DISTRIBUZIONE E FUNZIONALITA’ DI CICLOMODULINE IN ESCHERICHIA COLI INTESTINALI ED EXTRA-INTESTINALI ISOLATI DA ANIMALI

A total of 336 Escherichia coli strains isolated from animals with diarrhoea and extra-intestinal infections were screened by PCR to investigate the prevalence of cyclomodulins: cycle-inhibiting factor (CIF), cytolethal distending toxins (CDTs I-V) and cytotoxic necrotising factors (CNFs 1 e 2). Seventy-eight strains were positive for at least one cyclomodulin; in isolates of intestinal origin 14 strains had cif gene, 13 cdt, 7 cnf and 11 strains harboured two cyclomodulins. In extra-intestinal isolates 28 strains carried cnf gene, 2 cdt and 3 strains had both genes. The association between cyclomodulins and other virulence factors was analyzed, and their functional expression was investigated. A wide range of virulence factors was found and some gene combinations occurred more frequently. The majority of cif+ and the totality of cdt+ and cnf+ strains showed a cytopathic effect. Further study will be requested to know their clinical significance and their role in pathogenesis.