Extra-intestinal infections with multiply drug-resistant Salmonella typhimurium in hospitalized patients in Jordan.

During the 12-year period from 1978 to 1989, Salmonella typhimurium was the most frequently isolated serotype (592/1,500; 39.5%) among all clinical Salmonella isolates at Jordan University Hospital. Extra-intestinal infections due to Salmonella typhimurium accounted for 68 (11.5%) isolates. A high percentage of Salmonella typhimurium strains (52-90%) were resistant to commonly used drugs in Jordan. Most of the antibiotic-resistant strains of Salmonella typhimurium (10/12) examined which were from extra-intestinal sources contained a large plasmid (55 MDa) in addition to two to four small plasmids. These strains were also able to transfer most or part of their drug resistance in vitro. It is concluded that the invasive potential of Salmonella typhimurium isolates is probably associated with the presence of a large virulence plasmid and multiple antibiotic resistance.