title: Prevalence of carbapenemases among high-level aminoglycoside-resistantAcinetobacter baumanniiisolates in a university hospital in China.
abstract: The prevalence of aminoglycoside resistant enzymes has previously been reported and extended-spectrum β-lactamase amongAcinetobacter baumannii. To track the risk of multidrug-resistantA. baumannii, the present study aimed to determine the prevalence of carbapenemases in high-level aminoglycoside resistantA. baumanniiover two years. A total of 118 strains ofA. baumanniiwere consecutively collected in the First Affiliated Hospital of Chengdu Medical College, Chengdu, China. These isolates were investigated on the genetic basis of their resistance to aminoglycosides. The results showed that 75 (63.56%) isolates were high-level resistant to aminoglycosides, including gentamicin and amikacin (minimum inhibitory concentration, ≥256 µg/ml). Aminoglycoside-resistant genesant(2″)-Ia,aac(6')-Ib,aph(3')-Ia,aac(3)-Ia,aac(3)-IIa,armA,rmtA,rmtB,rmtC,rmtD,rmtE,rmtF,rmtG,rmtHandnpmA, and carbapenem-resistant genesblaOXA-23,blaOXA-24,blaOXA-51,blaOXA-58,blaSIM,blaIMP,blaNDM-1andblaKPC, were analyzed using polymerase chain reaction. The positive rate ofant(2″)-Ia,aac(6')-Ib,aph(3')-Ia,aac(3)-Iaandaac(3)-IIawas 66.95, 69.49, 42.37, 39.83 and 14.41%, respectively.armAwas present in 72.0% (54/75) ofA. baumanniiisolates with high-level resistance to aminoglycosides. The remaining nine 16S ribosomal RNA methlyase genes (rmtA,rmtB,rmtC,rmtD,rmtE,rmtF,rmtG,rmtHandnpmA) and aminoglycoside-modifying enzyme geneaac(6')-Ib-crwere not detected. Among the 54armA-positive isolates, the prevalence of the carbapenem resistantblaOXA-23andblaOXA-51genes was 79.63 and 100%, respectively.armA,ant(2″)-Iaandaac(6')-Ibwere positive in 43 isolates. The results of multilocus sequence typing revealed 31 sequence types (STs) in all clinical strains. Among these STs, the high-level aminoglycoside-resistantA. baumanniiST92, which mostly harboredblaOXA-23, was the predominant clone (29/75). In conclusion,A. baumanniiharboring carbapenemases and aminoglycoside-resistant enzymes are extremely prevalent in western China, emphasizing the need to adopt surveillance programs to solve the therapeutic challenges that this presents.
authors.affiliation: Non-Coding RNA and Drug Discovery Laboratory, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Non-Coding RNA and Drug Discovery Laboratory, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Shen
authors.affiliation: Non-Coding RNA and Drug Discovery Laboratory, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Jingni
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Laboratory Medicine, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Dai
authors.affiliation: Small Molecule Drugs Sichuan Key Laboratory, Institute of Materia Medica, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Yaowen
authors.initials: Y
authors.lastname: Chang
authors.affiliation: Small Molecule Drugs Sichuan Key Laboratory, Institute of Materia Medica, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Non-Coding RNA and Drug Discovery Laboratory, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Guangxin
authors.initials: G
authors.lastname: Luan
authors.affiliation: Small Molecule Drugs Sichuan Key Laboratory, Institute of Materia Medica, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Baodong
authors.initials: B
authors.lastname: Ling
authors.affiliation: Non-Coding RNA and Drug Discovery Laboratory, Chengdu Medical College, Chengdu, Sichuan 610500, P.R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Jia
keywords: 16S ribosomal RNA methylase; Acinetobacter baumannii; aminoglycosides; carbapenemases; multilocus sequence typing