Antibiotic treatment failure in four common infections in UK primary care 1991-2012: longitudinal analysis.

OBJECTIVE

To characterise failure of antibiotic treatment in primary care in the United Kingdom in four common infection classes from 1991 to 2012.

DESIGN

Longitudinal analysis of failure rates for first line antibiotic monotherapies associated with diagnoses for upper and lower respiratory tract infections, skin and soft tissue infections, and acute otitis media.

SETTING

Routine primary care data from the UK Clinical Practice Research Datalink (CPRD).

MAIN OUTCOME MEASURES

Adjusted rates of treatment failure defined by standardised criteria and indexed to year 1 (1991=100).

RESULTS

From 58 million antibiotic prescriptions in CPRD, we analysed 10,967,607 monotherapy episodes for the four indications: 4,236,574 (38.6%) for upper respiratory tract infections; 3,148,947 (28.7%) for lower respiratory tract infections; 2,568,230 (23.4%) for skin and soft tissue infections; and 1,013,856 (9.2%) for acute otitis media. In 1991, the overall failure rate was 13.9% (12.0% for upper respiratory tract infections; 16.9% for lower respiratory tract infections; 12.8% for skin and soft tissue infections; and 13.9% for acute otitis media). By 2012, the overall failure rate was 15.4%, representing an increase of 12% compared with 1991 (adjusted value indexed to first year (1991) 112, 95% confidence interval 112 to 113). The highest rate was seen in lower respiratory tract infections (135, 134 to 136). While failure rates were below 20% for most commonly prescribed antibiotics (amoxicillin, phenoxymethylpenicillin (penicillin-V), and flucloxacillin), notable increases were seen for trimethoprim in the treatment of upper respiratory tract infections (from 29.2% in 1991-95 to 70.1% in 2008-12) and for ciprofloxacin (from 22.3% in 1991-95 to 30.8% in 2008-12) and cefalexin (from 22.0% in 1991-95 to 30.8% in 2008-12) in the treatment of lower respiratory tract infections. Failure rates for broad spectrum penicillins, macrolides, and flucloxacillin remained largely stable.

CONCLUSIONS

From 1991 to 2012, more than one in 10 first line antibiotic monotherapies for the selected infections were associated with treatment failure. Overall failure rates increased by 12% over this period, with most of the increase occurring in more recent years, when antibiotic prescribing in primary care plateaued and then increased.