Availability of Abbott / Murex Single Use Diagnostic System
(SUDS) HIV-1 Test
October 18, 2000
In a letter dated October 18, 2000, Abbott Diagnostics informed
their customers that the Abbott / Murex Single Use Diagnostic System
(SUDS) HIV-1 test, the only rapid HIV test currently licensed for
the U.S. market, will not be available for an undetermined period of
time due to manufacturing problems. FDA has received assurance from
Abbott that the company is working to resolve these problems as
quickly as possible.
The most significant impact that the shortage of this test has is
in healthcare situations where transmission of HIV may be prevented
if therapy is initiated within 24 to 48 hours. These situations
include testing of the source patient in the event of healthcare
worker needlestick injuries and testing pregnant women presenting
for delivery with an unknown HIV status. In both cases, initiation
of treatment as soon as possible after the event (optimally within a
few hours rather than days for needlestick exposures or within 12-24
hours after delivery for the newborn) is recommended by CDC and may
decrease the number of transmissions when instituted within that
timeframe. In these situations, many healthcare providers have been
using the SUDS test to provide an initial result in 10 minutes.
While there are no other approved rapid HIV tests for use during
this time, there are several possible interim measures which may be
undertaken by healthcare providers. These include:
- Immediate testing with one of the currently licensed
enzyme-linked immunoassays (EIAs). These tests can usually be
performed in 90 to 160 minutes (list of
licensed tests). Typically, samples are tested in batches so
that results may not be available for several days. However, if
healthcare providers arrange for the EIA tests to be performed on
samples as needed, results could be available within 90 to 160
minutes. In order to validate whether a reactive result is
repeatedly reactive, any sample testing reactive on the initial
assay (EIA or SUDS) normally would have to be repeated in
duplicate in a separate assay. To avoid a lengthy delay due to a
second round of testing of any initially reactive samples,
performance of the initial assay in triplicate should be done.
Repeatedly reactive samples would be those found reactive in at
least two of the three replicate tests.
- Use of the Sano Chemia (originally Waldheim) Fluorognost HIV-1
Indirect Immunofluorescence Assay (IFA), which is licensed as a
screening test where EIAs are not practical. This test requires a
fluorescence microscope and a well-trained technician and can be
performed within about 100 minutes. No further testing is
necessary for either negative or positive test results.
Although urgent medical decisions can be based on the result of a
screening test for HIV, repeatedly reactive screening test results
should be confirmed by the performance of a supplemental test. Approved
supplemental tests for HIV include the indirect
immunofluorescence test (IFA) test or western blot tests. The IFA
test takes about 100 minutes to perform, while a western blot can be
done in as little as 150 minutes (more typically western blots
include an initial overnight incubation). In any case, the minimum
time for providing a confirmed positive result would be 190 minutes
with an EIA test (initial run in triplicate) as compared to 120
minutes with the SUDS test.
Since the length of time that this test will not be
available is not certain at this time, FDA recommends that
healthcare providers implement one of the suggested interim measures
to replace the SUDS HIV-1 Test while it remains
unavailable. The long range solution to this problem will
include the availability of multiple rapid HIV tests. FDA continues
to encourage the development of rapid HIV tests and has recently
taken action to facilitate approval of rapid HIV tests as evidenced
by presentations made during Blood Products Advisory Committee
Meetings that have taken place this year (see transcripts
of June 15 and September 15, 2000 BPAC).
Healthcare providers with questions, concerns, or suggestions
should contact the Center for Biologics Evaluation and Research’s
(CBER) Consumer Affairs Branch, Office of Communication, Training
and Manufacturer Assistance at 800-835-4709 or 301-827-1800.
Murex
SUDS HIV-1 (Rapid EIA) - MedWatch - 10/18/2000
Last Updated:
1/19/2001
|