MRSA

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. 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. While 25% to 30% of people are colonized* in the nose with staph, less than 2% are colonized with MRSA

Symptoms of MRSA

As with all regular staph infections, recognizing the signs and receiving treatment for MRSA skin infections in the early stages reduces the chances of the infection becoming severe.

Severe Infections

MRSA in healthcare settings usually causes more severe and potentially life-threatening infections, such as bloodstream infections, surgical site infections, or pneumonia. The signs and symptoms will vary by the type and stage of the infection.

Skin Infections

In the community, most MRSA infections are skin infections that may appear as pustules or boils which often are red, swollen, painful, or have pus or other drainage. They often first look like spider bites or bumps that are red, swollen, and painful. These skin infections commonly occur at sites of visible skin trauma, such as cuts and abrasions, and areas of the body covered by hair (e.g., back of neck, groin, buttock, armpit, beard area of men).

Causes of MRSA Infections

How MRSA is Spread in the Community

MRSA infections, as with all staph, are usually spread by having contact with someone’s skin infection or personal items they have used, like towels, bandages, or razors that touched their infected skin. These infections are most likely to be spread in places where people are in close contact with others—for instance, schools and locker rooms where athletes might share razors or towels.

Factors that have been associated with the spread of MRSA skin infections include: close skin-to-skin contact, openings in the skin such as cuts or abrasions, contaminated items and surfaces, crowded living conditions, and poor hygiene. People may be more at risk in locations where these factors are common, including: athletic facilities, dormitories, military barracks, households, correctional facilities, and daycare centers.

Risks from Contaminated Surfaces

MRSA is found on people and not naturally found in the environment (e.g., soil, the ocean, lakes). MRSA could get on objects and surfaces outside the body if someone touches infected skin or certain areas of the body where these bacteria can live (like the nose) and then touches the object or surface. Another way that items can be contaminated with staph and MRSA is if they have direct contact with a person’s skin infection. Keeping skin infections covered with bandages is the best way to reduce the chance that surfaces will be contaminated with MRSA.

Even if surfaces have MRSA on them, this does not mean that you will definitely get an infection if you touch these surfaces. MRSA is most likely to cause problems when you have a cut or scrape that is not covered. That’s why it’s important to cover your cuts and open wounds with bandages. MRSA can also get into small openings in the skin, like the openings at hair follicles. The best defense is good hygiene. Keep your hands clean, use a barrier like clothing or towels between you and any surfaces you share with others (like gym equipment) and shower immediately after activities that involve direct skin contact with others. These are easy ways to decrease your risk of getting MRSA.

Hospitals and Healthcare Settings

Healthcare procedures can leave patients vulnerable to MRSA, which is typically spread in healthcare settings from patient to patient on unclean hands of healthcare personnel or through the improper use or reuse of equipment.

Hands may become contaminated with MRSA by contact with:

• colonized or infected patients;
• colonized or infected body sites of the personnel themselves; or
• devices, items, or environmental surfaces contaminated with body fluids containing MRSA.

Appropriate hand hygiene such as washing with soap and water or using an alcohol-based hand rub can prevent the spread of MRSA.
 

Treatment of MRSA Infections

Treatment of MRSA will vary by the type and location of infection.

MRSA Skin Infections

Treatment for MRSA skin infections may include having a healthcare professional drain the infection and, in some cases, prescribe an antibiotic. Do not attempt to treat an MRSA skin infection by yourself; doing so could worsen or spread it to others. This includes popping, draining, or using disinfectants on the area. If you think you might have an infection, cover the affected skin, wash your hands, and contact your healthcare provider.

If you are given an antibiotic, be sure to take all of the doses (even if the infection is getting better), unless your healthcare professional tells you to stop taking it. Do not share antibiotics with other people or save unfinished antibiotics to use at another time.

If within a few days of visiting your healthcare provider the infection is not getting better, contact them again. If other people you know or live with get the same infection tell them to go to their healthcare provider.

