Development of Resistance in Escherichia coli ATCC25922 under Exposure of Sub-Inhibitory Concentration of Olaquindox

Abstract

Quinoxaline1,4-di-N-oxides (QdNOs) are a class of important antibacterial drugs of veterinary use, of which the drug resistance mechanism has not yet been clearly explained. This study investigated the molecular mechanism of development of resistance in Escherichia coli (E. coli) under the pressure of sub-inhibitory concentration (sub-MIC) of olaquindox (OLA), a representative QdNOs drug. In vitro challenge of E. coli with 1/100× MIC to 1/2× MIC of OLA showed that the bacteria needed a longer time to develop resistance and could only achieve low to moderate levels of resistance as well as form weak biofilms. The transcriptomic and genomic profiles of the resistant E. coli induced by sub-MIC of OLA demonstrated that genes involved in tricarboxylic acid cycle, oxidation-reduction process, biofilm formation, and efflux pumps were up-regulated, while genes involved in DNA repair and outer membrane porin were down-regulated. Mutation rates were significantly increased in the sub-MIC OLA-treated bacteria and the mutated genes were mainly involved in the oxidation-reduction process, DNA repair, and replication. The SNPs were found in degQ, ks71A, vgrG, bigA, cusA, and DR76-4702 genes, which were covered in both transcriptomic and genomic profiles. This study provides new insights into the resistance mechanism of QdNOs and increases the current data pertaining to the development of bacterial resistance under the stress of antibacterials at sub-MIC concentrations.

The evolution of fluoroquinolone resistance in Salmonella under exposure to sub-inhibitory concentration of enrofloxacin

“…Another research showed that purL or purM mutant disrupted purine biosynthesis in Burkholderia [47] . It was also demonstrated that purA gene was up-regulated in olaquindox resistance E. coli [24] . Previous study showed that KEGG pathway of purine metabolism, pyrimidine metabolism was enriched in the proteomics analysis of…”

“…To select de novo generated mutants, S. Enteritidis CICC21527 was cultured and passaged respectively in LB medium containing ENR at concentrations lower than MIC values, including 0.031 μg/mL (1/2×MIC), 0.016 μg/mL (1/4×MIC), 0.008 μg/mL (1/8×MIC), 0.004 μg/mL (1/16×MIC), 0.002 μg/mL (1/32×MIC), 0.001 μg/mL (1/64×MIC) and 0.0005 μg/mL (1/128×MIC). The culturing, passaging and mutant screening methods were carried as previously described [23,24] . The MICs of the selected mutants were confirmed by antimicrobial susceptibility testing.…”

“…The total RNA of parental S. Enteritidis CICC21527, reduced susceptibility mutant 8M (1/128M), and resistant mutants 16M (1/8M) and 32M (1/2M) was processed as the reference described [24] . The samples were paired-end sequenced using an Illumina HiSeq™ 2000 system (Personalbio technology Co. Ltd, Nanjing, China).…”

The Evolution of Fluoroquinolone Resistance in Salmonella under Exposure to Sub-Inhibitory Concentration of Enrofloxacin

“…Another research showed that purL or purM mutant disrupted purine biosynthesis in Burkholderia [38]. It was also demonstrated that purA gene was up-regulated in olaquindox resistance Escherichia coli (E. coli) [39]. Previous study showed that KEGG pathway of purine metabolism, pyrimidine metabolism was enriched in the proteomics analysis of FQs resistance E. coli [40].…”

Effects of the Quinone Oxidoreductase WrbA on Escherichia coli Biofilm Formation and Oxidative Stress

“…When glutathione was added during the antimicrobial challenge, the H 2 O 2 tolerance of the BW25113-∆wrbA biofilms increased. Significant upregulation of WrbA was observed in Salmonella enterica serovar Enteritidis ATCC 4931 biofilms exposed to benzalkonium chloride [100] and in resistant E. coli cells challenged with sub-lethal concentrations of olaquindox [101]. The gene wrbA was upregulated in persister cells, suggesting the contribution of the WrbA in antimicrobial defense mech-anisms [102][103][104].…”