[Cytotoxicity and invasive virulence of Yersinia enterocolitis strains in various mammalian cell lines].

The authors tested the suitability of 10 cell lines for assessment of the virulence of strains of Yersinia enterocolitica by the cytotoxicity test. Line LLC-MK2, HEp-2, HeLa, L-132 and L929 are most suitable. Lines LEP, 3T3, MDCK and McCoy are usable, line BHK-21 is unsuitable. On the same cell lines also the invasiveness of the virulent and non-virulent strains of Y. enterocolitica was assessed. For detection of the internalization of bacteria a modified method of double fluorescent staining was used which is simpler and more rapid. The invasiveness, similarly as the cytotoxicity of the virulent strain was proved on all tested cell lines, contrary to the non-virulent strain which was neither cytotoxic nor invasive. Using strains of Y. enterocolitica, isolated from faeces of patients with diarrhoea of infectious etiology or another bowel disease and from water, the cytotoxicity method was compared with recommended biochemical virulence tests used in this country: bond with Congo red, crystal violet, dependence on Ca2+ and pyrazinamidase activity. Strains of serotype 0:5, 0:6.31 and 0:7.8 biotype 1 gave in all tests negative results, strains of serotype 0:3 biotype 4 differed. The highest number of positive strains was detected by the cytotoxicity test. The positivity of strains of this serotype was assessed by the invasiveness test in vitro. The cytotoxicity test was thus proved to be a very effective, rapid and easy test of detection of the virulence of Y. enterocolitica strains.