MRSA Methicillin Resistant Staph aureus Geog 380 GENERAL

MRSA (Methicillin Resistant Staph. aureus) Geog 380

GENERAL COMMENTS about resistance § § § Inevitable “dance” of co-evolution Post WW II—steadily growing Widespread overuse Use in cattlefeed

“The way to the wound is through the nose”--Creech II et al, 2006

Chronology of MRSA § First reported UK 1961 § First reported USA 1968 § Community associated MRSA (CAMRSA) first reported 1980 – Initially US – Pts lack risk factors for MRSA

CA-MRSA Georaphically Dispersed (community acquired) § Australia--Aboriginals/native peoples § Native Americans in US--rural § Subpopulations in US – IDUs – Prisoners – Sports players – kids

Bilateral Necrotizing Fasciitis--Pseudomonas Source: Akamine et al, Internal Medicine 2008; 47: 553 -6

Paradigms of CA-MRSA § It spread from hospital – Patients – Visitors – Staff § Current findings – It has been in reservoirs in community – The strain has been different than hospital MRSA – Some nosocomial MRSA is CA-MRSA!!!!

Sobering Quotes § “Communityassociated…MRSA now appears to be among the most common etiologies of skin and soft tissue infections. ”

“MRSA may be replacing methicillin-susceptible S. aureus (MSSA) as the typical community staphylococcal strain. ”

“it is difficult to justify using drugs like cephalexin…if it is known that the majority of patients will be infected with resistant isolates. ” See Moran and Talan, Annals of Emergency Medicine, 2004; 11: 321 -22.

Prevalence of CA-MRSA § § No national data collected Community data difficult to get Hospital data easier Varies 76% of MRSA in AK to 12% MN for soft tissue infections § Huang et al, Journal of Clinical Microbiology 2006; 44: 2423 -27

Hospital MRSA § Formerly: – Few large university hosps – ICUs § Now: – 97% teaching hosps report MRSA § Risk factors: – Long hospital stay, surgery, catheter sites (prop to # of sites), long or recurrent exp to abx’s

Evidence of CA-MRSA Increase § § § 10/100, 000 admissions, kids, 1988 -90 259/100, 000 1993 -5 See Herold et al, JAMA 1998; 279: 593 -8 1993: 2, 000 MRSA 2005: 368, 000 APIC: 46/1000 hosp adm had life threatening MRSA § CDC: 94, 000 life threatening hosp MRSA infs and 19, 000 deaths!!!! § STAY HEALTHY

Frazee Study (Frazee et al, Annals of Emergency Med, 2005; 45: 31 -20 § Done in ER in Alameda County, CA § 18% homeless, 28% IDU, 63% w abscess, 26% admitted to hosp § Nearly 50% patients w/ skin and soft tissue infections MRSA § 74% of staph was MRSA § “When skin and soft tissue infections require antibiotic therapy, we recommend choosing an agent that is active against MRSA”

Findings of Huang et al § 45% of pts w/MRSA had community associated MRSA § Not susceptible to usual abx’s for soft tissue infections but susceptible to: – TMP/SMX (Bactrim or Septra) – Gentamicin – Rifampin – Vancomicin – Clindamicin

Necrotizing Fasciitis § § § “flesh eating bacteria” Fairly rate Spectacular Life-threatening Surgical emergency Polymicrobial – Toxin producing – Necrosis of fascia

Historical Background § Hippocrates 5 th Cent BCE § 19 th C: – “gangrenous ulcer”, “malignant ulcer”, “putrid ulcer”, phagedema gangrenosa § 1800’s – Feared in the military… § Confused by multiple terms@ present

Epidemiology § Estimated 500 -150 cases/yr in US § Not specific by age or sex § Increased risk in: – IVDU – Alcoholics – Immunosuppressed – Peripheral vascular disease – diabetics

Typical Presentation § Any break in the skin § Increased risk w/trauma – – – – Penetrating Blunt Surgical wound IVDU SC drug use Perirectal abscesses Bites Da da da da

Clinical Presentation § Within 7 days of “injury” § Red, swollen, tender, hot, painful area § Pain out of proportion to physical findings § Pain extends beyond boundaries of erythematous area § Rapid, rapid expansion

CFR § Typically 75% – Sepsis – ARDS § Higher at Harborview

WARNING: SOME SLIDES AFTER THIS GET VERY GRAPHIC. NO KIDDING

A 65 -year-old woman with a 15 -year history of diabetes presented with fever (temperature, 38. 5{degrees}C), chills, malaise, and a rash on the medial surface of the right thigh, vulva, and lower abdominal wall (Panel A) Hsiao F and Hsieh C. N Engl J Med 2008; 358: 940

Necrotizing � Fasciitis of Left Lower Leg Source: Kihiczak et al, JEADV

Nec Fasc of the Perineum

Infections and Layers

NDM-1 New Delhi Metallo-betalactamase-1

HUH? ? § “What’d the dude say? ” § “Sounded like he was barfing” § “I’m texting my girlfriend. How do you spell that? ” § “Will it be on the test? ” § “You mean this isn’t Philosophy 101”?

NDM-1 § Not a specific bacterium § A genetically coded mechanism in gram negatives (klebsiella, etc), E. coli § Cleaves ring in carbapenems (carbapenamase) § Relatively new broad spectrum antibiotics including imipenem, meropenem

Why should we care? § Renders a major class of antibiotics useless § These antibiotics are frequently the only effective ones against enterobaceteriacae § Also many other pathogens § Few if any treatments then work

Lancet ID, April 7, 2011 § “such pathogens typically are resistant to multiple other antibiotic classes, leaving very few treatment options available”

So let me explain § Enzyme is made by the bacterium based on instructions from its genome § This attacks the chemical structure of the “new” class of antibiotics § Cuts a ring § Neutralizes the antibiotic

Journal of Chinese Medical Association, Nov. 2010

NDM-1 in Water Supply, New Delhi Source: Lancet ID, 4 -2011