methicillin resistant staphylococcus aureus (mrsa) in the community: epidemiology and management

Methicillin ResistantStaphylococcus aureus (MRSA)

in the Community:Epidemiology and Management

Rachel Gorwitz, MD, MPHDivision 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

Dice (Opt:0.50%) (Tol 1.3%-1.3%) (H>0.0% S>0.0%) [0.0%-100.0%]

100

9080706050

PFT SCCmecMLST 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)

100

%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

Pneumonia (AL, AR, IL, MD, TX, WA) 1

00%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

Pneumonia (AL, AR, IL, MD, TX, WA) 1

00%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

Pneumonia (AL, AR, IL, MD, TX, WA) 1

00%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

Pneumonia (AL, AR, IL, MD, TX, WA) 1

00%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

Pneumonia (AL, AR, IL, MD, TX, WA) 1

00%

80%

60%

Athletes

Prisoners

Children

Hospital StrainHospital Strain

MissouriCalifornia

Texas

Pennsylvania

Texas

MississippiColorado

Georgia

Missouri

Tennessee

USA300-114USA100USA200

CommunityCalifornia

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 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

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 ContactCrowding

Factors that Facilitate Transmission

Frequent ContactCrowding

Compromised Skin

Factors that Facilitate Transmission

Frequent Contact

Contaminated Surfacesand Shared Items

Crowding

Factors that Facilitate Transmission

Compromised Skin

Frequent Contact

Cleanliness

Crowding

Contaminated Surfacesand Shared ItemsCompromised Skin

Factors that Facilitate Transmission

Contaminated Surfacesand 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

CaliforniaColorado

Tennessee

Georgia

Maryland

Connecticut

New YorkMinnesota

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

Age Group (yr)

Atlanta, 2001-2002 Baltimore, 2002

0

10

20

30

40

50

60

70

80

<2 2-18 19-64 >64

01020304050607080

<2 2-18 19-64 >64

Incidence, Cases per 100,000

Age Group (yr)

BlackWhite

BlackWhite

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

Healthcare-Associated

Community-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

0

2

4

6

8

10

<1 1 2-4 5-17 18-34 35-49 50-64 >64

Age in years

Infections DeathsIncidence per 100,000 persons

Klevens et al JAMA 2007;298:1763-71

Overall Incidence (all ages):Infections: 4.6 per 100,000Deaths: 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

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 (EMERGEncy ID Net), August 2004

Moran et al NEJM 2006;355:666-674

S. aureus Nasal ColonizationNational Health and Nutrition Examination Survey 2001-02

0

5

10

15

20

25

30

35

40

45

50

1--5 6--11 12--19 20--29 30--39 40--49 50--59 60--69 70+

Age (years)

Pre

va

len

ce

(%

)

Male

Female

S. aureus: 32.4% = 89.4 M people

MRSA: 0.8% = 2.3 M people

MRSA colonization associated with age >= 60 years & being female

0

5

10

15

20

Year 1 Year 2 Year 3

% C

linda

myc

in R

esis

tant

Community Onset, Healthcare-associated MRSA

Community-associated MRSA

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

n=551

n=915 n=1192n=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 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.

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 infectionsGrady 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

0%10%20%30%40%50%60%70%80%

CenterA

CenterB

CenterC

CenterD

Total

Pe

rce

nta

ge

CA

-MR

SA

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

CCE

-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 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 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

http://www.cdc.gov/mrsa

CA-MRSA Working Group Meeting Participants, July 2004

Gordon L. ArcherCarol L. BakerElizabeth BancroftHenry F. ChambersRobert S. DaumJeffrey S. DuchinMonica FarleyJames HadlerJim JorgensenSheldon K. KaplanNewton E. KendigKathleen HarrimanFranklin D. LowyRuth LynfieldJ. Kathryn MacDonaldLoren Miller

Gregory MoranOlga NunoJohn H. PowersL. Barth RellerNalini SinghMarcus ZervosCraig Zinderman

CDCDaniel B. Jernigan*John Jernigan*Jay C. ButlerDenise CardoRoberta CareyRachel GorwitzJeffrey C. HagemanThomas HennessyJames M. HughesJean PatelFred TenoverJ. Todd Weber

*Meeting Co-Chair

DHQP Inquiries

hip@cdc.gov

Questions?