When Shell Lesions in Sea Turtles Become More Than Just a Wound

Shell erosions, ulcerative skin lesions, and traumatic wounds are among the most common findings in stranded sea turtles. In many cases, they appear manageable during the initial examination. But once marine bacteria gain access to damaged tissue, these superficial injuries can quickly progress into deep systemic infections. 

Several opportunistic bacteria including Vibrio alginolyticus, Aeromonas hydrophila, Pseudomonas spp., Citrobacter spp., and Serratia spp. have been associated with dermatitis, shell disease, pneumonia, hepatitis, osteomyelitis, and septicemic conditions in sea turtles^1,2,3. 

Why Marine Wounds Deteriorate So Quickly 

Unlike terrestrial injuries, wounds in sea turtles remain constantly exposed to seawater loaded with environmental microorganisms. Trauma caused by fishing hooks, boat strikes, entanglement, predator attacks, or abrasive debris creates an ideal entry point for opportunistic pathogens. 

In loggerhead turtles, Vibrio alginolyticus has been linked with severe ulcerative disease involving hemorrhagic lesions affecting the neck, tail, and shell plates¹. Aeromonas hydrophila has also been associated with dermatitis, stomatitis, nephritis, osteomyelitis, and septicemic disease^1,4. 

What makes these infections particularly challenging is their ability to spread beyond the original lesion. Bacteria isolated from shell and skin wounds have also been recovered from internal organs, including lungs, liver, spleen, kidneys, and heart tissues⁵. 

Respiratory involvement appears especially common in debilitated turtles. Pseudomonas aeruginosa and Pseudomonas putrefaciens were isolated from loggerhead turtles with pulmonary disease and respiratory compromise⁶. 

Antibiotic Resistance Is Becoming a Serious Concern 

Another major challenge is antimicrobial resistance. Several bacterial isolates recovered from sea turtles showed resistance to multiple antibiotics^1,7,8,9,10. 

Sea turtles are now considered important sentinel species for monitoring antibiotic resistance in marine ecosystems¹⁰. Long-term environmental exposure and pollution likely contribute to the spread of resistant organisms in these animals. 

This becomes clinically important during rehabilitation, especially in chronic wound infections or cases that fail to respond to empirical treatment. Non-healing shell lesions, recurrent abscessation, persistent respiratory signs, and septicemic presentations may all require culture and sensitivity testing rather than routine antibiotic selection. 

The Importance of Early Management 

Many severe infections described in sea turtles likely begin as relatively small traumatic injuries. Delayed intervention, poor water quality, stress, and compromised immunity allow opportunistic bacteria to invade deeper tissues and cause systemic disease. 

Management often depends on: 

• early wound cleaning,  

• regular debridement,  

• minimizing environmental contamination,  

• supportive care,  

• and close monitoring for systemic involvement.  

Changes in appetite, buoyancy, activity, or respiratory effort should never be overlooked in turtles with visible shell or skin lesions. 

Clinical Takeaway 

In sea turtle medicine, external wounds rarely remain “just external.” A shell lesion may be the first sign of an evolving bacterial infection with the potential to involve multiple organ systems. Early intervention and careful monitoring often determine whether a turtle recovers or progresses toward septicemia. 

Reference 

1. Ebani VV. Bacterial infections in sea turtles. Veterinary sciences. 2023 May 6;10(5):333. https://www.mdpi.com/2306-7381/10/5/333 

2. Orós J, Camacho M, Calabuig P, Rial-Berriel C, Montesdeoca N, Déniz S, Luzardo OP. Postmortem investigations on leatherback sea turtles (Dermochelys coriacea) stranded in the Canary Islands (Spain)(1998–2017): Evidence of anthropogenic impacts. Marine pollution bulletin. 2021 Jun 1;167:112340. https://www.sciencedirect.com/science/article/pii/S0025326X2100374X 

3. Pace A, Meomartino L, Affuso A, Mennonna G, Hochscheid S, Dipineto L. Aeromonas induced polyostotic osteomyelitis in a juvenile loggerhead sea turtle Caretta caretta. Diseases of Aquatic Organisms. 2018 Dec 11;132:79-84. https://www.int-res.com/articles/dao2018/132/d132p079.pdf 

4. Pace A, Meomartino L, Affuso A, Mennonna G, Hochscheid S, Dipineto L. Aeromonas induced polyostotic osteomyelitis in a juvenile loggerhead sea turtle Caretta caretta. Diseases of Aquatic Organisms. 2018 Dec 11;132:79-84. https://www.int-res.com/articles/dao2018/132/d132p079.pdf 

5. Alduina R, Gambino D, Presentato A, Gentile A, Sucato A, Savoca D, Filippello S, Visconti G, Caracappa G, Vicari D, Arculeo M. Is Caretta caretta a carrier of antibiotic resistance in the Mediterranean Sea?. Antibiotics. 2020 Mar 10;9(3):116. https://www.mdpi.com/2079-6382/9/3/116 

6. Ciccarelli S, Valastro C, Di Bello A, Paci S, Caprio F, Corrente ML, Trotta A, Franchini D. Diagnosis and treatment of pulmonary disease in sea turtles (Caretta caretta). Animals. 2020 Aug 5;10(8):1355. https://www.mdpi.com/2076-2615/10/8/1355 

7. Trotta A, Marinaro M, Sposato A, Galgano M, Ciccarelli S, Paci S, Corrente M. Antimicrobial resistance in loggerhead sea turtles (Caretta caretta): a comparison between clinical and commensal bacterial isolates. Animals. 2021 Aug 18;11(8):2435. https://www.mdpi.com/2076-2615/11/8/2435 

8. Blasi MF, Migliore L, Mattei D, Rotini A, Thaller MC, Alduina R. Antibiotic resistance of gram-negative bacteria from wild captured loggerhead sea turtles. Antibiotics. 2020 Apr 6;9(4):162. https://www.mdpi.com/2079-6382/9/4/162 

9. Alduina R, Gambino D, Presentato A, Gentile A, Sucato A, Savoca D, Filippello S, Visconti G, Caracappa G, Vicari D, Arculeo M. Is Caretta caretta a carrier of antibiotic resistance in the Mediterranean Sea?. Antibiotics. 2020 Mar 10;9(3):116. https://www.mdpi.com/2079-6382/9/3/116 

10. Drane K, Huerlimann R, Power M, Whelan A, Ariel E, Sheehan M, Kinobe R. Testudines as sentinels for monitoring the dissemination of antibiotic resistance in marine environments: An integrative review. Antibiotics. 2021 Jun 25;10(7):775. https://www.mdpi.com/2079-6382/10/7/775