Patients at risk from inaccurate antibiotic test kits used in
hospital pathology labs
13 February 2013
An investigation by the British Medical Journal (BMJ) has found
that one of the world’s leading producers of diagnostic tests has
been falsely marketing one of their products.
Oxoid, owned by US diagnostics giant Thermofisher, has been
selling antimicrobial susceptibility test (AST) discs that do not
always contain the advertised amount of antibiotic, says the BMJ.
Internal documents seen by the BMJ show how the company used
flawed data and misled the UK regulator, the Medicines and
Healthcare Products Regulatory Agency (MHRA), when concerns were
raised. The company say they comply with all legal and regulatory
At worst, patients may have been prescribed the wrong antibiotic
or moved from oral to intravenous treatment unnecessarily. This
comes at a time when health agencies around the world are concerned
about antibiotic resistance and the shortage of new antimicrobial
treatments in the drug pipeline.
Only last month, the Chief Medical Officer of England, Dame Sally
Davies, described antibiotic resistance as an “apocalyptic
AST discs are used in hospitals around the world to guide the
choice of antibiotic treatment. The discs, containing specified
amounts of antibiotic drugs, are put onto agar jelly swabbed with a
sample of the infection from a patient. A clear zone forms around
discs impregnated with drugs that are effective against infection,
with the size of the zone roughly proportional to the drug's
Like hip replacements and breast implants, in-vitro diagnostics
like Oxoid’s AST discs, must have a safety certificate. In the US,
the discs are classed as medical devices and companies have to
provide detailed evidence before a product can be approved for sale.
But in Europe, companies can self-certify their products and say
what it does without any external scrutiny.
Oxoid’s website claims that their discs are produced to “the
tightest international standard” but emails seen by the BMJ suggest
that accuracy may not be Oxoid’s primary concern.
Internal documents show that batches of the disc have been
released that do not contain the advertised amount of drug and
sometimes no drug at all. Documents also show that antibiotics were
not handled as carefully as they should have been, leading to
The British In-vitro Diagnostic Association says that: “Using the
right antibiotic is fundamental to successful treatment; using the
wrong antibiotic wastes time and money, extends the period of
illness and may exacerbate the emergence of resistance, endangering
Yet when this problem was raised internally, emails show how the
company “used flawed methods” which allowed them to release batches
onto the market. The company deny this allegation. Even when
clinicians said they were having problems with their discs, Oxoid’s
response was that they were storing their discs incorrectly.
Professor Mark Wilcox, a consultant microbiologist at Leeds
Teaching Hospitals, said it would be of “great concern” if any
manufacturer failed to act on reports and queries from clinicians.
In 2005, Oxoid misled the MHRA, suggesting that a recalled batch of
discs had stability issues rather than admitting that one component
was completely missing.
Emails seen by the BMJ suggest that employees within the company
have raised issues with Oxoid’s practice, but they have been
ignored. In 2009, one employee became so disgruntled with Oxoid,
they contacted the MHRA with documentary evidence.
In June 2011, Professor Sir Kent Woods, chief executive of the
MHRA replied to the employee, saying “I can confirm that we did
correspond with the company on the basis of your allegations with a
view to satisfying ourselves that the product in question complied
with the regulations.”
The response has worrying implications for how well the MHRA act
on concerns of employees and is happy to take companies at their
word, says BMJ Investigations Editor, Deborah Cohen. As the employee
put it, the MHRA has “failed in its duty to protect the public.”
In an accompanying editorial, Professor Wilcox argues that the
whole system of regulating in vitro diagnostic medical devices
(IVDs) needs to be improved.
There are plans to reform European IVD legislation, but he says
it “remains unclear” by how much the new requirements will improve
quality and, crucially, clinical utility. He believes IVD testing in
designated centres “would be a step forward” in dealing with the
current weaknesses, but argues that “a more comprehensive, indeed
systematic, approach is needed to strengthen the current CE marking
Meanwhile users of diagnostic tests “should be particularly alert
to unexplained findings and should be encouraged to report
suspicious results, so that trends can be identified and
investigated,” he says. He also calls for any new test to undergo a
formal review “to determine its clinical utility, in a similar way
that hospitals review the prescribing of a new drug.”