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MRSA - Methicillin Resistant Staphylococcus Aureus


MRSA - Methicillin Resistant Staphylococcus Aureus

Another type of infection that is causing increasing concern and alarm is  Methicillin Resistant Staph Aureus, commonly referred to as MRSA.  This most common setting for acquiring a MRSA infection is actually in a healthcare facility.  This is a particular problem for those of us with lymphedema as we ar so often hospitlized anyway with cellulitis infections.


MRSA Information for the Public

What is Staphylococcus aureus (staph)?

Staphylococcus aureus, often referred to simply as "staph," are bacteria commonly carried on the skin or in the nose of healthy people. Approximately 25% to 30% of the population is colonized (when bacteria are present, but not causing an infection) in the nose with staph bacteria. Sometimes, staph can cause an infection. Staph bacteria are one of the most common causes of skin infections in the United States. Most of these skin infections are minor (such as pimples and boils) and can be treated without antibiotics (also known as antimicrobials or antibacterials). However, staph bacteria also can cause serious infections (such as surgical wound infections, bloodstream infections, and pneumonia).

What is MRSA (methicillin-resistant Staphylococcus aureus)?

Some staph bacteria are resistant to antibiotics. MRSA is a type of staph that is resistant to antibiotics called beta-lactams. Beta-lactam antibiotics include methicillin and other more common antibiotics such as oxacillin, penicillin and amoxicillin. While 25% to 30% of the population is colonized with staph, approximately 1% is colonized with MRSA.

Who gets staph or MRSA infections?

Staph infections, including MRSA, occur most frequently among persons in hospitals and healthcare facilities (such as nursing homes and dialysis centers) who have weakened immune systems. These healthcare-associated staph infections include surgical wound infections, urinary tract infections, bloodstream infections, and pneumonia.

What is community-associated MRSA (CA-MRSA)?

Staph and MRSA can also cause illness in persons outside of hospitals and healthcare facilities. MRSA infections that are acquired by persons who have not been recently (within the past year) hospitalized or had a medical procedure (such as dialysis, surgery, catheters) are know as CA-MRSA infections. Staph or MRSA infections in the community are usually manifested as skin infections, such as pimples and boils, and occur in otherwise healthy people.

How common are staph and MRSA infections?

Staph bacteria are one of the most common causes of skin infection in the United States and are a common cause of pneumonia, surgical wound infections, and bloodstream infections. The majority of MRSA infections occur among patients in hospitals or other healthcare settings; however, it is becoming more common in the community setting. Data from a prospective study in 2003, suggests that 12% of clinical MRSA infections are community-associated, but this varies by geographic region and population.

What does a staph or MRSA infection look like?

Staph bacteria, including MRSA, can cause skin infections that may look like a pimple or boil and can be red, swollen, painful, or have pus or other drainage. More serious infections may cause pneumonia, bloodstream infections, or surgical wound infections.

Are certain people at increased risk for community-associated staph or MRSA infections?

CDC has investigated clusters of CA-MRSA skin infections among athletes, military recruits, children, Pacific Islanders, Alaskan Natives, Native Americans, men who have sex with men, and prisoners.
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.

How can I prevent staph or MRSA skin infections?

Practice good hygiene:

  1. Keep your hands clean by washing thoroughly with soap and water or using an alcohol-based hand sanitizer.
  2. Keep cuts and scrapes clean and covered with a bandage until healed.
  3. Avoid contact with other people’s wounds or bandages.
  4. Avoid sharing personal items such as towels or razors.

Are people who are positive for the human immune deficiency virus (HIV) at increased risk for MRSA? Should they be taking special precautions?

People with weakened immune systems, which include some patients with HIV infection, may be at risk for more severe illness if they get infected with MRSA. People with HIV should follow the same prevention measures as those without HIV to prevent staph infections, including practice good hygiene, cover wounds (e.g., cuts or abrasions) with clean dry bandages, avoid sharing personal items such as towels and razors, and contact their doctor if they think they have an infection.

Can I get a staph or MRSA infection at my health club?

In the outbreaks of MRSA, the environment has not played a significant role in the transmission of MRSA. MRSA is transmitted most frequently by direct skin-to-skin contact. You can protect yourself from infections by practicing good hygiene (e.g., keeping your hands clean by washing with soap and water or using an alcohol-based hand rub and showering after working out); covering any open skin area such as abrasions or cuts with a clean dry bandage; avoiding sharing personal items such as towels or razors; using a barrier (e.g., clothing or a towel) between your skin and shared equipment; and wiping surfaces of equipment before and after use.

