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MRSA, Community Acquired, Emergency Medicine

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MRSA, Community Acquired, Emergency Medicine

Basics

Description

HA-MRSA (see below) is a different genotypic form of MRSA that frequently causes morbidity among the elderly, especially those living within extended-care facilities or those with healthcare-related exposures.

MRSA is the leading cause of skin and soft tissue infections among children presenting to the emergency department.

Cultures of skin and soft tissue infections are frequently obtained to monitor microbiology and antimicrobial resistance patterns should a patient fail a course of therapy.

Begin resuscitation and administer early empiric antibiotics if pneumonia, fasciitis, or sepsis is suspected:

Review antimicrobial resistance patterns of CA-MRSA within your community prior to choosing a specific antibiotic regimen, as many antibiotics listed below may not be 100% effective against CA-MRSA.

Avoid the use of tetracyclines in pregnancy

Healthy, well-appearing patients with simple skin and soft tissue infections may be followed in the outpatient setting.

MRSA infection refractory to multiple medications may require infectious disease consultation.

041.12 Methicillin resistant Staphylococcus aureus in conditions classified elsewhere and of unspecified site

  • Methicillin-resistant Staphylococcus aureus (MRSA) has historically been a pathogen endemic within healthcare settings, usually affecting the elderly and chronically ill. This strain of S. aureus has been termed "healthcare-associated MRSA "  (HA-MRSA).
  • Throughout the past decade, MRSA has become an increasingly common pathogen among younger, healthier populations who do not have a healthcare-related exposure history. This type of MRSA pathogen has been termed "community-acquired MRSA "  (CA-MRSA).
  • CA-MRSA is the most common cause of skin and soft tissue infections seen in the ED
  • While CA-MRSA may cause skin and soft tissue infection, it may also lead to severe multisystem disease, including sepsis and necrotizing pneumonia

Etiology

  • S. aureus is a gram-positive cocci frequently colonizing the skin
  • MRSA refers to a specific strain of S. aureus that has resistance against the antimicrobial properties of numerous antibiotics, including methicillin
  • Prisoners, athletes, soldiers, children in daycare, IV drug users, and those with prior treatment for MRSA or exposure to MRSA are at highest risk for colonization and subsequent infection.

Diagnosis

Signs and Symptoms

  • Skin and soft tissue infections:Increasing rednessPainWarmthSwellingFeverChillsMalaise
  • Sepsis/pneumonia:WeaknessDyspneaFeverRigorsProductive coughChest pain
  • Inquire about prior diagnosis of MRSA infections, MRSA exposures, and family members or close contacts with a history of MRSA, as such a patient is at risk for CA-MRSA infection.
  • Increasing redness
  • Pain
  • Warmth
  • Swelling
  • Fever
  • Chills
  • Malaise
  • Weakness
  • Dyspnea
  • Fever
  • Rigors
  • Productive cough
  • Chest pain
  • Skin and soft tissue infections:Abscess: Tender, raised boil with underlying induration and fluctuanceCellulitis: Warm erythema possibly with lymphangitic streaking
  • Sepsis:Vital sign abnormalities including tachycardia and hypotension, respiratory failure, mental status changes, petechiae, systemic signs of toxicity
  • Pneumonia:Tachypnea, crackles, retractions, hypoxiaAlveolar opacities on chest radiographs
  • Abscess: Tender, raised boil with underlying induration and fluctuance
  • Cellulitis: Warm erythema possibly with lymphangitic streaking
  • Vital sign abnormalities including tachycardia and hypotension, respiratory failure, mental status changes, petechiae, systemic signs of toxicity
  • Tachypnea, crackles, retractions, hypoxia
  • Alveolar opacities on chest radiographs

Essential Workup

  • Abscess:I&D with packing and prompt follow-up is warranted for abscessMicrobiology often performed for antibiotic sensitivity given the changing antimicrobial resistance patterns
  • Sepsis:Source identification, including blood culture/urine culture, CXR, is indicated as resuscitation begins
  • Pneumonia:Chest radiographs and continuous vital sign monitoring is indicated
  • I&D with packing and prompt follow-up is warranted for abscess
  • Microbiology often performed for antibiotic sensitivity given the changing antimicrobial resistance patterns
  • Source identification, including blood culture/urine culture, CXR, is indicated as resuscitation begins
  • Chest radiographs and continuous vital sign monitoring is indicated

Diagnosis Tests & Interpretation

  • Skin and soft tissue infections:Bacterial culture is often warranted to monitor for CA-MRSA resistance patterns
  • Sepsis and pneumonia:Blood, urine, and body fluid cultures. CBC, CMP to assess for organ dysfunction
  • Bacterial culture is often warranted to monitor for CA-MRSA resistance patterns
  • Blood, urine, and body fluid cultures. CBC, CMP to assess for organ dysfunction
  • Bedside US:Abscess: Anechoic fluid collectionCellulitis: "Cobblestoning "  within the soft tissue
  • CXR:Indicated for patients with presumed sepsis, systemic illness, or pneumonia
  • Abscess: Anechoic fluid collection
  • Cellulitis: "Cobblestoning "  within the soft tissue
  • Indicated for patients with presumed sepsis, systemic illness, or pneumonia

Differential Diagnosis

  • Other skin and soft tissue infections:Pathogens beyond MRSA which cause abscesses and cellulites should be considered (i.e., streptococcus)
  • Necrotizing fasciitis
  • Contact dermatitis
  • Deep vein thrombosis
  • Spider/insect bite
  • Drug reaction
  • Pathogens beyond MRSA which cause abscesses and cellulites should be considered (i.e., streptococcus)

Treatment

Pre-Hospital

  • Contact precautions for all providers if MRSA is suspected
  • IV access and fluid resuscitation if sepsis is suspected

