Molecular mechanisms of quinolone resistance in clinical isolates of Aeromonas caviae and Aeromonas veronii bv. sobria

Autores/as

  • Antonina Arias Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain
  • Cristina Seral Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain. Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain
  • M. José Gude Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain
  • F. Javier Castillo Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain. Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain

Palabras clave:

Aeromonas spp., quinolone resistance, nalidixic acid resistance, ciprofloxacin

Resumen

Mutations in quinolone targets were studied together with quinolone efflux pump activation and plasmid-mediated quinolone resistance determinants in nalidixic-acid-resistant isolates of Aeromonas caviae and Aeromonas veronii. Among 135 clinical Aeromonas spp. isolated from stools of patients with gastrointestinal symptoms, 40 nalidixic acid-resistant strains belonging to A. caviae and A. veronii were selected and their susceptibility to different quinolones (ciprofloxacin, norfloxacin, ofloxacin) further evaluated. Susceptibility to nalidixic acid and ciprofloxacin in the presence/absence of Phe- Arg-β-naphthylamide was also determined. The 16 nalidixic-acid-resistant strains identified as A. caviae were more resistant than the 24 A. veronii bv. sobria strains to ciprofloxacin, norfloxacin, and ofloxacin. All strains showed a mutation (single or double) at position 83 of the QRDR sequence of gyrA, with Ser-83 → Ile as the most frequent substitution. By contrast, no mutations were found at position 87 of gyrA. Double substitutions (GyrA-ParC) were detected in 50% of A. veronii bv. sobria isolates and in 43.75% of A. caviae strains. Both species showed decreases in the MICs of ciprofloxacin. A qnrS gene was found in an A. caviae strain. Thus, in the two species of nalidixic-acid-resistant Aeromonas isolates examined, resistance mediated by efflux pumps contributed only slightly to ciprofloxacin resistance. While two isolates were positive for the aac(6′)-Ib gene, no -cr variants were detected. [Int Microbiol 2010; 13(3):135-141]

Biografía del autor/a

Antonina Arias, Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain

Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain.

Cristina Seral, Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain. Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain

Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain.
Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain

M. José Gude, Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain

Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain.

F. Javier Castillo, Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain. Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain

Microbiology Department, “Lozano Blesa” University Clinical Hospital, Zaragoza, Spain.
Department of Microbiology, Faculty of Medicine, University of Zaragoza, Spain

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Publicado

2010-09-28

Número

Vol. 13 Núm. 3 (2010)

Sección

Research Articles

Licencia

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