Methicillin Resistant Staphylococcus aureus (MRSA) in the Community: Epidemiology and Management

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Methicillin ResistantStaphylococcus aureus
(MRSA)in the CommunityEpidemiology and
Management
Rachel Gorwitz, MD, MPH Division of Healthcare
Quality Promotion Centers for Disease Control and
Prevention
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Staphylococcus aureus

• Staphylococcus aureus common cause of infection
  in the community
• Methicillin-resistant Staphylococcus aureus
  (MRSA)
• Increasingly important cause of
  healthcare-associated infections since 1970s
• In 1990s, emerged as cause of infection in the
  community

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MRSA Strain Characteristics Were Initially
Distinct
MRSA in Healthcare MRSA in the Community
Prevalent genotypes (U.S.) USA100, USA200 USA300, USA400
Antimicrobial resistance Multiple agents Few agents
SCCmec (genetic element carrying mecA resistance gene) Types I-III Types IV, V
PVL toxin gene Rare Common
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National Database of MRSA Pulsed-Field Types
(Highlighted PFTs historically
community-associated)
PFT
SCCmec
MLST
pvl
USA300 8 IV POS
USA700 72 IV NEG
USA100 5 I I NEG
USA800 5 IV NEG
USA400 1 IV POS
USA500 8 IV, I I NEG
USA1000 59 IV NEG/POS
USA900 15 MSSA NEG
USA600 45 I I NEG
USA200 36 I I NEG
USA1100 30 IV POS
USA1200 MSSA POS
McDougal et al J Clin Micro 2003415113-5120
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A Single Pulsed-Field Type (USA300) has Accounted
for Most Community-Associated MRSA Infections in
the U.S.
100
100
80
60
80
60
Pneumonia (AL, AR, IL, MD, TX, WA)
Pneumonia (AL, AR, IL, MD, TX, WA)
Missouri
Missouri
California
California
Athletes
Athletes
Pennsylvania
Pennsylvania
Colorado
Colorado
Mississippi
Mississippi
Texas
Texas
Prisoners
Prisoners
Georgia
Georgia
Tennessee
Tennessee
Texas
Texas
Children
Children
Missouri
Missouri
California
California
USA300-114
USA300-114
Community
Community
USA100
USA100
Hospital Strain
Hospital Strain
Hospital Strain
Hospital Strain
USA200
USA200
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Community-Associated MRSACDC Population-Based
Surveillance Definition

• MRSA culture in outpatient setting or 1st 48
  hours of hospitalization AND patient lacks risk
  factors for healthcare-associated MRSA
• Hospitalization
• Surgery
• Long-term care
• Dialysis
• Indwelling devices
• History of MRSA

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Outbreaks of MRSA in the Community

• Often first detected as clusters of abscesses or
  spider bites
• Various settings
• Sports participants
• Inmates in correctional facilities
• Military recruits
• Daycare attendees
• Native Americans / Alaskan Natives
• Men who have sex with men
• Tattoo recipients
• Hurricane evacuees in shelters

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Factors that Facilitate Transmission
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Factors that Facilitate Transmission
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Factors that Facilitate Transmission
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Factors that Facilitate Transmission
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Factors that Facilitate Transmission
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Factors that Facilitate Transmission
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2004/2005 ABCs MRSA Surveillance Areas
Minnesota
New York
Oregon
Connecticut
California
Maryland
Colorado
Tennessee
Georgia
Total Population 16.3 million
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CA-MRSA Infections are Mainly Skin Infections
Disease Syndrome () Skin/soft tissue 1,266
(77) Wound (Traumatic) 157 (10) Urinary Tract
Infection 64 (4) Sinusitis 61
(4) Bacteremia 43 (3) Pneumonia 31
(2)
Fridkin et al NEJM 20053521436-44
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CA-MRSA Incidence Varies by Age and Race
Atlanta, 2001-2002
Baltimore, 2002
26 per 100,000
18 per 100,000
Age Group (yr)
Age Group (yr)

• Fridkin et al NEJM 20053521436-44

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Most Invasive MRSA Infections Are
Healthcare-Associated
86
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Klevens et al JAMA 20072981763-71
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Incidence of Invasive CA-MRSA Infections and
Deaths by AgeActive Bacterial Core surveillance
(ABCS), 2005
Incidence per 100,000 persons
Overall Incidence (all ages) Infections 4.6 per
100,000 Deaths 0.5 per 100,000
Klevens et al JAMA 20072981763-71
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S. aureus-Associated Skin and Soft Tissue
Infections in Ambulatory Care

