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. INTRODUCTIONUrinary tract infection (UTI), although one of the most easily treatable diseases, has been reported to be the most common hospital-acquired infection, affecting mainly women, children and the elderly (Foxman & Brown, 2003;Gupta et al., 2001;Russo & Johnson, 2003;Tartof et al., 2007). Escherichia coli is the primary aetiological agent, accounting for 75-90 % cases of UTI (Gupta et al., 2001;Kaper et al., 2004;Nicolle, 2002). The acquisition of resistance genes by horizontal transfer is currently thought to play a major role in the development of multi-drugresistant (MDR) strains because a substantial proportion of the resistance genes are located on conjugative plasmids, transposons, insertion sequences and integrons (Chang et al., 2011;Fierer & Guiney, 1999;Moritz & Hergenrother, 2006). Integrons are mobile DNA elements with the ability to integrate and express gene cassettes by site-specific recombination (Mazel, 2006;Rowe-Magnus & Mazel, 2002). Site-specific recombination is catalysed by an integrase that is encoded within the conserved 59 region of integrons. Several classes of integrase have been described with those classes of integrons, i.e. class I integrase (intI1) defines class I integrons (Collis et al., 2002;Nield et al., 2001).With the standard treatment for UTI being a combination of trimethoprim and sulphamethoxazole (Grape et al., 2003), the sulphonamides are classified as a highly important antimicrobial agent for treatment of E. coli infections, and the presence of sulphonamide resistance can lead to treatment failure in cases of UTI. In E. coli, sulphonamide resistance ofte...

Forty-nine strains of multiresistant Aceinetobacter baumannii isolated from intensive care unit patients in Royal Brisbane and Women Hospital (RBWH) between 2001 and 2003 and four epidemiologically unrelated strains from three other hospitals were tested (n = 53) for their genetic relatedness using pulsed-field gel electrophoresis (PFGE) and for the presence of different classes of integrons. With PFGE, these strains were divided into three common (C) but closely related types (i.e., C1, C1a, and C1b) and eight single (S) types (S1-S8). C1 contained 40 isolates, while C1a and C1b contained 5 and 2 isolates, respectively. All isolates from Royal Brisbane and Women Hospital (RBWH) were resistant to 12 or more antibiotics. Four common pattern of antibiotic resistance (PAR) was observed among the isolates. The dominant PAR contained 39 strains from RBWH, isolated during 2000 (n = 6), 2001 (n = 16), and 2002 (n = 17) and were resistant to 14 antibiotics. Of these, 36 strains (92%) had identical PAR/PFGE types. Class 1 integrase genes were detected in all of the 53 isolates with 5 isolates also having class 2 integrase gene. No class 3 integrase gene was detected among the isolates. Our data suggest the presence of a dominant and persistent clone of multiresistant A. baumannii strain carrying class 1 integron in this hospital setting.

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