"Staph," or staphylococcus, is a type of bacteria that naturally exist in the environment, including on people's skin. If the bacteria enter under the skin through a cut or scrape, the staph bacteria may cause skin infections that look like pimples or boils. Infections caused by staph may be red, swollen, painful, or have pus or other drainage. Most staph infections are minor and can be treated without antibiotics. Some staph infections resist treatment to a class of antibiotics and are known as Methicillin-Resistant Staphylococcus aureus or MRSA. This makes these infections harder to treat because it is resistant to the antibiotic most commonly used. There are however, a couple of other antibiotics to which the bacteria are susceptible and can be used to treat the infection. Show Who is at risk for MRSA infection?People who are generally healthy are not at high risk for MRSA infections. If they get a staph infection, they can usually fight it off. Staph infections, including MRSA infections, occur most frequently among people in hospitals and health-care facilities who have weakened immune systems. MRSA infections are becoming more common in the community, but are still rare. Are school children at greater risk for MRSA infection?The average child is not at increased risk. However, a child who participates in team and contact sports might be. Staph infects a person through skin-to-skin contact; the bacteria must get under the skin through openings such as cuts or abrasions. The risk increases if children share personal items, such as towels or razors. Staph-contaminated items and surfaces, crowded conditions, and poor personal hygiene increase the risk of infection, and may be found in school settings. However, it is important to note that staph infections can be prevented by simple measures such as washing hands thoroughly before cooking or eating and after using the restroom, and cleaning and covering all cuts and scrapes until they are healed. Is a MRSA infection treatable?MRSA infections are treated effectively using other antibiotics and draining the infected site of pus. More serious infections, such as pneumonia, bloodstream infections, or bone infections, are very rare in healthy people who get MRSA infections. How can I protect myself from MRSA and staph infections?It is important to practice good hygiene. You can protect yourself from infections by:
In the community, contact your doctor if you think you have an infection. Early treatment is very important.
The prevention of MRSA infections in health care is based upon standard infection control precautions, which include routine practices, and contact precautions as required for all antibiotic-resistant organisms. Steps include, but are not limited to: Source ControlContact precautions should be used with patients with known or suspected infections. It is not necessary to wait for testing to confirm a diagnosis. Use contact precautions (e.g., procedures to prevent droplet or aerosols). Post signs at the entrance to patient area. Single patient rooms may be used with designated toilets and sinks. Separating patients by 2 metres may also be used when a respiratory infection is present. Hand HygieneHand hygiene can be performed with an alcohol-based hand rub or with soap and water. Alcohol-based hand rub is used at the point of care in healthcare settings when hands are not visibly soiled. If hands are visibly soiled, wash with soap and water. GlovingWear gloves when touching blood, body fluids and contaminated items. Remove gloves between patient contacts and clean hands immediately. MaskingWear a mask and eye protection, or face shields, or masks with a visor attachment during procedures that are likely to generate splashes or droplets of respiratory secretions, blood, or body fluids. GowningLong-sleeved cuffed gowns are not routine, but may be needed in specific situations. Follow your organization’s policies. Patient Care EquipmentAppropriate cleaning, disinfection and sterilization of patient care equipment and rooms are important in limiting the transmission of organisms. Equipment may be dedicated to a single patient when possible. Surfaces that are likely to be touched or used should be cleaned and disinfected more frequently (e.g., bedrails, tables, call bells, door knobs, bathroom facilities, etc.). Education of Patient, Families and VisitorsAll people involved should be educated about the importance of the precautions being used to help prevent the transmission of the disease. Hand hygiene is particularly important. Handling of LaundryIn healthcare settings, while care should be taken when handling soiled linen, special handling of linen from patients with additional precautions is not required. When at home, linens, wash towels and bed linens in a washing machine set to the hottest water setting (with added bleach, if possible) and dry them in a hot dryer. Wash gym and athletic clothes after each wearing. For further information refer to Routine Practices and Additional Precautions for Preventing the Transmission of Infection in Healthcare Settings (2107) from the Public Health Agency of Canada. See the OSH Answers on Antibiotic/Antimicrobial Resistance in Bacteria and Organisms for more information.
Surveillance of drug-resistant strains of MRSA As strains of staph continue to adapt and change over time, it is critical for healthcare workers to track these changes. They need to know which strains are present within a community at any point in time, to which antibiotics the strains are resistant, and the severity of disease caused by the circulating strains. Two researchers affiliated with the Department of Molecular Virology Microbiology at Baylor College of Medicine, Drs. Edward Mason and James Versalovic and their colleagues have been conducting surveillance of both HA-MRSA and CA-MRSA in pediatric patients at Texas Children’s Hospital beginning in 2001. By analyzing strains isolated from these patients, the scientists have found that CA-MRSA accounts for an increasing percentage and number of infections. This information can help doctors select the optimal antibiotic treatment for infected patients. Genetics changes in MRSA Scientists would further like to understand the genetic changes in MRSA that allow the bacterium to cause serious illness in otherwise healthy individuals. To begin to answer this question, MVM scientists and others at Baylor College of Medicine initiated a project to obtain the DNA sequence of a strain of CA-MRSA called USA300. They chose the USA300 strain, one of two strains that cause the majority of CA-MRSA cases, because it has emerged as the predominant strain causing skin infections, as well as more serious infections, in both pediatric and adult patients in many states. Before 2000 this strain was rarely found in the community; today it accounts for 70 percent of CA-MRSA patients at Texas Children’s Hospital. Another reason for the interest in the USA300 strain is that it appears to be more virulent than other strains. Drs. Sarah Highlander and Joseph Petrosino and colleagues at the Baylor Human Genome Sequencing Center sequenced the genome of this MRSA-resistant strain from a pediatric patient along with a community-associated staph strain that is susceptible to methicillin. They then compared the DNA sequences. They also compared the DNA sequence of these strains with the previously published staph genomes of isolates obtained elsewhere. Based on the results of this analysis, the scientists concluded that the USA300 strain that they sequenced was very similar to other staph strains. This suggests that the increased virulence of the USA300 strain is due to subtle genetic changes within its genome. One intriguing finding of their study is that the bacterium has picked up a plasmid that contains a gene that confers resistance to bacitracin, an antibiotic commonly found in over-the-counter skin ointments. With the genetic information describing USA300 in hand, the scientists can now zoom in on the regions that differ from other strains to pinpoint genes that may account for the ability of USA300 to cause serious illness in some people. Mechanism of resistance to methicillin Beta-lactam antibiotics are the most widely used class of drugs for the treatment of bacterial infections. They include penicillin and its derivatives, such as methicillin and amoxicillin. The beta-lactam ring portion of the antibiotic targets the penicillin-binding proteins (PBP), found in the bacterial cell membrane, which function in the synthesis of the cell wall. Binding of the antibiotic to the PBPs prevents the PBPs from performing their essential role and results in the death of the bacterial cell. Dr. Timothy Palzkill, professor of Pharmacology and Chemical Biology and Molecular Virology and Microbiology, and his research team have been studying mechanisms of resistance to methicillin and other beta-lactam antibiotics. Gram-positive bacteria acquire resistance to beta-lactam antibiotics through the production of a protein called PBP2a, which is able to avoid the inhibitory effects of the antibiotics. This is the mechanism by which MRSA is able to persist despite treatment with multiple beta-lactam antibiotics. Dr. Palzkill and coworkers conducted a study in which they found that the protein BLIP-II was able to weakly bind and inhibit PBP2a, making it susceptible to beta-lactam antibiotics. They are continuing this line of research by searching for mutations that increase the affinity of BLIP-II to PBP2a.
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