Aminoglycoside susceptibility profiles of Enterobacter cloacae isolates harboring the aac(6')-Ib gene.
The aminoglycoside 6'-N-acetyltransferases of type Ib (aac(6')-Ib) gene confers resistance to amikacin, tobramycin, kanamycin, and netilmicin but not gentamicin. However, some isolates harboring this gene show reduced susceptibility to amikacin. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommends a revision of the phenotypic description for isolates harboring the aac(6')-Ib gene. In this study, we determined the aminoglycoside susceptibility profiles of 58 AAC(6')-Ib-producing Enterobacter cloacae isolates. On the basis of the CLSI and EUCAST breakpoints, a large proportion (84.5% and 55.2%, respectively) of these 58 isolates were found to be susceptible to amikacin. However, among the isolates that were shown to be anikacin-susceptible according to the CLSI and EUCAST breakpoints, only 30.6% and 18.8% isolates, respectively, could be considered to have intermediate resistance on the basis of the EUCAST expert rules. Further studies should be conducted to determine the aminoglycoside susceptibility profiles of aac(6')-Ib-harboring isolates from various geographic regions and to monitor the therapeutic efficacy of amikacin in infections caused by these isolates.
Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, St. Vincent's Hospital, Suwon, Korea.
Soo-Young
SY
Kim
Yeon-Joon
YJ
Park
Jin Kyung
JK
Yu
Yeong Sic
YS
Kim
D000123:Acetyltransferases / Q000235:genetics*; D000583:Amikacin / Q000494:pharmacology; D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016972:Enterobacter cloacae / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000175:diagnosis / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000583:Amikacin; D000123:Acetyltransferases; C056532:aminoglycoside N(6')-acetyltransferase