Exploring Aeromonas dhakensis in Aldabra giant tortoises: a debut report and genetic characterization

• Published in: BMC microbiology 2024-03, Vol.24 (1), p.76-76, Article 76
• Main Authors: Zhao, Chenxu, Qin, Panpan, Li, Shuai, Chen, Zilu, Wang, Tianliang, Liang, Qunchao, He, Weishi, Peng, Zeyu, Yang, Yurong, Peng, Zhifeng, Li, Yongtao
• Format: Article
• Language: English
• Subjects: Aeromonas; Aeromonas dhakensis; Aldabra giant tortoise; Amoxicillin; Ampicillin; Anaerobic infections; Animals; Antibiotics; Antimicrobial agents; Bacteria; Biotechnology; Causes of; Distribution; Environmental aspects; Erythromycin; Gene sequencing; Genes; Genetic aspects; Hemorrhage; Humans; Identification and classification; Infections; Ionization; Lethal dose; Mass spectrometry; Mass spectroscopy; Mice; Microscopy; Multidrug resistance; Pathogenicity; Pathogens; Penicillin; Phylogenetics; Physiological aspects; Public health; Reptiles; Reptiles & amphibians; Sepsis; Sequence analysis; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Testudines; Tortoises; Turtles; Virulence; Virulence - genetics; Wildlife diseases; Zoonoses
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/s12866-024-03203-w

Aeromonas dhakensis (A. dhakensis) is becoming an emerging pathogen worldwide, with an increasingly significant role in animals and human health. It is a ubiquitous bacteria found in terrestrial and aquatic milieus. However, there have been few reports of reptile infections. In this study, a bacterial strain isolated from a dead Aldabra giant tortoise was identified as A. dhakensis HN-1 through clinical observation, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS), and gene sequencing analysis. Subsequently, to evaluate its pathogenicity, the detection of virulence genes and mice infection experiments were performed. A. dhakensis HN-1 was found to contain seven virulence genes, including alt, ela, lip, act, aerA, fla, and hlyA. Mice infected with A. dhakensis HN-1 exhibited hemorrhage of varying degrees in multiple organs. The half-maximal lethal dose (LD ) value of A. dhakensis HN-1 for mice was estimated to be 2.05 × 10 colony forming units (CFU)/mL. The antimicrobial susceptibility test revealed that A. dhakensis HN-1 was resistant to amoxicillin, penicillin, ampicillin and erythromycin. This is the first report of A. dhakensis in Aldabra giant tortoises, expanding the currently known host spectrum. Our findings emphasize the need for One Health surveillance and extensive research to reduce the spread of A. dhakensis across the environment, humans, and animals.