Clinical Observations, Identification, and Antimicrobial Susceptibility of Fungi Isolated from Sea Turtles with Histologically Confirmed Mycotic Infections: 20 Cases, 2005–2020
Fungal infections were histologically confirmed in 20 stranded sea turtles, including 18 Kemp’s ridley turtles (Lepidochelys kempii), 1 green turtle (Chelonia mydas), and 1 leatherback turtle (Dermochelys coriacea). Infection was detected antemortem in six cases. Gross external findings in live turtles included carapace lesions (n = 3) and dermatitis (n = 1). Radiographs revealed evidence of pneumonia in 18 animals. Bronchoscopy detected excessive fluid, mucus, clotted blood, or caseous material within the bronchi and lungs of three turtles. At necropsy, the most common gross lesions were pulmonary granulomas, consolidation, and/or hemorrhage (n = 18), and the most common histologic lesion was severe heterophilic-to-granulomatous pneumonia (n = 18). Nine animals had fungal infection at sites outside of the lung. The most commonly identified genera were Purpureocillium, Beauveria, and Fusarium. Other isolates included Metarhizium sp., Trichoderma sp., Clavispora lusitaniae (Candida lusitaniae), Leptospherulina sp., Penicillium chrysogenum, Mucor sp., and Aspergillus section Nigri. Antifungal susceptibility performed for 10 isolates indicated minimum inhibitory concentrations (milligrams per liter) for fluconazole ranging from 8 to >64, often >32; itraconazole from 0.06 to 16, often ≤1; voriconazole from 0.06 to 2, often ≤0.5; and terbinafine from 0.06 to >2, often ≤2. These data indicate that fluconazole resistance is common among the fungi that cause infection in sea turtles. Based on susceptibility data, itraconazole, voriconazole, or terbinafine may be appropriate for treatment of such infections, but additional clinical research is needed. Results of this study indicate that fungal infections can be difficult to diagnose antemortem in sea turtles, and more aggressive methods of diagnosis, such as lung biopsy, may be indicated for suspected cases.Abstract
Gross, radiographic, and bronchoscopic lesions associated with histologically confirmed fungal infections in Kemp’s ridley turtles (Lepidochelys kempii). (A) Bilateral crateriform lesions of the costal carapace scutes from which Fusarium solani species complex was isolated (case 6). (B) Ulcerative dermatitis of the right shoulder from which Fusarium sp. was identified (case 12). (C) Dorsal-ventral radiograph showing multifocal zones of dense soft tissue opacity (arrows) within the lung fields; Purpureocillium lilacinum was cultured (case 16). (D) Bronchoscopic image from a green turtle (Chelonia mydas) showing a large plug of mucoid debris within a distal bronchiole. Beauvaria sp. was isolated (case 9).
Images from sea turtles with histologically confirmed pneumonia. (A) Cytologic image from a bronchoscopic lung lavage of a Kemp’s ridley turtle (Lepidochelys kempii) showing pale to moderately basophilic, septate, branching, parallel-walled fungal hyphae and few degenerating heterophils. Beauvaria bassiana was cultured. Dip Quick stain (Jorvet, Loveland, CO, USA), × 1,000 (case 15). (B) Gross necropsy image showing caseous pulmonary granulomas containing tan-to-white fungal plaques; Purpureocillium lilacinum was cultured (case 16). (C, D) Histologic images showing heterophilic and granulomatous fungal pneumonia in a Kemp’s ridley turtle. Hyphae are parallel-walled, slender, irregularly septate, nonmelanized, ranging from 1–2 to 4–5 µm in width, with right-angle branching. Purpureocillium sp. was identified (C: H&E stain; D: methenamine silver stain) (case 11).
Identification of a Trichoderma guizhouense isolate (bold blue) from the lung of a Kemp’s ridley turtle (Lepidochelys kempii, case 7) as shown by phylogenetic relationships inferred using maximum likelihood. Numbers at nodes represent values for aBayes (>0.95, left)/bootstrap (>75%, right). Bar indicates the number of nucleotide changes. Outgroup = UTHSCSA DI22-114 Bisfusarium dimerum; T = type strain.
Identification of a Metarhizium robertsii isolate (bold blue) from the epicardium of a Kemp’s ridley turtle (Lepidochelys kempii, case 18) as shown by phylogenetic relationships inferred using maximum likelihood. Numbers at nodes represent values for aBayes (>0.95, left)/bootstrap (>75%, right). Bar indicates the number of nucleotide changes. ARSEF = Agricultural Collection of Entomopathogenic Fungal Cultures, U.S. Department of Agriculture, Peoria, Illinois, USA. BCC = Biotec Culture Collection, National Center for Genetic Engineering and Biotechnology, Patumwan, Bangkok, Thailand. CBS = CBS culture collection housed at the Westerdijk Institute, Utrecht, The Netherlands. Outgroup = Purpureocillium lilacinum CBS 284.36.
Identification of Beauveria sp. isolates (bold blue) from the lungs of three Kemp’s ridley turtles (Lepidochelys kempii, cases 13–15) as shown by phylogenetic relationships inferred using maximum likelihood. Numbers at nodes represent values for aBayes (>0.95, left)/bootstrap (>75%, right). Bar indicates the number of nucleotide changes. ARSEF = Agricultural Collection of Entomopathogenic Fungal Cultures, U.S. Department of Agriculture, Peoria, Illinois, USA. BCC = BIOTEC Culture Collection, National Center for Genetic Engineering and Biotechnology, Patumwan, Bangkok, Thailand. BCRC = Bioresource Collection and Research Center, Food Industry Research and Development Institute, Hsinchu, Taiwan. CBS = CBS culture collection housed at the Westerdijk Institute, Utrecht, The Netherlands. IMI = CAB International Culture Collection, Egham, U.K. (formerly International Mycological Institute); T = type strain; Outgroup = Aspergillus fumigatus.
