Vancomycin resistant staphylococcus aureus (vrsa).pptx

2.  VRSA is a type of antibiotic resistant Staph. While most Staph
bacteria can be treated with an antibiotic known as vancomycin,
some have developed a resistance and can no longer be treated
with vancomycin. Other antibiotics can be used to treat VRSA.
 In 1996 the first clinical isolate in japan , then in 2002
vancomycin –resistant S.aureus isolated from intravenous
catheter site in U.S .
 All cases of VRSA in the U.S. began as MRSA and acquired
vancomycin-resistance through co-colonization between MRSA
and vancomycin-resistant enterococci (VRE ).

4.  CDC definitions for classifying isolates of S. aureus with reduced
susceptibility to vancomycin are based on the laboratory breakpoints
established by the Clinical and Laboratory Standards Institute (CLSI).
The CLSI breakpoints for S. aureus and vancomycin were last modified
in :
 Vancomycin-susceptible S. aureus (VSSA)
Vancomycin MIC ≤2 μg/ml
 Vancomycin-intermediate S. aureus (VISA)
Vancomycin MIC =4-8 μg/ml.
 Vancomycin-resistant S. aureus (VRSA)
Vancomycin MIC ≥16 μg/ml.

5.  All VRSA described to date have acquired the Van A vancomycin
resistance gene and operon carried by transposon Tn1546 , commonly
found in vancomycin-resistant enterococci (VRE).
 The mechanism of resistance identified in the transposon Tn1546 -
based antibiotic resistance was shown to involve alteration of this
dipeptide residue from D-ala-D-ala to D-alanyl-D-lactate (D-ala-D-lac),
in peptidoglycan synthesis resulting in vancomycin resistance .

6.  Risk factors :
1. Surgical wound/burn.
2. Diabietes mellitus wounds .
3. Compromised immune system .
4. long durations of antibiotics.
5. beyond hospitals,infecting patients in health care settings
such as nursing homes and rehabilitation facilities.