Vancomycin-Resistant Staphylococcus Aureus (VRSA)

Original Editor - Audrey Brown
Top Contributors - Audrey Brown

Introduction[edit | edit source]

Under a very high magnification of 50,000x, this scanning electron micrograph (SEM) shows a strain of Staphylococcus aureus bacteria taken from a vancomycin intermediate resistant culture (VISA).

Bacteria may sometimes evolve to become resistant to antibiotics. Whenever this occurs, these new bacteria are called "antibiotic resistant". Staphylococcus aureus, also known as "staph", is a common type of bacteria that is often found on the skin and in the nose of healthy, asymptomatic people.[1]Over time, staph bacteria have become difficult to treat with certain types of antibiotics, including vancomycin and methicillin.[1] Vancomycin-resistant Staphylococcus aureus (VRSA) is a type of antimicrobial-resistant bacteria that was first reported in the US in 2002.[2][3]

Vancomycin-intermediate S. aureus (VISA) bacteria are moderately resistant to antibiotics, while VRSA bacteria are strongly resistant to antibiotics.[1]The total number of human VRSA infections to date is only 15 known in the US, with the most recent occurring in June 2021. [3][4] Most of these strains have been isolated in hospitalized patients, but there have been a few cases reported from the community.[5]

With the discovery of penicillin in 1941, infectious disease, including those caused by S. aureus became treatable through antibiotics. However, the bacteria S. aureus developed rapid antibiotic resistance only a few years after the first use of penicillin (PRSA).[3] In the late 1950s, Methicillin was introduced as a therapy for PRSA infections. In a similar cycle to penicillin, the first MRSA strains were reported within two years of clinical use. Vancomycin was then introduced as a therapy for MRSA infections in hospital settings in the 1980s.[3]

Pathological Process[edit | edit source]

VRSA bacteria are spread by direct person-to-person contact, usually on hands. VRSA bacteria may also spread by contact with VRSA-contaminated items, such as bandages, medical equipment, or surfaces. VRSA exposure does not guarantee illness. People who have been exposed to VRSA bacteria may carry the bacteria on their skin or in their nose and may not get sick at all, or may get sick from VRSA days, weeks, or months later.[1]

VRSA strains have been found to have thicker cell walls that strains vulnerable to vancomycin.[5]Vancomycin in VRSA bacteria is trapped in the out layers of the cell wall and sequestered by the bacteria, not deactivated. [5]

Risk Factors[edit | edit source]

Patients with the following conditions are at higher risk for VRSA infection:[1]

  • Co-morbid conditions (ex. diabetes, kidney disease, chronic skin ulcers, gangrenous wounds, surgical wounds)[6][4]
  • Previous infection with MRSA
  • Recent hospitalization
  • Tubes going into the body (ex. catheter)
  • Recent use of vancomycin or other antibiotics, especially glycopeptides[5]
  • Antibiotic use in hospitals, agriculture, fisheries, and animal husbandry[5]

Clinical Presentation[edit | edit source]

Patients with a VRSA infection may exhibit the following signs and symptoms, which are similar to a typical S. aureus infection:[7]

  • Red, warm skin around a wound
  • Soreness, swelling, and drainage from a wound
  • Fever, chills, and body aches
  • Weakness
  • Cough

VRSA strains may also cause serious infections such as bacteremia (infection of bloodstream), pneumonia, endocarditis (infection of heart values), and osteomyelitis (infection of bone).[8]

Diagnostic Procedures[edit | edit source]

Staph bacteria is identified as VRSA based on laboratory testing. These tests determine the minimum inhibitory concentration (MIC) of an antimicrobial agent that inhibit the Staph bacteria growth. Staph bacteria are classified as VRSA if the MIC is ≥16μg/mL.[2]

Management / Intervention[edit | edit source]

If a patient suspects they have a VRSA infection or has been exposed to VRSA, they should immediately contact their healthcare provider. If a patient experiences a sudden shortness of breath, fast heartbeat or chest pain, dizziness, or lips and fingernails turning blue in color, they should seek immediately emergency medical treatment.[7]

Aspects of VRSA management involve systemic antimicrobial therapy, wound care (as wounds provide environments for co-infection and co-colonization of MRSA), and proper patient management such as patient isolation, contact tracing, and notification to infection control and local health authorities.[6]

As of 2010, VRSA is treatable with several FDA-approved drugs. [2]These antimicrobial drugs include quinupristin-dalfopristin and linezolid that act against drug-resistant strains of S. aureus. Another bactericidal agent, Daptomycin, is undergoing clinical trials.[5]

Prevention[edit | edit source]

Preventing the emergence of VRSA/VISA requires a comprehensive approach that includes administrative involvement and measure (e.g. nurse staffing, communication systems, procedures for infection control), education and training of all healthcare personnel, and judicious, rational antibiotic use.[5] Use of personal protective equipment (PPE) and appropriate hand hygiene by healthcare personnel can also reduce the spread of VRSA.[2]

References[edit | edit source]