Previous research has shown that children who were prescribed amoxicillin had twice the level of resistant bacteria than children who received no amoxicillin.
For the latest study , the researchers analysed data taken from 162 practices across the UK.
In patients with common respiratory infections, they examined the risk of developing serious complications in the month after diagnosis of infection.
They then calculated and compared this risk in those who were treated with antibiotics and those who were not.
There were 749,389 episodes of chest infection. The risk of pneumonia in the month after diagnosis was high and was substantially reduced by antibiotics.
Without an antibiotic prescription, 4 per cent of those aged 65 and over were diagnosed with pneumonia in the month after diagnosis of chest infection compared with 1.5 per cent of those who were treated without an antibiotic.
However, the use of antibiotics was not as effective in treating upper respiratory tract infections, otitis media and sore throats.
The risk of serous complications in these infections was low and the number of courses of antibiotic needed to prevent one serious complication was high, at over 4,000.
Lead researcher Dr Andrew Hayward, from the department of infectious disease epidemiology at University College London, said that the study showed that antibiotics were important in reducing the risk of pneumonia in those with chest infections.
‘GPs already prescribe to around 80 per cent of patients consulting with chest infection even though current guidance suggests that this is unnecessary.
‘This research indicates that GPs may be justified in their decisions to prescribe antibiotics for chest infections.’
But prescribing for other respiratory tract infections is unnecessary, said Dr Hayward.
‘The study does not justify high prescribing levels because around half of the antibiotics prescribed for respiratory tract infections are for sore throats and otitis media.’
Antibiotic resistance is a potential consequence of over prescribing but so far it has not greatly complicated the management of respiratory infections in the community, he added.
Comment below and tell us what you think