Thursday, January 8, 2009

CAMRSA: Dx and Tx Update for Plastic Surgeons – an Article Review

Beginning the year trying to catch up on some of my journals.  Reading my Plastic and Reconstructive Journals, I noticed this very nice review article on community acquired methicillin resistant Staph aureus (first article referenced below).  It seems even more timely as HHS has just issued it’s “Action Plan to Prevent Health Care-Associated Infections”.

It begins by noting that MRSA was first discovered in the 1960’s and until “recently” was considered a hospital-acquired infection.  Looking at the genes of the S. aureus bacteria has given a clearer picture of the two (hospital acquired vs community acquired) diseases.

There are five types of SCCmec. Hospital-acquired methicillin-resistant S. aureus strains contain SCCmec types I, II, III, and V4, and community-acquired methicillin-resistant S. aureus strains contain a smaller version of SCCmec type IV. The smaller size of the SCCmec type IV is responsible for the wider susceptibility of the community-acquired methicillin-resistant S. aureus to antimicrobials, as it does not carry the genes for other drug resistance. This genetic package gives community-acquired methicillin-resistant S. aureus resistance always to methicillin and almost always to erythromycin, in addition to other drugs that may be used to treat an infection……

Of clinical importance is that almost 100 percent of community-acquired methicillin-resistant S. aureus strains contain the Panton-Valentine leukocidin (PVL) gene allowing for production of a necrotizing, cell membrane pore-forming cytotoxin that targets leukocytes and erythrocytes.  Panton-Valentine leukocidin is responsible for the localized invasiveness in community-acquired methicillin-resistant S. aureus soft-tissue infections. In contrast, only 5 percent of methicillin-sensitive S. aureus and hospital-acquired methicillin-resistant S. aureus isolates contain the PVL gene.

 

The article compares the two HA-MRSA and CA-MRSA

 

HA-MRSA

CA-MRSA

Health-care contact

yes

no

Mean age at infection

older

younger

Skin and soft-tissue infection

25%

75%

Antibiotic resistance

many agents

some agents

PVL toxin gene

5%

100%

 

The article reviews who is more likely (risk factors) to acquire CA-MRSA

  • History of MRSA infection or colonization in patient or close contact
  • High prevalence of CA MRSA in local community or patient population
  • Recurrent skin disease
  • Crowded living conditions (e.g. homeless shelters, military barracks)
  • History of incarceration
  • Participation in contact sports
  • Skin or soft tissue infection with poor response to B-lactam antibiotics
  • Recent and/or frequent antibiotic use
  • Injection drug use
  • Member of Native American, Pacific Island, Alaskan Native populations
  • Child under 2 years of age
  • Male with history of having sex with men
  • Shaving of body hair


It is important to be more suspicious of CA-MRSA if the patient is one of those with the risk factors listed above, but also if their clinical presentation includes the following

  • looks like spider bite
  • folliculitis, pustular lesions
  • furuncle, carbuncle (boils)
  • abscess (esp. with tissue necrosis)
  • cellulites
  • impetigo
  • infected wound

 

The article covers treatment  of CA-MRSA skin infections.  They make a point that not all need to be treated with antibiotics.

Abscesses should be incised and drained with material sent for aerobic culture. Abscess drainage alone suffices in patients with a soft-tissue abscess less than 5 cm in diameter and who are not systemically ill. There is no benefit in using antibiotics for cutaneous abscesses if adequate drainage is performed; however, this does not apply to patients with cellulitis.

They then go on to point out the ones who do need antibiotics.

In a patient with comorbidities, moderate illness, or a soft-tissue infection larger than 5 cm in diameter, antibiotic therapy should be started after incision and drainage.

If community-acquired methicillin-resistant S. aureus is suspected but there is not a definite abscess, antibiotic treatment should be started. If this course is chosen, the patient should follow up 48 to 72 hours after treatment has begun, as the aggressiveness of the community-acquired methicillin-resistant S. aureus may lead to development of an abscess.

 

The article notes that, currently, CA-MRSA is frequently sensitive to clindamycin, gentamicin, rifampin, and trimethoprim / sulfamethoxazole, as well as vancomycin.  Linezolid is also effective but very expensive.

Currently, 90-95% of CA-MRSA strains are currently susceptible to trimethoprim/sulfamethoxazole at double strength and doxycycline.

 

In CA-MRSA,  there is minimal evidence at this time to support decolonization protocols in the community.    There may be some benefit in decolonization of patients with recurrent methicillin-resistant S. aureus soft-tissue infections or high-risk contacts of patients with methicillin-resistant S. aureus soft tissue infections.   Topical mupirocin in the nares has been shown to eradicate methicillin resistant S. aureus colonization in health care workers and patients for a short time.   This effect may be lost over time as individuals become recolonized, and prolonged use of mupirocin has been associated with resistance.

 

Preventive Measures Include

Personal hygiene

  • Shower daily
  • Wash hands frequently
  • Keep wounds covered
  • Avoid contact with wound drainage


Environmental control

  • Clean shared equipment (e.g., athletic equipment)
  • Clean contaminated surfaces
  • Use a barrier to bare skin when in contact with shared
    equipment


Health care–associated control

  • Use antimicrobials judiciously
  • Diagnose and treat methicillin-resistant S. aureus lesions
    early
  • Educate patients about wound care
  • Consider decolonization
  • Consult with an infectious disease specialist when
    appropriate

 

 

REFERENCES

Community-Acquired Methicillin-Resistant Staphylococcus aureus: Diagnosis and Treatment Update for Plastic Surgeons; Plastic & Reconstructive Surgery. 122(4):120e-127e, October 2008; Stacey, D Heath M.D.; Fox, Barry C. M.D.; Poore, Samuel O. M.D., Ph.D.; Bentz, Michael L. M.D.; Gutowski, Karol A. M.D.

Community Associated Methicillin Resistant Staphylococcus Aureus (CA MRSA); Guidelines for Clinical Management and Control of Transmission; PPH 42160, October, 2005 (pdf file)

Community-associated MRSA (CA-MRSA) Information for Clinicians; CDC,February, 2005

 

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1 comment:

Stepping Thru said...

Very interesting article. As a layperson I have two family members who have recently been diagnosed with MRSA. My cousin's lesion was on his spinal cord and he has lost the use of this legs. My brother-in-law's began as a boil on his neck. Thanks for the additional information.