Abstract
A multiparous 34-year-old, 404 kg (weight at death), female beluga whale (Delphinapterus leucas) housed at the New York Aquarium had a lifetime medical history that included intermittent anorexia, lethargy, depression, anemia, azotemia, leukopenia, elevated erythrocyte sedimentation rate (ESR), genital tract discharge, chronic corneal disease, and presumed herpetic dermatitis. On 28 Oct 2000 she presented with mammary gland enlargement and subsequent anorexia, lethargy, depression, and hematologic changes consistent with inflammation. For a period of two years she exhibited the intermittent mammary gland abnormality and similar clinical signs that would resolve subsequent to antibiotic therapy and supportive care. On 7 Jan 2003 she again presented with inflammatory hematologic changes and mammary gland enlargement, with subsequent depression, lethargy, and anorexia. Generalized subcutaneous abscessation with ulceration and draining skin lesions later developed, followed by genital tract and mammary gland discharge. These clinical findings and hematologic changes varied over the next 15 months. However, they persisted and gradually progressed until her death, despite aggressive medical treatment and abscess drainage.
Diagnostic testing during her illness included complete blood cell counts; ESR; fibrinogen; serum biochemical profiles; GGT; amylase; lipase; serum iron; total iron binding capacity; ferritin; serum electrophoresis; lead; zinc; progesterone; West Nile virus serology; fungal serology panel (Blastomyces, Coccidioides, Histoplasma, Aspergillus, and Cryptococcus); Leptospira serology panel (22 Leptospira serovars); morbillivirus serology panel (CDV, DMV, PDV, PMV); cytology and aerobic, anaerobic, and fungal culture of blowhole, blood, feces, urine, gastric reflux, genital slit, mammary gland discharge; urinalysis; urine Leptospira fluorescent antibody testing; and urine protein:creatinine ratio.
Hematologic and biochemical abnormalities during the course of her illness included elevations of ESR (up to 70 mm/hr), fibrinogen (up to 800 mg/dl), leukocytosis (13,470 cells/ul) or leucopenia (3,080 cells/ul) with a left shift (presence of up to 15% band neutrophils, myelocytes, and metamyelocytes), non-responsive anemia (values as low as red blood cell count of 1.49 x 106, Hct of 23%, hemoglobin 8.9 g/dl, and reticulocyte counts of 0.8-1%) and good response (increased Hct and reticulocyte count of 4-6%) subsequent to recombinant epoetin alpha treatment. There were also elevations of phosphorus (11.78 mg/dl), creatinine (2.6 mg/dl), and blood urea nitrogen (92).
Ultrasound examination 16 Apr 2003 demonstrated a fluid filled uterus and cystic mammary gland changes. Ultrasound-guided percutaneous centesis of the mammary gland yielded turbid yellow fluid which contained high numbers of white blood cells. Initial culture was reported to be positive for Nocardia sp., but this was later determined to be Mycobacterium abscessus. Repeated ultrasound examinations throughout her illness demonstrated progression of mammary gland abscessation, persistence of uterine enlargement and a fluid filled uterus, lymphadenopathy of lymph nodes associated with the mammary gland, and fluid filled subcutaneous structures compatible with abscesses.
Supportive treatments at times during her care included force feeding and provision of water by orogastric tube (via manual restraint or voluntary behavior), ferrous sulfate, vitamin B complex, vitamin E, megestrol acetate (40-200 mg PO SID), recombinant epoetin alpha (40,000-80,000 IU SQ or IM q 2-7 d), ranitidine (1.2 g PO BID), omeprazole (300 mg PO SID), sucralfate (4-5 g PO SID), folic acid (7 mg PO SID), and stanozolol (250 mg IM q 7 d). Analgesic therapy included flunixin meglumine (50-100 mg IM SID), carprofen (1 g PO SID), and meperidine (200 mg IM SID to BID).
During the course of her extended illness she was treated at different times with the following antibiotics: clavulanic acid/amoxicillin 11.25 g PO BID; trimethoprim sulfadiazine 13.2 g PO SID; azithromycin 2 g PO SID (alone or in combination with amikacin 5 g IM q 48 h); isoniazid 1.2 g PO SID; amikacin (with 1% lidocaine) 7.5 g IM q 48 h (via voluntary trained presentation behavior); amikacin 4 g intramammary infusion or abscess infusion; ciprofloxacin 8.5 g PO BID; and a combination of ciprofloxacin 6.75 g PO SID, clarithromycin 3.5 g PO BID, and amikacin 6 g IM SID. Antifungals (nystatin 5x106 units PO BID or itraconazole 1.5 g PO BID) were also administered.