• 11.6 million ambulatory care visits per year in
  2001-03 for skin infections typical of S. aureus
• Increase in hospital outpatient and ED visits
  (2001-03 versus 1992-94)

McCaig et al Emerg Infect Dis 2006121715-1723
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MRSA Was the Most Commonly Identified Cause of
Purulent SSTIs Among Adult ED Patients (EMERGEncy
ID Net), August 2004
59 (97 USA300)
54
39
15
55
74
51
68
60
60
72
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Moran et al NEJM 2006355666-674
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S. aureus Nasal ColonizationNational Health and
Nutrition Examination Survey 2001-02
S. aureus 32.4 89.4 M people
MRSA 0.8 2.3 M people
MRSA colonization associated with age gt 60 years
being female
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Clindamycin Resistance Among MRSA Isolates,
Texas Childrens Hospital, Houston
Texas,2001-2004
n181
n163
n915
n1192
n198
n551
Source Hulten et al. PIDJ 200625349-53, and
Kaplan et al. Clin Infect Dis 2005401785-91
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Emerging Multi-Drug Resistance in USA300?

• Clusters of USA300 isolates with multiple
  resistance to erythromycin, clindamycin,
  tetracycline, ciprofloxacin, and mupirocin1
• Resistance to one class of antibiotics other
  than beta-lactams is still the most common
  resistance pattern in MRSA USA300
• TMP/SMX resistance rare in MRSA USA300

1Diep et al Lancet 2006. Han et al J Clin Micro
2007.
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Distribution of PFGE types among MRSA isolates
from nosocomial bloodstream infectionsGrady
Memorial Hospital, 2004
PFGE type No. () of nosocomial cases(n 49)
USA300 10 (20)
USA100 21 (43)
USA500 18 (37)
USA800 0 (0)
Seybold U, et al. Clin Infect Dis  200642647-656

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Strategies for Clinical Management of MRSA in the
Community
httpwww.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html
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Clinical Considerations - Evaluation

• MRSA belongs in the differential diagnosis of
  skin and soft tissue infections (SSTIs)
  compatible with S. aureus infection

• Abscesses, pustular lesions, boils
• Spider bites
• Cellulitis?

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Clinical Considerations - Evaluation

• MRSA should also be considered in differential
  diagnosis of severe disease compatible with S.
  aureus infection
• Osteomyelitis
• Empyema
• Necrotizing pneumonia
• Septic arthritis
• Endocarditis
• Sepsis syndrome
• Necrotizing fasciitis
• Purpura fulminans

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management
• Empiric antimicrobial therapy may be needed

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management
• Empiric antimicrobial therapy may be needed
• Alternative agents have s and s More data
  needed to identify optimal strategies

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management
• Empiric antimicrobial therapy may be needed
• Alternative agents have s and s More data
  needed to identify optimal strategies
• Use local data for treatment

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management
• Empiric antimicrobial therapy may be needed
• Alternative agents have s and s More data
  needed to identify optimal strategies
• Use local data for treatment
• Patient education is critical!

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Management of Skin Infections in the Era of
CA-MRSA

• ID should be routine for purulent skin lesions
• Obtain material for culture
• No data to suggest molecular typing or
  toxin-testing should guide management
• Empiric antimicrobial therapy may be needed
• Alternative agents have s and s More data
  needed to identify optimal strategies
• Use local data for treatment
• Patient education is critical!
• Maintain adequate follow-up

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Clinical Considerations - Management
Antimicrobial Selection (SSTIs)

• Alternative agents (More data needed to establish
  effectiveness!)
• Clindamycin Potential for inducible resistance,
  Relatively higher risk of C. difficile associated
  disease?
• TMP/SMX Group A strep isolates commonly
  resistant
• Tetracyclines Not recommended for lt8yo
• Rifampin Not as a single agent
• Linezolid Expensive, Potential for resistance
  with inappropriate use

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Clinical Considerations - Management
Antimicrobial Selection (SSTIs)

• Not optimal for MRSA (High prevalence of
  resistance or potential for rapid development of
  resistance)
• Macrolides
• Fluoroquinolones

