Methicillin-Resistant Staphylococcus aureus: a clinical

policy

John M. Howell, MD, FACEP, FAAEMBest Practices, Inc

Inova Fairfax HospitalDepartment of Emergency Medicine

June 25 - 27, 2009

Sometimes MRSA can be intimidating

Even a little scary

But we can usually get what we want

Let’s start with two cases that will lead up to our clinical question.

8 year old boy with ankle pain

• Twisted his ankle playing basketball 6 days prior

• Lateral ankle swelling

• Xray negative

• Discharged with ankle sprain

Returns to the ED 3 days later

• Temperature 102oF• Tachycardic• Lower leg swollen from the knee to the foot,

brawny-red appearance• Warm and tender lower leg• WBC 9,800/mm3

• CRP - 45

And the MRI shows …

In retrospect, there was no history of skin lesion or trauma, although the child did play basketball frequently.

Seven Year Old Male with Cough and Fever

• 3 days of cough, fever, and “abd pain”

• Decreased intake

• PMH: ED visit 1/12/08, left hip abscess, grew MRSA, treated with clindamycin

• BP 104/55; P 118/min, RR 20/min, T 99.7, pulse ox 95% on RA

Seven Year Old with Cough and Fever: Physical Exam

• WD/WN, alert and laying quietly• HEENT: Normal• Resp: Tachypnea, nasal flaring, rales L lung• CV: Tachycardic• Abd: Soft, diffusely tender without guarding.

Normal BSs• Skin: No rash• Neuro: Non-focal examination

Seven Year Old with Cough and Fever: Diagnostic Studies

• WBC: 20,000, 81S, 12L, 6M, 1E

• H/H 10.5/32; Plat 382

• Chemistry: K 3.0

• Flu Swab: Negative

Seven Year Old with Cough and Fever: Clinical Course

• In ED, child became more SOB• pulse ox dropped to 92%.• Given IV fluids, Rocephin, Clindamycin• Admitted to IFH PICU• Remained 12 days. Blood cultures: MRSA• Chest CT – pulmonary consolidation with

pleural effusion

MRSA Overview

• Nosocomial MRSA has been around since the 1960’s.

• Community acquired MRSA became a problem in the 1990’s.

• Although CA MRSA is more virulent, it is usually sensitive to more antimicrobials.

MRSA Virulence Factors

• Type IV SCC mec - mechanism for antimicrobial resistance

• Panton Valentine Leukocidin (PVL) – Pokes holes in leukocytes– More prominent in CA MRSA– Associated with pneumonia and severe

skin infections

MRSA Community Acquired Pneumonia

• Jan 2007 – 10 cases of MRSA CAP in healthy kids during flu season: 6 deaths

• Association with flu was either by lab test or clinical presentation

• All MRSA isolates positive for PVL• All had 3-4 day interval between presentation and

severe illness or death• 4/10 had documented MRSA in themselves or

contacts

So if we know that MRSA has varying levels of antimicrobial resistance and, via PVL, can cause severe disease …

Clinical Question

Should skin abscesses be treated routinely by I and D followed by a course of oral antibiotics that cover MRSA?

Following I and D of a skin abscess, I …

A. Do not routinely prescribe oral antibiotics

B. Routinely prescribe oral antibiotics that cover MRSA

C. Routinely prescribe oral antibiotics that cover MSSA (e.g., cephalexin)

D. Routinely prescribe oral antibiotics only for pateints with immune compromise

Let’s look at the literature

Rajendran et al, J Am Coll Surg, 2006

• Prospective placebo controlled trial of cephalexin following I and D

• 50% MRSA incidence• High prevalence of HIV and other immune

issues• In the MRSA subgroup (about 50 subjects),

the rates of abscess recurrence were 88% and 89% for cephalexin vs. placebo.

Lee et al, Pediatr Infect Dis, 2004

• Prospective observational study of 67 children with MRSA skin abscesses

• 5 treated with appropriate antibiotics, 62 with “discordant” antibiotics

• At follow up, all 5 with appropriate therapy improved, but 58 of 62 (94%) in discordant group improved. Most who did not improve were admitted.

Moran et al, NEJM, 2006

• Prospective cohort of patients with abscesses in an ED

• 78% of staph isolates were MRSA• About 400 subjects, but 40% dropped out or

were excluded• No difference in recurrence rates for

concordant and discordant antibiotics• Treatment not standardized and many

subjects either not included or lost to follow up

Paydar et al, Arch Surg, 2006

• Restrospective cohort of 280 patients with MRSA abscesses

• When corrected for intention to treat, 99% cure rate for concordant therapy, and 92% cure rate for discordant antimicrobial treatment.

Clinical Policy

• Guidelines (2008) for the prophylaxis and treatment of MRSA infections in the United Kingdom

• Journal of Antimicrobial Chemotherapy• Antibiotic therapy is not generally

required after the I and D of small (< 5 cm) abscesses without surrounding cellulitis.

Clinical Policy

• This clinical policy bases it’s recommendation on one reference, Rajendran.

• Prospective cohort of about 50 MRSA abscesses treated with cephalexin or placebo, which found no difference in recurrence rates

I don’t know about you, but this can all be a lot to take in …

And so, knowing that:

• MRSA isolates occur frequently

• A small number of patients with MRSA skin infections may develop serious pneumonia, necrotizing fasciitis, and osteomyelitis

• The literature is what it is

Where is your acceptable level of risk?

• Given the risk of distant infection, how many times out of one hundred are you willing to under treat a MRSA skin infection?

• 1, 2, 5, 10 … ???

Our final step is to write a management recommendation for our clinical policy on the treatment of cutaneous abscesses.

Pick one of the following clinical policy recommendations:

A. Routinely prescribe oral antibiotics that cover MRSA following I and D of cutaneous abscesses.

B. Routinely prescribe oral antibiotics that cover MSSA following I and D of cutaneous abscesses.

C. No not routinely prescribe oral antibiotics following I and D of cutaneous abscesses.

D. Prescribe oral antibiotics that cover MRSA, following I and D of cutaneous abscesses, only for patients with immune competency issues (e.g., HIV, DM, PVD).

If I did choose to treat, I would prescribe:

• Clindamycin

• Doxycycline

• Trimethoprim/Sulfamethoxasole

• Cepahlexin

• Augmentin