1. MRSA Definition 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. 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.Staphylococcus aureusbacteriuminfectionsantibiotics beta-lactamspenicillinscephalosporinsStaphylococcus aureusbacteriuminfectionsantibiotics beta-lactamspenicillinscephalosporins

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. 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. Courtesy of the CDC

3. Evolution From 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. Cutaneous abscess caused by methicillin– resistant Staphylococcus aureus bacteria. Courtesy of the CDC

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

6.  Vancomycin100%  Rifampin100%  Chloramphnicole 94  Clindamycin89  Ciprofloxacin87  Co-trimoxazole85  Gentamycin70  Cephalothin70  Amikacin66  Erythromycin70 Pattern of sensitivity Staphylococcus aureus, Nemazi hospital -2000

7. Gentamicin Penicillin G Linozolid Vancomycin Cotrimoxazol Oxacillin Ciprofloxacin Erythromycin Clindamycin Rifampicin Cefexime S 60 (64.5) 9 (9.7) 93 (100) 65 (69.9) 44 (47.3) 58 (62.4) 50 (53.8) 56 (60.2) 71 (76.3) IR 1 (1.1) 3 (3.2) 2 (2.2) 1 (1.1) R 33 (35.5) 84 (90. 3) 27 (29) 46 (49.5) 33 (35.5) 43 (46.2) 37 (39.8) 21 (22.6) 92 (98.9) Total93 (100) 93 (100) 93 (100) 93 (100) Staphylococcus aureus antibiotic pattern in nemazi hospital -2010

8. MRSA in IRAN 224 S.aureus Isolated from: blood210 blood210 Pelural5 Pelural5 CSF5 CSF5 ascitis3 ascitis3 Joint1 Joint1 Total224 Total224

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

10. MRSA & VISA in Iran  Growing on Oxacillin Agar Screen plate (ASP) 224 Isolates 224 Isolates 84(37.5%) positive MIC OX > 8 μg/ml MRSA 84(37.5%) positive MIC OX > 8 μg/ml MRSA  Vancomycin MIC(Etest) All Isolates MIC< 4 μg/ml 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 ER LZD PG TS RP OX CIP C KF AK T VA QD GM FU R53(24)80(36)4(2)215(96)92(41)20(9)78(35)72(32)5(2)71(32)70(31)102(45)0(0)0(0)72(32)8(4) S170(76)130(58)220(98)9(4)131(58)203(90)146(65)148(66)218(97)151(67)150(68)122(55)224(100)224(100)152(68)216(96) IR1(0.5)14(6)0(0)0(0)1(.5)1(.5)0(0)4(2)1(.5)2(1)3(1)0(0)0(0)0(0)0(0)0(0) 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