Methicillin-Resistant Staphylococcus Aureus (MRSA)

Background

• Two kinds:
  • Hospital acquired (MRSA)
    • Multi-drug resistant, most commonly seen in ventilator associated pneumonia, post operative infections, and catheter associated infections
  • Community acquired (see CA-MRSA)
    • Tends to be resistant to beta-lactams, most commonly seen in Skin and Soft Tissue Infections and rarely in necrotizing pneumonia

Risk Factors

1. multiple skin sites
2. recurrent infection
3. pt who has been in close contact of person with Hx of MRSA
4. infection showing early necrosis

Treatment

1. Antibiotics
   1. Vancomycin IV if severe infection/sepsis
   2. Linezolid
      1. Indicated in severe soft tissue infections and pneumonia thought to be caused by CA-MRSA or HA-MRSA

Antibiotic Sensitivities

Organisms	'	Staph. aureus (MRSA)
Penicillins	Penicillin G	0
	Penicillin V	0
Anti-Staphylocccal Penicillins	Methicillin	0
	Nafcillin/Oxacillin	0
	Cloxacillin/Diclox.	0
Amino-Penicillins	AMP/Amox	0
	Amox/Clav	0
	AMP-Sulb	0
Anti-Pseudomonal Penicillins	Ticarcillin	0
	Ticar-Clav	0
	Pip-Taxo	0
Carbapenems	Piperacillin	0
	Doripenem	0
	Ertapenem	0
	Imipenem	0
	Meropenem	0
	Aztreonam	0
Fluroquinolones	Ciprofloxacin	0
	Ofloxacin	0
	Pefloxacin	0
	Levofloxacin	0
	Moxifloxacin	+/-
	Gemifloxacin	+/-
	Gatifloxacin	+/-
1st G Cephalosporin	Cefazolin	0
2nd G. Cephalosporin	Cefotetan	0
	Cefoxitin	0
	Cefuroxime	0
3rd/4th G. Cephalosporin	CefoTAXime	0
	Cefizoxime	0
	CefTRIAXone	0
	Ceftobiprole	+
	Ceftaroline	+
	CefTAZidime	0
	Cefepime	0
Oral 1st G. Cephalosporin	Cefadroxil	0
	Cephalexin	0
Oral 2nd G. Cephalosporin	Cefaclor/Loracarbef	0
	Cefproxil	0
	Cefuroxime axetil	0
Oral 3rd G. Cephalosporin	Cefixime	0
	Ceftibuten	0
	Cefpodox/Cefdinir/Cefditoren	0
Aminoglycosides	Gentamicin	0
	Tobramycin	0
	Amikacin	0
	Chloramphenicol	0
	Clindamycin	0
Macrolides	Erythromycin	0
	Azithromycin	0
	Clarithromycin	0
Ketolide	Telithromycin	0
Tetracyclines	Doxycycline	+/-
	Minocycline	+/-
Glycylcycline	Tigecycline	+
Glyco/Lipoclycopeptides	Vancomycin	+
	Teicoplanin	+
	Telavancin	+
	Fusidic Acid	+
	Trimethoprim	+/-
	TMP-SMX	+
Urinary Agents	Nitrofurantoin	+
	Fosfomycin
Other	Rifampin	+
	Metronidazole	0
	Quinupristin dalfoppristin	+
	Linezolid	+
	Daptomycin	+
	Colistimethate	0

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia

Prevention

1. good hand hygiene
2. avoid sharing personal items with carriers
3. wash common household items with bleach and hot water
4. wash soiled sheets, towels, clothes in hot water with bleach and dry in hot dryer
5. Eradicate carriers:
   1. mupirocin 2%: apply to each nostril TID x 5days
   2. Hibiclens wash daily x 5 days
   3. consider oral antibiotics

See Also

• Microbiology (Main)
• Staph. aureus

Source

• EBmedicine.net