What should I do if I think I have a staph or MRSA infection?

See your healthcare provider.

Are staph and MRSA infections treatable?

Yes. Most staph and MRSA infections are treatable with antibiotics. If you are given an antibiotic, take all of the doses, even if the infection is getting better, unless your doctor tells you to stop taking it. Do not share antibiotics with other people or save unfinished antibiotics to use at another time.

However, many staph skin infections may be treated by draining the abscess or boil and may not require antibiotics. Drainage of skin boils or abscesses should only be done by a healthcare provider.

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

Is it possible that my staph or MRSA skin infection will come back after it is cured?

Yes. It is possible to have a staph or MRSA skin infection come back (recur) after it is cured. To prevent this from happening, follow your healthcare provider’s directions while you have the infection, and follow the prevention steps after the infection is gone.

If I have a staph, or MRSA skin infection, what can I do to prevent others from getting infected?

You can prevent spreading staph or MRSA skin infections to others by following these steps:

  1. Cover your wound. Keep wounds that are draining or have pus covered with clean, dry bandages. Follow your healthcare provider’s instructions on proper care of the wound. Pus from infected wounds can contain staph and MRSA, so keeping the infection covered will help prevent the spread to others. Bandages or tape can be discarded with the regular trash.
  2. Clean your hands. You, your family, and others in close contact should wash their hands frequently with soap and warm water or use an alcohol-based hand sanitizer, especially after changing the bandage or touching the infected wound.
  3. Do not share personal items. Avoid sharing personal items such as towels, washcloths, razors, clothing, or uniforms that may have had contact with the infected wound or bandage. Wash sheets, towels, and clothes that become soiled with water and laundry detergent. Drying clothes in a hot dryer, rather than air-drying, also helps kill bacteria in clothes.
  4. Talk to your doctor. Tell any healthcare providers who treat you that you have or had a staph or MRSA skin infection.

What should I do if someone I know has a staph or MRSA infection?

If you know someone that has a staph or MRSA infection you should follow the prevention steps.


What are the criteria for distinguishing community-associated MRSA (CA-MRSA) from healthcare-associated MRSA (HA-MRSA)?

Persons with MRSA infections that meet all of the following criteria likely have CA-MRSA infections:

What is the main way that staph or MRSA is transmitted in the community?

The main mode of transmission of staph and/or MRSA is via hands which may become contaminated by contact with a) colonized or infected individuals, b) colonized or infected body sites of other persons, or c) devices, items, or environmental surfaces contaminated with body fluids containing staph or MRSA. Other factors contributing to transmission include skin-to-skin contact, crowded conditions, and poor hygiene.

How is a MRSA infection diagnosed?

In general, a culture should be obtained from the infection site and sent to the microbiology laboratory. If S. aureus is isolated, the organism should be tested as follows to determine which antibiotics will be effective for treating the infection.

Skin Infection: Obtain either a small biopsy of skin or drainage from the infected site. A culture of a skin lesion is especially useful in recurrent or persistent cases of skin infection, in cases of antibiotic failure, and in cases that present with advanced or aggressive infections.

Pneumonia: Obtain a sputum culture (expectorated purulent sputum, respiratory lavage, or bronchoscopy).

Bloodstream Infection: Obtain blood cultures using aseptic techniques.

Urinary Infection: Obtain urine cultures using aseptic techniques.

How are CA-MRSA infections treated?

Staph skin infections, such as boils or abscesses, may be treated by incision and drainage, depending on severity. Antibiotic treatment, if indicated, should be guided by the susceptibility profile of the organism.

How do CA-MRSA and HA-MRSA strains differ?

Recently recognized outbreaks of MRSA in community settings have been associated with strains that have some unique microbiologic and genetic properties compared with the traditional hospital-based MRSA strains, suggesting some biologic properties (e.g., virulence factors) may allow the community strains to spread more easily or cause more skin disease. Additional studies are underway to characterize and compare the biologic properties of HA-MRSA and CA-MRSA strains.

There are at least three different S. aureus strains in the United States that can cause CA-MRSA infections. CDC continues to work with state and local health departments to gather organisms and epidemiologic data from known cases to determine why certain groups of people get these infections.

Are MRSA infections a reportable disease?

MRSA is reportable in several states. The decision to make a particular disease reportable to public health authorities is made by each state, based on the needs of that individual state. To find out if MRSA is reportable in your state, call your state health department.


