Blood flow
The study, carried out by researchers at St George’s Medical School, London, measured the efficiency of participants’ blood flow in the brachial artery in the arm.
In a healthy artery, which also has a healthy endothelium, blood vessels are able to relax if the blood flow increases - called flow-mediated dilation.
Measures of substances in the blood which indicate damage to the endothelium, and levels of protein present when there is inflammation, were also checked.
Patients were examined before and after the study.
Those given the antibiotic showed improved flow-mediated dilation and a fall in the levels in the markers for endothelial problems.
But researchers suggest the antibiotic may not be benefiting patients because the antibiotic’s benefit on patients with high levels of C. pneumoniae antibodies was essentially the same as those with low levels.
It is possible that the drug works directly to reduce inflammation, as azithromycin is in a class of drugs called macrolides, which have anti-inflammatory effects.
Inflammation is one of the body’s responses to infection. But azithromycin did not reduce the levels of C-reactive protein in this study.