More evidence is needed to help guide antibiotic use for insect bites, say GP researchers, who found it accounted for a large proportion of prescribing.
An analysis of more than 5,600 patients who had attended a large GP out-of-hours service in Birmingham with an insect bite over a seven-year period found two-thirds were prescribed antibiotics, most receiving flucloxacillin.
Over the whole study period insect bites accounted for a fifth of all flucloxacillin prescriptions from the out-of-hours service with most being in the summer months.
A more detailed review of the cases in 500 patients showed the presence of pain, swelling and signs of spreading meant they were more likely to be prescribed an antibiotic.
But there was no strong association with antibiotics being offered and discharge, itch, systemic upset or comorbidity, they reported in BMJ Open.
Patients under the age of 16 were less likely to be prescribed antibiotics and prescribing rates were lower in those in the most deprived quintile, the analysis found.
GPs were less likely to prescribe antibiotics than advanced nurse practitioners (60.5% compared with 71.1%), they also reported.
Lyme disease was only suspected in eight patients five of whom were given antibiotics which probably reflects the urban demographic of the out-of-hours provider, the researchers said.
The seasonality of prescribing was also shown in overall figures for Birmingham ‘suggesting the burden of insect-bite related infections are similar in core hours general practice’.
Using Open Prescribing data on flucloxacillin as a guide, the team of GP researchers estimated that England general practice sees around 1.5 million insect bites every year.
Given the high proportion of bites for which antibiotics were prescribed, more research is needed to help clinicians and patients decide which may benefit from the treatment and which can be left alone, especially given the population risk of antimicrobial resistance they concluded.
The research shows this is not a trivial issue, said study lead Dr Samuel Finnikin, a GP in Sutton Coldfield and researcher at the Institute for Applied Health Research at the University of Birmingham.
‘One in five prescriptions of flucloxacillin for insect bites is a big chunk. I think primary care is really serious about antimicrobial resistance and trends show prescribing is decreasing but there are areas like this where more information could help us make better decisions.’
He pointed out that NICE do have recommendations but they are based on expert opinion because no one has done the research.
‘Some insect bites can have a very marked inflammatory response,’ he said.
‘The general consensus is that we’re probably overtreating but that’s because we don’t know which ones to offer treatment for. Even those where there may be a superficial infection, we don’t know what the natural course of that may be.
‘It is quite a big issue and one that needs further investigation.’