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Antibiotic slows atherosclerosis
in people with Chlamydia pneumonia antibodies
Oct 16 (American Heart Association) - Long-term antibiotic treatment
may slow the progress of early atherosclerosis in stroke patients
who have antibodies to a pneumonia-causing bacteria in their bloodstream.
Scientists reported these findings in yesterday's rapid access issue
of Circulation: Journal of the American Heart Association.
"Our data imply for the first time to our knowledge that antibiotic treatment
in patients over age 55 with Chlamydia pneumoniae (Cp) antibodies
and prevalent cerebrovascular disease is associated with a reduced
progression of early stages of carotid atherosclerosis," says study
author Dirk Sander, M.D., a researcher with the neurology department
at Technical University of Munich.
Chlamydia pneumoniae - the bacteria that causes pneumonia - has been associated
with atherosclerosis. Studies have also associated the Cp antibody
with heart attack and stroke. Other research has corroborated the
association of Cp with atherosclerosis based on the organism's presence
in atherosclerotic lesions and its absence in healthy artery tissue.
Other researchers have also described the benefits of antibiotics on vessel
disease.
Sander's team evaluated the effect of the antibiotic roxithromycin on progressive
thickening of the carotid (neck) artery in 272 stroke patients (average
age 64) for two years. Of the 125 that tested positive for the Cp
antibody, 62 received a twice-daily, 150-milligrams dose of roxithromycin,
while 63 got twice-daily placebo for 30 days. Of the 147 Cp-negative
patients, 74 were assigned to the drug and 73 to placebo.
Researchers measured intima to media thickness (IMT) of the common carotid
artery with ultrasound. Increased IMT indicates atherosclerosis.
Each patient had undergone both IMT and blood tests for Cp antibodies
at least three years before the start of the study's antibiotic
regimen. Patients infected with Cp in the past have antibodies that
react when their blood is exposed to the microorganism in the laboratory.
C-reactive protein (CRP) levels were also established for each
patient. CRP is a marker of general systemic inflammation, including
irritation of vascular walls.
In the baseline period, IMT progressed in Cp patients at a rate of 0.12 millimeters
a year (mm/year) compared to 0.07 mm/year in patients without the
antibody, regardless of other cardiovascular risk factors. After
two years of antibiotic treatment, progression was significantly
reduced Cp positive patients compared to Cp-positive patients who
did not receive roxithromycin. The progression was 0.07 mm/year
in patients taking antibiotics versus 0.11 mm/year in untreated
patients.
Treatment significantly decreased CRP levels in treated Cp-positive patients
but not in the placebo Cp-positive group, an effect that remained
unchanged even after adjusting for smoking, age, diabetes, blood
pressure or cholesterol levels.
However, researchers observed no significant difference
between the groups in subsequent cardiovascular events at
follow-up, and saw no change in IMT in Cp-negative patients
who received antibiotic therapy.
Roxithromycin therapy was associated with an average reduction of IMT progression
of 0.04 mm a year, which equals about a 1.5 percent to 2 percent
reduction in heart risk, Sander says. This small risk reduction
requires clinical trials with long-term follow-up to demonstrate
the probable benefits of antibiotic therapy in patients testing
positive for Cp antibodies, he says.
Co-authors include Kerstin Winbeck, M.D.; Jurgen Klingelhofer, M.D.; Thorleif
Etgen, M.D. and Bastian Conrad, M.D.
Copyright 2000 - 2002 American Heart Association. All
rights reserved.
Publish Date: October 16, 2002
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