Methicillin resistant Staphylococcus aureus

MRSA is the term used for bacteria of the Staphylococcus aureus group (S. aureus) that are resistant to the usual antibiotics used in the treatment of infections with such organisms. Traditionally MRSA stood for methicillin resistance but the term increasingly refers to a multi-drug resistant group. Such bacteria often have resistance to many antibiotics traditionally used against S.aureus.

This resistance to methicillin is due to the presence of the mec gene in the bacteria. This alters the site at which methicillin binds to kill the organism. Hence, methicillin is not able to effectively bind to the bacteria.

Infections caused by MRSA are the same as other staphylococcal infections because the organism itself is not any more virulent (or infectious) than usual type S.aureus.

Like other S.aureus, MRSA can colonise the skin and body of an individual without causing sickness, and in this way it can be passed on to other individuals unknowingly. Problems arise in the treatment of overt infections with MRSA because antibiotic choice is very limited.

Where is MRSA found?

MRSA is found worldwide, predominantly in hospitals and institutions such as nursing homes. Much less commonly, MRSA is found in the general community. There are three main reservoirs (and hence sources of spread and infection) for MRSA in hospital and institutions: staff, patients and inanimate objects such as beds, linen and utensils. By far the most important reservoir is patients who may be colonised with MRSA without evidence of infection. The usual sites of colonisation with MRSA are the nostrils, skin, groin, axilla, and wounds.

Most health professionals who are colonised with MRSA do not develop infection and many spontaneously clear the organism without treatment. Once colonisation has been present for more than three months, it becomes much more difficult to clear.

Patients, however, have a 30-60% risk of infection following colonisation. This is probably due to factors related to the illness for which they are hospitalised, which impair their ability to clear or control colonisation with the organism.

Most MRSA infections occur in wounds (e.g. surgical wounds), skin (e.g. intravenous access sites), or in the bloodstream. Mortality from these infections is not significantly different from those seen with usual type S.aureus infections.

Prevention and Management of MRSA

In hospitals, patients who have been transferred from another hospital or institution may have swabs taken on admission to screen for MRSA colonisation or infection. The swabs are taken from the nostrils, armpits, groins, genital region and any areas of broken skin (e.g. surgical wounds, ulcers, sores).

New or transferring hospital staff are also screened. The results of swabs take a few days to be reported.

If an inpatient is found to have MRSA colonisation or infection:

In order to limit spread of MRSA throughout a ward or hospital, such precautions should be strictly enforced until repeat swabs from the patient are negative for MRSA. This may take some weeks. Staff found to be colonised with MRSA should be removed from patient contact.

Eradication treatment consists of:

The antibiotic of choice for an infected impatient is vancomycin given intravenously. Oral clindamycin may be used in minor soft tissue infections in outpatients. These antibiotics are no better than flucloxacillin in the treatment of usual type S.aureus but are much more effective in MRSA infections.

Less effective alternatives are:

In life-threatening infections such as infective endocarditis multiple antibiotics are often prescribed simultaneously (e.g. vancomycin plus an aminoglycoside plus rifampicin).

Concerns about MRSA in the future

There is growing concern about MRSA infections. They appear to be increasing in frequency and displaying resistance to a wider range of antibiotics.

Of particular concern are the VISA strains of MRSA (vancomycin intermediate susceptibility S.aureus). These are beginning to develop resistance to vancomycin, which is currently the most effective antibiotic against MRSA. This new resistance has arisen because another species of bacteria, called enterococci, relatively commonly express vancomycin resistance. In the laboratory enterococci are capable of transferring the gene for vancomycin resistance over to S.aureus.

New antibiotics such as linezolid and synercid look promising for treatment of infections not responding to vancomycin. Other antibiotics are under development.



What does antibiotic resistance mean?
Germs called bacteria may cause infections. Antibiotics are drugs used to treat infections caused by bacteria. Sometimes these drugs will no longer kill the germs. This is called antibiotic drug resistance.

What is Staphylococcus aureus?
Staphylococcus aureus, or Staph aureus for short, is a germ (bacteria) usually found on a person's skin and mucous membranes. It may cause infections on broken skin or wounds. Methicillin is a type of antibiotic used to treat infections caused by Staph aureus. If Staph aureus is resistant to Methicillin it is called MRSA. This means that the infection may be more difficult to treat. If someone has a MRSA infection there are other antibiotics that can be used.

What is infection vs. colonization?
An infection means that germs are in or on the body and make you sick which results in signs and symptoms such as fever, pus from a wound, a high [[white blood cell count]], or pneumonia. Germs can also be in the body, but not make you sick. This is called colonization. People who are colonized will have no signs or symptoms. They feel fine. MRSA can cause infection or colonization.

