Background.Escherichia coli sequence type ST131 (O25:H4), associated with the CTX-M-15 extended-spectrum β-lactamase, has emerged internationally as

The efficacy of antimicrobial urinary catheters in hospitalized patients is poorly defined. To assess currently marketed antimicrobial urinary catheters for preventing catheter-associated urinary tract infection (UTI). Electronic databases, conference proceedings, bibliographies, trialists, and catheter manufacturers (search dates, 1966 to June 2005). Randomized and quasi-randomized trials of nitrofurazone-coated or silver alloy–coated antimicrobial urinary catheter use for less than 30 days; no language restriction. Study design, study sample, inclusion and exclusion criteria, allocation, blinding, UTI definition, ascertainment methods, and proportion developing symptomatic UTI (primary end point) or bacteriuria (secondary end point) were extracted by using a structured data collection instrument. Twelve qualifying trials (13 392 total participants or catheters) were identified. They compared nitrofurazone-coated silicone (n = 3) or silver-coated latex (n = 9) catheters with silicone or latex catheters. No study addressed symptomatic UTI. All trials suggested protection against bacteriuria with test catheter use. However, effect size varied considerably and postrandomization exclusions were very common. Effect size was greatest in trials of nitrofurazone-coated catheters (all post-1995) and in pre-1995 silver alloy–coated catheter trials and was smallest in post-1995 silver alloy–coated catheter trials. Control group bacteriuria rate, control catheter type (latex vs. silicone), and patient sample (urology vs. other) also predicted effect size. Few studies addressed secondary bloodstream infection, mortality, costs, or microbial resistance. Short-term adverse effects were minimal. The study was limited by the number, size, and quality of studies and by lack of the following: intention-to-treat analyses, data on clinical end points, and trials comparing nitrofurazone-coated with silver alloy–coated catheters. According to fair-quality evidence, antimicrobial urinary catheters can prevent bacteriuria in hospitalized patients during short-term catheterization, depending on antimicrobial coating and several other variables. Older data probably lack current relevance. Cost implications and effect on infectious complications remain undefined.

Background. Fluoroquinolone-resistant Escherichia coli are increasingly prevalent. Their clonal origins—potentially critical for control efforts—remain undefined. Methods. Antimicrobial resistance profiles and fine clonal structure were determined for 236 diverse-source historical (1967–2009) E. coli isolates representing sequence type ST131 and 853 recent (2010–2011) consecutive E. coli isolates from 5 clinical laboratories in Seattle, Washington, and Minneapolis, Minnesota. Clonal structure was resolved based on fimH sequence (fimbrial adhesin gene: H subclone assignments), multilocus sequence typing, gyrA and parC sequence (fluoroquinolone resistance-determining loci), and pulsed-field gel electrophoresis. Results. Of the recent fluoroquinolone-resistant clinical isolates, 52% represented a single ST131 subclonal lineage, H30, which expanded abruptly after 2000. This subclone had a unique and conserved gyrA/parC allele combination, supporting its tight clonality. Unlike other ST131 subclones, H30 was significantly associated with fluoroquinolone resistance and was the most prevalent subclone among current E. coli clinical isolates, overall (10.4%) and within every resistance category (11%–52%). Conclusions. Most current fluoroquinolone-resistant E. coli clinical isolates, and the largest share of multidrug-resistant isolates, represent a highly clonal subgroup that likely originated from a single rapidly expanded and disseminated ST131 strain. Focused attention to this strain will be required to control the fluoroquinolone and multidrug-resistant E. coli epidemic.

The extent to which clonal spread contributes to emerging antimicrobial resistance in Escherichia coli is incompletely defined. To address this question within a recent, nationally representative strain collection, three established drug-resistant E. coli clonal groups (i.e., clonal group A, E. coli O15:K52:H1, and sequence type 131 [ST131]) were sought among 199 E. coli urine isolates recovered from across Canada from 2002 to 2004, with stratification by resistance to trimethoprim-sulfamethoxazole (TS) and fluoroquinolones (FQs). The isolates' clonal backgrounds, virulence genotypes, and macrorestriction profiles were assessed. The three clonal groups were found to account for 37.2% of isolates overall, but accounted for 0% of TS-susceptible (TS-S) and FQ-susceptible (FQ-S) isolates, 20% of TS-resistant (TS-R) and FQ-S isolates, 60% of TS-S and FQ-R isolates, and 68% of TS-R and FQ-R isolates ( P < 0.001). E. coli ST131, the most prevalent clonal group, accounted for 23.1% of isolates overall and for 44% of the FQ-R isolates. Nearly all ST131 isolates were FQ-R (96%) but, notably, cephalosporin susceptible (98%). Although the distinctive virulence profiles of the FQ-R clonal group isolates were less extensive than those of the susceptible isolates, they were significantly more extensive than those of the other FQ-R isolates. These findings indicate that among the E. coli urine isolates studied, resistance to TS and FQs has a prominent clonal component, with the O15:K52:H1 clonal group and especially E. coli ST131 being the major contributors. These clonal groups appear to be more virulent than comparably resistant isolates, possibly contributing to their success as emerging multi-drug-resistant pathogens.

In Escherichia coli infection, the implications of fluoroquinolone (FQ) and extended-spectrum cephalosporin plus cephamycin (AmpC) resistance for phy