title: Viridans group streptococci are donors in horizontal transfer of topoisomerase IV genes to Streptococcus pneumoniae.
abstract: A total of 46 ciprofloxacin-resistant (Cip(r)) Streptococcus pneumoniae strains were isolated from 1991 to 2001 at the Hospital of Bellvitge. Five of these strains showed unexpectedly high rates of nucleotide variations in the quinolone resistance-determining regions (QRDRs) of their parC, parE, and gyrA genes. The nucleotide sequence of the full-length parC, parE, and gyrA genes of one of these isolates revealed a mosaic structure compatible with an interspecific recombination origin. Southern blot analysis and nucleotide sequence determinations showed the presence of an ant-like gene in the intergenic parE-parC regions of the S. pneumoniae Cip(r) isolates with high rates of variations in their parE and parC QRDRs. The ant-like gene was absent from typical S. pneumoniae strains, whereas it was present in the intergenic parE-parC regions of the viridans group streptococci (Streptococcus mitis and Streptococcus oralis). These results suggest that the viridans group streptococci are acting as donors in the horizontal transfer of fluoroquinolone resistance genes to S. pneumoniae.
authors.affiliation: Unidad de Genética Bacteriana (Consejo Superior de Investigaciones Científicas), Centro Nacional de Microbiología, Instituto de Salud Carlos III, 28220 Majadahonda, Madrid, Spain.
authors.forename: Luz
authors.initials: L
authors.lastname: Balsalobre
authors.forename: María José
authors.initials: MJ
authors.lastname: Ferrándiz
authors.forename: Josefina
authors.initials: J
authors.lastname: Liñares
authors.forename: Fe
authors.initials: F
authors.lastname: Tubau
authors.forename: Adela G
authors.initials: AG
authors.lastname: de la Campa
mesh_terms: D001483:Base Sequence; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics*; D021901:DNA, Intergenic; D022761:Gene Transfer, Horizontal; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D011995:Recombination, Genetic; D015183:Restriction Mapping; D013296:Streptococcus pneumoniae / Q000201:enzymology / Q000235:genetics*; D034363:Viridans Streptococci / Q000201:enzymology / Q000235:genetics*
chemical_list: D021901:DNA, Intergenic; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase