title: Multidrug-resistant and epidemic clones of Escherichia coli from natural beds of Venus clam.
abstract: Epidemic Escherichia coli clones have been recovered in marine sediment along the coast of Marche, an Adriatic region in central Italy. In the present study, E. coli strains from the clam Chamelea gallina, sampled from seven natural beds in the same area, were detected. Selected E. coli isolates from all sampling sites were screened for antimicrobial susceptibility, genetic diversity and correlation. The majority (60%) belonged to phylogroups A or B1, 31% to the other groups (B2, C, D, E, F), 8% to cryptic clades, and 1% were untypable. Moreover, 33.3% of isolates were resistant to at least one drug and 11% were multidrug resistant (MDR). The most common resistance was to tetracycline, ampicillin, and streptomycin. No clonality was detected, but the strains' high genetic heterogeneity pointed at multiple sources of microbiological contamination. MLST analysis found potentially pathogenic and even epidemic MDR strains in clams collected in class A (ST746 and ST46) and class B (ST393, ST58 and ST131) areas, indicating that strains of clinical origin are detectable in clams. These data highlight that eating raw or lightly cooked clams may pose a health risk if purification is not performed or is ineffective.
authors.affiliation: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy. Electronic address: c.vignaroli@univpm.it.
authors.forename: C
authors.initials: C
authors.lastname: Vignaroli
authors.affiliation: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Di Sante
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Sezione di Ancona, Laboratorio Nazionale di Riferimento (LNR) per il Controllo delle Contaminazioni Batteriche dei Molluschi Bivalvi Vivi, Via Cupa di Posatora 3, 60126 Ancona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Leoni
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Sezione di Ancona, Laboratorio Nazionale di Riferimento (LNR) per il Controllo delle Contaminazioni Batteriche dei Molluschi Bivalvi Vivi, Via Cupa di Posatora 3, 60126 Ancona, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Chierichetti
authors.affiliation: Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Sezione di Ancona, Laboratorio Nazionale di Riferimento (LNR) per il Controllo delle Contaminazioni Batteriche dei Molluschi Bivalvi Vivi, Via Cupa di Posatora 3, 60126 Ancona, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Ottaviani
authors.affiliation: Dipartimento di Scienze Biomolecolari, sez. di Scienze Tossicologiche, Igienistiche e Ambientali, Università di Urbino "Carlo Bo", 61029 Urbino, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Citterio
authors.affiliation: Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Biavasco
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D049872:Bivalvia / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D058872:Epidemics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D005516:Food Microbiology; D059022:Food Safety; D014644:Genetic Variation; D006801:Humans; D007558:Italy; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D012307:Risk Factors; D012758:Shellfish / Q000382:microbiology*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D037521:Virulence Factors
keywords: Chamelea gallina; Escherichia coli; Food safety; ST131 clone