What are the risk factors for getting MRSA?
Patients who have been in a hospital for a long time, sick with a long term illness, are on dialysis, or those who use IV drugs are at risk of getting MRSA.

How do I know if I have MRSA?
Your doctor may order a test sample from your wound, blood, urine, nose, or sputum to be sent to the lab. This test is called a culture. If there is MRSA in the sample, the culture is positive. This means you have MRSA in your body.

What will this mean for my hospital care?
All patients who have a positive culture for MRSA are placed in isolation. Isolation is used to keep from spreading MRSA to other patients. There will be a cart outside the room to hold supplies. A card will be placed on the door to alert everyone to what precautions are needed to enter your room. Hospital staff will wear gowns and gloves to care for you and will sometimes wear a mask. Visitors should report to the nurses station for directions on what to do to enter your room. All of these steps are to keep germs from spreading to others.

Am I Contagious?
Contact with the infected/colonized part of the body is usually what spreads MRSA. You can distribute it to anything you touch if you do not clean your hands. Hands may be washed with soap and water for ten seconds or sanitized with an alcohol-based cleanser.
In some cases MRSA will go away for a time, but then it may come back. For this reason, Hospital Epidemiology & Infection Control (HEIC) does not recommend routinely discontinuing isolation.

What will happen when I go home?
At home, in most cases, you only need to use good handwashing. Healthy family members, who do not have large open wounds, skin diseases, or have diabetes, are not likely to get MRSA. Based on your discharge needs, instructions will be given by the nursing staff.

What will happen if I'm back in the hospital or come to the clinic?
The Johns Hopkins Hospital wants to prevent the spread of MRSA. If you come back into the hospital, you will be placed in isolation again. Cultures may be taken to see if MRSA is still present. When you go to the doctor's office or to hospital clinic appointments, you should tell the doctors and nurses that you have MRSA, so they can take steps to avoid spreading it to others.

Will I ever get rid of MRSA?
Over time your normal skin organisms may take the place of MRSA. You will no longer be isolated when cultures are negative for MRSA.

Where can I get more information about MRSA?

Developed by The Johns Hopkins Hospital: Hospital Epidemiology and Infection Control Department.


Antibiotic Selection for Infections Involving Methicillin-Resistant Staphylococcus aureus

John G. Bartlett, MD

Choosing Appropriate Therapy for MRSA

The mainstay antibiotic for treatment of infections caused by MRSA has been vancomycin, a drug that was approved by the US Food and Drug administration (FDA) in 1956 but not used extensively until the last 20 years.[1] The escalating use of vancomycin is attributed to the increase in nosocomial infections caused by MRSA from 2% in 1974 to more than 50% in 2000.[1,21] Vancomycin is used mainly to treat patients with infections caused by MRSA, patients with infections caused by gram-positive bacteria in whom beta-lactam antibiotics are contraindicated, and patients with device- and catheter-associated infections.

Vancomycin has established efficacy and is currently recommended for endocarditic prophylaxis in penicillin-allergic patients undergoing invasive genitourinary or gastrointestinal procedures likely to result in transient bacteremia.[22] However, there are major concerns with the use of this drug. First, rapid infusion with vancomycin is associated with histamine release syndrome (red man syndrome), which usually can be corrected by slow infusion. However, 3% to 4% of patients appear to have true hypersensitivity reactions expressed as a maculopapular rash, and a small percentage have reversible marrow suppression.[21,23] Second, vancomycin is not available in an oral formulation for treatment of systemic infection, so patients are exposed to the risks and expenses of intravenous therapy. Third, some clinicians question the potency of vancomycin in selected settings because of slow clinical responses, clinical failures, and high rates of relapse.[24-28] Finally, many clinicians are concerned about the clinical significance of reduced susceptibility with VISA strains and the threat of vancomycin-resistant S aureus (VRSA).[17,18,29-31] Although the clinical significance of VISA is unclear,[16,29-31] the emergence of this organism alarmed those concerned about possibility of a vancomycin resistant strain. This became a reality in 2002, when the Centers for Disease Control and Prevention (CDC) published reports of 2 patients with infections caused by VRSA.[17,32] In both cases, the isolates contained the vanA gene of vancomycin resistance, presumably by transfer from vancomycin-resistant enterococci (VRE) at a co-infected site.

