Rates of community-acquired Clostridium difficile
are on the rise and a team of McGill University researchers
may have uncovered one of the reasons why. Their study,
published in the December 21 issue of the Journal of
the American Medical Association, showed a direct
link between the use of drugs that suppress stomach acid
and C difficile-associated disease (CDAD).
"It's well known that less stomach
acid puts patients at risk for diarrhea," said lead
author Dr Sandra Dial, a professor of respiratory epidemiology
and clinical research at McGill. "Stomach acids act
like a barrier and prevent any bacteria a patient may
ingest from making it past the stomach." The theory
that stomach acids protect against bacteria isn't new,
explained Dr Dial. Studies as far back as 1996 associated
acid-suppressive agents to gastric and intestinal bacterial
overgrowth.
GASTRIC
ACIDITY LINK
Decreased stomach acidity is a known risk factor for
other diarrheal illnesses like salmonellosis, cholera
and travellers' diarrhea. But C difficile is
supposed to be transmitted via spores — which are
acid resistant — negating any sort of link with
stomach acid. But this study offers more support to
the theory that C difficile is like other bacteria
and increased risk of infection is related to the degree
of gastric acid suppression. "I think people are convinced
now," said Dr Dial.
Her latest research showed that
proton pump inhibitors (PPIs) were linked with nearly
three times the rate of CDAD, and less-potent acid suppressants,
like H2-receptor antagonists, were associated with twice
the rate of infection. Use of non-steroidal anti-inflammatories
also resulted in a 30% increased risk.
Dr Dial and her team examined data
on over 18,000 patients from the United Kingdom Gen—eral
Practice Research Database for the period 1994 to 2004.
Over the 10 years, 1,672 C difficile cases were
found. The data showed an increase in the incidence
of C difficile cases from one per 100,000 in
1994, to 22 per 100,000 in 2004. Surprisingly, 70% of
the patients with CDAD hadn't been in hospital and less
than 50% had been on antibiotics — the two most
common risk factors for contracting the bacteria. The
startling rise in cases may be due in part to increased
testing for C difficile, speculated the authors.
But they also noted that most of the data they analyzed
predated the introduction of mandatory reporting of
CDAD in the UK in 2004.
NO
REASON NOT TO Rx
These findings don't suggest that physicians should
stop prescribing PPIs and other acid suppressive meds.
"Each doctor knows his or her own patients and whether
the benefits of using these drugs outweigh the risks
of getting CDAD," said Dr Dial. "All these medications
have a long record of safety and the risk of developing
C difficile in the community is rare," she said.
"The risk is in the order of 100 times less than in
the hospital." Dr Dial added that patients over 75 years
old have the highest chance of getting an infection.
Dr James Gray, a Vancouver gastroenterologist,
greeted the findings with interest, but didn't interpret
them as a reason to bid PPIs adieu. "This is certainly
an important observation," he said. "However we can't
over-appreciate the value of PPIs in improving quality
of life and reducing acid-related complications."
For her part, Dr Dial thinks some
physicians may be a little too quick to write up a script
for these kinds of drugs. "Lots of people are being
prescribed meds they don't need," she said. "Other patients
are on these drugs for specific reasons, but when the
condition clears up they don't stop the meds."
"This paper offers caution and
awareness to always try to taper or reduce meds if they
aren't always needed," added Dr Gray.
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