1. Navpreet Sahsi

2.  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

3.  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

4.  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

5.  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

6.  Skin Infections – Emergency Dept.  New York – 15 %  Minneapolis – 39 %  New Orleans – 67 %  Atlanta – 72 %  Moran et al. NEJM 2006; 355: 666

7.  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

8.  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

9.  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??

10.  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

11.  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?

12.  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.

14.  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.

15.  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?

16.  Should NOT be used  Resistance develops rapidly during therapry and widespread resistance prevalent

17. Soft Tissue Infection First episode of infx. No RF’s Underlying predisposing condition OR Recurrent 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) PLUS Septra DS q 12 h Doxycycline 100 mg q 12 h

18.  More guidelines  Extensive soft tissue involvement  Fever or signs of systemic illness  Diabetes Mellitus  Immunodeficiency  Blood Cultures?

19.  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

20. 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

21.  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

22.  Hand Hygiene – evidence- based! ◦ Decrease in rate of patient infections and healthcare workers  Environmental Cleaning  Contact precautions with MRSA carriers  Appropriate use of Abx.