TN contributed to the study design, analyzing of the data, drafting of the manuscript, and critical revision of the manuscript.
TF and TM contributed to the study conception, analysis and interpretation of the data, drafting of the manuscript and critical revisions for important intellectual content.
EA: acquisition of data, drafting of the manuscript.
JB: acquisition of data, drafting of the manuscript.
BP: study concept and design, acquisition of data, drafting of the manuscript.
CS: conception and design, analysis and interpretation of the data, drafting of the manuscript.
CV, MJR: PFGE analysis, interpretation of data, drafting of the manuscript.
SKM: Study design, carried out the majority of experiments, analyzed data, drafting of the manuscript.
MB participated in the design of the study, interpretation of data, drafting of the manuscript.
YCC (first author) carried out the analysis and interpretation of the data; drafting of the article.
ELG: study concept, experimental design, acquisition of data, drafting of the manuscript.
