Antimicrobial resistance and distribution of sul genes and integron-associated intI genes among uropathogenic Escherichia coli in Queensland, Australia.

We studied 137 uropathogenic Escherichia coli (UPEC) isolates from hospitalized adult patients (Queensland, Australia) for their resistance to 17 antimicrobial agents using the calibrated dichotomous sensitivity method and the presence of class I, II and III integron-associated integrase (intI) genes, including functional class II intI2, as well as the presence of sul1, sul2 and sul3 genes, using PCR. Randomly amplified polymorphic DNA PCR, a high-resolution biochemical-fingerprinting method (PhP) and phylogenetic grouping were also used to identify the clonality of the sulphonamide-resistant isolates. One hundred and twenty (87.6 %) isolates were resistant to one or more of the tested antimicrobial drugs, with the highest resistance (70.1 %) observed against sulphafurazole (96 isolates). Of these, 84 (87.5 %) contained one or more sul alleles, with sul1 being the most common allele [occurring in 69 (72 %) isolates]. Only 38 of 69 (55.1 %) strains carrying the sul1 gene were positive for class I integrase. Our results indicate a high prevalence of sulphafurazole-resistant UPEC strains belonging to different clones among patients with urinary tract infection in Queensland, Australia. We also conclude that these strains carry predominantly a sul1 gene that is not commonly associated with the presence of class I integrase, indicating that it may be carried on either a bacterial chromosome or other genetic elements.