**Abstract**

Chronic diabetic foot osteomyelitis (DFO) is a frequent complication in adult polyneuropathy patients with long-standing diabetes mellitus. Regarding the conservative therapy, there are several crucial steps in adequate diagnosing and approaches. The management should be performed in a multidisciplinary approach following the findings of recent research, general principles of antibiotic therapy for bone; and according to (inter-)national guidance. In this chapter we emphasize the overview on the state-of-the-art management regarding the diagnosis and antibiotic therapy in DFO. In contrast, in this general narrative review and clinical recommendation, we skip the surgical, vascular and psychological aspects.

**Keywords:** Diabetic foot osteomyelitis, remission, microbiology, diagnosis, antibiotic therapy

## **1. Introduction**

Patients with diabetes mellitus are at risk of complications of several organ systems and immunological problems of the cellular and humoral pathways [1]. Frequent clinical complications are diabetic foot infections, including acutely the soft tissues, or chronically the bone: diabetic foot osteomyelitis (DFO). In adult patients there is a lifetime risk of 25% for foot infections and a 15 times higher risk of lower limb amputation. The latter is associated with a high associated mortality risk of 50% within five years [1, 2]. Understandably, these infections are leading to massive healthcare costs and antibiotic consumption [3]. In this chapter, we provide an overview over the current conservative (antibiotic) approach to chronic DFO; emphasizing the state-of-the-art of diagnostic procedures and antibiotic regimens for the conservative, internist management. To keep this chapter as short as possible, we skip the discussion of the different surgical procedures, diabetic foot soft tissue infections [4], treatment of necrosis and gangrene [5], the management of angiopathy, topical antibiotic use of ulcers, implant-related DFO, non-infectious complications in the diabetic foot [6], podiatry, or off-loading, for which a broader literature is available.

## **2. Pathophysiology**

Several underlying mechanisms are leading to a chronic foot infection in adult diabetic patients [1, 7]. Of course, the immunological impairments are crucial

for development of all sorts of infections, but there are more important factors contributing to the appearance of DFO, of which the neuropathy and vasculopathy are the most important cornerstones. In general, and as first step, foot ulcers are induced by pressure and further maceration of the skin [8]. Additionally, there might be a peripheral (microangiopathic) arterial disease (PAD), for which diabetes is an independent risk factor [9]. Wound healing may be impaired if blood flow is reduced. Data show the presence of PAD in about 30% of diabetic foot ulcers [10].