It is possible to get repeat infections with MRSA. If you are cured of an infection, you do not become immune to future infections. Therefore, personal prevention steps are key.

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Clostridium difficile is a spore-forming, gram-positive anaerobic bacillus that produces two exotoxins: toxin A and toxin B. It is a common cause of antibiotic-associated diarrhea (AAD). It accounts for 15-25% of all episodes of AAD.

What diseases result from Clostridium difficile infection?

• pseudomembranous colitis (PMC)
• toxic megacolon
• perforations of the colon
• sepsis
• death (rarely)

What are the main clinical symptoms of Clostridium difficile infection?

Clinical symptoms include:

• watery diarrhea
• fever
• loss of appetite
• nausea
• abdominal pain/tendernes

Which patients are at increased risk for Clostridium difficile infection?

The risk for disease increases in patients with:

• antibiotic exposure
• gastrointestinal surgery/manipulation
• long length of stay in healthcare settings
• a serious underlying illness
• immunocompromising conditions
• advanced age

What are the differences between Clostridium difficile colonization and Clostridium difficile infection?

Clostridium difficile colonization

• patient exhibits NO clinical symptoms
• patient tests positive for Clostridium difficile organism and/or its toxin
• more common than Clostridium difficile infection

Clostridium difficile infection

• patient exhibits clinical symptoms
• patient tests positive for the Clostridium difficile organism and/or its toxin

Which laboratory tests are commonly used to diagnose Clostridium difficile infection?

• Stool culture for Clostridium difficile: While this is the most sensitive test available, it is the one most often associated with false-positive results due to presence nontoxigenic Clostridium difficile strains. However, this can be overcome by testing isolates for toxin production (i.e. so called “toxigenic culture”). Nonetheless, stool cultures for Clostridium difficile are labor intensive, require an appropriate culture environment to grow anaerobic microorganisms, and have a relatively slow turn-around time (i.e. results available in 48-96 hours) making them overall less clinically useful. Results of toxigenic cultures do serve as a gold-standard against which other test modalities are compared in clinical trials of performance.
• Molecular tests: FDA-approved PCR assays, which test for the gene encoding toxin B, are highly sensitive and specific for the presence of a toxin-producing Clostridium difficile organism.
• Antigen detection for Clostridium difficile: These are rapid tests (<1 hr) that detect the presence of Clostridium difficile antigen by latex agglutination or immunochromatographic assays. Because results of antigen testing alone are non-specific, antigen assays have been employed in combination with tests for toxin detection, PCR, or toxigenic culture in two-step testing algorithms.
• Toxin testing for Clostridium difficile:
  • Tissue culture cytotoxicity assay detects toxin B only. This assay requires technical expertise to perform, is costly, and requires 24-48 hr for a final result. It does provide specific and sensitive results for Clostridium difficile infection. While it served as a historical gold standard for diagnosing clinical significant disease caused by Clostridium difficile, it is recognized as less sensitive than PCR or toxigenic culture for detecting the organism in patients with diarrhea.
  • Enzyme immunoassay detects toxin A, toxin B, or both A and B. Due to concerns overtoxin A-negative, B-positive strains causing disease, most laboratories employ a toxin B-only or A and B assay. Because these are same-day assays that are relatively inexpensive and easy to perform, they are popular with clinical laboratories. However, there are increasing concerns about their relative insensitivity (less than tissue culture cytotoxicity and much less than PCR or toxigenic culture).
• Clostridium difficile toxin is very unstable. The toxin degrades at room temperature and may be undetectable within 2 hours after collection of a stool specimen. False-negative results occur when specimens are not promptly tested or kept refrigerated until testing can be done.

How is Clostridium difficile transmitted?

Clostridium difficile is shed in feces. Any surface, device, or material (e.g., commodes, bathing tubs, and electronic rectal thermometers) that becomes contaminated with feces may serve as a reservoir for the Clostridium difficile spores. Clostridium difficile spores are transferred to patients mainly via the hands of healthcare personnel who have touched a contaminated surface or item.

