Amoxicillin, a narrow-spectrum antibiotic, has been found to be as effective as the broad-spectrum antibiotic co-amoxiclav, which targets a wider range of bacteria, in people admitted to hospital with pneumonia, regardless of how severe it is.
In a paper published in the Journal of Infection, a University of Oxford research team say their findings could help to reduce the spread of antimicrobial resistance.
The research, supported by the NIHR Oxford Biomedical Research Centre, found that mortality rates were similar whether people received co-amoxiclav or amoxicillin.
Infections caused by bacteria that are resistant to antibiotics can be difficult to treat. Resistance is increased by using broad-spectrum antibiotics that work on many types of bacteria. To limit the spread of resistance, National Institute for Health and Care Excellence (NICE) guidelines recommend that clinicians use this class of antibiotics only when essential.
Pneumonia is an infection of the lungs, usually caused by bacteria. Symptoms include a cough, shortness of breath, and chest pain. Each year, between five and 10 in every 1,000 adults in the UK develop community-acquired pneumonia. Most recover in two to four weeks, but older people and those with heart or lung conditions are at risk of serious illness and hospital admission.
NICE recommends amoxicillin for low- to moderate-severity pneumonia, while co-amoxiclav is recommended only for severe pneumonia.
However, many people with non-severe pneumonia are prescribed co-amoxiclav when they arrive at hospital. This study compared co-amoxiclav with amoxicillin for people arriving at hospital with community-acquired pneumonia.
The research made use of the Infections in Oxfordshire Research Database (IORD), which is funded by the Oxford BRC.
Researchers analysed the electronic health records of 4,586 adults admitted to hospital with pneumonia in Oxfordshire between 2016 and 2023. Of these, 3,167 received co-amoxiclav and 1,419 amoxicillin 12 hours prior to or up to 24 hours after their admission.
People with the most severe pneumonia, and with other health conditions, were more likely to be prescribed co-amoxiclav. The researchers accounted for such differences to compare people who were similarly unwell but received different treatments. People in one treatment group were matched and compared to someone with similar risks (such as pneumonia severity) in the other group.
Thirty days after admission, the researchers found that there was a similar risk of dying whether people were prescribed co-amoxiclav or amoxicillin. They also found that taking additional antibiotics – such as clarithromycin or doxycycline to treat other rarer causes of pneumonia – did not change the risk of death within 30 days.
One of the authors, David Eyre, Professor of Infectious Diseases at the University of Oxford and Oxford University Hospitals, said: “Before starting this study, like many clinicians, I was concerned that sometimes by using amoxicillin rather than co-amoxiclav we might not be treating all the possible causes in patients coming to hospital with pneumonia. However, the findings have changed how I think about pneumonia treatment, as we found there was no evidence that co-amoxiclav was any better than amoxicillin.
“Our hospital guidelines now suggest treating mild, moderate, and severe community-acquired pneumonia with amoxicillin, adding in doxycycline for patients with moderate to severe infection. However, there are still some patients who may need other antibiotics, and we need to continue to work on developing better tests to detect who needs other treatments.”
The research team hope the findings will encourage clinicians to follow guidelines and prescribe amoxicillin for low- or moderate-severity community-acquired pneumonia, and so help to tackle antimicrobial resistance.
However, they say more research, in the form of a randomised controlled trial, is needed before guidelines could be changed to recommend amoxicillin for severe pneumonia.
Andy Whittamore, Clinical lead at Asthma + Lung UK, said: “This research clearly shows that using a narrow range antibiotic not only reduces the risk of anti-microbial resistance but doesn’t have a negative impact on mortality rates for people with pneumonia either. By changing prescribing habits now, the NHS can delay the worrying progression of resistance whilst reducing probable deaths from pneumonia in years to come too.”