Initial Stabilization/Therapy

  • Include early coverage with antibiotics effective against MRSA

Ed Treatment/Procedures

  • Skin and soft tissue infections:Abscess:I&D with packingAntibiotics may not be necessary if there is no evidence for deep tissue infection or cellulitisCellulitis:Cellulitis caused by CA-MRSA in a healthy, well-appearing patient may be treated with oral antibiotics in the outpatient settingIll appearing patients, patients with underlying medical conditions, and patients failing outpatient therapy require IV antibiotics with coverage against CA-MRSA
  • Sepsis and pneumonia:Early administration of broad-spectrum antibiotics that cover against MRSA should be given promptly if the patient is at risk for CA-MRSA
  • Abscess:I&D with packingAntibiotics may not be necessary if there is no evidence for deep tissue infection or cellulitis
  • Cellulitis:Cellulitis caused by CA-MRSA in a healthy, well-appearing patient may be treated with oral antibiotics in the outpatient settingIll appearing patients, patients with underlying medical conditions, and patients failing outpatient therapy require IV antibiotics with coverage against CA-MRSA
  • I&D with packing
  • Antibiotics may not be necessary if there is no evidence for deep tissue infection or cellulitis
  • Cellulitis caused by CA-MRSA in a healthy, well-appearing patient may be treated with oral antibiotics in the outpatient setting
  • Ill appearing patients, patients with underlying medical conditions, and patients failing outpatient therapy require IV antibiotics with coverage against CA-MRSA
  • Early administration of broad-spectrum antibiotics that cover against MRSA should be given promptly if the patient is at risk for CA-MRSA

Medication

  • Bactrim:Adults: Bactrim DS 160/800 PO BIDChildren: 10 mg/kg PO BID
  • Clindamycin:Adults: 150 " “450 mg PO QIDChildren: 5 mg/kg PO/IV TID " “QID
  • Doxycycline:Adults: 100 mg PO BIDChildren: 2.2 mg/kg PO BID
  • Vancomycin:Adults: 1 g IV q8 " “12hChildren: 15 mg/kg IV q8 " “12h
  • Adults: Bactrim DS 160/800 PO BID
  • Children: 10 mg/kg PO BID
  • Adults: 150 " “450 mg PO QID
  • Children: 5 mg/kg PO/IV TID " “QID
  • Adults: 100 mg PO BID
  • Children: 2.2 mg/kg PO BID
  • Adults: 1 g IV q8 " “12h
  • Children: 15 mg/kg IV q8 " “12h
  • Rifampin:Should not be used as monotherapy due to inducible resistanceAdults: 300 mg PO BIDChildren: 10 " “20 mg/kg/d in 2 div. doses PO for 5 days; not to exceed 600 mg/d
  • Linezolid:Adults: 600 mg PO/IV q12hChildren: 10 mg/kg PO/IV q8h
  • Should not be used as monotherapy due to inducible resistance
  • Adults: 300 mg PO BID
  • Children: 10 " “20 mg/kg/d in 2 div. doses PO for 5 days; not to exceed 600 mg/d
  • Adults: 600 mg PO/IV q12h
  • Children: 10 mg/kg PO/IV q8h

Follow-Up

Disposition

  • Patients with signs/symptoms of bacteremia, progressive infection, or systemic illness should be admitted:Fever, chills, lymphangitic streaking
  • Patients with underlying comorbid diseases such as diabetes or immunodeficiency should be admitted
  • Individuals who have failed a course of outpatient therapy should be admitted and given IV antibiotics effective against MRSA
  • Fever, chills, lymphangitic streaking

Follow-Up Recommendations

  • All skin and soft tissue infections should be re-evaluated within 24 " “48 hr to monitor for clinical improvement.
  • Individuals failing outpatient therapy require hospital admission and IV antibiotics.

Pearls and Pitfalls

  • CA-MRSA is the most common cause of skin and soft tissue infections seen in the ED.
  • CA-MRSA is a rare but serious cause of rapidly progressive pneumonia and sepsis.
  • Antibiotic resistance patterns are dynamic and vary widely across geographic boundaries.
  • Be cautious with long-term use of tetracyclines in children.

Additional Reading

  • Frazee ‚ BW, Lynn ‚ J, Charlebois ‚ ED, et al. High prevalence of methicillin-resistant Staphylococcus aureus in emergency department skin and soft tissue infections. Ann Emerg Med. 2005;45:311 " “320.
  • Klevens ‚ RM, Morrison ‚ MA, Nadle ‚ J, et al. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007;298:1763 " “1771.
  • Moran ‚ GJ, Krishnadasan ‚ A, Gorwitz ‚ RJ, et al. Methicillin-resistant S. aureus infections among patients in the emergency department. N Engl J Med. 2006;355:666 " “674.
  • Odell ‚ CA. Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) skin infections. Curr Opin Pediatr. 2010;22:273 " “277.
  • Wallin ‚ TR, Hern ‚ HG, Frazee ‚ BW. Community-associated methicillin-resistant Staphylococcus aureus. Emerg Med Clin North Am. 2008;26:431 " “455.

See Also (Topic, Algorithm, Electronic Media Element)

  • Abscess
  • Cellulitis
  • Pneumonia
  • Sepsis

Codes

ICD9

ICD10

  • A41.02 Sepsis due to Methicillin resistant Staphylococcus aureus
  • A49.02 Methicillin resis staph infection, unsp site

SNOMED

  • 423561003 community-acquired methicillin-resistant Staphylococcus aureus infection (disorder)
  • 448812000 Sepsis due to methicillin resistant Staphylococcus aureus (disorder)
  • 282028001 Multiple-resistant Staphylococcus aureus infection (disorder)