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Production of HlyA and ClyA haemolysins among quinolone-resistant Escherichia coli isolated from clinical samples

Alicia Márquez-López1*, Belén Ruiz del Castillo1, María Eliecer Cano1, Cristina Rodríguez-Mirones1, Jesús Oteo3, David Sáez3 and Luis Martínez-Martínez12

Author Affiliations

1 Service of Microbiology, University Hospital Marqués de Valdecilla-IFIMAV, Santander, Spain

2 Departament of Molecular Biology, University of Cantabria, Santander, Spain

3 Antibiotic Laboratory, Bacteriology Service, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Madrid, Spain

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SpringerPlus 2013, 2:71  doi:10.1186/2193-1801-2-71

Published: 27 February 2013


Most Escherichia coli resistant to quinolones are not haemolytic. The objective of this study was to determine the phylogroup, clonal relationship, mechanism of quinolone resistance and virulence factors in 70 haemolytic E. coli resistant to nalidixic acid. Sixty-six isolates contained the hlyA gene, belonged to phylogroup B2, and 61 of them presented low-level resistance to fluoroquinolones. Four isolates presented high-level resistance to fluoroquinolones, contained the clyA gene and were included in phylogroup D. One single isolate (phylogroup D, with low level resistance to fluoroquinolones) contained both cytotoxins.

Haemolysis; Escherichia coli; Quinolone resistance; hlyA; clyA