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Diabetic%20foot%20infection Signs and Symptoms
Introduction
- Patients w/ diabetes are prone to have invasion & multiplication of microorganisms in the soft tissue or bone (anywhere below the malleoli) called diabetic foot infection that leads to host inflammatory response that usually results to tissue destruction
Epidemiology
- Based on 2015 prevalence data from the International Diabetes Federation, foot ulcers develop annually in 9.1 to 26.1 million people w/ diabetes worldwide
- An estimated 10% of patients w/ diabetes will have diabetic foot ulcer that precedes more than 80% of non-traumatic amputations
- Lifetime risk of developing a foot ulcer in patients w/ diabetes is 15-25% before but additional data showed between 19% & 34% of persons w/ diabetes will likely to be affected
- Foot infection is very common in patients w/ diabetes, associated w/ the duration of the disease & likelihood of diabetic complications
- Infection of the foot is the most common diabetic complication that would require hospitalization
Etiology
- Staphylococci & streptococci are the most common causative organisms although most diabetic foot infections are polymicrobial
- Copathogens in chronic infections are aerobic Gram-negative bacilli while obligate anaerobes are copathogens in ischemic or necrotic wounds
Pathophysiology
- Most infections typically start w/ a break in the protective cutaneous envelope of the skin that resulted from trauma or neuropathic ulceration
- These open wounds will eventually be colonized by skin flora that in many cases result to infection
- Due to hyperglycemia-induced advanced glycation end-products, persistent inflammation & apoptosis the wounds in the feet of patients w/ diabetes become chronic
- The following factors predispose the patient w/ diabetes to have foot infection:
- Deep wound that is long-standing or recurrent or caused by trauma
- Ill-defined diabetes-related immunological perturbations related to neutrophil function
- Chronic renal failure
- Spread of infection
- Microorganisms spread proximally to the subcutaneous tissues including fascia, tendons, muscles, joints & bone
- This is due to the anatomy of the foot which is divided into several rigid but intercommunicating compartments
- The infection induces inflammatory response that causes compartmental pressure to exceed capillary pressure, resulting to ischemic tissue necrosis
- The tendons within the compartments cause proximal spread of infection that usually moves from higher to lower-pressure areas
- Bacterial virulence may play a role in these complex infections
- Isolate strains of Staphylococcus aureus from clinically non-infected ulcers have been shown to have a lower virulence potential than those that are infected
- Microorganisms spread proximally to the subcutaneous tissues including fascia, tendons, muscles, joints & bone
Signs and Symptoms
- It is not common in patients w/ diabetic foot infection to have systemic symptoms (eg fever & chills), marked leukocytosis or major metabolic disturbance but its presence will indicate a more severe, potentially limb or even life-threatening infection
- Patient may also present w/ symptoms of vascular disease (eg claudication, leg fatigue) & neuropathy (numbness, burning, pain)
Risk Factors
- Patients w/ diabetes who have the following characteristics are predisposed to foot ulcer that leads to infection & ultimately lower extremity amputation:
- Repetitive stress over an area that is subject to high vertical or shear stress in patients w/ peripheral neuropathy
- Impaired immunity
- Peripheral artery disease (PAD)
- Positive probe-to-bone test
- Presence of foot ulcer for >30 days
- Foot wound that is traumatic
- Previous ulceration or amputation
- Structural deformity
- Limited joint mobility
- Renal insufficiency
- History of walking barefoot
- Microvascular complications, peripheral neuropathy with loss of protective sensation (LOPS)
- High levels of hemoglobin A1c
- Onychomycosis
- Visual impairment
- Preulcerative corn or callus
- Cigarette smoking
- The IWGDF categorized the risk of patients w/ diabetes for foot ulceration
| Category | Ulcer Risk | Characteristics |
| 0 | Very low | LOPS and PAD absent |
| 1 | Low | LOPS or PAD present |
| 2 | Moderate | LOPS and PAD or LOPS and foot deformity or PAD and foot deformity |
| 3 | High | LOPS or PAD plus ≥1 of the following: - History of foot ulcer - Lower extremity amputation - End-stage renal disease |
