresis with elution (CV 8.0--9.1%). Both commercial kits showed variable imprecision in different lots; one lot of Kit B gave erratic results due to resin leakage. From 49 patient specimens, Kit A microcolumns and those of the authors identified the same 14 patients with an elevated percentage of Hb A2 and showed good correlation (P = 0.90), although Kit A showed constant bias toward higher values. Electrophoresis with elution resulted in a false-positive and a false-negative value, did not correlate well with microcolumns (P = 0.78 and 0.76), and showed proportional bias toward lower values for an elevated percentage of Hb A2. Commercial kits were convenient, relatively quick, and cost-effective. Frozen, stabilized hemolysates performed well for quality control.