First Experimental Evidence for the Presence of Potentially Virulent Klebsiella oxytoca in 14 Species of Commonly Consumed Aquatic Animals, and Phenotyping and Genotyping of K. oxytoca Isolates.

Ling Ni,Lanming Chen,Yingwei Xu

doi:10.3390/antibiotics10101235

Ling Ni, Lanming Chen + Show 1 more

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https://doi.org/10.3390/antibiotics10101235

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Abstract

Klebsiella oxytoca is a recently emerging pathogen that can cause necrotizing enterocolitis, hemorrhagic colitis, sepsis-associated purpura fulminans, and infective endocarditis in humans. The bacterium is ubiquitous in water and soil environments. Nevertheless, current literature on K. oxytoca in aquatic products is rare. In this study, we surveyed K. oxytoca contamination in 41 species of consumable aquatic animals sold in July, August, and September of 2018 and 2019 in Shanghai, China, 40 of which had no history of carrying this bacterium. K. oxytoca was for the first time isolated from 14 species with high abundance in benthic animals. None of the K. oxytoca isolates (n = 125) harbored toxin genes mviM, tisB, and yqgB. However, a high occurrence of virulence-associated genes was observed, including brkB (73.6%), cdcB (66.4%), pduV (64.8%), and virk (63.2%). Resistance to sulphamethoxazole-trimethoprim (56.0%) was the most predominant among the isolates, followed by chloramphenicol (6.4%), tetracycline (5.6%), and kanamycin (3.2%). Approximately 8.0% of the isolates displayed multidrug resistant phenotypes. Meanwhile, high percentages of the isolates tolerated the heavy metals Cu2+ (84.8%), Pb2+ (80.8%), Cr3+ (66.4%), Zn2+ (66.4%), and Hg2+ (49.6%). Different virulence and resistance profiles were observed among K. oxytoca isolates in 3 types and 14 species of aquatic animals. The ERIC-PCR-based genome fingerprinting of the 125 K. oxytoca isolates revealed 108 ERIC genotypes with 79 singletons, which demonstrated the genetic diversity of the isolates. The results of this study fill gaps for policy and research in the risk assessment of K. oxytoca in consumable aquatic animals.

Highlights

Klebsiella oxytoca is a Gram-negative bacterium that ubiquitously resides in water and soil environments [1,2]
A total of 567 red, viscous, and single colonies grown on selective MacConkey Inositol Adonitol Carbenicillin (MIAC) agar plates were randomly picked out, which were recovered from 14 of the 41 species of consumable aquatic animals
One K. oxytoca isolate (K. o- N. cumingi crosse 8-1-6-19) displayed resistance to 4 antibiotics (CHL/ SXT/ KAN/ TET), and was tolerant to 3 heavy metals (Pb2+/ Hg2+/ Zn2+). Another K. oxytoca isolate (K. o- H. rubra 8-2-2-11) was resistant to 4 antibiotics (CHL/ SXT/ KAN/ TET) and 6 heavy metals (Cr3+/ Cu2+/ Hg2/ Mn2+/ Pb2+/ Zn2+). These results provided direct evidence for the cross-resistance between the Multidrug resistant (MDR) and heavy metals in the K. oxytoca isolates originating from consumable aquatic animals

Summary

Introduction

Klebsiella oxytoca is a Gram-negative bacterium that ubiquitously resides in water and soil environments [1,2]. The bacterium is found in the nasopharynx and intestine of healthy individuals in humans [3]. K. oxytoca was originally isolated from a yogurt specimen in 1886 and named Bacillus oxytoca. It has been reported that K. oxytoca is the causative agent of necrotizing enterocolitis [5], hemorrhagic colitis [6], sepsis-associated purpura fulminans [7], and infective endocarditis in humans [8], arguing that K. oxytoca is an emerging pathogen [1]. Outbreak of K. oxytoca in hospitals involved strains with extended-spectrum betalactamases and carbapenemases, which lead to therapeutic problems [9]

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