AUTHOR=Zhou Kexin , Liang Jialei , Dong Xu , Zhang Peiyao , Feng Chunlin , Shi Weina , Gao Mengdi , Li Qiaoling , Zhang Xueya , Lu Junwan , Lin Xi , Li Kewei , Zhang Hailin , Zhu Mei , Bao Qiyu 

TITLE=Identification and Characterization of a Novel Chromosomal Aminoglycoside 2′-N-Acetyltransferase, AAC(2′)-If, From an Isolate of a Novel Providencia Species, Providencia wenzhouensis R33

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.711037

DOI=10.3389/fmicb.2021.711037

ISSN=1664-302X

ABSTRACT=<p>Multidrug-resistant bacteria from different sources have been steadily emerging, and an increasing number of resistance mechanisms are being uncovered. In this work, we characterized a novel resistance gene named <italic>aac(2′)-If</italic> from an isolate of a novel <italic>Providencia</italic> species, <italic>Providencia wenzhouensis</italic> R33 (CCTCC AB 2021339). Susceptibility testing and enzyme kinetic parameter analysis were conducted to determine the function of the aminoglycoside 2′-<italic>N</italic>-acetyltransferase. Whole-genome sequencing and comparative genomic analysis were performed to elucidate the molecular characteristics of the genome and the genetic context of the resistance gene-related sequences. Among the functionally characterized resistance genes, AAC(2′)-If shares the highest amino acid sequence identity of 70.79% with AAC(2′)-Ia. AAC(2′)-If confers resistance to several aminoglycoside antibiotics, showing the highest resistance activity against ribostamycin and neomycin. The recombinant strain harboring <italic>aac(2′)-If</italic> (pUCP20-<italic>aac(2′)-If</italic>/DH5α) showed 256- and 128-fold increases in the minimum inhibitory concentration (MIC) levels to ribostamycin and neomycin, respectively, compared with those of the control strains (DH5α and pUCP20/DH5α). The results of the kinetic analysis of AAC(2′)-If were consistent with the MIC results of the cloned <italic>aac(2′)-If</italic> with the highest catalytic efficiency for ribostamycin (<italic>k<sub><italic>cat</italic></sub>/K<sub><italic>m</italic></sub></italic> ratio = [3.72 ± 0.52] × 10<sup>4</sup> M<sup>–1</sup><sup>⋅</sup>s<sup>–1</sup>). Whole-genome sequencing demonstrated that the <italic>aac(2′)-If</italic> gene was located on the chromosome with a relatively unique genetic environment. Identification of a novel aminoglycoside resistance gene in a strain of a novel <italic>Providencia</italic> species will help us find ways to elucidate the complexity of resistance mechanisms in the microbial population.</p>