What is the best treatment approach for a patient with an ingrown toenail infection, considering potential underlying conditions such as diabetes?

Treatment of Ingrown Toenail Infection

For an infected ingrown toenail, immediately assess infection severity and perform sharp debridement of the offending nail border, followed by empirical oral antibiotics targeting Staphylococcus aureus (cephalexin, dicloxacillin, or clindamycin for 1-2 weeks), with heightened vigilance in diabetic or prediabetic patients who require urgent evaluation for deeper infection and vascular compromise. 1

Immediate Assessment and Risk Stratification

The first critical step is determining whether this is a simple paronychia or a limb-threatening infection, particularly in patients with diabetes or prediabetes:

• Examine for signs of severe infection: erythema extending beyond the nail fold, purulent drainage, warmth, fluctuance (indicating deep abscess), or crepitus (indicating necrotizing infection) 1, 2
• Probe the depth of infection with a sterile instrument to determine if infection extends beyond the nail fold into deeper tissues or bone 1
• Check for systemic signs: fever, tachycardia, leukocytosis, or metabolic instability that would mandate hospitalization 1, 2
• Assess vascular status: palpate pedal pulses and check capillary refill, as peripheral arterial disease dramatically worsens outcomes 1
• Test for peripheral neuropathy using monofilament or tuning fork in diabetic/prediabetic patients 1

Critical pitfall: In diabetic patients, the absence of pain due to neuropathy can mask severe infection—do not be falsely reassured by minimal symptoms. 2

Culture Collection Before Antibiotics

Before starting antibiotics, obtain proper cultures to guide therapy:

• Cleanse and debride the lesion first to avoid contamination with colonizing organisms 1, 2
• Obtain tissue specimens from the debrided base using curettage with a sterile dermal curette or scalpel blade—this is the gold standard 1, 2
• Avoid swabbing undebrided wounds or drainage, as these yield unreliable results contaminated with surface flora 1, 2
• Send specimens promptly in appropriate sterile containers for both aerobic and anaerobic culture 1, 2

Definitive Local Treatment

The cornerstone of treatment is removing the mechanical irritation:

• Perform sharp debridement of the ingrown nail border using scalpel or nail nippers 1, 3
• Remove the offending nail spicule completely from the lateral nail fold 1
• Excise any granulation tissue and necrotic material at the nail border 1
• Consider partial nail avulsion if the infection is recurrent or severe and conservative measures have failed 1, 4

For mild cases without significant infection, conservative measures may suffice: gutter splinting to separate the nail from the lateral fold, cotton wisps under the nail edge, or taping the lateral nail fold. 3, 4 However, once infection is established, surgical debridement is superior to conservative management. 3

Empirical Antibiotic Selection

Start oral antibiotics immediately after obtaining cultures:

• First-line agents: cephalexin, dicloxacillin, or clindamycin for 1-2 weeks 1
• Target gram-positive cocci, particularly Staphylococcus aureus and streptococci, which are the predominant pathogens 1
• Consider MRSA coverage (trimethoprim-sulfamethoxazole, doxycycline, or linezolid) if there is local high prevalence or previous MRSA infection 1

In diabetic patients specifically: Terbinafine is preferred over itraconazole for any concurrent onychomycosis due to lower risk of drug interactions and cardiac effects. 2 However, for acute bacterial infection, standard anti-staphylococcal antibiotics remain the priority. 1

Wound Care and Off-Loading

• Dress the wound to allow daily inspection and maintain a moist healing environment 1
• Off-load pressure from the affected toe using appropriate footwear or padding 1
• Instruct the patient to avoid barefoot walking and wear properly fitting shoes that accommodate the toe 1

Patient Education for Prevention

This is essential to prevent recurrence, especially in diabetic patients:

• Teach proper nail trimming technique: cut nails straight across, not too short, and avoid rounding the corners 1, 2
• Instruct daily foot inspection to examine for early signs of redness, swelling, or drainage 1, 2
• Emphasize immediate reporting of any problems that develop 1
• Recommend appropriate footwear that fits properly and accommodates foot shape without compressing toes 1, 2

Follow-Up Protocol

• Re-evaluate in 3-5 days to assess response to therapy 1, 2
• Adjust antibiotics based on culture results and clinical response 1
• Continue antibiotics until infection resolves (typically 1-2 weeks for mild infections), not necessarily until complete wound healing 1
• For prediabetic/diabetic patients, establish regular foot screening every 6-12 months to monitor for development of neuropathy or vascular disease 1, 2

When to Escalate Care Immediately

Hospitalize or obtain urgent surgical consultation if:

• Systemic toxicity develops: fever, leukocytosis, or metabolic instability 1, 2
• Deep abscess forms or infection extends to bone or joint 1
• Infection fails to respond to initial therapy within 3-5 days 1
• Critical ischemia is present, requiring urgent vascular evaluation 1
• Signs of necrotizing infection appear: crepitus, tissue gas, rapidly progressive necrosis, or black eschar 5, 6

Critical pitfall in diabetic patients: Do not delay surgical consultation waiting for metabolic optimization—surgery should occur within 48 hours if deep infection or gangrene is present. 6 The combination of infection and peripheral arterial disease portends poor outcomes without revascularization. 5

Special Considerations for Diabetic Patients

Diabetic patients with ingrown toenail infections require more aggressive management:

• Provide appropriate treatment for ingrown toenails to help prevent foot ulcers in diabetic patients at risk of foot ulceration 2
• Onychomycosis is a significant predictor for the development of foot ulcers in diabetes, so concurrent fungal infection should be treated 2
• If osteomyelitis is suspected (probe-to-bone test positive), obtain plain radiographs initially; if negative but suspicion persists, repeat in 2-4 weeks or obtain MRI 2