By Amy Fallon
A new study has shown a 'significant increasing trend' in resistance to commonly-prescribed antibiotics to treat urinary tract infections, with trimethoprim showing by far the largest rise in resistance.
The eleven-year study of seven commonly prescribed antibiotics carried out by hospital urologists found inpatients with UTIs displayed higher resistance rates than the other groups.
The researchers warned trimethoprim and ampicillin are 'no longer represent suitable empirical antimicrobial agents in UTI'.
Resistance to trimethoprim increased by 0.7% over each year of the study. In total, trimethoprim resistance in samples taken from general practice UTI samples rose by 32.1%, and on average 33.5% of all the 42,000 urine samples tested for E.coli sensitivity between 1999 and 2009 were resistant to trimethoprim.
Ampicillin resistance in general practice samples also grew, by 0.5% per year to reach 57.5% in total by 2009, when on average 62.1% of all samples were resistant.
Co-amoxiclav showed a 0.09% increase in resistance each year and 10.6% overall resistance, but resistance to nitrofurantoin and ciproflaxin decreased by 0.06% and 0.8% per year, although this rate of decrease was not statistically significant.
Dr Michael Cullen, a consultant in urology at the Adelaide and Meath Hospital in Dublin, concluded: 'A significant increasing trend in antibiotic resistance is identified over the study period for most antibiotics. Ampicillin and trimethoprim no longer represent suitable empirical antimicrobial agents in UTI. Ciprofloxacin resistance in this study renders it unsuitable empirical therapy for UTI.'
The study was presented at European Congress of Clinical Microbiology and Infectious Disease Conference in Milan last week.
Trimethoprim 'not suitable' for empirical use in UTIs