title: R-plasmids in Salmonella isolates from sporadic cases of gastroenteritis.
abstract: Five-hundred and twenty seven strains of Salmonella isolated from different patients admitted to hospitals in Rome from 1982 to 1985 were screened for their resistance to antimicrobial drugs. Sixty-one strains (11.6%) were found to be resistant to two or more antibiotics; the most frequent resistances were to sulfathiazole, streptomycin, tetracycline, chloramphenicol and ampicillin. Of the thirty-eight strains showing resistance to three or more antibiotics, 17 were able to transfer their resistance to E. coli K 12. The isolates were heterogeneous in plasmid population: only few strains harbored a sole plasmid, most harbored many plasmids ranging between 20 and 120 megadaltons in weight. Most strains were found to carry a conjugative plasmid of incompatibility group Inc H of 100-120 megadaltons and Inc I alpha of 60-70 megadaltons.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003087:Colicins / Q000096:biosynthesis; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005144:F Factor / Q000187:drug effects; D005759:Gastroenteritis / Q000382:microbiology; D006801:Humans; D066298:In Vitro Techniques; D011815:R Factors / Q000235:genetics*; D012475:Salmonella / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D003087:Colicins