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Bordetella Species Are Distinguished by Patterns of Substantial Gene Loss and Host Adaptation. C. A. Cummings, 2004.Pathogens of the bacterial genus Bordetella cause respiratory disease in humans and animals . Although virulence and host specificity vary across the genus, the genetic determinants of this diversity remain unidentified . To identify genes that may underlie key phenotypic differences between these species and clarify their evolutionary relationships, we performed a comparative analysisof genome content in 42 Bordetella strains by hybridizationof genomic DNA to a microarray representing the genomes of three Bordetella species and by subtractive hybridization . Here weshow that B . pertussis and B . parapertussis are predominantly differentiated from B . bronchiseptica by large, species-specific regions of difference, many of which encode or direct synthesis of surface structures, including lipopolysaccharide O antigen,which may be important determinants of host specificity . Thespecies also exhibit sequence diversity at a number of surfaceprotein-encoding loci, including the fimbrial major subunitgene, fim2 . Gene loss, rather than gene acquisition, accompaniedby the proliferation of transposons, has played a fundamentalrole in the evolution of the pathogenic bordetellae and mayrepresent a conserved evolutionary mechanism among other groupsof microbial pathogens. In Vitro and Bactericidal Activities of ABT-492, a Novel Fluoroquinolone, against Gram-Positive and Gram-Negative Organisms. Laurel S. Almer, 2004.In vitro activities of ABT-492, ciprofloxacin, levofloxacin, trovafloxacin, moxifloxacin, gatifloxacin, and gemifloxacin were compared . ABT-492 was more potent against quinolone-susceptible and -resistant gram-positive organisms, had activity similar to that of ciprofloxacin against certain members of the family Enterobacteriaceae, and had comparable activity against quinolone-susceptible, nonfermentative, gram-negative organisms . Bactericidal activity of ABT-492 was also evaluated . Molecular Characterization of Vibrio cholerae O139 Bengal Isolated from Water and the Aquatic Plant Eichhornia crassipes in the River Ganga, Varanasi, India. R. Bhanumathi, 2003.A collection of ten strains of Vibrio cholerae O139, comprising six isolates from Eichhornia crassipes, two from water of the River Ganga, and one each from a well and a hand pump, were characterized . All the strains carried the CTX genetic element (ctxA, zot, and ace) except for the st gene and carried structural and regulatory genes for toxin-coregulated pilus (tcpA, tcpI, and toxR), adherence factor (ompU), and accessory colonization factor (acfB); all produced cholera toxin (CT) . These strains were resistant to trimethoprim, sulfamethoxazole, streptomycin, and to the vibriostatic agent pteridine . Results obtained by ribotyping and enterobacterial repetitive intergenic consensus sequence-PCR fingerprint analysis indicate that multiple clones of toxigenic-pathogenic V . cholerae O139 were present in the aquatic environment .
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