Mixed Infection in Common Carp (<i>Cyprinus carpio</i>) Caused by <i>Aeromonas veronii</i>, <i>Aeromonas hydrophila</i>, <i>Plesiomonas shigelloides</i>, and <i>Citrobacter freundii</i>

Mixed Infection in Common Carp (<i>Cyprinus carpio</i>) Caused by <i>Aeromonas veronii</i>, <i>Aeromonas hydrophila</i>, <i>Plesiomonas shigelloides</i>, and <i>Citrobacter freundii</i>

<i>Aeromonas veronii</i>, <i>Aeromonas hydrophila</i>, <i>Plesiomonas shigelloides</i>, and <i>Citrobacter freundii</i> are opportunistic pathogens that are widely distributed in aquatic environments and fish populations, causing fish diseases under st...

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Bibliographic Details
Main Authors:	Jinghang Zhang, Dan Qiao, Haoyu Wang, Xianliang Zhao, Xinyu Jiang, Lei Zhu, Jie Zhang, Li Li, Xianghui Kong, Chao Pei
Format:	Article
Language:	English
Published:	MDPI AG 2025-03-01
Series:	Animals
Subjects:	pathogenic bacteria challenge experiment opportunistic infection antibiotic resistance
Online Access:	https://www.mdpi.com/2076-2615/15/6/805
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Summary:	<i>Aeromonas veronii</i>, <i>Aeromonas hydrophila</i>, <i>Plesiomonas shigelloides</i>, and <i>Citrobacter freundii</i> are opportunistic pathogens that are widely distributed in aquatic environments and fish populations, causing fish diseases under stressful conditions. In this study, bacteria were isolated from a group of diseased common carp, <i>Cyprinus carpio</i>, with symptoms of hemorrhaging along the body surface, abdominal distention, and flatulence in the intestine. According to the results of biochemical characteristics and <i>16S rRNA</i> sequencing analyses, the isolates were identified as <i>A. veronii</i>, <i>A. hydrophila</i>, <i>P. shigelloides</i>, and <i>C. freundii</i>. The virulence genes from these four representative bacterial strains were amplified. The experimentally co-infected fish showed similar symptoms to those observed in the naturally infected common carp. The LD<sub>50</sub> of <i>C</i>. <i>freundii</i>, <i>P</i>. <i>shigelloides</i>, <i>A. veronii</i>, <i>A. hydrophila</i>, and the mixture group were 1.95 × 10<sup>4</sup>, 4.74 × 10<sup>4</sup>, 5.12 × 10<sup>4</sup>, 1.53 × 10<sup>5</sup>, and 5.41 × 10<sup>4</sup> CFU, respectively. The antibiotic resistance results showed that <i>P</i>. <i>shigelloides</i>, <i>A. veronii</i>, and <i>A. hydrophila</i> were most sensitive to ceftizoxime, florfenicol, enrofloxacin, and norfloxacin. <i>C</i>. <i>freundii</i> was most sensitive to ceftizoxime and gentamicin.
ISSN:	2076-2615