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

Disclosures

Wounds. 2022;34(4):e37-e41. 

In This Article

Abstract and Introduction

Abstract

Introduction: Diabetic foot osteomyelitis (DFO) is a severe complication of diabetic foot ulcerations (DFUs). Fusarium osteomyelitis in patients who are severely immunocompromised is not well documented in current literature. Fusarium is an invasive fungal species that has been shown to respond poorly to antifungal therapy alone, and bone debridement is usually required. Treatment for DFO may consist of surgical amputation, antimicrobial therapy, and/or conservative surgery (CS) or bone debridement.

Case Presentation: The authors present a case of Fusarium osteomyelitis in a 77-year-old female with type 2 diabetes and acute myeloid leukemia, simultaneously undergoing chemotherapy. The patient had a DFU to the second digit with DFO suggested by magnetic resonance imaging. Bone cultures revealed coagulase-negative staphylococci and Fusarium species. Due to the patient's severely immunocompromised state, they were treated with CS and joint antifungal and antibiotic therapy. The DFU was healed in 6 weeks with no reoccurrence at 6 months.

Conclusions: This case report, to the authors' knowledge, is the first to demonstrate successful remission of Fusarium osteomyelitis with a conservative procedure and adjunct antifungal therapy in an immunocompromised patient.

Introduction

In the United States, the prevalence of diabetes increases annually.[1] With this increasing prevalence of diabetes, a rise in the number of diabetic complications is also seen. Diabetic foot infections (DFIs) are common and represent the leading cause of hospitalization among diabetic complications.[2] It is estimated that 19% to 34% of patients with diabetes are likely to have DFIs. Infection is affected by hyperglycemia and decreased vascular supply, and infection may spread into the underlying bone.[3]

Diabetic foot osteomyelitis (DFO) is defined as an infection of the bone and joint structures of the foot. It has been reported that DFO develops in 20% to 60% of patients with DFIs. Diabetic foot osteomyelitis is difficult to treat; it is associated with the risk of relapsing episodes, hospitalizations, and foot amputations.[2] Nearly all patients with diabetes and pedal osteomyelitis have contiguous chronic infections, meaning the bone becomes infected by an adjacent soft tissue infection. The most common sites of pedal osteomyelitis are the fifth metatarsal, first metatarsal, calcaneus, and great toe distal phalanx.[4]

In the presence of clinical signs or symptoms of infection, it is recommended that a deep specimen of tissue or bone should be obtained for pathology to confirm the diagnosis of osteomyelitis as well as for culture (aerobic, anaerobic, fungal, and acid-fast bacteria [AFB]) to guide antimicrobial therapy.[5] Cultures of bone specimens provide more accurate microbiologic data than those of soft tissue specimens from patients with DFO. The main advantage of a bone biopsy is to provide reliable data on the organism responsible for the infection and determine its susceptibility profile to antimicrobial agents.[2] The microbiology of DFO is usually polymicrobial, and Staphylococcus aureus is the most common pathogen cultured from bone samples. Other gram-positive cocci frequently isolated from bone samples are represented by Staphylococcus epidermidis and other coagulase-negative staphylococci, beta-hemolytic streptococcus, and diphtheroids. Gram-negative bacilli (especially Pseudomonas aeruginosa and Escherichia coli) are frequent in some warm climates. The role of other infectious agents such as fungi or dermatophytes in the setting of DFO appears to be less consistent.[2]

The main objective of the treatment of DFO is to eliminate the infection, reduce the number of amputations, and maintain functional foot biomechanics. Surgical resection of the infected bone(s) can play an important part in the treatment as it effectively and rapidly reduces the infectious organism load at the infected site and removes necrotic tissue that cannot be managed with antimicrobial agents alone. Medical management is characterized by using antimicrobial agents directed against microbes that have been identified by deep tissue or bone biopsy without any bone resection or as an adjunct to surgical management. The main advantages of medical management are the absence of biomechanical changes that may occur after surgical intervention, decreased morbidity and mortality associated with amputation, and a better cost-effectiveness profile.[6] Conservative surgery (CS) or bone debridement for DFO consists of the minimal resection of infected bones while avoiding amputation. Conservative surgery has proven to be effective in the setting of DFO with a high rate of limb salvage and could also reduce the period of antimicrobial therapy.[6] Treatment of DFO can be complicated, even more so when a patient has comorbidities such as cancer.

Multiple modalities are involved in the treatment of patients with cancer, all of which affect the ability to treat wounds. Chemotherapeutic agent regimens are frequently used as monotherapy or in conjunction with surgery and radiation in cancer treatment. These pharmacologic agents target proliferating cells. Although chemotherapeutic agents preferentially target rapidly dividing cells, any tissue can be affected by these treatments; macrophages and fibroblasts involved in wound healing areas are susceptible to these effects as cancer cells.[7] In addition to the effects of chemotherapeutic agents on a cellular level, the nutritional needs of patients must be considered. An estimated 40% to 80% of patients with cancer are clinically malnourished; these patients are increasingly susceptible to infectious complications and delayed wound healing.[7]

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