Septicaemic form of Aeromonas hydrophila infection in a mugger crocodile (Crocodylus palustris)

The present report describes Aeromonas hydrophila associated septicaemia and its molecular characterization in free range Indian mugger crocodile. A carcass of male free ranging mugger crocodile was presented for necropsy examination. Grossly, multiple old cutaneous wounds with necrotic debris throughout the body, severely congested and haemorrhagic gastrointestinal tracts and other visceral organs were observed. Histopathological examination revealed necrosed superficial epidermis extending deep into the dermis and surrounded by infiltration of heterophils and macrophages with haemorrhages. Similarly, the gastrointestinal tract and other visceral organs showed severely engorged blood capillaries with extravasation of red blood cells, degeneration and severe infiltration of polymorphonuclear leukocytes and large mononuclear cells especially macrophages. Large numbers of bacterial colonies were also found in the necrosed areas of the skin, heart and gastrointestinal mucosa. A. hydrophila was isolated from the skin scrapings, heart blood and intestinal contents. A. hydrophila strain was found to be virulent as it was found positive for aerolysin, AHCYTOEN, cytotonic enterotoxin and lipase genes. Antibiotic sensitivity test revealed that the isolate was resistant to ampicillin and cefazolin and sensitive to Ceftriaxone, Ciprofloxacin, Trimethoprim-Sulfamethoxazole, Amikacin and levofloxacin but partially susceptible to imipenem antibiotics.