Treatment of Fusarium Osteomyelitis in a Diabetic Foot Ulcer Complicated by Antineoplastic Chemotherapy

Tyson O. Strom, DPM; Rebecca A. Burmeister, DPM, MPH; Gary M. Rothenberg, DPM, CWS; Sari J. Priesand, DPM


Wounds. 2022;34(4):e37-e41. 

In This Article

Case Report

A case of a 77-year-old female with a past medical history of type 2 diabetes with peripheral neuropathy, hyperlipidemia, and relapsed acute myeloid leukemia (AML) currently on FLAG (fludarabine, arabinofuranosyl cytidine, granulocyte colony-stimulating factor) chemotherapy is reported. The type 2 diabetes was well controlled, with a most recent hemoglobin A1c of 6.3%. Metformin and lifestyle modifications were used to manage the diabetes. The patient was preestablished to the podiatry service at the authors' hospital, as the patient also had a past surgical history of right foot bunionectomy with retained hardware and hammertoe correction of the right second toe.

The patient was admitted to Michigan Medicine, Ann Arbor, Michigan, for antineoplastic chemotherapy for AML. This was the third course of chemotherapy for AML. Podiatry was consulted during this hospitalization for a chronic diabetic foot ulcer (DFU) of the right second toe at the distal tuft of the toe and a new DFU on the plantar aspect of the right hallux (Figure 1). The DFU of the right second toe was present for more than 4 months and had been complicated by cellulitis approximately 1 month earlier, requiring hospitalization. During that hospitalization, the patient received intravenous (IV) vancomycin for 3 days and was discharged on a regimen of oral sulfamethoxazole-trimethoprim twice daily for 7 days. The cellulitis resolved on this antimicrobial regimen, but the DFU remained open. During the current hospitalization, there was a return of cellulitis associated with the right second toe DFU. The patient also had a new, superficial ulcer on the right hallux, which correlated with the placement of a crest pad to take pressure off the second toe DFU. No signs of acute infection were associated with the right hallux ulcer, and it did not probe to the bone.

Figure 1.

(A) Plantar view of the right diabetic foot ulcers prior to debridement. (B) Dorsal view of right foot with cellulitis and erythema of right second digit at initial presentation.

At presentation, the patient was febrile (39.2°C) and neutropenic, with blood cultures positive for P aeruginosa. The DFU of the right second toe was full thickness and probed to the distal phalanx bone, which was also visible in the wound bed. The DFU measured 1.4 cm × 1.0 cm × 1.5 cm. There was erythema streaking greater than 2 cm from the DFU, approximately to the second metatarsal phalangeal joint level. There was nonpitting edema to the right second toe, creating a sausage digit appearance. There was moderate serosanguinous drainage from the DFU, but no purulent drainage was appreciated. The wound base was a mix of granular and fibrotic tissues, with no necrosis to the soft tissue. Pedal pulses were palpable, and all toes had a brisk capillary refill time bilaterally. A previous ankle-brachial index and toe-brachial index did not suggest peripheral vascular occlusive disease to the lower extremities.

Erythrocyte sedimentation rate (ESR) was elevated to 46 mm per hour, and the C-reactive protein (CRP) level was elevated to 29.2 mg/L. The white blood cell count (WBC) and platelet count were extremely below normal (<0.1 K/uL and 8 K/uL, respectively) and were attributed to the current FLAG chemotherapy treatment. Multiple platelet transfusions were administered throughout the hospitalization; however, the platelet count remained below normal and was attributed to active chemotherapy treatment. A right foot plain radiograph demonstrated cortical irregularity and lucency of the distal phalanx of the second toe (Figure 2). Magnetic resonance imaging (MRI) of the right foot revealed changes consistent with osteomyelitis to the second toe distal phalanx only and no appreciated abscess.

Figure 2.

Plain film radiograph of the right foot, second digit at initial presentation.

The patient's medications included oral amoxicillin-clavulanate 875/125 mg twice daily, voriconazole 200 mg twice daily, acyclovir 400 mg once daily, and sulfamethoxazole-trimethoprim 800/160 mg 3 times per week for infection prevention in conjunction with chemotherapy. Due to the P aeruginosa bacteremia from day 1 following inpatient admission, the patient was started on IV cefepime and vancomycin, and the amoxicillin-clavulanate and sulfamethoxazole-trimethoprim were held.

Since worsening osteomyelitis and cellulitis associated with the second toe DFU developed in this patient, the options of partial phalangectomy with bone cultures versus partial toe amputation were presented to the patient. Also discussed was the thrombocytopenia with the possibility of excessive bleeding during the procedure and the postoperative period. Given the risks and benefits of the 2 different procedure options, the patient elected for a bedside wound debridement with partial distal phalangectomy. Antimicrobial therapy was not held for the procedure. A #15 blade, sterile rongeur, and sterile curette were used for the debridement. The bone was sent for anatomic pathology and aerobic, anaerobic, fungal, and AFB cultures. As expected, there was more bleeding than anticipated with the procedure due to the thrombocytopenia. The site was packed with an oxidized cellulose polymer for hemostasis. The postprocedure compression dressing was left intact, and the patient was non-weightbearing, with the foot elevated for 48 hours. Postprocedural plain radiographs were obtained (Figure 3). These revealed greater than 50% removal of the distal phalanx bone. Figure 4 shows clinical photos from status postprocedure day 2. The edema and erythema to the second toe greatly improved after the partial phalangectomy.

Figure 3.

Plain radiographs of the right foot after second toe partial distal phalangectomy performed at bedside.

Figure 4.

(A) Plantar view of the right foot second toe diabetic foot ulcer (DFU) 2 days after bedside debridement with partial distal phalangectomy. (B) Dorsal view of right foot second toe DFU 2 days after bedside debridement with partial distal phalangectomy.

The bone culture resulted in coagulase-negative staphylococci and Fusarium species. An infectious disease specialist recommended 14 days of IV cefepime with the transition to oral doxycycline 100 mg twice daily for an additional 6 weeks. The patient also remained on oral voriconazole 200 mg twice daily until the DFU was healed.

The patient was followed up in the outpatient setting with the hospital's podiatry team every 1 to 2 weeks for additional wound care. The DFU was offloaded with a wound shoe with heel weightbearing to the right foot. At 6 weeks after the debridement with partial distal phalangectomy, the DFU was healed (Figure 5). The patient transitioned to depth inlay shoes with custom, multidensity, accommodative orthotics with offloading to the previous ulceration site. At the patient's last appointment, the DFU remained healed with no further signs of preulceration skin breakdown for 6 months.

Figure 5.

Six weeks after debridement with partial distal phalangectomy, fully healed.