Dermatopathy Caused by Enterobacter aerogenes and Pseudomonas aeruginosa in Boa constrictor amarali

Abstract

Background: Bacterial diseases are the main cause of the high mortality rates of snakes, especially those caused by gramnegative agents. However, studies on dermatopathy caused by these bacterial agents in snakes are scarce; and no reports have been found on Enterobacter aerogenes as causative agent of dermatopathy in snake species. Thus, the objective of this study was to describe the clinical signs, and lesion evolution of a dermatopathy in a male snake (Boa constrictor amarali) specimen of approximately seven years old; and to describe the isolation and identification of the Enterobacter aerogenes and Pseudomonas aeruginosa agents involved in the cause of this disease.

Case: The Boa constrictor amarali evaluated presented blackened cutaneous lesions in the dorsal, snout-vent and tail regions; and well-defined subcutaneous nodules of 2.0-3.0 cm diameter, with soft consistency, reddish color, cutaneous flaccidity, and areas of scale ulceration in the dorsolateral region. The clinical evaluation of the animal showed dehydration signs and pale mucous membranes. The blackened lesions were subjected to mycological analysis - after procedure of deep scale scraping - which showed presence of septate hyphae. The nodule was punctured for microbiological and biochemical analysis. The sample was collected with a sterilized alginate cotton tip swab, and was stored in a plastic tube containing a semi-solid Stuart transport medium, for microbiological analysis. Then, this sample was incubated in a bacteriological oven at 37°C for 24 h. Typical colonies of Pseudomonas and Enterobacter grew on MacConkey agar medium; these bacteria were identified by the colony morphology and their typical odor. The colonies grown in MacConkey agar were also identified through biochemical tests in the mediums: Phenol red, Lysine, Phenylalanine, Citrate, Urea and SIM (Sulfide, Indole, Motility). The results of these tests were able to confirm and identify the P. aeruginosa and E. aerogenes species. The animal died within 36 h, before the identification of the causative agents of the disease, thus, no pharmacological interference was possible.

Discussion: Immunodepression, malnutrition, and temperatures and humidity outside the animal thermal comfort zone, are predisposing factors for the development of bacterial diseases in reptiles. Little information about pathogen agents affecting Boa constrictor specimens in their native area is available; however, captive snakes are subject to a wide variety of diseases - most of which caused or intensified by the captivity conditions. Among the bacteria involved in reptile diseases, few are primary causative agents. In general, clinical bacterial infections tend to be secondary to viral infections. The bacterial agents found in this study are commonly described in scientific literature with location in the oral cavity, differently from the results found in this study. Moreover, the bacterium E. aerogenes has not yet been described in other studies as a causative agent of dermatopathy. Reptiles are considered reservoirs of important zoonotic microorganisms, such as P. aeruginosa, which can be transmitted by fecal contact, bites and wounds. However, the little information on P. aeruginosa in captive reptiles indicates the need for further studies to establish its zoonotic potential. A most adequate management conditions for the snake species could have decreased the severity of the lesions. The occurrence of P. aeruginosa and E. aerogenes found in this work may alert professionals for future clinical suspicions and adequate therapeutic management.