What antibiotic is recommended for an 11-year-old male patient weighing 35 kilograms with a skin infection on the plantar surface of his foot?

From the Guidelines

For a skin infection on the foot of an 11-year-old male weighing 35 kg, cephalexin is typically the first-line antibiotic choice, as recommended by the Infectious Diseases Society of America 1. The recommended dosage would be 25-50 mg/kg/day divided into four doses, which translates to approximately 250-500 mg four times daily for 7-10 days.

• The choice of cephalexin is based on its effectiveness against common skin pathogens like Staphylococcus aureus and Streptococcus species, which are the most frequent causes of skin infections in children 1.
• Alternatively, amoxicillin-clavulanate could be used at 45 mg/kg/day divided into two doses, as outlined in the guidelines for the diagnosis and management of skin and soft tissue infections 1. Before starting antibiotics, the foot should be cleaned with soap and water, and the infection should be monitored for improvement within 48 hours of starting treatment.
• If the infection appears severe with spreading redness, fever, or significant pain, the child should be evaluated by a healthcare provider immediately as intravenous antibiotics might be necessary 1. It's essential to complete the full course of antibiotics even if symptoms improve before finishing the prescription to ensure the infection is fully cleared and reduce the risk of antibiotic resistance.
• The guidelines emphasize the importance of considering the presence or absence of systemic inflammatory response syndrome (SIRS) when deciding on the need for antibiotics and the choice of antibiotic 1.

From the FDA Drug Label

For intramuscular gluteal injections, care should be taken to avoid sciatic nerve injury. With intravenous administration, particularly in elderly patients, care should be taken because of the possibility of thrombophlebitis RECOMMENDED DOSAGES FOR DICLOXACILLIN SODIUM, USP IN MILD TO MODERATE AND SEVERE INFECTIONS DRUGADULTSCHILDREN Mild to ModerateSevereMild to ModerateSevere

• Patients weighing less than 40 kg (88 lbs.) Dicloxacillin 125 mgevery6 hours 250 mgevery6 hours 12. 5 mg/kg/day* inequallydivideddoses every6 hours 25 mg/kg/day* inequallydivideddoses every6 hours

For a skin infection on the bottom of the foot of an 11-year-old male weighing 35 kg, the recommended dosage of dicloxacillin is 12.5 mg/kg/day in equally divided doses every 6 hours for mild to moderate infections, and 25 mg/kg/day in equally divided doses every 6 hours for severe infections 2.

Key considerations:

• The patient's weight is less than 40 kg, so the dosage is based on weight.
• The dosage should be adjusted according to the severity of the infection.
• Dicloxacillin should be taken on an empty stomach, at least 1 hour before or 2 hours after meals, with at least 4 fluid ounces of water.

From the Research

Antibiotic Options for Skin Infection

For an 11-year-old male weighing 35 kg with a skin infection on the bottom of his foot, the following antibiotic options can be considered:

• Cephalexin: effective against streptococcal and staphylococcal skin infections, with cure rates of 90% or higher 3
• Dicloxacillin: comparable to cephalexin in treating staphylococcal skin and skin structure infections 4
• Clindamycin: an alternative for less serious methicillin-susceptible S. aureus (MSSA) infections, such as skin and soft tissue infections 5
• Erythromycin: also an option for less serious MSSA infections, although cephalosporins are generally preferred due to their broader spectrum of activity 5, 3

Considerations for MRSA Infections

In cases where community-acquired MRSA is suspected, cephalosporins may still be effective in treating uncomplicated skin and skin structure infections 6. However, for more serious MRSA infections, parenteral vancomycin or teicoplanin may be necessary 5.

Dosage and Administration

Cephalexin can be administered twice daily, which may enhance medication compliance 3, 4. The specific dosage will depend on the severity of the infection and the patient's weight, and should be determined by a healthcare professional.

Allergy Considerations

For patients with penicillin allergy, cephalosporins can be prescribed safely, although some cephalosporins (e.g. cephalexin) may confer an increased risk of allergic reaction 7.