Genetic Variability of AdeRS Two-Component System Associated with Tigecycline Resistance in XDR-Acinetobacter baumannii Isolates.
The emergence of tigecycline resistance has increased in the last years. Although tigecycline-resistant Acinetobacter baumannii isolates were described all over the world, few reports regarding the molecular basis of this resistance are available. It has been recognized that the overexpression of AdeABC efflux pump is related to the tigecycline-resistant phenotype. In 37 clinical A. baumannii isolates we first determined the tigecycline-resistant phenotype and then, within a selected group, we analyzed the sequence of the adeRS operon, which is involved in the expression of the AdeABC efflux pump. Nucleotide sequence analysis of adeR and adeS showed the presence of 5 and 16 alleles, respectively. These results expose a high genetic variability in both genes, the adeS gene being more susceptible to genetic variation. The presence of 2 AdeR and 2 AdeS new variants were reported. Two of the new AdeRS variants were present in the intermediate and the resistant tigecycline A. baumannii isolates, suggesting a putative role in the development of the observed phenotype. More studies need to be addressed to determine the role of the genetic variability observed in the adeRS operon.
Instituto de Microbiología y Parasitología Médica (IMPaM, UBA-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
S
S
Montaña
E
E
Vilacoba
G M
GM
Traglia
M
M
Almuzara
M
M
Pennini
A
A
Fernández
A
A
Sucari
D
D
Centrón
M S
MS
Ramírez
D040981:Acinetobacter baumannii / Q000187:drug effects* / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001693:Biological Transport, Active; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D014644:Genetic Variation; D008911:Minocycline / Q000031:analogs & derivatives* / Q000494:pharmacology; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D015398:Signal Transduction; D000078304:Tigecycline
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D000078304:Tigecycline; D008911:Minocycline