Abstract
Urine was collected twice weekly from one patient during a 25-month period. Escherichia coli harbouring a resistance plasmid, pUK28, which confers trimethoprim, ampicillin, sulphamethoxazole, spectinomycin and streptomycin resistance was identified in the urine. Carriage of strains containing plasmid pUK28 was observed during three separate periods which totalled 16 months, even though the patient did not receive antibacterial drug therapy for most of that time. The plasmid was able to acquire the genes responsible for mannose-resistant haemagglutination and these genes were increasingly associated with the plasmid towards the end of the study period.