Navpreet Sahsi

Major pathogen of skin and soft tissue Major nosocomial flora Penicillin resistance in 1940’s Methicillin resistance in 1960’s Vancomycin resistance in 2000’s Now…..community acquired

Around since 1960’s Prevalent – in US 24,000 cases of S. aureus

bacteremia, methicilling resistance increased from 22 to 57 percent between 1995 and 2001 (likely greater now) (Wislinghoff H, Clin Inect Dis 2004;39: 309)

MRSA pathogen can make biofilm on a variety of foreign devices (ET tubes, catheters, central lines)

Implicated in nearly every type of nosociomial infections

Antibiotic use Prolonged hospitalization Surgical site infection ICU care Hemodialysis MRSA colonization Proximity to others with colonization or

infection

Boyce, JM. Infect Clin North Am 1989; 3: 901

Most often in skin and soft tissue infections in young, healthy individuals with no recent health care exposure

Think abcesses, carbuncles, wound infections, impetigo, cellulitis

Different strain from HA-MRSA Most frequent cause of skin and soft tissue infections

presenting to US ED’s and ambulatory clinics (of 422 pts. measured in various ED’s in 2004 – 76% had MRSA implicated)

Most often skin and soft tissue but can cause invasive disease◦ Wound infections◦ Otitis media and externa◦ Osteomyelitis◦ UTI◦ Endocarditis◦ Sepis◦ Necrotizing pneumonia

Skin Infections – Emergency Dept.

New York – 15 % Minneapolis – 39 % New Orleans – 67 % Atlanta – 72 %

Moran et al. NEJM 2006; 355: 666

Skin and soft tissue – 87% Urinary Tract – 4% Sinus – 4% Bacteremia – 3% Pneumonia – 2% Joint, Bursa, Bone -1%

Fridkin et. al. NEJM 2005; 352: 1436

Poor predictive value

Skin trauma (lac’s, abrasions, tattoos, IVDU) Cosmetic body shaving Incarceration Sharing equipment that has not been laundered

between users (eg. Sport equipment) Men who have sex with men Physical contact with others who have MRSA

colonization

Fridkin, Sk et. al. NEJM 2005; 352: 1436

CA-MRSA classification and HA-MRSA classifications no longer distinct

20% of nosocomial bloodstream infections are CA-MRSA (Seybold et al. Clin Infect Dis 2006; 42:674)

One hospital in LA – CA-MRSA is more common that HA – MRSA in nosocomial infections (Maree et. al. Emerg Infect Dis 2007; 13: 236)

Case report – 6 neonates with CA-MRSA bacteremia (50% mortality!) (Healy et. al Clin. Infect Dis 2004 39: 1460)◦ NICUA-HA-CA – MRSA??

Reservoir for transmission About 1.5% of general population, but 4-15 % of

health care workers (Fridkin et. al. NEJM 2005; 352: 1436)

Anterior nares most common site of MRSA colonization, but can be colonized in other sites (throats, GI tract, rectum/perineum)

How to get colonized?◦ Contact with contaminated wounds or dressings of

infected patients◦ Contact with another individual’s colonized intact skin◦ Contact with contaminated inanimate objects

(read:stethoscopes)◦ Inhalation of aerosolized droplets from chronic nasal

carriers

Case: An otherwise healthy 26 year old male comes to the minor side of the ED with a 3 cm red, swollen, fluctuant mass in his axilla. He has a history of IVDU.

What would you do?

Abx?

Incision and Drainage alone.◦ Llera, Levy. Ann Emerg Med 1985; 14: 15.

“No Abx for CA-MRSA” (Clinda vs. Keflex)◦ Young et. al Arch Surg 2004; 139: 951

Equal outcomes cephalexin vs. Placebo (84% vs. 90%)◦ Rajendran et al. Antimicrob Agents Chemo

2007;51: 4044.

Guidelines – not evidence based!

Surrounding cellulitis > 5 cm Immunocompromise Fever Lymphangitis Central Face involvement (What about abscesses > 5 cm?)

Slaven, Ellen. The Menace of MRSA. LSU. April 18, 2009.

Septra (DS BID)– generally first line. Poor resistance pattern. Does not cover Group A Streptococcus.

Clindamycin (300-450 mg q 6-8h) – good MRSA activity. Careful in areas with higher resistance rates > 10 % (combine w Septra)

Tetracycline – can be reasonable choice (no GAS coverage)

Linezolid – GAS and MRSA coverage – expensive, high potential for resistance, use in refractory cases and with combo therapy

Rifampin – good MRSA coverage – use with other agent b/c of high resistance potential

What about Fluroquinolones?

Should NOT be used Resistance develops rapidly during therapry

and widespread resistance prevalent

Soft Tissue Infection

First episode of infx. No RF’s

Underlying predisposing condition

ORRecurrent episode in known

MRSA infection

Empiric coverage for:-Beta – Hemolytic Strep

-MSSA

Suggested:-Cephalexin 500 mg q 6h-Dicloxacillin 500mg q 6h

Empiric coverage for:-Beta –hemolytic Strep

-MRSA

Suggested:-Clinda 300 mg q 6h

-Linezolid 600 mg q 12 h -Penicillin (500 mg q 6h)

PLUSSeptra DS q 12 h

Doxycycline 100 mg q 12 h

More guidelines

Extensive soft tissue involvement Fever or signs of systemic illness Diabetes Mellitus Immunodeficiency

Blood Cultures?

Vancomycin – remains drug of choice

For those who can’t tolerate Vancomycin, alternative parenteral agent not known◦ Linezolid◦ Daptomycin◦ Tigecycline◦ Clindamycin – in areas of low resisitance

Decolonization◦ Does not appear to be consistently effective◦ Asymptomatic nasal infection can precede

infection but not always◦ Can be carriers of MRSA with neg. nasal swabs◦ Right now not enough evidence to support

decolonization – unknown optimal approach or population to decolonize

In health care workers◦ 68 HCW’s recevied topical treatment with

intranasal mupirocin ointment BID for five days or placebo

◦ Treatment associated with 91% reduction in prevalance of S. aureus carriage

◦ Proportion of hand cultures colonized with MRSA was lower than in placebo group (2.9% vs. 57%)

◦ However, recolonization obeserved within four weeks in 26 % and half within 6 months.

Doebbeling, Bn. Clin Infect Dis 1993; 17: 466

Hand Hygiene – evidence-based! ◦ Decrease in rate of patient

infections and healthcare workers

Environmental Cleaning Contact precautions with

MRSA carriers Appropriate use of Abx.