UK doctors' prescribing practices threaten to increase the risk of antibiotic resistance, according to studies presented at the British Pharmaceutical Conference in Manchester this week which highlight inappropriate and over-use of antibiotics in primary care and hospitals.

Researchers at the University of Sunderland found that 74% of surgical patients at Sunderland Royal Hospital received more antibiotic than the recommended dose. Data were collected between November 2005 and January 2006 from 50 patients admitted to vascular and gastrointestinal surgery wards who were prescribed cefuroxime and metronidazole, which are widely used in combination in general surgery to reduce post-operative wound infections. Current prescribing guidelines recommend a maximum of two peri-operative and three post-operative antibiotic prophylactic doses. However, 34 patients in the study received prolonged prophylactic treatment of more than five doses, with the number of doses ranging from zero to 34 doses.

Furthermore, the rate of over-prescribing at the Sunderland Royal Hospital had increased 20% since a previous study in 2006. After the earlier study, the hospital's pharmacy department adjusted the electronic prescribing system to include a mandatory stop date for antibiotics. However, the researchers suggest that the stop dates may actually serve to prolong antibiotic courses as there is no need to review patients' medication on an ongoing basis.

The use of antibiotics in primary care, which accounts for 80% of antibiotics prescribed in the UK, has also been called into question by an investigation of 13 GP practices in a primary care trust (PCT) in the north-west of England. Pharmacists at Liverpool's John Moore's University investigated whether GPs were adhering to local PCT guidelines for infection control when prescribing co-amoxiclav, clarithromycin and all drugs in the 4-quinolone class during December 2006 – a month generally associated with high prescribing rates. The results were compared with a previous study carried out 12 months earlier.

Of 4,429 prescriptions issued by the GPs for an antibacterial in December 2006, 15% were for the specialist antibiotics which are indicated as first line treatment for very few conditions. Prescribing was often outside the conditions and guidance in the formulary and treatment choices in these circumstances often relied on personal preferences and experience rather than evidence. Although the figures were 10% lower than those for 2005, the researchers note that unnecessary or inappropriate prescribing of these antibiotics may increase the potential of resistance and raise costs to the PCT. The PCT is supplementing education to support antibacterial prescribing with a new software package for GPs' prescribing systems to highlight alternative drug therapies.