MRSA in Our Community Tony Chang, MD Primary Care Case Conference August 2, 2006

Staphylococcus aureus Electron micrograph from Visuals Unlimited

Objectives What kind of skin infections are associated with Staphylococcus aureus? What kind of skin infections are associated with Staphylococcus aureus? What is community-acquired methicillin- resistant Staphylococcus aureus (ca-MRSA)? What is community-acquired methicillin- resistant Staphylococcus aureus (ca-MRSA)? How much of a problem is ca-MRSA around the country? How much of a problem is ca-MRSA around the country? How much of a problem is it in Madison? How much of a problem is it in Madison?

Cellulitis

Clinical Case Mr. N is a 58 year old man who presents to with a nonhealing right lower leg skin infection beginning 1 month ago. Works at Oscar Meyer engineering Works at Oscar Meyer engineering Scraped his right leg climbing around freight elevator Scraped his right leg climbing around freight elevator Seen at IMC 2 days later - Augmentin x 10 days Seen at IMC 2 days later - Augmentin x 10 days Seen at employee health - Cephalexin (day #8) Seen at employee health - Cephalexin (day #8) Soaking in a hot tub Soaking in a hot tub

PMFS PMH Hypertension Hypertension Hypothyroidism Hypothyroidism Depression Depression Glaucoma Glaucoma FH/SH Parents deceased Youngest of 12 4 sisters with diabetes Married with 2 children Quit smoking drinks per week Enjoys curling

Meds NKDA Cephalexin 500 mg 4 times daily Cephalexin 500 mg 4 times daily Atenolol 50 mg daily Atenolol 50 mg daily Synthroid 100 mcg daily Synthroid 100 mcg daily Ranitidine 150 mg twice daily as needed Ranitidine 150 mg twice daily as needed Xalatan, Betimol Xalatan, Betimol

Exam Afebrile, BP 134/66, HR 72, RR 16 Afebrile, BP 134/66, HR 72, RR 16 Original scrape: 1 cm ulcer, dark base, partially covered by dry epithelial roof Original scrape: 1 cm ulcer, dark base, partially covered by dry epithelial roof Another 5 mm ulcer similar in appearance Another 5 mm ulcer similar in appearance 17 satellite lesions 1-3 mm, some pustular 17 satellite lesions 1-3 mm, some pustular Pustule unroofed with #15 scalpel and cultured

Folliculitis

Culture Results Resistant to Cefazolin Cefazolin Erythromycin Erythromycin Oxacillin Oxacillin Sensitive to Vancomycin Clindamycin Light growth Staphylococcus aureus

MRSA in Hospital vs. Community Hospital multiresistant multiresistant clonal clonal catheter infections catheter infections Community pauciresistant polyclonal (?) skin diseases pneumonia Mandell, Bennett, & Dolin: Principles and Practice of Infectious Diseases, 6th ed

Furuncle (boil)

MRSA around the country What is the incidence of ca-MRSA? What is the incidence of ca-MRSA? What type of infections are associated with ca- MRSA? What type of infections are associated with ca- MRSA? What portion of S. aureus skin infections are caused by ca-MRSA? What portion of S. aureus skin infections are caused by ca-MRSA? How serious are these skin infections? How serious are these skin infections? How is ca-MRSA transmitted? How is ca-MRSA transmitted?

Baltimore, Atlanta, Minnesota Study Design: Prospective population-based surveillance supplemented by patient interviews Prospective population-based surveillance supplemented by patient interviews 11 Baltimore hospitals 11 Baltimore hospitals Health District 3 in Greater Atlanta Health District 3 in Greater Atlanta Laboratory-based surveillance in Minnesota Laboratory-based surveillance in Minnesota 12 Minnesota hospitals 12 Minnesota hospitals NEJM 2005;352:

Baltimore, Atlanta, Minnesota Patients with MRSA: NEJM 2005;352: ,5539,972 health-care associated MRSA 2, also health-care associated 1,063 interviewed ? 2107 suspected cases of ca-MRSA 1647 associated with clinical illness

Baltimore, Atlanta, Minnesota NEJM 2005;352: AtlantaBaltimoreMinnesota Bacteremia3076 Meningitis110 Osteomyelitis1167 Bursitis1207 Arthritis1302 Invasive ca-MRSA Infections

Baltimore, Atlanta, Minnesota NEJM 2005;352: AtlantaBaltimoreMinnesota Bacteremia2%6%3% Meningitis<1%1%<1% Osteomyelitis1%5%1% Bursitis1%01% Arthritis1%01% Invasive ca-MRSA Infections

Baltimore, Atlanta, Minnesota NEJM 2005;352: AtlantaBaltimoreMinnesota Skin & soft tissue Wound Pneumonia2344 Urinary tract 5743 Sinus6001 Other ca-MRSA Infections

