Objectives: We investigated whether sulphonamide resistance in Escherichia coli remained prevalent in 2004, 9 years since the formal introduction of a UK prescribing restriction on co-trimoxazole. Resistance to other agents no longer in common use was also examined. Methods: Consecutive urinary E. coli isolates were obtained at the diagnostic microbiology laboratory of the Royal London Hospital from January to March 2004. The presence of the sulphonamide resistance genes, sul1, sul2 and sul3, and the class I integrase gene, int1, were determined by PCR. Results: Of the 391 E. coli isolates recovered in 20 04, 45.5% were sulphonamide-resistant compared with 46.0% in 1999 and 39.7% in 1991. The sul2 gene remained the most prevalent sulphonamide resistance determinant, present in 81% of resistant isolates in 2004 compared with 79% and 67% in 1999 and 1991, respectively; 28% of resistant isolates carried both sul1 and sul2 genes; sul3 was not found. Resistance to streptomycin also remained common, whereas resistance to chloramphenicol and kanamycin had decreased since 1999. Conclusion: Sulphonamide resistance in E. coli persists undiminished despite the prolonged withdrawal of this antibiotic in the UK; resistance to streptomycin also seems stable whilst that to chloramphenicol and kanamycin is declining.
Bibliographical noteFunding Information:
We are grateful to the staff of the Microbiology Laboratory at the Royal London Hospital for provision of E. coli isolates. We thank Vincent Perreten for supplying sul3 plasmid pUVP4401 and Peter Stephens of IMS Health for provision of antibiotic prescribing data. This study was funded by the Department of Health (Resistance to Antibiotics and Other Antimicrobial Agents Programme, Grant No. 91).