MRSA Agent Information Sheet
Research Occupational Health Program (ROHP)
Boston University
617-358-7647
Agent
Staphylococcus aureus belongs to the family Staphylococcaceae. It is a facultatively anaerobic, nonmotile, gram positive cocci bacteria that forms irregular clusters. Methicillin-resistant Staphylococcus Aureus (MRSA) is a type of staph bacteria that is resistant to certain antibiotics called beta-lactams. These antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin, and amoxicillin.
Disease/Infection
In the community, most MRSA infections are skin infections. More severe or potentially life-threatening MRSA infections occur most frequently among patients in healthcare settings.
Pathogenicity
Opportunistic pathogen, normal flora; produces a variety of syndromes with a range of clinical manifestations; clinically different in general community, newborns, menstruating women, and hospitalized patients; food intoxication is characterized by abrupt/violent onset, severe nausea, cramps, vomiting, and diarrhea using lasting 1-2days; animal bites can result in localized infections; may cause surface or deep/system infections in both community and hospital settings; surface infections include impetigo, folliculitis, abscesses, boils, infected lacerations; deep infections include endocarditis, meningitis, septic arthritis, pneumonia, osteomyelitis; newborns are susceptible to scalded skin syndrome (SSS) caused by exfoliative toxins; may be colonized during delivery resulting in sepsis meningitis; toxic shock syndrome is an acute multi-system illness caused by TSST-1 a super antigen; characterized by sudden onset, high fever, vomiting, profuse watery diarrhea, myalgia, hypotension and erythematous rash.
Biosafety Information
Risk Group/BSL
Risk Group 2
Biosafety Level 2 practices
Modes of Transmission
| Transmission | |
| Skin Exposure (Needlestick, animal bite, or scratch): | Yes |
| Mucous Membrane Exposure Splash to Eye(s), Nose or Mouth: | Yes |
| Inhalation: | Unlikely |
| Ingestion: | Yes |
Host Range/Reservoir
Host Range includes humans; to a lesser extent, warm-blooded animals
Reservoir – Human; patients with indwelling catheters or IVs act as reservoirs for nosocomial infections; food borne – occasionally cows with infected udders
Symptoms
Symptoms are dependent on the site of infection. Systemic infection may cause fever, headache malaise, and myalgia.
Incubation Period
4-10 days
Viability
Susceptible to many disinfectants – 1% sodium hypochlorite, iodine/alcohol solutions, glutaraldehyde, and formaldehyde.
Survival Outside Host
Carcass and organs – up to 42 days; floor – less than 7 days; glass – 46 hours; sunlight – 17 hours; UV – 7 hours; meat products – 60 days; coins – up to 7 days; skin from 30 min to 38 days.
Information for Lab Workers
Laboratory PPE
Lab coat, gloves and eye protection when direct skin contact with infected materials or animals is unavoidable.
Containment
BSL-2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures. Procedures that are likely to generate aerosols should be conducted in a biosafety cabinet. Practices may be enhanced based on risk assessment.
In Case of Exposure/Disease
- For injuries in the lab which are major medical emergencies (heart attacks, seizures, etc…):
- Medical Campus: call or have a coworker call the Control Center at 617-414–4144.
- Charles River Campus: call or have a coworker call campus security at 617-353-2121.
You will be referred to or transported to the appropriate health care location by the emergency response team.
- For lab exposures (needlestick injuries, cuts, scratches, splashes, animal bites, etc…) involving this infectious agent, or for unexplained symptoms or illness
- You will be connected with the BU Research Occupational Health Program (ROHP) medical officer. ROHP will refer you to the appropriate health care location.
- Under any of these scenarios, always inform the physician of your work in the laboratory and the agent(s) that you work with.
- Provide the wallet-size agent ID card to the physician.
Vaccination
None available
Information for First Responders/Medical Personnel
Public Health Issues
S aureus is a common community pathogen and most cases of infection with this pathogen can be handled with standard precuations. MRSA patients should be placed in contact precautions and providers should don gloves and gown, in addition to practicing hand hygiene.
Diagnosis/Surveillance
Diagnosis is made via clinical cultures and gram stain. Site of cultures are based on manifestation of infection.
First Aid/Post Exposure Prophylaxis
Perform one of the following actions:
| Skin Exposure (Needlestick or scratch): | Immediately go to the sink and thoroughly wash the wound with soap and water for 15 minutes. Decontaminate any exposed skin surfaces with an antiseptic scrub solution. |
| Mucous Membrane Splash to Eye(s), Nose or Mouth: | Exposure should be irrigated vigorously. |
| Splash Affecting Garments: | Remove garments that may have become soiled or contaminated and place them in a double red plastic bag. |
Treatment
Treatment of MRSA infections should be based on the results of the sensitivities from the clinical cultures. Empiric treatment for non-critical illnesses can include Doxycycline, Bactrim, Clindamycin and Vancomycin. For more severe infections, empiric treatment should include intravenous antibiotics.
References
Mandell, Douglas, and Bennett’s Principles and practices of Infectious Disease 6th Edition, Elsevier, 2005.
CDC – http://www.cdc.gov/mrsa/community/index.html
Health Canada – http://www.phac-aspc.gc.ca/id-mi/mrsa-eng.php