Treatment: Staphylococcal Infections - Suppurative collections should be surgically drained. The emergence of CA-MRSA has increased the importance of culturing material from all collections to identify the pathogen and determine its antimicrobial susceptibility.
- In most cases of prosthetic-device infection, the device should be removed, although some CoNS infections can be managed medically.
- Antibiotic therapy for S. aureus infection is generally prolonged (i.e., 4-8 weeks), particularly if blood cultures remain positive 96 h after initiation of therapy, if the infection was acquired in the community, if a removable focus of infection is not removed, or if cutaneous or embolic manifestations of infection occur. For immunocompetent pts in whom shorter therapy is planned, a transesophageal echocardiogram to rule out endocarditis is warranted.
- Antimicrobial therapy for serious staphylococcal infections is summarized in Table 86-2.
- - Penicillinase-resistant β-lactams, such as nafcillin, oxacillin, and cephalosporins, are highly effective against penicillin-resistant strains.
- - The incidence of MRSA is high in hospital settings, and strains intermediately or fully resistant to vancomycin have been described. In general, vancomycin is less reliably bactericidal than the β-lactams and should be used only when absolutely indicated.
- - Among newer antistaphylococcal agents, ceftaroline is a fifth-generation cephalosporin with bactericidal activity against MRSA; daptomycin is bactericidal but is not effective in pulmonary infections; quinupristin/dalfopristin is typically bactericidal but is only bacteriostatic against isolates resistant to erythromycin or clindamycin; linezolid is bacteriostatic and offers similar bioavailability after oral or parenteral administration; and telavancin—a derivative of vancomycin—is active against strains with reduced susceptibility to vancomycin (i.e., vancomycin-intermediate S. aureus, or VISA). Tigecycline, a broad-spectrum minocycline analogue, is bacteriostatic against MRSA.
- Other alternatives include the quinolones, but resistance to these drugs is increasing, especially among MRSA strains.
- Trimethoprim-sulfamethoxazole (TMP-SMX) and minocycline have been used successfully to treat MRSA infections in cases of vancomycin toxicity or intolerance.
- Combinations of antistaphylococcal agents have been used to enhance bactericidal activity (e.g., daptomycin plus a β-lactam antibiotic) and, in selected instances (e.g., right-sided endocarditis), to shorten the duration of therapy.
Special considerations for treatment include: - Uncomplicated skin and soft tissue infections: Oral agents are usually adequate.
- Native-valve endocarditis: A β-lactam is recommended for methicillin-sensitive S. aureus and vancomycin (1 g q12h) or daptomycin (6 mg/kg q24h) for MRSA. Treatment should continue for 4-6 weeks.
- Prosthetic-valve endocarditis: Surgery is often needed in addition to antibiotics. A β-lactam drug (or either vancomycin or daptomycin if MRSA is involved) with gentamicin and rifampin is indicated.
- Hematogenous osteomyelitis or septic arthritis: A 4-week treatment course is adequate for children, but adults require longer courses. Joint infections require repeated aspiration or arthroscopy to prevent damage from inflammatory cells.
- Chronic osteomyelitis: Surgical debridement—in addition to antibiotic therapy—is needed in most cases.
- Prosthetic-joint infections:Ciprofloxacin and rifampin have been used successfully in combination, particularly when the prosthesis cannot be removed.
- TSS: Supportive therapy and removal of tampons or other packing material or debridement of an infected site are most important. The role of antibiotics is less clear, but a clindamycin/semisynthetic penicillin combination is often recommended.
- - Clindamycin is recommended because it is a protein synthesis inhibitor and has been shown to decrease toxin synthesis in vitro; its efficacy in vivo is less clear.
- - Anecdotally, IV immunoglobulin is helpful.
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