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Three transposon-containing 'suicide' plasmids were evaluated for their efficiency in promoting insertional mutagenesis in Brucella abortus. All three plasmids are mobilizable vectors and so were conjugally transferred from mobilizing strains of the donor Escherichia coli. The transposition frequencies were expressed as the ratio of Kmr exconjugants per total recipient cells at the initiation of mating. The pUT/Km-based delivery system, which utilizes a derivative of Tn5, yielded a very high frequency of 2.7 x 10(-5) of transposition in B. abortus. In comparison to previously reported accounts of transposition in B. abortus, both the over thousand-fold higher and more stable number of mutants, makes the pUT/Km system a very useful tool for in vivo transposon mutagenesis of Brucella strains.

A 58-year-old patient with lupus erythematosus (LE) who needed treatment with azathioprine, due to resistant myopathy to steroids, is presented. Clinical and histological features, as well as therapy, are discussed.

An assay for plasmid DNA content was carried out in 100 strains of Legionella pneumophila of distinct serogroups and isolated from various sources (clinical, environment). The strains were isolated from different geographic regions in our country. The presence of plasmids was proved in one of the 11 clinical isolates and in 68 of the 89 isolated of environmental origin studied. In the strains belonging to serogroup 1 and isolated in our region (Cantabria), three plasmid profiles were observed, whereas in strains of the same serogroup from other geographic regions, two profiles were shown which exhibited differences compared to the former ones. Analysis by means of restriction endonucleases suggested that plasmids of similar size in serogroup 1 strains of different source, were related. The results obtained do not appear to reveal any correlation between plasmid profile and source of isolation or serogroup.