What antibiotics are used to treat Staphylococcus (Staph) infections?

Antibiotics for Treating Staphylococcus (Staph) Infections

The first-line antibiotics for treating staph infections depend on whether the infection is methicillin-susceptible (MSSA) or methicillin-resistant (MRSA), with vancomycin, trimethoprim-sulfamethoxazole (TMP-SMX), clindamycin, doxycycline, and linezolid being the primary options for MRSA infections. 1

Treatment Based on Methicillin Susceptibility

For Methicillin-Susceptible Staph Aureus (MSSA):

• Penicillinase-resistant penicillins (flucloxacillin, dicloxacillin) are the antibiotics of choice for serious MSSA infections 2
• First-generation cephalosporins (cefazolin, cephalothin, cephalexin) are effective alternatives for less serious MSSA infections or in patients with non-immediate penicillin hypersensitivity 2
• Clindamycin, lincomycin, and erythromycin can be used for less serious infections or in penicillin-allergic patients 2

For Methicillin-Resistant Staph Aureus (MRSA):

Outpatient Treatment (Skin and Soft Tissue Infections):

• TMP-SMX (160-320/800-1600 mg PO twice daily for adults) 1
• Doxycycline (100 mg PO twice daily) or minocycline (200 mg initial dose, then 100 mg PO twice daily) 1
• Clindamycin (300-450 mg PO three times daily) if local resistance rates are low (<10%) 1, 3
• Linezolid (600 mg PO twice daily) for more severe infections 1
• Fusidic acid (500 mg PO every 8 hours or 750 mg every 12 hours) in combination with rifampin in some regions 1

Inpatient Treatment (Complicated Infections):

• Vancomycin (30-60 mg/kg/day IV in 2-4 divided doses) - primary option 1
• Teicoplanin (6-12 mg/kg/dose IV every 12 hours for three doses, then daily) 1
• Linezolid (600 mg IV/PO twice daily) 1, 4
• Daptomycin (4-6 mg/kg/dose IV daily for skin infections; 6-10 mg/kg/dose for bacteremia) 1, 5
• Telavancin (10 mg/kg/dose IV once daily) 1, 4
• Ceftaroline - newer cephalosporin with MRSA activity 4, 6

Treatment Based on Infection Type

Skin and Soft Tissue Infections (SSTIs):

• For simple abscesses or boils, incision and drainage is the primary treatment 1
• For outpatient treatment of non-purulent cellulitis, coverage for both beta-hemolytic streptococci and MRSA may be needed 1, 3
• Options for dual coverage include: clindamycin alone, TMP-SMX or tetracycline plus amoxicillin, or linezolid alone 1, 3
• Duration: 5-10 days for uncomplicated infections; 7-14 days for complicated infections 1, 3

Bacteremia and Endocarditis:

• Vancomycin is the primary treatment for MRSA bacteremia 1
• Daptomycin (6 mg/kg/dose IV daily) is an alternative for MRSA bacteremia and right-sided endocarditis 4, 7
• For complicated bacteremia, treatment duration is 4-6 weeks 1
• For prosthetic valve endocarditis: vancomycin plus rifampin (300 mg PO/IV every 8 hours) for at least 6 weeks plus gentamicin for 2 weeks 1

Pneumonia:

• Vancomycin or linezolid (600 mg PO/IV twice daily) for 7-21 days 1
• Clindamycin (600 mg PO/IV three times daily) if the strain is susceptible 1
• Daptomycin should not be used for MRSA pneumonia 4, 7

Osteomyelitis:

• Surgical debridement plus antimicrobial therapy 1
• IV options: vancomycin, daptomycin (6 mg/kg/dose IV daily) 1
• Oral options: TMP-SMX with rifampin, linezolid, clindamycin 1
• Treatment duration: minimum 6-8 weeks 1

Special Population Considerations

Pediatric Patients:

• Vancomycin (15 mg/kg/dose IV every 6 hours) for serious infections 1
• Clindamycin (10-13 mg/kg/dose IV every 6-8 hours) if local resistance rates are low 1
• Linezolid (10 mg/kg/dose PO/IV every 8 hours for children <12 years; 600 mg twice daily for ≥12 years) 1
• Tetracyclines should not be used in children <8 years of age 1

Clinical Pearls and Pitfalls

• Always obtain cultures before starting antibiotics when possible to guide targeted therapy 1, 3
• Monitor local resistance patterns, especially for clindamycin, as resistance rates vary by region 1, 3
• Consider D-zone testing for inducible clindamycin resistance when using for serious infections 3, 8
• Rifampin should never be used as monotherapy due to rapid development of resistance 1
• Vancomycin may be less effective for MRSA isolates with higher MICs within the susceptible range 4, 6
• For recurrent MRSA infections, consider decolonization strategies along with hygiene measures 1

By selecting appropriate antibiotics based on susceptibility patterns, infection type, and patient characteristics, effective treatment of staph infections can be achieved while minimizing the risk of treatment failure and antibiotic resistance.