Methicillin-resistant Staphylococcus Aureus (MRSA) Information

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Staphylococcus aureus, often referred to simply as “staph,” are bacteria commonly carried on the skin or in the nose of healthy people. Methicillin-resistant Staphylococcus aureus (MRSA), often pronounced “mersa”, is the resistant variant of this bacteria which is resistant to ß-lactam antibiotics such as methicillin, oxacillin, penicillin, and amoxicillin. Risk of infection is greater for patients in hospitals, nursing homes, and other healthcare facilities who have open wounds and/or weakened immune systems.

Infection typically presents as skin infections that resemble pimples, boils, and spider bites which may be red, swollen, painful and may have pus or other drainage associated. They can very quickly develop into deep, painful abscesses which require surgical incision and drainage. More serious infection may also involve surgical wounds, the bloodstream, bones, joints, heart valves, and lungs.

Colonization can unknowingly occur in the anteriornares, skin, open wounds, and urinary tracts of otherwise healthy people. A swab collected from the nasopharyngeal area of an asymptomatic person can be used by healthcare facilities who have instituted measures to control the spread of MRSA by screeningpatients. Rising colonization rates lead to increased infection rates in both the communities and in hospitals.Rapid detection of MRSA-colonized patients has the potential to limit the spread of this organism thereby decreasing the MRSA disease burden in healthcare facilities.

Although Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities who have Methicillin-resistantStaphylococcus aureus(MRSA)weakened immune systems;Staph and MRSA can also cause illness in persons outside of these facilities. MRSAinfections that are acquired by persons who have not been hospitalized within the previous year or who had a medical procedure are known as community acquired MRSA (CA-MRSA) infections. Staph or MRSA infections in the community occur in otherwise healthy people.CAMRSA strains were first reported in the late 1990s and were defined by a lack of exposure to the health care setting. In the next several years, it became clear that CA-MRSA infections were caused by strains of MRSA that have different genetic characteristics than other strains. Panton-Valentine leukocidin (PVL) is a cytotoxin which is associated with increased virulence of certain strains of Staphylococcus aureus. It is present in the majority of CA-MRSA isolates studied and is the cause of necrotic (“flesh-eating”) lesions involving the skin or mucosa,including necrotic hemorrhagic pneumonia. The new CA-MRSA strains have rapidly spread in the United States to become the most common cause of culturedskin infections among individuals seeking medical care for these infections at emergency rooms in cities. These strains also commonly cause skin infections in athletes, jail and prison detainees, and soldiers.

MDL has developed two highly sensitive and specific PCR-based assays utilizing the OneSwab® and NasoSwab® platforms for the detection of MRSA and CA-MRSAfrom a single specimen.

Test 1118: Methicillin resistantStaphylococcus aureus(MRSA) by conventional PCR

Test 1119: Panton-Valentine Leukocidin (PVL) DNAby Real-Time PCR (Type IV + #1118 Req.) [Community Acquired MRSA= Type IV MRSA+ and PVL+]

Benefits of these platforms include:

• One vial, multiple pathogens
• High diagnostic specificity and sensitivity
• High precision robotic accuracy
• No refrigeration required before or after collection
• Rapid turnaround time of only 24-48 hours
• Specimen viability up to five (5) days
• Test additions available for up to 30 days

Medical Diagnostic Laboratories, L.L.C.
2030 Avon CT. Suite #5, Charlottesville VA, 22902
Dermatopathology | Cytopathology | Oral | Surgical and Clinical Pathology
Routine and Consultative Laboratory Services That’s Our Way! Personalized & Prompt Professional ProDia Laboratories
Phone: 434-563-7392 – Fax: 888-249-0039 – www.ProDiaLab.com
YES NO YES
Is the lesion purulent (i.e., are any of the following signs present)? Fluctuance—palpable fluid-filled ?cavity, movable, compressible Yellow or white center ? Central point or “head” ?Draining pus ? Possible to aspirate pus with ? needle and syringe
1. Drain the lesion
2. Send wound drainage for culture
and susceptibility testing
3. Advise patient on wound care
and hygiene
4. Discuss follow-up plan with
patient
If systemic symptoms, severe local symptoms, immunosuppression, or failure to respond to I&D, consider antimicrobial therapy with coverage for MRSA in addition to I&D. (See below for options) Possible cellulitis without abscess: Provide antimicrobial therapy ? with coverage for Streptococcus spp. and/or other suspected pathogens Maintain close follow-up ? Consider adding coverage for ? MRSA (if not provided initially),if patient does not respond † For severe infections requiring inpatient management, consider consulting an infectious disease specialist.‡ Visit www.cdc.gov/mrsafor more information.Abbreviations:I&D—incision and drainage MRSA—methicillin-resistant S. aureus SSTI—skin and soft tissue infection Patient presents with signs/symptoms of skin infection: Redness ? Swelling ? Warmth ? Pain/tenderness ? Complaint of “spider bite” ?

Outpatient management of skin and soft tissue infections in the era of community-associated MRSA

The use of the CDC logo on this material does not imply endorsement of AMA products/services or activities promoted or sponsored by the AMA.Options for empiric outpatient antimicrobial treatment of SSTIs when MRSA is a consideration Published September 2007 Drug name Considerations Precautions** Clindamycin FDA-approved to treat serious infections due to ? S. aureus D-zone test should be performed to identify inducible ? clindamycin resistance in erythromycin-resistant isolates Clostridium difficile ? -associated disease, while uncommon, may occur more frequently in association with clindamycin compared to other agents. Tetracyclines Doxycycline ? Minocycline ? Doxycycline is FDA-approved to treat ? S.aureusskin infections. Not recommended during pregnancy. ?Not recommended for children under the age of 8. ? Activity against group A streptococcus, a common cause of cellulitis, ? unknown.TrimethoprimSulfamethoxazole NotFDA-approved to treat any staphylococcal infection ? May not provide coverage for group A streptococcus, a common cause of ? cellulitis Not recommended for women in the third trimester of pregnancy. ? Not recommended for infants less than 2 months. ? Rifampin Use only in combination with other agents. ? Drug-drug interactions are common. ? Linezolid Consultation with an infectious disease ? specialist is suggested. FDA-approved to treat complicated skin infections, ? including those caused by MRSA. Has been associated with myelosuppression, neuropathy and lactic acidosis ? during prolonged therapy.MRSA is resistant to all currently available beta-lactam agents (penicillins and cephalosporins) ? Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) and macrolides (erythromycin, clarithromycin, azithromycine) are not optimalfor treatment of MRSA SSTIs ? because resistance is common or may develop rapidly.
* Data from controlled clinical trials are needed to establish the comparative efficacy of these agents in treating MRSA SSTIs. Patients with signs and symptoms of severe illness should be treated as inpatients.
** Consult product labeling for a complete list of potential adverse effects associated with each agent.Role of decolonizationRegimens intended to eliminate MRSA colonization should not be used in patients with active infections. Decolonization regimensmay have a role in preventing recurrent infections, but more data are needed to establish their efficacy and to identify optimal regimens for use in communitysettings. After treating active infections and reinforcing hygiene and appropriate wound care, consider consultation with an infectious disease specialist regarding use of decolonization when there are recurrent infections in an individual patient or members of a household.The use of the CDC, AMA and IDSA logos on this material does not imply endorsement of MDL products/services or activities promoted or sponsored by MDL