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D-zone test for Inducible Clindamycin Resistance
E
CC

• Perform on erythromycin-resistant,
  clindamycin-susceptible S. aureus isolates
• Clinical implications unclear, but treatment
  failures have occurred
• Does not require pre-treatment or co-treatment
  with erythromycin in vivo

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Management of Severe / Invasive Infections

• Vancomycin remains a 1st-line therapy for severe
  infections possibly caused by MRSA
• Other IV agents may be appropriate Consult an
  infectious disease specialist.
• Final therapy decisions should be based on
  results of culture and susceptibility testing
• Severe community-acquired pneumonia Vancomycin
  or linezolid if MRSA is a consideration

IDSA/ATS Guidelines for treatment of CAP in
adults Mandell et al. CID 200744S27-72
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Screening and Decolonization

• In general, colonization cultures of infected or
  exposed persons in community settings are not
  recommended. (May have a role in public health
  investigations).
• Decolonization regimens
• May have a role in preventing recurrent
  infections (more data needed to establish
  efficacy and optimal regimens for use in
  community settings).
• After treating active infections and reinforcing
  hygiene and appropriate wound care, consider
  consultation with an infectious disease
  specialist regarding use of decolonization when
  there are recurrent infections in an individual
  patient or members of a household.

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Preventing Transmission

• Persons with skin infections should keep wounds
  covered, wash hands frequently (always after
  touching infected skin or changing dressings),
  dispose of used bandages in trash, avoid sharing
  personal items.
• Uninfected persons can minimize risk of infection
  by keeping cuts and scrapes clean and covered,
  avoiding contact with other persons infected
  skin, washing hands frequently, avoiding sharing
  personal items.

www.cdc.gov
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Preventing Transmission

• Exclusion of patients from school, work, sports
  activities, etc should be reserved for those that
  are unable to keep the infected skin covered with
  a clean, dry bandage and maintain good personal
  hygiene.
• In general, it is not necessary to close schools
  to disinfect them when MRSA infections occur.
• In ambulatory care settings, use standard
  precautions for all patients (hand hygiene before
  and after contact, barriers such as gloves, gowns
  as appropriate for contact with wound drainage
  and other body fluids).

www.cdc.gov
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Role of Pets

• Greatest risk of Staph aureus / MRSA exposure in
  most humans is other humans
• When household pet animals carry MRSA, likely
  acquired from a human
• Transmission of MRSA from an infected or
  colonized pet to a human is possible, but likely
  accounts for a very small proportion of human
  infections
• Reasonable to consider pet as a source if
  transmission continues in a household despite
  optimizing other control strategies
• Little evidence that antimicrobial-based
  eradication therapy is effective in pets
  however, colonization tends to be short-term

Barton et al 2006Can J Infect Dis Med Microbiol
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Conclusions

• New strains of MRSA have emerged in the
  community, with implications for management of
  skin infections and other staphylococcal
  infections.
• Incision and drainage remains a primary therapy
  for purulent skin infections.
• Oral treatment options are available for patients
  with skin infections that require ancillary
  antibiotic therapy.
• Patient education on proper wound care is a
  critical component of case management for
  patients with skin infections.
• Strategies focusing on increased awareness, early
  detection and appropriate management, enhanced
  hygiene, and maintenance of a clean environment
  have been successful in controlling clusters /
  outbreaks of infection.

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DHQP Posters and Patient Tear Sheet
http//www.cdc.gov/mrsa
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CA-MRSA Working Group Meeting Participants, July
2004
Gordon L. Archer Carol L. Baker Elizabeth
Bancroft Henry F. Chambers Robert S. Daum Jeffrey
S. Duchin Monica Farley James Hadler Jim
Jorgensen Sheldon K. Kaplan Newton E.
Kendig Kathleen Harriman Franklin D. Lowy Ruth
Lynfield J. Kathryn MacDonald Loren Miller
Gregory Moran Olga Nuno John H. Powers L. Barth
Reller Nalini Singh Marcus Zervos Craig Zinderman
CDC Daniel B. Jernigan John Jernigan Jay C.
Butler Denise Cardo Roberta Carey Rachel
Gorwitz Jeffrey C. Hageman Thomas Hennessy James
M. Hughes Jean Patel Fred Tenover J. Todd Weber
Meeting Co-Chair
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Questions?

• email coca_at_cdc.gov