Amoxicillin, the antibiotic doctors often prescribe for persistent coughs caused by uncomplicated chest infections such as bronchitis, is no more effective at easing symptoms than no medication at all, even in older patients. This was the finding of the largest randomised placebo controlled trial of antibiotics for lower respiratory tract infections (LRTI) done to date.

The study, which was led by the University of Southampton in the UK, is from the GRACE (Genomics to Combat Resistance against Antibiotics in Community-acquired LRTI in Europe) consortium and was funded by the European Community’s Sixth Framework Programme.

A paper on the findings appears in the 19 December online issue of The Lancet Infectious Diseases.

First author Paul Little, Professor of Primary Care Research at Southampton, says in a statement:

“Patients given amoxicillin don’t recover much quicker or have significantly fewer symptoms.”

In fact, he adds, using amoxicillin to treat patients with respiratory infections who don’t have pneumonia could not only be ineffective, but might actually harm them.

“Overuse of antibiotics, which is dominated by primary care prescribing, particularly when they are ineffective, can lead to side effects such as diarrhea, rash, vomiting and the development of resistance,” he explains.

The European Centre for Disease Prevention and Control (ECDC) recently put out a statement saying that antibiotic resistance remains a major threat to public health around the world, and for the large part, the cause is misuse of antibiotics.

Chest infections, also known as lower respiratory tract infections (LRTI), are one of the most common acute illnesses treated in primary care settings in developed countries.

There is a lot of controversy about whether LRTI, especially in older people, should be treated with antibiotics, especially since viruses are thought to cause most of them, and previous studies have shown inconsistent results.

A recent study presented at CHEST 2012, the annual meeting of the American College of Chest Physicians, also suggests antibiotics are not successful in treating cough due to the common cold in children.

For this latest GRACE study, the researchers recruited 2,061 adults attending primary care practices with straightforward mild chest infections. The practices were located in 12 European countries: England, Wales, Netherlands, Belgium, Germany, Sweden, France, Italy, Spain, Poland, Slovenia, and Slovakia.

The participants were randomly assigned to be prescribed either amoxicillin or a placebo, to be taken three times a day for seven days.

The prescribing general practitioners (GPs) assessed their patients’ symptoms at the start of the study period, and the patients also filled in diaries of their daily symptoms.

When they analyzed this data, the researchers found there was little difference in how severe the symptoms were or how long they lasted for, between the amoxicillin and placebo groups.

Even in those aged 60 and over with no other illnesses, antibiotics seemed to offer little benefit over placebo.

Patients in the antibiotic group reported significantly more side effects, including rash, nausea and diarrhea.

The researchers did conclude, however, that while most people seem to get better on their own, there is a small number of patients who do benefit from antibiotics, and “the challenge remains to identify these individuals,” says Little.

In an accompanying commentary, Philipp Schuetz, from the University of Basel in Switzerland, notes:

“Little and colleagues have generated convincing data that should encourage physicians in primary care to refrain from antibiotic treatment in low-risk patients in whom pneumonia is not suspected.”

However, the question remains, he says, of whether this “one-size-fits-all approach can be further improved”.

He suggests perhaps one way to avoid the “toxic effects and costs” of antibiotics and “the development of resistance in the other patients”, is to test for “specific blood biomarkers of bacterial infection”, so as to “identify the few individuals who will benefit from antibiotics despite the apparent absence of pneumonia”.

Written by Catharine Paddock PhD