In April 2004, the CDC reported on the third documented clinical isolate of VRSA, which was obtained from a long-term care facility resident in New York.[33] On March 17, 2003, the isolate yielded S aureus, and laboratory tests indicated that it was resistant to vancomycin. Further testing revealed that the isolate contained both the mecA and vanA genes; however, the CDC states that the isolate appears unrelated epidemiologically to the 2 previously identified VRSA isolates. Although the New York isolate contained the vanA gene, the vancomycin MIC of the isolate appeared low when initially tested by an automated method. Vancomycin resistance was revealed using the broth microdilution reference method, a nonautomated testing technique. The CDC concluded that additional VRSA infections might have occurred but were undetected by laboratories using automated methods and recommends that potential VRSA isolates should be saved for confirmatory testing using nonautomated methods such as broth microdilution, agar dilution, or agar-gradient diffusion. The patient remains in a long-term care facility, and the New York State Department of Health continues to investigate this case

In the past 5 years, the FDA has approved 3 alternatives to vancomycin for treatment of infections caused by MRSA: quinupristin-dalfopristin, linezolid, and daptomycin. These agents have good in vitro activity against MRSA and most other clinically important gram-positive bacterial pathogens. A general comparison of these drugs is summarized in Table 3. In addition, important advantages and disadvantages of these drugs include the following:


Bactericidal vs Bacteriostatic Agents

Clinicians continue to debate the relevance of choosing a bactericidal over a bacteriostatic agent for the treatment of infections. The first publication dealing with the distinction of antimicrobial agents as bactericidal or bacteriostatic is credited to Shah and colleagues[40] in the 1970s, and the implication is that bactericidal agents kill microbes, whereas bacteriostatic agents simply inhibit growth. The thesis is attractive for clinical use, based on the intuitive conclusion that bactericidal activity is preferred. Nevertheless, despite nearly 30 years of debate, no consensus exists regarding the clinical utility of this distinction.

Bacteriostatic agents include macrolides, tetracyclines, sulfonamides, clindamycin, linezolid, and chloramphenicol. An antimicrobial agent is considered bacteriostatic when the minimal bactericidal concentration (MBC)/MIC ratio is greater than or equal to 16 for the pathogen isolated. When the MBC/MIC ratio is less than or equal to 4, the agent is considered bactericidal. The National Clinical Committee for Laboratory Standards (NCCLS) further suggests that an agent is bactericidal when it causes greater than a 3-log (99.9%) reduction in colony-forming units (CFU)/mL after 18 to 24 hours of incubation in liquid media.[41] To insure an accurate estimation of approximately 99.9% killing, the inoculum used to perform MBC analysis must be at least 5x105 CFU/mL in a volume of 0.01 mL.

Bactericidal agents include beta-lactams, aminoglycosides, vancomycin, fluoroquinolones, daptomycin, and metronidazole. The traditional definition of bactericidal activity is based on in vitro activity showing the usual 99.9% (3-log) inhibition of growth. The typical method to testing this in the laboratory has been the standard broth microdilution susceptibility test to determine the MIC and MBC. After incubation for 18 to 24 hours, the wells that fail to show macroscopic growth are subcultured to determine the MBC, which is usually identical to or within 1 or 2 doubling dilutions of the MIC; if the MBC exceeds the MIC by 32-fold or more, the microbe is defined as tolerant. The literature on the clinical relevance of tolerant strains of S aureus is extensive, but the data are difficult to interpret because of variations in methods and definitions.[42,43]

Time-kill curve studies are another method of determining the rate at which antibiotics kill bacteria. These studies measure microbial killing as a function of time and concentration and result in a definition of 4 different classes of microbe-drug interaction.[44] One concern, however, is the feasibility of routine laboratory use of time-kill curve studies because of the complexity of the testing, lack of consensus regarding interpretation, and expense. Possible exceptions to this concern are the use of the time-kill curve to study drug interactions and to evaluate the synergy of penicillins and aminoglycosides in the treatment of endocarditis caused by enterococci. The serum bactericidal test (SBT), or the Schlichter test, which is a modification of the broth dilution method, has been used for more than 40 years to determine bactericidal activity.[45] A potential advantage of this method is that serum from the infection site, such as joint or cerebrospinal fluid, can be used to measure bactericidal activity; however, this test rarely is used because of the technical difficulties in standardizing and interpreting the test results.


Methicillin-Resistant Staphylococcus aureus Disease in Three Communities

Scott K. Fridkin, M.D., Jeffrey C. Hageman, M.H.S., Melissa Morrison, M.P.H., Laurie Thomson Sanza, R.N., Kathryn Como-Sabetti, M.P.H., John A. Jernigan, M.D., Kathleen Harriman, Ph.D., Lee H. Harrison, M.D., Ruth Lynfield, M.D., Monica M. Farley, M.D., for the Active Bacterial Core Surveillance Program of the Emerging Infections Program Network


Background Methicillin-resistant Staphylococcus aureus (MRSA) infection has emerged in patients who do not have the established risk factors. The national burden and clinical effect of this novel presentation of MRSA disease are unclear.

