Molecular relationship amongSalmonella dublinisolates identified at the Center for Enterobacteriaceae of Palermo during the years 1971–85

Abstract

SUMMARYA molecular epidemiological study was carried out on 60Salmonella dublinisolates identified at the Southern Italy Enterobacteriaceae Center between 1971 and 1985. These included 23 isolates from children with diarrhoea in Palermo obtained during 1984.All isolates from the outbreak of gastroenteritis in children were resistant to chloramphenicol and streptomycin and harboured two plasmids of 50 MDa and 3 MDa molecular weight, whereas the majority of the isolates identified before 1984 were susceptible to these antibiotics and carried only a 50 MDa molecular weight plasmid. FourS. dublinstrains successively identified from cattle (Palermo, Foggia, Portici) and from a child (Palermo) were shown to possess similar antibiotic resistance patterns and plasmid profiles toS. dublinisolates from the outbreak of gastroenteritis in children.The 50 MDa plasmid was shown to be associated with virulence in mice, while it was not possible to assign any genetic function to the 3 MDa plasmid.

The prevalence of plasmids in Danish bovine and human isolates of Salmonella dublin

“…The 80 kb plasmid present in all plasmid-canying strains corresponds in size and restriction patterns to the serovar-specific and virulence-associated plasmid of S. dublin ( 19, 2 I , 26). The high incidence of this plasmid is reported in several papers (7,19,26) and points to the selective advantage of this plasmid in connection with the invasive S. dublin infection. One strain (Table I , group VIII) isolated from blood of a human patient carried the virulence plasmid with a very low copy number, and we are presently studying whether the low copy number has an influence on the virulence of S. dublin towards mice.…”

Toward a population genetic analysis of Salmonella: genetic diversity and relationships among strains of serotypes S. choleraesuis, S. derby, S. dublin, S. enteritidis, S. heidelberg, S. infantis, S. newport, and S. typhimurium.

“…Phage subtyping schemes have been developed for strains of several of the common medically important serotypes (8)(9)(10), and plasmid profiling (11)(12)(13)(14)(15) and several methods of detecting nucleotide sequence variation, including restriction endonuclease digestion of plasmid and chromosomal DNA (12,(16)(17)(18), sometimes combined with the use of chromosomal probes (19), have also recently been applied in epidemiological research (20). But these techniques have contributed little to an understanding of the evolutionary relationships of strains and have as yet had no application in population genetics.…”

Salmonella serovars identified at the centre for enterobacteriaceae of palermo over the 5-year period 1983-87

“…In contrast, Dublin, a serovar closely associated with cattle and rarely recovered from humans, was responsible in 1984 for a food-borne outbreak, which resulted in a large number of isolations from humans. These serovar Dublin strains showed chloramphenicol and streptomycin resistance, presumably chromosome encoded (17), and homogeneous plasmid profiles, suggesting that increased frequency of detection of this organism was attributable to clonal dissemination of a single strain. Similarly, the 5-year study period has registered an increase in isolations of Infantis serovar, which peaked in 1984, when it was implicated in a food-poisoning outbreak, which occurred in a pediatric care unit in Palermo.…”