Functional Proteomics Analysis of Norfloxacin-Resistant Edwardsiella tarda

Abstract

Multidrug-resistant Edwardsiella tarda threatens both sustainable aquaculture and human health, but the control measure is still lacking. In this study, we adopted functional proteomics to investigate the molecular mechanism underlying norfloxacin (NOR) resistance in E. tarda. We found that E. tarda had a global proteomic shift upon acquisition of NOR resistance, featured with increased expression of siderophore biosynthesis and Fe3+-hydroxamate transport. Thus, either inhibition of siderophore biosynthesis with salicyl-AMS or treatment with another antibiotic, kitasamycin (Kit), which was uptake through Fe3+-hydroxamate transport, enhanced NOR killing of NOR-resistant E. tarda both in vivo and in vitro. Moreover, the combination of NOR, salicyl-AMS, and Kit had the highest efficacy in promoting the killing effects of NOR than any drug alone. Such synergistic effect not only confirmed in vitro and in vivo bacterial killing assays but also applicable to other clinic E. tarda isolates. Thus, our data suggest a proteomic-based approach to identify potential targets to enhance antibiotic killing and propose an alternative way to control infection of multidrug-resistant E. tarda.

Edwardsiella tarda Attenuates Virulence upon Oxytetracycline Resistance

“…A recent study investigating the resistance mechanism of norfloxacinresistant E. tarda identified that siderophore biosynthesis and Fe 3+ -hydroxamate transport were upregulated and proposed to simultaneously inhibit siderophores and administer another antibiotic, kitasamycin, to reverse norfloxacin resistance. 18 Similarly, proteomic analysis of ciprofloxacin-resistant E. tarda suggested that the pyruvate cycle was downregulated while fatty acid biosynthesis was upregulated in resistant bacteria, from which inhibition of fatty acid biosynthesis could enhance ciprofloxacin killing. 47 In E. tarda, proteomic analysis of antibiotic resistance has been extensively studied in other aquatic pathogens, 48−54 from which metabolite-antibiotic and antibiotic-antibiotic combinations have been proposed to reverse antibiotic resistance.…”

“…52,55−58 Although these studies specifically addressed resistance-relevant proteins, virulenceassociated proteins were also identified, such as flagellum, LPS biosynthesis proteins, chemotaxis proteins, and the Type IV secretory system. 18,55 These studies suggest that bacteria may downregulate virulence-associated proteins in certain types of antibiotic-resistant bacteria, which could be a fitness cost to allow bacteria to survive better under antibiotic stress.…”

“…A recent study investigating the resistance mechanism of norfloxacin-resistant E. tarda identified that siderophore biosynthesis and Fe 3+ -hydroxamate transport were upregulated and proposed to simultaneously inhibit siderophores and administer another antibiotic, kitasamycin, to reverse norfloxacin resistance . Similarly, proteomic analysis of ciprofloxacin-resistant E.…”

“…As previously described, 18 LTB4-S and LTB4-R OTC with an OD 600 = 0.5 were collected by centrifugation at 8000 g for 3 min at 4 °C. Bacterial pellets were washed three times with sterile saline buffer (0.85% NaCl) and resuspended in saline buffer to an OD 600 of 1.0.…”

“…To better understand the functional protein association networks, a PPI network analysis was adopted. Using the STRING online tool, 18 a potential PPI network was predicted. Among the four identified PPI networks, only alanine, aspartate, and glutamate metabolism contained both increased and decreased proteins.…”