*Correspondence to Dr P. Cappuccinelli, Istituto di Microbiologia e Virologia, Viale S. Pietro 43B, 07100 Sassari, Italy. Tel. 79 228302; fax 79 212345.
Summary: The phenotypic and genotypic characteristics of 69 wild-type strains of Salmonella abortusovis from Sardinia and other Italian regions, representing four different epidemic outbreaks, were studied. Biochemical profiles, pathogenicity factors, resistance to antibacterial drugs and genomic organization were investigated. None of the strains tested showed any haemagglutination with different types of red blood cells, and electron microscopy revealed no fimbriae. Adhesivity to epithelial cells was present in all strains tested. Only 16% of the strains were resistant to streptomycin, and no other drug resistances were found. The restriction patterns of chromosomal DNA did not show heterogeneity and a high-molecular-mass (50-67 kb) plasmid was found in all strains. Restriction analysis of plasmid DNA from strains from different geographical areas, collected over a period of 30 years, showed a HindIII restriction profile characterized by two patterns, one with three fragments, stable and common to all strains, and a second polymorphic pattern with five fragments. The stable pattern included a 3·7 kb HindIII fragment that hybridized with a S. typhimurium probe containing a virulence region including the spvC and spvD genes. These studies allowed us to outline a genetic correlation among S. abortusovis isolated from different outbreaks.
AUSUBELF. M.
,
BRENTR.
,
KINGSTONR. E.
,
MOORED. D.
,
SEIDMARJ. G.
,
SMITHJ. A.
,
STRUHLK.
.
1987Current Protocols in Molecular Biology. New York: Greene Publishing Associates & Wiley-Interscience;
BRENNERD. J.
.
1984 Family I. Enterobacteriaceae.
. Bergey's Manual of Systematic Bacteriology1408–516N. R.Krieg
,
J. G.Holt
.
Baltimore: Williams & Wilkins;
BRUNNERF.
,
MARGADANTΑ.
,
PEDUZZIR.
,
PIFFARETTIJ.
.
1983; The plasmid pattern as an epidemiological tool for Salmonella typhimurium epidemics: comparison with the lysotype. Journal of Infectious Diseases 148:7–11
DUGUIDJ. P.
,
ANDERSONE. S.
,
ALFREDSSONG. Α.
,
BARKERR.
,
OLDC. D.
.
1975; A new biotyping scheme for Salmonella typhimurium and its phylogenetic significance. Journal of Medical Microbiology 8:149–166
FIELDP. I.
,
SWANSONR. V.
,
HAIDARISC. G.
,
HEFFRONF.
.
1986; Mutants of Salmonella typhimurium that cannot survive within the macrophage are virulent. Proceedings of the National Academy of Sciences of the United States of America 83:5189–5193
GULIGP. A.
,
CHIODOV. A.
.
1990; Genetic and DNA sequence analysis of the Salmonella typhimurium virulence plasmid gene encoding the 28,000-molecular weight protein. Infection and Immunity 58:2651–2658
GULIGP. A.
,
CURTISSR., III
.
1988; Cloning and transposon insertion mutagenesis of virulence genes of the 100-kilobase plasmid of Salmonella typhimurium. Infection and Immunity 56:3262–3271
LEUNKR. D.
,
MOONR. J.
.
1982; Association of type 1 pili with the ability of livers to clear Salmonella typhimurium. Infection and Immunity 36:1168–1174
PLAGEMANNΟ.
.
1989; The differential diagnosis of Salmonella abortus ovis and Yersinia pseudotuberculosis in sheep abortions. Zentralblatt für Veterinärmedizin 36:509–514
POPPEC.
,
CURTISSR., III
,
GULIGP. A.
,
GYLESC. L.
.
1991; Hybridization studies with a DNA probe derived from the virulence region of the 60 Mdal plasmid of Salmonella typhimurium. Canadian Journal of Veterinary Research 53:378–384
POPOFFM. Y.
,
MIRASL.
,
COYNALTC.
,
LASSELINC.
,
PARDONP.
.
1984; Molecular relationships between virulence plasmids of Salmonella serotypes typhimurium and dublin and large plasmids of other Salmonella serotypes. Annales de Microbiologie 135:389–398
SORUMH.
,
POPPET. T.
,
OLSVIKD.
.
1988; Plasmid in Vibrio salmonicida isolated from salmonids with hemorrhagic syndrome (Hitra disease). Journal of Clinical Microbiology 26:1679–1683
TINGES. A.
,
CURTISSR., III
.
1990; Conservation of Salmonella typhimurium virulence plasmid maintenance regions among Salmonella serovars as a basis for plasmid curing. Infection and Immunity 58:3084–3092
WILLIAMSONC. M.
,
BAIRDG. D.
,
MANNINGE. J.
.
1988; A common virulence region on plasmids from eleven serotypes of Salmonella. Journal of General Microbiology 134:975–982