How is Clostridium difficile infection usually treated?

In about 20% of patients, Clostridium difficile infection will resolve within 2-3 days of discontinuing the antibiotic to which the patient was previously exposed. The infection can usually be treated with an appropriate course (about 10 days) of antibiotics, including metronidazole, vancomycin (administered orally), or recently approved fidaxomicin. After treatment, repeat Clostridium difficile testing is not recommended if the patients’ symptoms have resolved, as patients may remain colonized.

How can Clostridium difficile infection be prevented in hospitals and other healthcare settings?

• Use antibiotics judiciously
• Use Contact Precautions: for patients with known or suspected Clostridium difficile infection:
  • Place these patients in private rooms. If private rooms are not available, these patients can be placed in rooms (cohorted) with other patients with Clostridium difficile infection.
  • Use gloves when entering patients’ rooms and during patient care.
  • Perform Hand Hygiene after removing gloves.
    • Because alcohol does not kill Clostridium difficile spores, use of soap and water is more efficacious than alcohol-based hand rubs. However, early experimental data suggest that, even using soap and water, the removal of C. difficile spores is more challenging than the removal or inactivation of other common pathogens.
    • Preventing contamination of the hands via glove use remains the cornerstone for preventing Clostridium difficile transmission via the hands of healthcare workers; any theoretical benefit from instituting soap and water must be balanced against the potential for decreased compliance resulting from a more complex hand hygiene message.
    • If your institution experiences an outbreak, consider using only soap and water for hand hygiene when caring for patients with Clostridium difficile infection.
  • Use gowns when entering patients’ rooms and during patient care.
  • Dedicate or perform cleaning of any shared medical equipment.
  • Continue these precautions until diarrhea ceases.
    • Because Clostridium difficile-infected patients continue to shed organism for a number of days following cessation of diarrhea, some institutions routinely continue isolation for either several days beyond symptom resolution or until discharge, depending upon the type of setting and average length of stay.
• Implement an environmental cleaning and disinfection strategy:
  • Ensure adequate cleaning and disinfection of environmental surfaces and reusable devices, especially items likely to be contaminated with feces and surfaces that are touched frequently.
  • Consider using an Environmental Protection Agency (EPA)-registered disinfectant with a sporicidal claim for environmental surface disinfection after cleaning in accordance with label instructions; generic sources of hypochlorite (e.g., household chlorine bleach) also may be appropriately diluted and used. (Note: Standard EPA-registered hospital disinfectants are not effective against Clostridium difficile spores .) Hypochlorite-based disinfectants may be most effective in preventing Clostridium difficile transmission in units with high endemic rates of Clostridium difficile infection.
  • Follow the manufacturer’s instructions for disinfection of endoscopes and other devices.
• Recommended infection control practices in long term care and home health settings are similar to those practices taken in traditional health-care settings.

What can I use to clean and disinfect surfaces and devices to help control Clostridium difficile?

Surfaces should be kept clean, and body substance spills should be managed promptly.Routine cleaning should be performed prior to disinfection. EPA-registered disinfectants with a sporicidal claim have been used with success for environmental surface disinfection in those patient-care areas where surveillance and epidemiology indicate ongoing transmission of Clostridium difficile.
Note: EPA-registered disinfectants are recommended for use in patient-care areas. When choosing a disinfectant, check product labels for inactivation claims, indications for use, and instructions.

How is the epidemic strain detected?

Like other strains of C. difficile, BI/NAP1/027 can be detected in the stool of infected patients by using laboratory tests that are commonly available in most hospitals. However, none of the FDA-approved tests differentiate between the various strains of C. difficile. Fortunately, because the control measures for outbreaks of any strain of C. difficile are similar, identification of the specific strain is not imperative for controlling outbreaks.