A case published in the American College of Physicians' Annals of Internal Medicine follows Ms. M, a 49-year-old woman with diabetes complicated by neuropathy, proliferative retinopathy, chronic kidney disease post–kidney transplant, and prior toe amputations, who presented with a 2-week, progressively painful right foot ulcer accompanied by chills, nausea, and swelling. Physical examination revealed a small but tender lateral foot ulcer without purulence and intact pulses. Labs showed mild leukocytosis and a markedly elevated CRP (101 mg/L), and plain radiographs identified soft-tissue gas with no bone erosions. Although outwardly stable and afebrile, the combination of systemic symptoms, immunosuppression, and radiographic abnormalities signaled a severe diabetic foot infection (DFI).
The 2023 IWGDF/IDSA guideline provides a structured framework for evaluating such cases, emphasizing severity classification (mild, moderate, severe) as the anchor for all subsequent decisions. The guideline highlights the use of inflammatory markers when exam findings are subtle or masked by neuropathy or vascular disease, the primacy of plain radiographs as the first diagnostic step, and the role of MRI only when osteomyelitis remains uncertain. Tissue or bone cultures are preferred over superficial swabs, and bone culture is recommended before starting antibiotics when osteomyelitis is suspected. Importantly, the guideline recommends hospitalization for all severe DFIs and for moderate infections in immunocompromised patients, which is criteria Ms. M clearly meets.
The expert discussion offers two complementary clinical lenses. The infectious diseases specialist grounds the assessment in guideline-defined severity, laboratory escalation, and a stepwise imaging algorithm. From this viewpoint, Ms. M’s radiographic soft-tissue gas, elevated CRP, systemic symptoms, and immunosuppressed state warrant admission, broad-spectrum IV antibiotics (MRSA, gram-negative, and anaerobic coverage), and urgent surgical evaluation. Antibiotic duration depends on whether osteomyelitis is present (2–3 weeks for soft-tissue infection alone vs 3–6 weeks if infected bone remains after debridement).
The podiatrist, while agreeing with the overall severity and management plan, emphasizes bedside assessment—probing the ulcer to assess depth, detecting sinus tracts, and combining the probe-to-bone test with radiographs to approach the diagnostic accuracy of MRI. This perspective stresses the importance of distinguishing superficial from deep involvement and tailoring wound management after debridement, including decisions about packing vs closure and the value of bone margin pathology.
Across both viewpoints, several practical lessons stand out: new pain in a neuropathic foot should trigger concern for deep infection; soft-tissue gas on radiograph demands urgent evaluation regardless of fever; and immunosuppressed patients often present with deceptively mild external findings. CRP values >100 mg/L strongly support moderate to severe infection. Although MRI is valuable, clinicians should not overlook the combined diagnostic power of bedside probing and plain films before escalating imaging.
Together, these considerations shaped the major decisions in Ms. M’s care: classifying her infection as severe, admitting her for IV antibiotics, prioritizing urgent surgical debridement with deep culture acquisition, and individualizing antibiotic duration based on operative findings.
Why This Case Falls Between the Cracks
Ms. M’s presentation is misleading: a small ulcer, intact pulses, no fever, and no probe-to-bone findings suggest mild disease, yet she harbors severe infection driven by immunosuppression, high inflammatory burden, neuropathy masking symptoms, and soft-tissue gas. This discordance between appearance and severity is exactly how high-risk diabetic patients slip through clinical filters. Her case underscores the necessity of structured, guideline-based evaluation to prevent delayed recognition and avoidable limb loss.
Disclosures can be found in the published article.
Source: Annals of Internal Medicine
