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

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

MRSA Strain Characteristics Were Initially Distinct MRSA in Healthcare MRSA in the Community Prevalent genotypes (U.S.)USA100, USA200 USA300, USA400 Antimicrobial resistanceMultiple agents Few agents SCCmec (genetic element carrying mecA resistance gene) Types I-IIITypes IV, V PVL toxin geneRareCommon

PFTSCCmecMLSTpvl USA300 8 IV POS USA IV NEG USA100 5 I I NEG USA800 5 IV NEG USA400 1 IV POS USA500 8 IV, I I NEG USA IV NEG/POS USA MSSA NEG USA I I NEG USA I I NEG USA IV POS USA1200 MSSA POS McDougal et al J Clin Micro 2003;41: National Database of MRSA Pulsed-Field Types (Highlighted PFTs: historically community-associated)

100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) 100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) 100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) 100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) 100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) 100% 80% 60% Athletes Prisoners Children Hospital Strain Missouri California Texas Pennsylvania Texas Mississippi Colorado Georgia Missouri Tennessee USA USA100 USA200 Community California Pneumonia (AL, AR, IL, MD, TX, WA) A Single Pulsed-Field Type (USA300) has Accounted for Most Community-Associated MRSA Infections in the U.S.

Community-Associated MRSA: CDC Population-Based Surveillance Definition MRSA culture in outpatient setting or 1 st 48 hours of hospitalization AND patient lacks risk factors for healthcare-associated MRSA: – Hospitalization – Surgery – Long-term care – Dialysis – Indwelling devices – History of MRSA

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

Factors that Facilitate Transmission Crowding

Frequent Contact Crowding Factors that Facilitate Transmission

Frequent Contact Crowding Compromised Skin Factors that Facilitate Transmission

Frequent Contact Contaminated Surfaces and Shared Items Crowding Factors that Facilitate Transmission Compromised Skin

Frequent Contact Cleanliness Crowding Contaminated Surfaces and Shared Items Compromised Skin Factors that Facilitate Transmission

Contaminated Surfaces and Shared Items Frequent Contact Cleanliness Crowding Compromised Skin Factors that Facilitate Transmission Antimicrobial Use

2004/2005 ABCs MRSA Surveillance Areas Total Population: ~ 16.3 million Oregon California Colorado Tennessee Georgia Maryland Connecticut New York Minnesota

CA-MRSA Infections are Mainly Skin Infections Disease Syndrome (%) Skin/soft tissue1,266 (77%) Wound (Traumatic) 157 (10%) Urinary Tract Infection 64 (4%) Sinusitis 61 (4%) Bacteremia 43 (3%) Pneumonia 31 (2%) Fridkin et al NEJM 2005;352:

Age Group (yr) Atlanta, Baltimore, 2002 Incidence, Cases per 100,000 Age Group (yr) Black White Black White CA-MRSA Incidence Varies by Age and Race 26 per 100,00018 per 100,000 Fridkin et al NEJM 2005;352:

Most Invasive MRSA Infections Are Healthcare-Associated Healthcare-Associated Community-Associated Klevens et al JAMA 2007;298: % 86%

Incidence of Invasive CA-MRSA Infections and Deaths by Age Active Bacterial Core surveillance (ABCS), 2005 Incidence per 100,000 persons Klevens et al JAMA 2007;298: Overall Incidence (all ages): Infections: 4.6 per 100,000 Deaths: 0.5 per 100,000

S. aureus -Associated Skin and Soft Tissue Infections in Ambulatory Care 11.6 million ambulatory care visits per year in for skin infections typical of S. aureus Increase in hospital outpatient and ED visits ( versus ) McCaig et al Emerg Infect Dis 2006;12:

54% 51% 60% 67% 74% 39% 15% 55% 68% 72% 59% (97% USA300) MRSA Was the Most Commonly Identified Cause of Purulent SSTIs Among Adult ED Patients (EMERGEncy ID Net), August 2004 Moran et al NEJM 2006;355:

S. aureus Nasal Colonization National Health and Nutrition Examination Survey S. aureus: 32.4% = 89.4 M people MRSA: 0.8% = 2.3 M people MRSA colonization associated with age >= 60 years & being female

Clindamycin Resistance Among MRSA Isolates, Texas Children’s Hospital, Houston Texas, n=551 n=915n=1192 n=198 n=163 n=181 Source: Hulten et al. PIDJ 2006;25:349-53, and Kaplan et al. Clin Infect Dis 2005;40:

Emerging Multi-Drug Resistance in USA300? Clusters of USA300 isolates with multiple resistance to erythromycin, clindamycin, tetracycline, ciprofloxacin, and mupirocin 1 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 1 Diep et al Lancet Han et al J Clin Micro 2007.

PFGE type No. (%) of nosocomial cases (n = 49) USA30010 (20) USA10021 (43) USA50018 (37) USA8000 (0) Distribution of PFGE types among MRSA isolates from nosocomial bloodstream infections Grady Memorial Hospital, 2004 Seybold U, et al. Clin Infect Dis 2006;42:

Strategies for Clinical Management of MRSA in the Community

Clinical Considerations - Evaluation MRSA belongs in the differential diagnosis of skin and soft tissue infections (SSTI’s) compatible with S. aureus infection: Abscesses, pustular lesions, “boils” “Spider bites” Cellulitis?

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

Management of Skin Infections in the Era of CA-MRSA I&D should be routine for purulent skin lesions

Management of Skin Infections in the Era of CA-MRSA I&D should be routine for purulent skin lesions Obtain material for culture

Management of Skin Infections in the Era of CA-MRSA I&D should be routine for purulent skin lesions Obtain material for culture No data to suggest molecular typing or toxin-testing should guide management

Management of Skin Infections in the Era of CA-MRSA I&D 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

Management of Skin Infections in the Era of CA-MRSA I&D 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

Management of Skin Infections in the Era of CA-MRSA I&D 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

Management of Skin Infections in the Era of CA-MRSA I&D 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!

Management of Skin Infections in the Era of CA-MRSA I&D 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

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 <8yo – Rifampin – Not as a single agent – Linezolid – Expensive, Potential for resistance with inappropriate use

Clinical Considerations - Management Antimicrobial Selection (SSTIs) Not optimal for MRSA (High prevalence of resistance or potential for rapid development of resistance): – Macrolides – Fluoroquinolones

D-zone test for Inducible Clindamycin Resistance CC E -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

Management of Severe / Invasive Infections Vancomycin remains a 1 st -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 2007;44:S27-72

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.

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.

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).

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 2006;Can J Infect Dis Med Microbiol

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.

DHQP Posters and Patient Tear Sheet

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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