Abstract
A 47-year-old female Asian elephant was diagnosed with osteomyelitis of the left front digit 5, involving phalanges 1 and 2. Based on culture results of Pseudomonas and Bacteroides, enrofloxacin and metronidazole rectal suppository treatment was started. Serum levels were measured, and different formulations were developed to attempt to deliver appropriate drug levels.
The osteomyelitis progressed over the next 55 days. Enrofloxacin was discontinued based on culture and sensitivities (C&S) and regional limb perfusion (RLP) using amikacin started. From this point on, daily treatments with RLP have been performed. The 3 g amikacin dose was based on 5% of the elephant’s systemic dose. Two weeks later RLP with 6 g of ampicillin was started on alternate days based on C&S, and the following week 400 mg fluconazole was added on a third day in response to C&S and tissue biopsies indicating invasive Candida.
Despite aggressive medical therapy, radiographs and bone biopsy indicated the osteomyelitis continued. Surgery was performed three months after systemic antibiotics were initiated. All infected bone and tissue was identified with methylene blue and removed. Only the most proximal third of P1 remained post-surgery. Post-surgery, daily sterile bandage changes were performed and rotational RLP treatment was continued with amikacin (8 g), ampicillin (15 g), and fluconazole (800 mg). This daily treatment regime, with some drug adjustments, has been continued for six months.
One month after surgery, P1 was radiolucent at the distal margin and was progressing to a fragmented appearance, indicating the osteomyelitis may still be present. Amikacin serum levels were collected post-RLP, before the tourniquet was removed. Systemic therapeutic levels were reached, but not the recommended 10 times MIC. Amikacin was replaced with 12 g of ceftazidime in the RLP rotation. Two months post-surgery a fragment of the remaining P1 was easily biopsied from the healing surgical tract with culture results indicating Enterococcus, but not Pseudomonas. Three months post-surgery we reinstituted enrofloxacin suppositories at a higher dose.
At five months post-surgery, cultures indicated that we had successfully eliminated Pseudomonas and anaerobic growth; however, the healing site continued to yield various gram-negative bacteria, including a Klebsiella resistant to ceftazidime. We replaced ceftazidime with 12 g of ceftriaxone and continued ampicillin and fluconazole in the three-day RLP rotation. Since this last medical alteration, the remaining P1 fragments have been radiographically unchanged for three months and the surgical wound has been reduced to a tract that is <2 mm in diameter and 4 cm deep.
The current success of this treatment is attributed to a very tractable patient that has allowed daily medical care for over eight months. We are continuing her daily treatments and I will give an update on the progression of the case.
Acknowledgments
The authors would like to acknowledge the RVTs and elephant keepers who have worked above and beyond their duties in providing excellent care for this elephant. For a large part of this treatment period, the elephant keepers have been providing 24-hour care.