What is the recommended treatment and dosage for Dicloxacillin (Dicloxacillin) in bacterial infections?

Dicloxacillin Treatment and Dosing for Bacterial Infections

Dicloxacillin is the oral agent of choice for methicillin-susceptible Staphylococcus aureus (MSSA) skin and soft tissue infections in adults, dosed at 500 mg every 6 hours orally, while pediatric dosing is 25-50 mg/kg/day divided into 4 doses. 1, 2, 3

Adult Dosing by Infection Type

Mild to Moderate Infections:

• 125 mg every 6 hours orally for mild infections 3
• 250 mg every 6 hours orally for impetigo 2

Moderate to Severe Infections:

• 500 mg every 6 hours (four times daily) orally for MSSA skin and soft tissue infections, non-purulent cellulitis, and as part of combination therapy for animal bites (with penicillin) 1, 2, 3

Pediatric Dosing (Children <40 kg)

Mild to Moderate Infections:

• 12.5 mg/kg/day divided into 4 doses every 6 hours for impetigo 2, 3

Moderate to Severe Infections:

• 25-50 mg/kg/day divided into 4 doses every 6 hours for MSSA skin and soft tissue infections 1, 2, 3

Treatment Duration

• 7 days for impetigo and uncomplicated skin infections, adjusted based on clinical response 1, 2
• 7-10 days for most uncomplicated skin and soft tissue infections 2
• At least 48 hours after the patient becomes afebrile, asymptomatic, and cultures are negative 3
• At least 14 days for severe staphylococcal infections 3
• Longer duration may be required for endocarditis and osteomyelitis 3

Administration Guidelines

Critical administration instructions to optimize absorption and prevent adverse effects:

• Take on an empty stomach: at least 1 hour before or 2 hours after meals 3
• Take with at least 4 fluid ounces (120 mL) of water 3
• Do not take in the supine position or immediately before going to bed to prevent esophageal irritation 3

Antimicrobial Spectrum and Efficacy

Effective against:

• Methicillin-susceptible Staphylococcus aureus (MSSA) 1, 2, 4
• Streptococcus pyogenes, Streptococcus pneumoniae, and Streptococcus epidermidis 2

Not effective against:

• Methicillin-resistant Staphylococcus aureus (MRSA) - this is a critical limitation 1, 2, 4
• Most gram-negative organisms 5

Clinical Context and Alternatives

When dicloxacillin is appropriate:

• Dicloxacillin remains the penicillinase-resistant penicillin of choice for oral treatment of MSSA infections, with clinical response rates exceeding 95% 4, 6, 7
• It is particularly favored in adults but is "not used much in pediatrics" where cephalexin is often preferred due to suspension availability and less frequent dosing requirements 1

For penicillin-allergic patients (except immediate hypersensitivity):

• Cephalexin 500 mg four times daily orally (adults) or 25-50 mg/kg/day in 4 divided doses (children) 1
• Cefazolin 1 g every 8 hours IV for severe infections 1

For immediate penicillin hypersensitivity (urticaria, angioedema, bronchospasm, anaphylaxis):

• Clindamycin 300-450 mg four times daily orally (adults) or 30-40 mg/kg/day in 3 divided doses (children) 1, 4

Important Caveats

• Do not use as initial therapy in serious, life-threatening infections - parenteral agents (nafcillin, cefazolin) are required 1, 3
• Always obtain cultures before initiating therapy to confirm susceptibility and rule out MRSA 3
• Resistance patterns: S. aureus shows 89.5% resistance to penicillin/ampicillin but maintains 93% sensitivity to dicloxacillin and related agents 8
• Concurrent probenecid administration increases and prolongs serum penicillin levels, reserved for infections requiring very high serum levels 3