Aeromonas dhakensis, a pathogen associated with red abdominal shell disease in Chinese soft-shelled turtle Pelodiscus sinensis

Abstract

Red abdominal shell disease is a major disease that has caused significant economic losses in Chinese soft-shelled turtle Pelodiscus sinensis aquaculture. Yet scarce information is available on Aeromonas dhakensis as a causal agent of red abdominal shell disease in P. sinensis. In the present study, a haemolytic and proteolytic A. dhakensis isolate (F04) was demonstrated as a causative agent of red abdominal shell disease in cultured P. sinensis. It carried virulent aerolysin, heat-labile cytotoxic enterotoxin, polar flagella, and lipase-encoding genes aer, alt, flaA, and lip, exhibited the mean lethal dose (LD50) value of 4.27×105 CFU/ml in P. sinensis, and developed multiple resistances against aminoglycosides, chloramphenicols, cephalosporins, lincosamides, macrolides, penicillins, peptides, sulfonamides, and tetracyclines antimicrobials. To our knowledge, this is the first study to identify a multiply resistant A. dhakensis strain as a pathogen of red abdominal shell disease in P. sinensis, and the findings of this study can also provide valuable insights into the virulence and antimicrobial resistance in Chinese soft-shelled turtle-pathogenic A. dhakensis.