Staphylococcus

Infection	First-line drugs ^a	Second-line drugs^a^,^b	Comments
Folliculitis, impetigo	Mupirocin		Community-acquired MRSA (CA-MRSA) causes >50% outpatient SSTI
Simple abscesses	Incision and drainage

Cellulitis Outpatient Rx			Treat for 5–10 d
Nonpurulent	Dicloxacillin, 250 mg, or	Clindamycin, 300 mg q6h
	Cephalexin, 250 mg
	PO q6h
Purulent	TMP–SMX,160/800 mg PO q12h	Linezolid, 600 mg PO q12h	Suspect CA-MRSA if cellulitis has pus present
	Clindamycin, 300 mg q6h	Doxycycline 100 mg PO q 12
Inpatient Rx	See moderate to severe wound infections		Treat IV until patient afebrile and nontoxic, then switch to oral agent
Moderate to severe wound infections Inpatients
MSSA MRSA	Nafcillin, 2 g q4h, or Cefazolin, 2 g IV q8h Vancomycin, 1 g IV q12h	Vancomycin, 1 g IV q12h Linezolid, 600 mg PO q12h Daptomycin, 4 mg/kg IV q24h	Drainage and culture of abscesses essential for resolution Treat minimum 7–14 d based on extent of infection and response Monitor vancomycin troughs Aim for 10–15 µg/mL
Osteomyelitis
MSSA MRSA	Nafcillin, 2 g IV q4h, or Cefazolin, 2 g IV q8h Vancomycin, 1 g IV q12h	Vancomycin, 1 g IV q12h Daptomycin, 4 mg/kg IV q24h Linezolid, 600 mg PO q12h	Vertebral osteomyelitis, with or without paraspinous or epidural abscess, often requires longer duration of therapy Treat IV 6–8 wk followed by an oral regimen Monitor vancomycin troughs Aim for 15–20 µg/mL
Septic arthritis
MSSA MRSA	Nafcillin, 2 g q4h, or Cefazolin, 2 g IV q8h Vancomycin, 1 g IV q12h	Vancomycin, 1 g IV q12h Daptomycin, 4 mg/kg IV q24h Linezolid, 600 mg PO q12h	Repeated needle aspiration, arthroscopic drainage, or operative drainage of joint fluid essential for resolution of infection Treat 3–4 wk
Pneumonia
MSSA MRSA	Nafcillin, 2 g IV q4h Vancomycin 1 g IV q12h	Vancomycin, 1 g IV q12h Linezolid, 600 mg IV/PO q12h	Empyema, when present, must be drained Treat 7–21 d Daptomycin not effective
Bacteremia
MSSA MRSA	Nafcillin 2 g IV q4h (see text for discussion regarding length of therapy) Vancomycin 1 g IV q12h (see text for discussion)	Vancomycin, 1 g IV q12h (see text for discussion regarding length of therapy) Daptomycin, 6 mg/kg IV q24h (see text)	Length of therapy depends on source of bacteremia and whether visceral foci of infection, including endocarditis, are present. Careful diagnostic workup and clinical assessment of the patient is essential regarding length of therapy

Abbreviations: MSSA = methicillin-susceptible Staphylococcus aureus; MRSA = methicillin-resistant Staphylococcus aureus; SSTI = skin and soft-tissue infection; TMP–SMX = trimethoprim–sulfamethoxazole.

^a Usual adult doses. Doses of cefazolin and vancomycin dependent on renal function. Linezolid, monitor complete blood count weekly. Daptomycin, monitor creatine phosphokinase 1×–2× weekly.

^b Second-line drugs used mostly for patients allergic or intolerant to β-lactam antibiotics.

Superficial infections such as impetigo may be treated with topical agents such as mupirocin. Incision and drainage alone is generally reserved for small localized abscesses in healthy patients; it is not clear that antibiotic use improves the outcome from infection. Initial empiric treatment with systemic antibiotics is recommended when infection is extensive, involves multiple sites, is in an area that is difficult to drain, or is rapidly progressive. Antibiotic therapy should be considered in older adults, diabetics, patients with human immunodeficiency virus (HIV) or neoplasms, or in patients with symptoms and signs of systemic illness or septic phlebitis.

In most instances where antibiotic therapy is warranted, empiric treatment should be directed against MRSA. Culture of abscess or purulent exudate should be performed in patients with severe infection or signs and symptoms of systemic illness, those who do not respond to initial treatment, and in suspected outbreak settings.

For patients with less severe infection who can take and tolerate oral medications, empiric therapy with TMP–SMX, doxycycline or minocycline, clindamycin, and linezolid can be considered. In patients with systemic toxicity and rapidly progressive or worsening infection, empiric IV vancomycin, daptomycin, telavancin, ceftaroline, and linezolid can be given.

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