title: Population structure and characterization of viridans group streptococci (VGS) including Streptococcus pneumoniae isolated from adult patients with cystic fibrosis (CF).
abstract: A study was undertaken to examine the population structure of viridans group streptococci (VGS) in the sputum of adult patients with cystic fibrosis (CF). Freshly expectorated sputa (n=58) from 45 adult CF patients were examined by selective conventional culture on Mitis-Salivarius agar and yielded 190 isolates of VGS. Sequence analyses of the rpnB and 16-23S rRNA ITS genes identified these isolates to belong to 12 species of VGS and included S. anginosus, S. australis, S. cristatus, S. gordonii, S. infantis, S. mitis, S. mutans, S. oralis, S. parasanguinis, S. pneumoniae, S. salivarius and S. sanguinis. The most frequently VGS organism isolated was S. salivarius (47/190; 24.7%), followed by S. mitis (36/190; 19%), S. sanguinis (25/190; 13.2%), S. oralis (20/190; 11.0%), S. pneumoniae (19/190; 10.0%), S. parasanguinis (16/190; 8.4%), S. infantis (11/190; 5.8%), S. gordonii (7/190; 3.7%), S. anginosus (4/190; 2.1%), S. cristatus (2/190; 1.1%), S. australis (1/190; 0.5%), S. mutans (1/190; 0.5%) and S. agalactiae (1/190; 0.5%). All, but four, patients harboured at least one VGS species, which ranged from one to five streptococcal species, with a mean of 2.85 species per patient. There was no clonality at the subspecies level employing ERIC RAPD PCR. Antibiotic susceptibility was determined by Minimum Inhibitory Concentration (MIC) testing against penicillin, erythromycin and ciprofloxacin. Overall, resistance to penicillin with all VGS was 73/190 (38.4%) and 167/190 (87.9%) for erythromycin. With regard to ciprofloxacin, 27/190 (14.2%) were fully resistant, whilst a further 21/190 (11.1%) showed intermediate resistance, which equated to approximately three quarters (74.7%) of isolates being fully sensitive to this agent. In addition, as a comparator control population, we examined antibiotic susceptibility, as above, in a non-CF population comprising 12 individuals (50 VGS isolates), who were not receiving chronic antibiotics. In comparison, 8% and 38% of VGS isolates from non-CF individuals were resistant by disk susceptibility testing to penicillin and erythromycin, respectively. None of the non-CF VGS organisms were resistant to ciprofloxacin, but 42% showed intermediate resistance.
authors.affiliation: Northern Ireland Public Health Laboratory, Department of Bacteriology, Belfast City Hospital, Lisburn Road, Belfast, Northern Ireland, BT9 7AD, UK.
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Maeda
authors.forename: J Stuart
authors.initials: JS
authors.lastname: Elborn
authors.forename: Michael D
authors.initials: MD
authors.lastname: Parkins
authors.forename: James
authors.initials: J
authors.lastname: Reihill
authors.forename: Colin E
authors.initials: CE
authors.lastname: Goldsmith
authors.forename: Wilson A
authors.initials: WA
authors.lastname: Coulter
authors.forename: Charlene
authors.initials: C
authors.lastname: Mason
authors.forename: B Cherie
authors.initials: BC
authors.lastname: Millar
authors.forename: James S G
authors.initials: JS
authors.lastname: Dooley
authors.forename: Colm J
authors.initials: CJ
authors.lastname: Lowery
authors.forename: Madeleine
authors.initials: M
authors.lastname: Ennis
authors.forename: Jacqueline C
authors.initials: JC
authors.lastname: Rendall
authors.forename: John E
authors.initials: JE
authors.lastname: Moore
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000382:microbiology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D008826:Microbial Sensitivity Tests; D013183:Sputum / Q000382:microbiology; D013290:Streptococcal Infections / Q000188:drug therapy / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D034363:Viridans Streptococci / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents