Abstract
The prevalence of aac(6′)-Ib variants has been demonstrated in numerous epidemiological studies. We revisited the polymorphic diversity of aminoglycoside 6’-N-acetyltransferase gene [aac(6′)-Ib] in the bacterial genome databases based on One Health perspectives. aac(6′)-Ib was searched against bacterial complete and draft genome databases of NCBI. Based on the major polymorphic residues 102, 117, and 179, taxonomy, ecology, and temporal emergence of bacterial isolates harboring variants of aac(6′)-Ib gene were evaluated using whole-genome sequences available in the databases. A total of 3,964 aac(6′)-Ib sequences were found to be present in the genomes of 34 bacterial genera, mostly found in Gammaproteobacteria. Among these, aac(6′)-Ib-cr variant, known to confer fluoroquinolone resistance, were increasingly detected in bacterial genomes and most abundant in the genera Klebsiella and Escherichia, thereby suggesting that these genera were the major reservoirs of the plasmid-mediated quinolone resistance (PMQR) determinant. The proportions of the cr variant were higher in animal and environmental isolates than in human isolates, among which the variant was dominant (>50%) in the genomes of intestinal, rectal, and fecal origins. In addition, our study suggested that the prevalence of the cr variant was associated with the occurrence of a variant with the mutation L117 (IbL). An integrated surveillance system for antimicrobial resistance in human, animal, and environmental sectors, based on whole-genome sequencing, would provide a better insight into the evolution, ecology, and epidemiology of antimicrobial-resistant bacteria.
Highlights
The emergence and dissemination of antibiotic resistance cause a global public health crisis, a problem for humans, and for animals and the environment, since the spread of resistant bacteria and resistance determinants appears to occur across human, animal, and environmental sectors (McEwen and Collignon, 2018)
Analysis of gene location designated in the complete genome database revealed that IbL (89.3%) and cr (84.9%) variants were much more frequent in plasmids than in chromosomes (Table 1), whereas Ib sequences were similar among chromosomes and plasmids, thereby indicating that plasmids form a major vehicle for the plasmid-mediated quinolone resistance (PMQR) dissemination
Previous epidemiological studies demonstrated the prevalence of aac(6 )-Ib-cr in many bacterial isolates
Summary
The emergence and dissemination of antibiotic resistance cause a global public health crisis, a problem for humans, and for animals and the environment, since the spread of resistant bacteria and resistance determinants appears to occur across human, animal, and environmental sectors (McEwen and Collignon, 2018). Its variant AAC(6 )-Ib-cr, which harbors mutations at two amino acid residues (W102R and D179Y) and confers additional resistance against piperazine-containing fluoroquinolones, was first described in 2006 in the plasmids of clinical isolates of Escherichia coli isolated from Shanghai during 2000–2001 (Robicsek et al, 2006) and subsequently found to be widely disseminated around the world (Poirel et al, 2012; Jacoby et al, 2014) Earlier, another mutation (S117L) was reported to be associated with the altered resistance spectra against aminoglycosides (Casin et al, 1998). Numerous studies have been conducted for the epidemiology of wildtype and its variants using isolates of various origins (Park et al, 2006; Jiang et al, 2008; Yang et al, 2008; Kim et al, 2009; Sabtcheva et al, 2009; Frasson et al, 2011; Briales et al, 2012)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call