Methods We evaluated MRSA infections in patients identified from population-based surveillance in Baltimore and Atlanta and from hospital-laboratory–based sentinel surveillance of 12 hospitals in Minnesota. Information was obtained by interviewing patients and by reviewing their medical records. Infections were classified as community-acquired MRSA disease if no established risk factors were identified.

Results From 2001 through 2002, 1647 cases of community-acquired MRSA infection were reported, representing between 8 and 20 percent of all MRSA isolates. The annual disease incidence varied according to site (25.7 cases per 100,000 population in Atlanta vs. 18.0 per 100,000 in Baltimore) and was significantly higher among persons less than two years old than among those who were two years of age or older (relative risk, 1.51; 95 percent confidence interval, 1.19 to 1.92) and among blacks than among whites in Atlanta (age-adjusted relative risk, 2.74; 95 percent confidence interval, 2.44 to 3.07). Six percent of cases were invasive, and 77 percent involved skin and soft tissue. The infecting strain of MRSA was often (73 percent) resistant to prescribed antimicrobial agents. Among patients with skin or soft-tissue infections, therapy to which the infecting strain was resistant did not appear to be associated with adverse patient-reported outcomes. Overall, 23 percent of patients were hospitalized for the MRSA infection.

Conclusions Community-associated MRSA infections are now a common and serious problem. These infections usually involve the skin, especially among children, and hospitalization is common.

Source Information

From the Division of Bacterial and Mycotic Diseases (S.K.F.) and Division of Healthcare Quality Promotion (J.C.H., M.M., J.A.J.), National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta; Emory University School of Medicine and the Veterans Affairs Medical Center, Atlanta (M.M., J.A.J., M.M.F.); Johns Hopkins University Bloomberg School of Public Health, Baltimore (L.T.S., L.H.H.); and the Minnesota Department of Health, Minneapolis (K.C.-S., K.H., R.L.).

Address reprint requests to Dr. Fridkin at the CDC, NCID, DBMD, MDB, MS C-09, 1600 Clifton Rd., NE, Atlanta, GA 30333, or at


Community-Associated MRSA — Resistance and Virulence Converge

Henry F. Chambers, M.D.

Laypeople and health care professionals alike recognize Staphylococcus aureus as an important cause of disease and understand that antibiotic-resistant strains pose a threat to the community. Before the availability of antibiotics, invasive staphylococcal disease was often fatal, and the introduction of penicillin in the 1940s dramatically improved survival. Although penicillinase-producing strains soon emerged, methicillin and other penicillinase-stable {beta}-lactam agents filled the breach. However, methicillin-resistant strains of S. aureus (MRSA), which are resistant to the entire class of {beta}-lactam agents, were identified almost immediately and are now found in hospitals worldwide. Despite the growing prevalence of MRSA in hospitals, these strains . . .


Vancomycin-intermediate Staphylococcus aureus selected during vancomycin therapy of experimental endocarditis are not detected by culture-based diagnostic procedures and persist after treatment arrest.

Dec. 2011
Moreillon P, Bizzini A, Giddey M, Vouillamoz J, Entenza JM.


Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland.


ObjectivesLaboratory detection of vancomycin-intermediate Staphylococcus aureus (VISA) and their heterogeneous VISA (hVISA) precursors is difficult. Thus, it is possible that vancomycin failures against supposedly vancomycin-susceptible S.aureus are due to undiagnosed VISA or hVISA. We tested this hypothesis in experimental endocarditis.MethodsRats with aortic valve infection due to the vancomycin-susceptible (MIC 2 mg/L), methicillin-resistant S. aureus M1V2 were treated for 2 days with doses of vancomycin that mimicked the pharmacokinetics seen in humans following intravenous administration of 1 g of the drug every 12 h. Half of the treated animals were killed 8 h after treatment arrest and half 3 days thereafter. Population analyses were done directly on vegetation homogenates or after one subculture in drug-free medium to mimic standard diagnostic procedures.ResultsVancomycin cured 14 of 26 animals (54%; P < 0.05 versus controls) after 2 days of treatment. When vegetation homogenates were plated directly on vancomycin-containing plates, 6 of 13 rats killed 8 h after treatment arrest had positive cultures, 1 of which harboured hVISA. Likewise, 6 of 13 rats killed 3 days thereafter had positive valve cultures, 5 of which harboured hVISA. However, one subculture of vegetations in drug-free broth was enough to revert all the hVISA phenotypes to the susceptible pattern of the parent. Thus, vancomycin selected for hVISA during therapy of experimental endocarditis due to vancomycin-susceptible S. aureus. These hVISA were associated with vancomycin failure. The hVISA phenotype persisted in vivo, even after vancomycin arrest, but was missed in vitro after a single passage of the vegetation homogenate on drug-free medium.ConclusionshVISA might escape detection in clinical samples if they are subcultured before susceptibility tests.


