Prevalence of Fluoroquinolone-Resistant Escherichia coli O25:H4-ST131 (CTX-M-15-Nonproducing) Strains Isolated in Japan
ABSTRACT Fluoroquinolone-resistant and extended-spectrum β-lactamase (ESBL)-carrying multidrug-resistant Escherichia coli have become severely problematic. In particular, a lineage of multilocus sequence-type ST131 which belongs to O25:H4 and carries ESBL CTX-M-15 has spread worldwide.
Fluoroquinolone-resistant E. coli strains were isolated from various clinical specimens in a commercial clinical laboratory in 2008 and 2009 in Hokkaido Prefecture, Japan.
Among 478 clinical isolates, 112 strains (23.4%) showed levofloxacin (LVX) resistance. About 80% of the fluoroquinolone-resistant strains (88 strains) showed common features, namely O25:H4-ST131, phylogenetic group B and the same mutation pattern in quinolone resistance-determining regions. Pulsed field gel electrophoresis patterns suggested numerous lineages of O25:H4-ST131. The fluoroquinolone-resistant strains, including strains of O25:H4-ST131 and other types, more frequently shared CTX-type ESBL genes than did fluoroquinolone-susceptible strains. The ESBL genes fell into the CTX-M-9 and CTX-M-2 groups. CTX-M-15 (CTX-M-1 group) was not found among any of the strains isolated in this study. Sitafloxacin showed markedly potent activity against E. coli isolates compared with LVX, ciprofloxacin and ulifloxacin.
The most prevalent fluoroquinolone-resistant strains of E. coli isolated in Hokkaido Prefecture, Japan, are O25:H4-ST131. However, similar to other areas of Japan, the ST131 clones represent distinct lineages from the general worldwide dispersal of multidrug-resistant clones which carry CTX-M-15.
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ABSTRACT: Contribution of homologous exchange (recombination) of core genes in the adaptive evolution of bacterial pathogens is not well understood. To investigate this, we analyzed fully-assembled genomes of two Escherichia coli strains from ST131 - a clonal group that is both the leading cause of extra-intestinal E. coli infections and the main source of fluoroquinolone-resistant E. coli. Although sequences of each of the seven multi-locus sequence typing genes were identical in two ST131 isolates, the strains diverged from one another by homologous recombination that affected at least 9% of core genes. This was on a par with the contribution to genomic diversity of horizontal gene transfer and point gene mutation. Genomic position of recombinant and mobile genetic regions were partially linked, suggesting their concurrent occurrence. One of the genes affected by homologous recombination was fimH which encodes mannose-specific type1 fimbrial adhesin, resulting in functionally-distinct copies of the gene in ST131 strains. One strain, a uropathogenic isolate, had a pathoadaptive variant of fimH that was acquired by homologous replacement into the commensal strain background. Close examination of FimH structure and function in additional ST131 isolates revealed that recombination led to acquisition of several functionally distinct variants that, upon homologous exchange, were targeted by a variety of pathoadaptive mutations under strong positive selection. Different recombinant fimH also show strong clonal association with ST131 isolates that have distinct fluoroquinolone-resistance profiles. Thus, homologous recombination of core genes plays a significant role in adaptive diversification of bacterial pathogens, especially at the level of clonally-related groups of isolates.Journal of bacteriology 11/2012; DOI:10.1128/JB.01524-12 · 2.69 Impact Factor
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ABSTRACT: This study aimed to investigate the genetic association between fluoroquinolone (FQ)- and/or cephalosporin (CEP)-resistance in Escherichia coli isolates from dogs, and its risk to human health. We characterized E. coli clinical isolates derived from fecal samples of dogs attending veterinary hospitals, using phylogenetic grouping, determination of virulence factor prevalence, multilocus sequence typing (MLST), and O-serotyping. The D group was the dominant phylogenetic group among strains resistant to FQ and/or CEP. In contrast, the dominant group among susceptible strains was group B2. Group D strains showed a significantly higher prevalence of virulence factors than strains belonging to groups A and B1, and were resistant to significantly more antimicrobials than group B2 strains. The phylogenetic distribution of FQ-CEP-resistant E. coli groups (FQ-CEPRECs) and FQ-resistant groups was significantly correlated (r = 0.98), but FQ-CEPRECs and CEP-resistant E. coli groups were not correlated (r = 0.58). Data from pulsed-field gel electrophoresis, O-serotype, and multilocus sequence type analyses indicated that the majority of FQ-resistant strains derived from a particular lineage of phylogenetic group D, viz., serotype O1-ST648. Some D-O1-ST648 strains carried blaCMY-2, showed multidrug resistance, and possessed a high number of virulence factors. Our data indicate that emergence of FQ-CEP-resistant E. coli is primarily based on FQ-resistant E. coli. Moreover, as strains of the D-O1-ST648 lineage have been found in clinical isolates derived from humans at a relatively high frequency, our findings indicate that the spreading of D-O1-ST648 strains may cause serious difficulties in the both the veterinary and human clinical fields in the future.Journal of Medical Microbiology 02/2013; DOI:10.1099/jmm.0.054676-0 · 2.27 Impact Factor
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ABSTRACT: (See the commentary by Rogers and Doi, on pages 370-372 .) Objective. To determine prevalence, predictors, and outcomes of infection due to Escherichia coli sequence type ST131. Design. Retrospective cohort. Setting. All healthcare settings in Olmsted County, Minnesota (eg, community hospital, tertiary care center, long-term care facilities, and ambulatory clinics). Patients. Ambulatory and hospitalized children and adults with extraintestinal E. coli isolates. Methods. We analyzed 299 consecutive, nonduplicate extraintestinal E. coli isolates submitted to Olmsted County laboratories in February and March 2011. ST131 was identified using single-nucleotide polymorphism polymerase chain reaction and further evaluated through pulsed-field gel electrophoresis. Associated clinical data were abstracted through medical record review. Results. Most isolates were from urine specimens (90%), outpatients (68%), and community-associated infections (61%). ST131 accounted for 27% of isolates overall and for a larger proportion of those isolates resistant to fluoroquinolones (81%), trimethoprim-sulfamethoxazole (42%), gentamicin (79%), and ceftriaxone (50%). The prevalence of ST131 increased with age (accounting for 5% of isolates from those 11-20 years of age, 26% of isolates from those 51-60 years of age, and 50% of isolates from those 91-100 years of age). ST131 accounted for a greater proportion of healthcare-associated isolates (49%) than community-associated isolates (15%) and for fully 76% of E. coli isolates from long-term care facility (LTCF) residents. Multivariable predictors of ST131 carriage included older age, LTCF residence, previous urinary tract infection, high-complexity infection, and previous use of fluoroquinolones, macrolides, and extended-spectrum cephalosporins. With multivariable adjustment, ST131-associated infection outcomes included receipt of more than 1 antibiotic (odds ratio [OR], 2.54 [95% confidence interval (CI), 1.25-5.17]) and persistent or recurrent symptoms (OR, 2.53 [95% CI, 1.08-5.96]). Two globally predominant ST131 pulsotypes accounted for 45% of ST131 isolates. Conclusions. ST131 is a dominant, antimicrobial-resistant clonal group associated with healthcare settings, elderly hosts, and persistent or recurrent symptoms.Infection Control and Hospital Epidemiology 04/2013; 34(4):361-9. DOI:10.1086/669865 · 3.94 Impact Factor