# Presentation: 667096

## 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 resistance | Multiple agents | Few agents |
| SCCmec (genetic element carrying mecA resistance gene) | Types I-III | Types IV, V |
| PVL toxin gene  | Rare | Common |

**Notes:**
These community strains do not appear to have been transferred from the hospitals. 
Patients with MRSA acquired in the community usually have no previous contact with healthcare centers 
clinical manifestations are also different, Community strains cause mostly skin and soft tissue infections, but rarely cause upper respiratory or urinary tract infections, which are common with healthcare strains   
The community strains are only resistant to beta-lactams and sometimes other antimicrobial group, in contrast to the multi-resistant pattern of the healthcare strains  
This different antimicrobial susceptibility is explained by a distinct genetic background
 and, although still in debate, the difference in clinical manifestations may be due to the presence in community strains of toxins such as PVL or Panton Vanlentine Leukocidine, that causes severe inflammation 

## National Database of MRSA Pulsed-Field Types (Highlighted PFTs: historically community-associated)

- PFT

- SCC*mec*

- 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 2003;41:5113-5120**

**National Database of MRSA Pulsed-Field Types (Highlighted PFTs: historically community-associated)**

## A Single Pulsed-Field Type (USA300) has Accounted for Most Community-Associated MRSA Infections in the U.S.  

- 100%

- 80%

- 60%

**Athletes**

**Prisoners**

**Children**

**Hospital Strain**

**Hospital Strain**

**Missouri**

**California**

**Texas**

**Pennsylvania**

**Texas**

**Mississippi**

**Colorado**

**Georgia**

**Missouri**

**Tennessee**

**USA300-114**

**USA100**

**USA200**

**Community**

**California**

**Pneumonia (AL, AR, IL, MD, TX, WA) **

- 100%

- 80%

- 60%

**Athletes**

**Prisoners**

**Children**

**Hospital Strain**

**Hospital Strain**

**Missouri**

**California**

**Texas**

**Pennsylvania**

**Texas**

**Mississippi**

**Colorado**

**Georgia**

**Missouri**

**Tennessee**

**USA300-114**

**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

**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**

## Slide 8

## Slide 9

## Factors that Facilitate Transmission

## Factors that Facilitate Transmission

**Factors that Facilitate Transmission**

## Factors that Facilitate Transmission

**Factors that Facilitate Transmission**

## Factors that Facilitate Transmission

**Factors that Facilitate Transmission**

## Factors that Facilitate Transmission

**Factors that Facilitate Transmission**

## Factors that Facilitate Transmission

**Factors that Facilitate Transmission**

## 2004/2005 ABCs MRSA Surveillance Areas 

**2004/2005 ABCs ****MRSA Surveillance Areas **

**Total Population: ~ 16.3 million**

**Oregon**

**California**

**Colorado**

**Tennessee**

**Georgia**

**Maryland**

**Connecticut**

**New York**

**Minnesota**

**Notes:**
These are the 9 sites participating in this collaboration, this surveillance project is population based, that is all residents of these areas are under surveillance; the green circles indicate that certain counties are included, whereas in CT, surveillance is state wide. 

## 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 2005;352:1436-44

## CA-MRSA Incidence Varies by Age and Race

** ****Atlanta, 2001-2002                          Baltimore, 2002**

**Age Group (yr)**

**CA-MRSA Incidence Varies by Age and Race**

**26 per 100,000**

**18 per 100,000**

**Fridkin et al NEJM 2005;352:1436-44**

## Most Invasive MRSA Infections Are Healthcare-Associated

**Klevens et al JAMA 2007;298:1763-71**

**14%**

**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;298:1763-71**

**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 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 2006;12:1715-1723**

## MRSA Was the Most Commonly Identified Cause of Purulent SSTIs Among Adult ED Patients (EMERGEncy ID Net), August 2004

**54%**

**51%**

**60%**

**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 ****(*****EMERGE*****ncy ID Net), August 2004**

**Moran et al NEJM 2006;355:666-674**

## S. aureus Nasal ColonizationNational 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 >= 60 years & being female**

## Clindamycin Resistance Among MRSA Isolates, 

**Clindamycin Resistance Among MRSA Isolates, **
**Texas Children’s Hospital, Houston Texas,2001-2004**

**n=551**

**n=915**

**n=1192**

**n=198**

**n=163**

**n=181**

**Source: Hulten et al. PIDJ 2006;25:349-53, and**
** ****Kaplan et al. Clin Infect Dis 2005;40:1785-91****  **

## 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 2006. Han et al J Clin Micro 2007.**

**Notes:**
37 kb plasmid with macrolide and high-level mupirocin resistance geness identified 

## Distribution of PFGE types among MRSA isolates from nosocomial bloodstream infectionsGrady Memorial Hospital, 2004 

| PFGE type | No. (%) of nosocomial cases(n = 49) |
| --- | --- |
| USA300 | 10 (20) |
| USA100 | 21 (43) |
| USA500 | 18 (37) |
| USA800 | 0 (0) |

**Distribution of PFGE types among MRSA isolates from nosocomial bloodstream infections****Grady Memorial Hospital, 2004**** **

**Seybold U, et al. Clin Infect Dis  2006;42:647-656**

## Strategies for Clinical Management of MRSA in the Community

**http:www.cdc.gov/ncidod/dhqp/ar_mrsa_ca.html**

## 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. **

**www.cdc.gov**

## 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**

## 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

**DHQP Posters and Patient Tear Sheet**

**http://www.cdc.gov/mrsa**

**Notes:**
Can hear more about this in one of the 2 break out sessions

## 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**

## email coca@cdc.gov

**Questions?**