Baltimore, Atlanta, Minnesota NEJM 2005;352: AtlantaBaltimoreMinnesota Skin & soft tissue 77%83%77% Wound11%7%10% Pneumonia2%3%2% Urinary tract 4%3%1% Sinus5%0<1% Other ca-MRSA Infections

Baltimore, Atlanta, Minnesota Observations: Annual disease incidence Annual disease incidence 25.7/100,000 in Atlanta 25.7/100,000 in Atlanta 18.0/100,000 in Baltimore 18.0/100,000 in Baltimore 6% were invasive 6% were invasive 77% involved skin and soft tissue 77% involved skin and soft tissue 23% of patients were then hospitalized 23% of patients were then hospitalized NEJM 2005;352:

Erysipelas

Los Angeles Study Design: Retrospective review of records of 843 patients Retrospective review of records of 843 patients Wound cultures that grew MRSA Wound cultures that grew MRSA January 15, 2003 – April 15, 2004 January 15, 2003 – April 15, /843 (1.7%) had necrotizing fasciitis 14/843 (1.7%) had necrotizing fasciitis NEJM 2005;352:

Los Angeles Observations: Risk factors: injection drug use, diabetes, chronic hepatitis C, cancer, HIV/AIDS Risk factors: injection drug use, diabetes, chronic hepatitis C, cancer, HIV/AIDS All isolates susceptible to clindamycin, TMP- SMX, rifampin All isolates susceptible to clindamycin, TMP- SMX, rifampin All isolates were the same genotype USA300 All isolates were the same genotype USA300 NEJM 2005;352:

Necrotizing Fasciitis Cohen & Powderly: Infectious Diseases, 2nd ed

Saint Louis Study Design: Retrospective cohort study and nasal-swab survey of 84 St. Louis Rams football players and staff members Retrospective cohort study and nasal-swab survey of 84 St. Louis Rams football players and staff members Investigation of an outbreak of MRSA abscesses Investigation of an outbreak of MRSA abscesses NEJM 2005;352:

Saint Louis Observations: During 2003 season, 8 MRSA infections occurred among 5/58 players During 2003 season, 8 MRSA infections occurred among 5/58 players Infections occurred at turf-abrasion sites Infections occurred at turf-abrasion sites Risk factors: Risk factors: lineman or linebacker position, high BMI lineman or linebacker position, high BMI All isolates were genotype USA All isolates were genotype USA NEJM 2005;352:

Saint Louis Observations: No MRSA recovered from nasal or environmental samples No MRSA recovered from nasal or environmental samples MSSA recovered from whirlpools and taping gel and from 35/84 nasal swabs (42%) MSSA recovered from whirlpools and taping gel and from 35/84 nasal swabs (42%) NEJM 2005;352: Chris Massey of the St. Louis Rams

Nasal carriage

Atlanta Study Design: Prospective laboratory surveillance to identify S. aureus recovered from skin and soft tissue Prospective laboratory surveillance to identify S. aureus recovered from skin and soft tissue Determine the proportion of infections caused by community-acquired MRSA Determine the proportion of infections caused by community-acquired MRSA Grady Health System in Atlanta Grady Health System in Atlanta 8/1/2003 – 11/15/2003 8/1/2003 – 11/15/2003 Ann Intern Med. 2006;144:

Atlanta Observations: 389 Episodes of community-onset S. aureus skin and soft tissue infections 279 (72%) MRSA 110 (28%) MSSA 244 (87%) ca-MRSA 35 (13%) Other MRSA

Impetigo

S. aureus at UWHC Outpatient isolates of S. aureus from any site

MRSA prevalence at UWHC

Brown Recluse Spider Bite

Cutaneous Anthrax Cohen & Powderly: Infectious Diseases, 2nd ed

Recommendations Be aware that ca-MRSA is on the rise Be aware that ca-MRSA is on the rise Have a low threshold for obtaining culture Have a low threshold for obtaining culture especially for “spider bites” especially for “spider bites” Recognize more invasive infections Recognize more invasive infections necrotizing fasciitis necrotizing fasciitis septic thrombophlebitis septic thrombophlebitis pneumonia pneumonia Ann Intern Med. 2006;144:

Continuing Questions For common skin infections, what empiric antibiotic do I use? For common skin infections, what empiric antibiotic do I use? What about nasal carriage? What about nasal carriage? Is it useful to obtain nasal cultures? Is it useful to obtain nasal cultures? If positive, is attempted eradication recommended? If positive, is attempted eradication recommended?

Special Thanks Carol Spiegel, PhD Carol Spiegel, PhD Department of Pathology & Laboratory Medicine Department of Pathology & Laboratory Medicine