Culture-based detection of methicillin-resistant Staphylococcus aureus by a network of European laboratories: an external quality assessment study.

Dec. 2011
Gazin M, Lee A, Derde L, Kazma M, Lammens C, Ieven M, Bonten M, Carmeli Y, Harbarth S, Brun-Buisson C, Goossens H, Malhotra-Kumar S; on behalf of the MOSAR WP2 Study Team.


Department of Medical Microbiology, Vaccine & Infectious Disease Institute, Universiteit Antwerpen, Antwerp, Belgium.


Twenty-three hospital laboratories from Europe and Israel participated in an external quality assessment (EQA) of the culture-based detection of methicillin-resistant Staphylococcus aureus (MRSA). Participants also reported the MRSA prevalence in clinical cultures and patient screening specimens, as well as the MRSA screening practices employed at their hospitals. An EQA panel of 18 samples consisting of two MRSA harbouring SCCmec IV and I, and one strain each of methicillin-resistantcoagulase-negative S. epidermidis, methicillin-sensitive S. aureus and Escherichia coli as pure strains or in mixtures at 10(7)-1 cfu absolute loads was analysed by the 23 participants. Seventeen (74%) participants identified 17 or more samples correctly. Of these, 15 (88%) utilised a chromogenic medium alone (ChromID, bioMérieux; BBL CHROMagar, BD Diagnostics; MRSA Select, Bio-Rad Laboratories) or combined with a conventional medium and up to three confirmatory tests. Proportions of MRSA among S. aureus isolated from clinical cultures varied widely, even among hospitals within countries, ranging from 11-20% to 61-70%. MRSA carriage rates were less variable (0-20%) between countries. Almost all participants (n = 22, 96%) screened patients for MRSA carriage during 2009-2010, of which 15 (68%) screened intensive care unit (ICU) patients alone or combined with other targeted high-risk groups, and 10 (45%) combined nasal screening with another body site.

[PubMed - as supplied by publisher]


External Links:

Methicillin Resistant Staphylococcus Aureus Infections of Soft Issues of the Oral Cavity, Face and Neck in Patients Hospitalized at the Cranio-maxillofacial Surgery Department. Apr 2011


Optimal dose of vancomycin for treating methicillin-resistant Staphylococcus aureus pneumonia in critically ill patients. Nov 2011


MRSA peritonitis secondary to perforation of sigmoid diverticulitis. Nov 2011


The Epidemiology of Methicillin-Resistant Staphylococcus aureus (MRSA) in Germany. Nov 2011


A Report on The First Case of Vancomycin-Intermediate Staphylococcus aureus(VISA) in Hawai'i. Nov 2011


Staphylococcus aureus (MRSA) in nursing homes for older people. Dec 2011


Changing epidemiology of methicillin-resistant Staphylococcus aureus in the Veterans Affairs Healthcare System, 2002-2009. Dec 2011


PubMed MRSA Abstracts and Articles


Yahoo Health Directory


Methicillin-resistant Staphylococcus aureus (MRSA) infection


Methicillin-resistant Staphylococcus aureus (MRSA) in rehabilitation and chronic-care-facilities: what is the best strategy?


MRSA in Healthcare Settings


Overview of Community-Associated MRSA


CDC Guideline "Management of Mulitdrug-Resistant Organisms in Healthcare Settings


Diagnostic Images:

Visual DX Health




ICD10  Diagnostic Code:


Coding departments should have had a letter giving the following advice about MRSA coding.

There has been a great deal of interest in the incidence of MRSA in hospitals, but codes at present do not distinguish MRSA from other types of staphylococcal infection. It has been decided in Scotland that we will use a 5th digit to identify whether staphylococcal infections are MRSA or not, and when MRSA was identified. Codes affected will be: 

A49.0 – Staphylococcal infection, unspecified

B95.6 – Staphylococcus aureus as the cause of diseases classified to other chapters

A41.0 - Septicaemia due to staphylococcus aureus

G00.3 - Staphylococcal meningitis

P36.2 - Sepsis of newborn due to staphylococcus aureus

Z22.3 – Carrier of other specified bacterial diseases (includes MRSA carrier and MRSA positive) 

Each of these codes will be allocated 5th digits as follows:

 0 not MRSA

1 MRSA identified before admission to this episode

2 MRSA identified after admission to this episode

3 MRSA not known when identified

9 Not known whether MRSA 

Note that the time identified refers to the episode, so the 5th digit could change between episodes in the same hospital stay. 

