Antibiotic prescribing does not increase the risk of Clostridium difficile infection, Canadian research suggests.
The findings contradict previous studies, which concluded that antibiotic use is to blame for the rise in cases of C difficile.
GPs have been advised to limit their prescribing of antibiotics, with recent NICE guidance recommending delayed antibiotic prescribing.
For this latest study, researchers analysed data on all hospital admissions for C difficile infection over an eight-year period.
They identified 836 patients, aged 65 and over who developed C difficile infection in the community and had been hospitalised for the infection.
Patients with hospital-acquired C difficile infections were excluded from the study because of the increased risk of infection in hospital.
Medical records were then analysed to identify whether patients had taken antibiotics and for how long.
Overall, they found that 53 per cent of patients had not been exposed to antibiotics during the 45 days preceding their C difficile-related hospitalisation.
This rate decreased to 46 per cent when the timeframe was extended to 90 days preceding hospital admission.
Lead researcher Dr Sandra Dial, from the Montreal Chest Institute of the McGill University Health Centre, said that the figures showed that half of community-acquired C difficile infections are not related to antibiotic use.
'While antibiotic use indeed plays an important role, other factors are likely to also be important,' she said.
'But we still need to determine what these other risk factors are.'
Testing for C difficile is mainly done on patients who have taken antibiotics, which probably means that not everyone is receiving a correct diagnosis, warned Dr Dial.
CMAJ 2008; 179: 767-72.
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