Abstract

Background: Extraintestinal pathogenic Escherichiacoli (ExPEC) bacteria have the abilityto cause diverse and serious diseases, such asurinary tract infections (UTIs) and bacteremia;incidence of bacteremia is increasing globally.The emergence of multidrug resistance in E.coli is also becoming a global concern, withparticular emphasis on E. coli sequence type(ST) 131, which is being increasingly reportedin UTIs. Drug resistance is mediated by extended-spectrum β-lactamases (ESBLs), mainly ofthe CTX-M family, particularly CTX-M-15, andless frequently of the SHV and OXA families.Few studies are available regarding the characterizationof E. coli strains causing bacteremia.Methods: We characterized 52 selected fluoroquinolonesand cephalosporins-resistant E.coli isolates from bacteremia patients treatedat Policlinico University Hospital (Palermo,Italy) over a 6-years period, with the aim of developingan epidemiologic profile of the populationof ExPEC that causes bacteremia. MultiplexPCR to determine the phylogenetic group,multiplex ERIC PCR to analyze the epidemiologicalcorrelations, multiplex PCR detectionof ESBL genes, multilocus sequence typingusing the Achtman scheme (http://mlst.ucc.ie/mlst/dbs/Ecoli), and virulence-associated gene(VAG) carriage screening by multiplex PCRwere performed on isolates.Results: The 86.5% of our strains belonged tophylogenetic group B2, while the phylogeneticgroup D appeared to be under-represented(13.5%) and no strain belonged to group A norB1. Clustering analysis by ERIC-PCR showeda high heterogeneity of the strains that did notallow a significant grouping and PCR screeningfor ESBL carriage showed significantly highercarriage for CTX-M 15. Multilocus sequencetypes were determined in all our bacteremiaE. coli isolates: ST131 dominated and was significantlyhigher in prevalence (75%) followedby ST167, 58, 38, 744, 405, 453, 707 and 1447.VAGs screening of all isolates showed that themost represented were kpsM II and iutA codingfor the capsule and an aerobactin (siderophore)receptor, respectively.Conclusions: Overall, our results show thatST131 is the predominant E. coli lineageamong the 52 extraintestinal pathogenicE. coli (ExPEC) isolates from bacteremia patientsincluded in this study. Our group B2ExPEC ST131 isolates produce extended-spectrumb-lactamases, especially CTX-M-15, andalmost all are resistant to fluoroquinolones.42ND
Lingua originaleEnglish
Pagine110-
Numero di pagine1
Stato di pubblicazionePublished - 2014

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