What is the best antibiotic for a subungual (under the nail) infection?

From the Guidelines

For a subungual infection, the best initial antibiotic is typically oral amoxicillin-clavulanate 875/125 mg twice daily for 7-10 days, as it effectively targets a broad range of bacteria, including Staphylococcus aureus and Streptococcus species, which are common causes of these infections 1.

Key Considerations

• The choice of antibiotic should be based on the severity of the infection and the patient's risk factors for methicillin-resistant Staphylococcus aureus (MRSA) 1.
• If the patient has risk factors for MRSA, alternative antibiotics such as trimethoprim-sulfamethoxazole (Bactrim DS) twice daily or clindamycin 300-450 mg three times daily may be more appropriate choices 1.
• For mild cases, topical antibiotics like mupirocin 2% ointment applied three times daily may be sufficient 1.
• Treatment should be accompanied by warm soaks 3-4 times daily and proper wound care to promote healing and prevent further infection.

Important Bacterial Coverage

• The selected antibiotic should have good activity against Staphylococcus aureus, Streptococcus species, and anaerobes, which are common pathogens in subungual infections 1.
• Amoxicillin-clavulanate is a good option as it provides broad-spectrum coverage, including activity against beta-lactamase-producing bacteria 1.

Special Considerations

• In severe cases or if there's evidence of cellulitis spreading beyond the nail, drainage of any abscess is essential before starting antibiotics 1.
• If the infection doesn't improve within 48-72 hours of antibiotic therapy, the patient should be reevaluated as culture and sensitivity testing may be needed to guide antibiotic selection 1.

From the Research

Antibiotic Options for Subungual Infection

• The choice of antibiotic for subungual infection depends on the causative pathogen and its susceptibility to various antibiotics 2, 3, 4.
• Common causative pathogens for subungual infections include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae 2.
• Cephalexin and amoxicillin/clavulanate are commonly used antibiotics for treating subungual infections, but their effectiveness depends on the susceptibility of the causative pathogen 2, 4.
• For methicillin-resistant Staphylococcus aureus (MRSA) infections, clindamycin and trimethoprim/sulfamethoxazole (TMP/SMX) may be considered as alternative treatment options 3, 4.

Considerations for Antibiotic Selection

• The prevalence of MRSA in the community and healthcare settings is increasing, which may affect the choice of antibiotic for subungual infection 3.
• The cost-effectiveness of different antibiotic regimens should be considered, taking into account the probability of MRSA infection and the cost of treatment 4.
• Cephalexin may be a cost-effective option for outpatient management of cellulitis, including subungual infections, at current estimated MRSA levels 4.
• Clindamycin may become a more cost-effective therapy at high likelihoods of MRSA infection 4.

Limitations of Current Evidence

• There is limited evidence specifically addressing the treatment of subungual infections, and more studies are needed to determine the most effective antibiotic regimens for this condition 2, 3, 4.