Mutations in gyrA and parC QRDRs are not relevant for quinolone resistance in epidemiological unrelated Stenotrophomonas maltophilia clinical isolates.
Clinical strains of Stenotrophomonas maltophilia are often highly resistant to multiple antibiotics and this resistance is steadily rising. Quinolones are included in the group of antimicrobial agents to which this microorganism is developing resistance. Therefore, the aim of this study was to analyze the epidemiological relationship among 22 clinical isolates of S. maltophilia as well as the molecular mechanisms responsible for the acquisition of quinolone-resistance in these strains. The results of the pulsed-field gel electrophoresis (PFGE) showed an heterogenicity of 82% among the strains used in the study. On the other hand, no amino acid changes were found in the quinolone resistance-determining region (QRDR) of either gyrA and parC genes among quinolone-susceptible and -resistant S. maltophilia strains. Besides, the amino acid of the GyrA found in the position equivalent to Ser-83 of E. coli was Gln instead of a Ser or Thr, the amino acids usually encountered in this position among Gram-negative bacteria. The results suggest that there is not a relationship between the presence of this Gln and the resistance to quinolones in S. maltophilia. We can conclude that, contrary to what has been described in other microorganisms, in these S. maltophilia isolates, the development of resistance to quinolones was not related to mutations in the QRDR of gyrA and parC genes. Thus, to our knowledge, this is the first report describing this phenomenon.
Ribera
Anna
A
Institut Clinic d'Infeccions i Immunologia, Hospital ClInic, IDIBAPS, Facultat de Medicina, Universitat de Barcelona, Villarroel, 170, 08036 Barcelona. Spain.
Doménech-Sanchez
Antonio
A
Ruiz
Joaquim
J
Benedi
Vicente Javier
VJ
Jimenez de Anta
Ma Teresa
MT
Vila
Jordi
J
D042462:4-Quinolones; D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001483:Base Sequence; D027081:DNA Gyrase / Q000235:genetics*; D027101:DNA Topoisomerase IV / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology; D020615:Stenotrophomonas maltophilia / Q000187:drug effects*
D042462:4-Quinolones; D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase