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MRSA Definition

MRSA Definition.

isham
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MRSA Definition

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  1. MRSADefinition Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterium responsible for difficult-to-treat infections in humans. MRSA is by definition a strain of Staphylococcus aureus that is resistant to a large group of antibiotics called the beta-lactams, which include the penicillins and the cephalosporins.

  2. HA–MRSA Characteristics • Hospital–associated strains of S. aureus still cause about 85% of all MRSA cases. • Hospital patients with S. aureus infections are five times more likely to die in the hospital than are patients without the infection. • Multi-drug resistant (MDR) • Vancomycin is one of the few remaining treatments for HA-MRSA, but it is no longer effective in every case due to rising MICs. Courtesy of the CDC This electron micrograph depicts large numbers of Staphylococcus aureus bacteria, which were found on the inside surface of a catheter. The sticky-looking substance woven between the round cocci bacteria is known as a “biofilm”. Biofilms help to protect the bacteria.

  3. EvolutionFrom HA and CA-MRSA • 1961 – MRSA first described • Until recently, most MRSA infections started in hospitals, especially among surgery and immunocompromised patients. (HA-MRSA) • In the 1990s, new strains of MRSA began to strike healthy people in community settings. (CA-MRSA) • These two types of MRSA are now known as hospital-associated MRSA (HA–MRSA) and community-associated MRSA (CA–MRSA).

  4. CA–MRSA Characteristics • Staphyloccal bacteria that have become resistant to beta-lactam antibiotics but NOT multi-drug resistant (MDR). • Several antibiotics remain effective against CA–MRSA, but it is an aggressive and rapidly evolving form of S. aureus. • Usually appears as a skin infection, but it can spread quickly to a bloodstream infection or a very serious form of pneumonia. Courtesy of the CDC Cutaneous abscess caused by methicillin–resistant Staphylococcus aureus bacteria.

  5. MRSAPrevalence in Shiraz • Prevalence is increasing!! MRSA in Nemazi hospital patients • 2000 = 33% • 2010 = 49.5%

  6. Pattern of sensitivity Staphylococcus aureus, Nemazi hospital -2000 • Vancomycin 100% • Rifampin 100% • Chloramphnicole 94 • Clindamycin 89 • Ciprofloxacin 87 • Co-trimoxazole 85 • Gentamycin 70 • Cephalothin 70 • Amikacin 66 • Erythromycin 70

  7. Staphylococcus aureus antibiotic pattern in nemazi hospital -2010

  8. MRSA in IRAN 224 S.aureus Isolated from: • blood 210 • Pelural 5 • CSF 5 • ascitis 3 • Joint 1 • Total 224

  9. Staphylococcus aureus Identification • Isolates identification: • Gram Stain ●Catalase • Coagulase ●Dnase • Antibiotic Susceptibility Test • Disk diffusion Method (CLSI protocol) • MRSA & VRSA : • Oxacillin & Vancomycin screen plate • MIC determination (E test) for Oxacillin & Vancomycin

  10. MRSA & VISA in Iran • Growing on Oxacillin Agar Screen plate (ASP) • 224 Isolates • 84(37.5%) positive MICOX> 8 μg/ml MRSA • Vancomycin MIC(Etest) • All Isolates MIC< 4 μg/ml No suspected VISA/VRSA

  11. Reporting:(according CLSI 2006 ) • MRSA and methicillin-resistant, coagulase-negative staphylococci should be reported as resistant to all other penicillins, carbapenems, cephems, and β-lactam/β-lactamase inhibitor combinations, regardless of in vitro test results with those agents.

  12. Staphylococcus aureus in Iran(N0=224) CD=Clindamycin, ER=erythromycin, LZD=linezolid, PG=PenicillinG, TS=Co-trimoxazol, RP=Rifampin, OX=Oxacillin, CIP=Ciprofloxacin, C=Chloramphenicol, KF=Cephalothin, AK=Amikacin, T=Tetracycline, VA=Vancomycin, QD=Quinupristin-dalfopristin, GM=Gentamycin, FU=Fusidic acid

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