Bartonella bacilliformis, endemic pathogen of the Andean region, is intrinsically resistant to quinolones.
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.
del Valle
Luis J
LJ
Departament d'Enginyeria Agroalimentària i Biotecnologia, ESAB, Universitat Politècnica de Catalunya, Castelldefels, Spain.
Flores
Lidia
L
Vargas
Martha
M
García-de-la-Guarda
Ruth
R
Quispe
Ruth L
RL
Ibañez
Zoila B
ZB
Alvarado
Débora
D
Ramírez
Pablo
P
Ruiz
Joaquim
J
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
D000900:Anti-Bacterial Agents; D015363:Quinolones; D009268:Nalidixic Acid; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase