infectious diseases
Staphylococcal Infections
Treatment of Staphylococcal Infections
Local measures (eg, debridement, removal of catheters) Antibiotics selected based on severity of infection and local resistance patterns Management of staphylococcal infections includes abscess drainage, debridement of necrotic tissue, removal of foreign bodies (including intravascular catheters), and use of antibiotics (see table). Initial choice and dosage of antibiotics depend on Infection site Illness severity Probability that resistant strains are involved Thus, it is essential to know local resistance patterns for initial therapy (and ultimately, to know actual drug susceptibility). (the most serious of which is Treatment ) involves decontamination of the toxin-producing area (exploration of surgical wounds, irrigation, debridement), intensive support (including IV fluids, vasopressors, and respiratory assistance), electrolyte balancing, and antimicrobials. In vitro evidence supports use of a combination of beta-lactamase–resistant, antistaphylococcal antimicrobial agent IV (eg, Many staphylococcal strains produce penicillinase, an enzyme that inactivates several beta-lactam antibiotics; these strains are resistant topenicillin G,ampicillin,amoxicillin, and antipseudomonal penicillins (eg, piperacillin). Community-acquired strainsare often susceptible to penicillinase-resistant penicillins (eg, methicillin,oxacillin,nafcillin, cloxacillin,dicloxacillin), cephalosporins, carbapenems (eg, imipenem,meropenem,ertapenem), tetracyclines, macrolides, fluoroquinolones,trimethoprim/sulfamethoxazole (TMP/SMX),gentamicin,vancomycin, and teicoplanin. MRSAisolates have become common, especially in hospitals. MRSA isolates are resistant to almost all beta-lactam antibiotics, including most cephalosporins and carbapenems; however, they may be susceptible to the newest class of MRSA-active cephalosporins (eg,ceftaroline, ceftobiprole [not available in the United States]). Hospital-acquired MRSA is also commonly resistant to many other antibiotics, includingerythromycin,clindamycin, and fluoroquinolones. In addition, community-associated MRSA (CA-MRSA) has emerged over the past several years in most geographic regions. CA-MRSA tends to be less resistant to multiple antibiotics than hospital-acquired MRSA. These strains, although resistant to most beta-lactams, are often susceptible to TMP/SMX and tetracyclines (minocycline,doxycycline) and are often susceptible toclindamycin, but there is the potential for emergence ofclindamycinresistance by strains inducibly resistant toerythromycin(laboratories may report these strains as D-test positive). Vancomycinis effective against most MRSA, sometimes withrifampinand an aminoglycoside added for some serious infections (ie, osteomyelitis, prosthetic joint infections, prosthetic valve endocarditis). An alternative antibiotic (daptomycin,linezolid,tedizolid,dalbavancin,oritavancin,telavancin,tigecycline,omadacycline,lefamulin,eravacycline,delafloxacin, quinupristin/dalfopristin, TMP/SMX,ceftaroline) should be considered when treating MRSA strains with avancomycinminimum inhibitory concentration (MIC) of ≥ 1.5 mcg/mL. Vancomycin-resistantS. aureus(VRSA; MIC ≥ 16 mcg/mL) andvancomycin-intermediate–susceptibleS. aureus(VISA; MIC 4 to 8 mcg/mL) strains have appeared in the United States. These organisms requirelinezolid,tedizolid, quinupristin/dalfopristin,daptomycin, TMP/SMX,delafloxacin,oritavancin, orceftaroline.Dalbavancinandtelavancinare active against VISA but have little activity against VRSA.Oritavancinis active against both VISA and VRSA. Because incidence of MRSA has increased, initial empiric treatment for serious staphylococcal infections (particularly those that occur in a health care setting) should include an antibiotic with reliable activity against MRSA. Thus, appropriate antibiotics include the following: Forproven or suspected bloodstream infections,vancomycinordaptomycin Forpneumonia,vancomycin,telavancin, orlinezolid(becausedaptomycinis not reliably active in the lungs) Tablesummarizes treatment options. 