Also if MRSA infection has been identified and coded, it is not necessary to add a code for MRSA carrier or MRSA positive (Z22.3)

ICD 9 Diagnostic Code

V09.0 Infection with microorganisms resistant to penicillins
Methicillin-resistant staphylococcus aureus (MRSA)


Related Lymphedema People Medical Blogs and Pages:


Antibiotics Blog

Antibiotic Glossary

Antibiotic Therapy, Types of Antibiotics

Bacterial Infections Blog



Cat Scratch Fever

Cellulitis Blog


Complications of Cellulitis




Infectious Disease Doctor



MRSA Information Blog

Methicillin Resistant Staphylococcus Aureus - MRSA

Necrotizing Fasciitis

Preventing Hospital Infections


Join us as we work for lymphedema patients everywehere:

Advocates for Lymphedema

Dedicated to be an advocacy group for lymphedema patients. Working towards education, legal reform, changing insurance practices, promoting research, reaching for a cure.


Pat O'Connor

Lymphedema People / Advocates for Lymphedema


For information about Lymphedema\

For Information about Lymphedema Complications

For Lymphedema Personal Stories

For information about How to Treat a Lymphedema Wound

For information about Lymphedema Treatment

For information about Exercises for Lymphedema

For information on Infections Associated with Lymphedema

For information on Lymphedema in Children

Lymphedema Glossary


Lymphedema People - Support Groups


Children with Lymphedema

The time has come for families, parents, caregivers to have a support group of their own. Support group for parents, families and caregivers of chilren with lymphedema. Sharing information on coping, diagnosis, treatment and prognosis. Sponsored by Lymphedema People.



Lipedema Lipodema Lipoedema

No matter how you spell it, this is another very little understood and totally frustrating conditions out there. This will be a support group for those suffering with lipedema/lipodema. A place for information, sharing experiences, exploring treatment options and coping.

Come join, be a part of the family!




If you are a man with lymphedema; a man with a loved one with lymphedema who you are trying to help and understand come join us and discover what it is to be the master instead of the sufferer of lymphedema.



All About Lymphangiectasia

Support group for parents, patients, children who suffer from all forms of lymphangiectasia. This condition is caused by dilation of the lymphatics. It can affect the intestinal tract, lungs and other critical body areas.



Lymphatic Disorders Support Group @ Yahoo Groups

While we have a number of support groups for lymphedema... there is nothing out there for other lymphatic disorders. Because we have one of the most comprehensive information sites on all lymphatic disorders, I thought perhaps, it is time that one be offered.


Information and support for rare and unusual disorders affecting the lymph system. Includes lymphangiomas, lymphatic malformations, telangiectasia, hennekam's syndrome, distichiasis, Figueroa
syndrome, ptosis syndrome, plus many more. Extensive database of information available through sister site Lymphedema People.




Lymphedema People New Wiki Pages

Have you seen our new “Wiki” pages yet?  Listed below are just a sample of the more than 140 pages now listed in our Wiki section. We are also working on hundred more.  Come and take a stroll! 

Lymphedema Glossary 


Arm Lymphedema 

Leg Lymphedema 

Acute Lymphedema 

The Lymphedema Diet 

Exercises for Lymphedema 

Diuretics are not for Lymphedema 

Lymphedema People Online Support Groups 



Lymphedema and Pain Management 

Manual Lymphatic Drainage (MLD) and Complex Decongestive Therapy (CDT) 

Infections Associated with Lymphedema 

How to Treat a Lymphedema Wound 

Fungal Infections Associated with Lymphedema 

Lymphedema in Children 


Magnetic Resonance Imaging 

Extraperitoneal para-aortic lymph node dissection (EPLND) 

Axillary node biopsy

Sentinel Node Biopsy

 Small Needle Biopsy - Fine Needle Aspiration 

Magnetic Resonance Imaging 

Lymphedema Gene FOXC2

 Lymphedema Gene VEGFC

 Lymphedema Gene SOX18

 Lymphedema and Pregnancy

Home page: Lymphedema People

Page Updated: Dec. 15, 2011