After isolation of the causative agent, antibiotic selection was based upon the M. abscessus isolate antibiotic sensitivity patterns (sensitive to imipenem, ciprofloxacin, clarithromycin, azithromycin, amikacin and kanamycin; intermediate or resistant to tobramycin, gentamicin, cefoxitin, ceftriaxone, cefepime, cefotaxime, doxycycline, minocycline, gatifloxacin, moxifloxacin, trimethoprim/sulfa, linezolid and augmentin.). A dose regimen of 6 g amikacin IM SID, 6.75 g ciprofloxacin PO SID, and 7.5 g clarithromycin PO BID resulted in circulating serum antibiotic levels within the expected normal human ranges for these antibiotics and appropriate abscess content drug levels for amikacin and ciprofloxacin, but limited to no clarithromycin levels detectable in abscess contents possibly due to drug precipitation in the inflammatory cellular and proteinacious debris or lack of penetration of the abscess wall.
Due to her declining condition and lack of response to treatment, euthanasia was elected 9 April 2004. She was anesthetized with midazolam (100 mg IM and 100 mg IV) and meperidine (1000 mg IM and 1000 mg IV) and died prior to intended administration of euthanasia solution. Significant gross necropsy findings included cachexia; mammary gland abscessation; and extensive dissecting body wall cellulitis, myositis, and abscessation associated with the infected mammary gland; tracheal lymph node abscessation; endometrial polypoid masses, mucometra, and uterine concretions; and chronic keratitis. Significant histologic findings included disseminated chronic granulomatous mastitis, cellulitis, myositis, lymphadenitis, tracheitis, and pneumonia. Other incidental findings included endometrial polyps; cystic endometrial hyperplasia; endometritis; pulmonary and lymph node histiocytosis; and cardiac fibrosis. Acid fast organisms within multiple granulomatous lesions were demonstrated by Kinyoun acid-fast staining. M. abscessus infection was confirmed in multiple organs and anatomic sites by culture and/or polymerase chain reaction (PCR) testing.
Serial retrospective serologic testing via multiantigen print immunoassay (MAPIA) and rapid test (RT) 3 demonstrated seroconversion and development of anti-mycobacterial antibodies by MAPIA in April 2000 and by RT in April 2002. These seroconversions occurred early in her clinical course, and greatly preceded the development of obvious mammary gland infection and diagnosis of M. abscessus infection.
Mycobacterial infections are rare in cetaceans.1,2 This case demonstrates the insidious nature and progression of mycobacterial infections, the diagnostic utility of ultrasonography and percutaneous diagnostic sampling, the value of culture and antibiotic sensitivity testing to guide appropriate antibiotic choice, documentation of pharmacokinetic data to verify therapeutic antibiotic levels, and illustrates the potential utility of MAPIA and RT for early diagnosis of mycobacterial infections in cetaceans.
Acknowledgements
The authors thank the New York Aquarium Laboratory and Animal Husbandry staffs and the Wildlife Health Center veterinary clinicians, pathology technicians, and pathologists for their assistance with this case. Cultures were performed at the National Jewish Medical and Research Center and the Diagnostic Testing Service of the Connecticut Veterinary Medical Diagnostic Laboratory, University of Connecticut, which also performed the PCR testing.
References
1. Bowenkamp KE, Frasca Jr. S, Draghi A, et al. 2001. Mycobacterium marinum dermatitis and panniculitis with chronic pleuritis in a captive white whale (Delphinapterus leucas) with aortic rupture. Journal of Veterinary Diagnostic Investigation, 13 (6): 524-530.
2. Dunn L, Buck JD, Robeck TR. Bacterial diseases of cetaceans and pinnipeds. 2001. In: Dierauf L.A., Gulland F.M.D. (eds). CRC Handbook of Marine Mammal Medicine, 2nd ed. Boca Raton. Pp: 309-328.
3. Lyashchenko K, Greenwald R, Esfandiari J, et al. 2006. Tuberculosis in Elephants: Antibody Responses to Defined Antigens of Mycobacterium tuberculosis, Potential for Early Diagnosis, and Monitoring of Treatment. Clinical and Vaccine Immunology 13 (7): 722-732.