title: Bartonella bacilliformis, endemic pathogen of the Andean region, is intrinsically resistant to quinolones.
abstract: OBJECTIVE
  To analyze the sequence of the region involved in the development of quinolone resistance of the gyrA and parC genes in a series of Bartonella bacilliformis isolates recovered prior to the introduction of quinolones, as well as one clinical isolate recovered in the 1970s, establishing the susceptibility levels to nalidixic acid and ciprofloxacin.
  
  
  METHODS
  Five B. bacilliformis were studied: four isolated before 1957, prior to the introduction of quinolones in clinical practice. The remaining strain was isolated in 1977. A fragment of the gyrA and parC genes was amplified and sequenced. Susceptibility to nalidixic acid and ciprofloxacin was established by the E-test method.
  
  
  RESULTS
  All the strains were resistant to nalidixic acid (minimum inhibitory concentration (MIC) >256 mg/l). Three isolates presented decreased susceptibility to ciprofloxacin and two were highly resistant (MIC >32 mg/l). All the strains presented an Ala at position 91 of GyrA and position 85 of ParC.
  
  
  CONCLUSIONS
  B. bacilliformis presents a constitutive resistance to quinolones, which may be related to the presence of Ala at position 91 of GyrA and 85 of ParC. These results advise against the current clinical guidelines recommending the use of ciprofloxacin to treat bartonellosis in some countries of the Andean area.
authors.affiliation: Departament d'Enginyeria Agroalimentària i Biotecnologia, ESAB, Universitat Politècnica de Catalunya, Castelldefels, Spain.
authors.forename: Luis J
authors.initials: LJ
authors.lastname: del Valle
authors.forename: Lidia
authors.initials: L
authors.lastname: Flores
authors.forename: Martha
authors.initials: M
authors.lastname: Vargas
authors.forename: Ruth
authors.initials: R
authors.lastname: García-de-la-Guarda
authors.forename: Ruth L
authors.initials: RL
authors.lastname: Quispe
authors.forename: Zoila B
authors.initials: ZB
authors.lastname: Ibañez
authors.forename: Débora
authors.initials: D
authors.lastname: Alvarado
authors.forename: Pablo
authors.initials: P
authors.lastname: Ramírez
authors.forename: Joaquim
authors.initials: J
authors.lastname: Ruiz
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001474:Bartonella Infections / Q000453:epidemiology* / Q000382:microbiology*; D045503:Bartonella bacilliformis / Q000187:drug effects* / Q000235:genetics; D002939:Ciprofloxacin / Q000494:pharmacology; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017720:Molecular Epidemiology; D009268:Nalidixic Acid / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology*; D020539:Sequence Analysis, Protein; D013030:Spain / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D015363:Quinolones; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase