Abstract

Simple SummaryAeromonas hydrophila, which is an opportunistic zoonotic bacterium, has the ability to infect animals with injuries involving the condition of the aquatic environments. Factors including poor sanitation and water quality, stress, overcrowding, and rough handling can make animals more sensitive to infections and trigger outbreaks of A. hydrophila. A. hydrophila was previously isolated from an African black-footed penguin that died while in captivity at a zoo, following clinical signs of depression and anorexia, and in this study, we investigated the effect of stress and serial passaging in mice on A. hydrophila virulence. Serial passaging in mice enhanced the virulence of A. hydrophila, and A. hydrophila infection combined with administration of stress hormones or fasting increased mortality.Aeromonas hydrophila was isolated from an African black-footed penguin (Spheniscus demersus) that died while in zoo captivity. At necropsy, the virulence of A. hydrophila appeared to be enhanced by stress, so was assessed in the presence of in vitro and in vivo stressors and serial passaging in mice. Virulence genes from the isolate were amplified by PCR. In vitro assays were conducted to test the hemolytic activity, cytotoxicity, and effect of stress hormones on A. hydrophila virulence. In vivo assays were conducted to test the stress effect on mortality of A. hydrophila-infected mice and virulence in mice. Two virulence genes coding for hemolysin (ahh1) and aerolysin (aerA) were detected, and the cytotoxic potential of the isolate was demonstrated in baby hamster kidney and Vero cells. Some or all mice inoculated with A. hydrophila and exposed to stress hormones (epinephrine and norepinephrine) or low temperature died, while mice inoculated with A. hydrophila and exposed to fasting or agitation stressors or no stressors survived. We concluded that stress can be fatal in mice experimentally infected with A. hydrophila and that serial passaging in mice dramatically enhances the virulence of A. hydrophila.

Highlights

  • Members of the genus Aeromonas are ubiquitous Gram-negative bacilli that are widespread in aquatic environments [1]

  • A. hydrophila was isolated from an African black-footed penguin (Spheniscus demersus) that died while in captivity at a zoo, following clinical signs of depression and anorexia with greenish vomitus [7] and we further investigated its virulence in several aspects, such as virulence genes, virulence change in serial passage, and administration of stress hormones or fasting in this study

  • To determine whether the virulence of A. hydrophila could be enhanced by serial passaging in mice, the A. hydrophila isolated from the liver of the dead penguin was streaked on blood agar (Asan Pharmacy, Seoul, Korea) and incubated at 37 ◦C for 18 h before inoculation into Mueller-Hinton broth (MHB, Difco)

Read more

Summary

Introduction

Members of the genus Aeromonas are ubiquitous Gram-negative bacilli that are widespread in aquatic environments [1]. Aeromonas spp., as a component of the natural microflora of aquatic bodies, are found in aquatic environments worldwide, including ground, surface, estuarine, marine, waste, and drinking water. Several motile Aeromonas species (e.g., A. hydrophila, A. caviae, A. dhakensis, and A. veronii biovar sobria) are known as pathogens of aquatic animals, and interest in this genus has increased due to its zoonotic potential [3,4]. The infection includes tissue swelling, skin ulcers, necrosis, and hemorrhagic septicemia [3,4,5]. In several freshwater fish both in the farm and field, motile Aeromonas spp. are natural gut microbiota and regarded as opportunistic pathogens; the disease is frequently associated with hemorrhagic septicaemia [13,14,15]

Methods
Findings
Discussion
Conclusion

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

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.