1. BJ Newcomer Resident Seminar July 7, 2011

3.  Brief history of MRSA  Index case  Characterization of LA-MRSA  MRSA ST398 Pigs Cattle Foodstuffs Zoonotic potential www.ashleyhardin.wordpress.com

4.  Gram (+), A-T rich cocci  Coagulase positive  Most important human Staph. species  1 of 3 major veterinary Staph. pathogens Cellulitis Osteomyelitis Pododermatitis MASTITIS www.randstarteam.blogspot.com

5.  MRSA contains mecA which conveys methicillin resistance  mecA encodes for penicillin-binding protein (PBP2a)  PBPs normally present in membrane  PBP2a decreased affinity for β -lactams Penicillin binding protein Nestorovich E M et al. PNAS 2002;99:9789-9794

6.  First isolated in UK hospital 1961  1970 – Emerged in U.S.  Most prevalent nosocomial infection Hospital-acquired MRSA (HA-MRSA)  In 2005: 278,000 cases ~95,000 serious infections ~20,000 deaths www.freewebs.com

7.  Most early HA-MRSA belonged to only 5 CC’s  Possessed larger SCCmec types (I-III) Afford resistance to most clinically available abx  Risk factors Prolonged abx therapy Prolonged hospitalization ICU care Surgical procedures  Common cause of: Wound dehiscence Thrombophlebitis UTI’s www.brettwilliams.wordpress.com

8.  Mid 1990’s MRSA infections increasingly documented in non-hospitalized patients Community-acquired MRSA (CA- MRSA)  Most possess smaller SCCmec types (IV, V) Greater suscept. to common abx  Distinct genetic lineage from HA-MRSA  Certain strains toxigenic Panton-Valentine leukocidin (PVL) Phenol-soluble modulin (PSM)

9.  1972 – MRSA first isolated from livestock Mastitic cow in Belgium Concluded isolate was of human origin  1990’s - increased isolation from companion animals Coincided with increase of CA-MRSA www.webweaver.nu

10.  July 2004: MRSA cultured from routine pre-op screening in 6 month old girl No history of traveling, hospital admission  Repeated decolonization attempts unsuccessful  Parents subsequently found to be colonized Voss, A, et al. Emerg Infect Dis. 2005 Dec;11(12):1965-6. www.flickr.com

11.  Family lived on farm and raised pigs  Nov 2004 – pigs tested Initially, nares of 10 pigs cultured - All MRSA negative Subsequently, 30 perineal cultures - 1 MRSA positive culture  Identical strain in pigs, child, and parents www.clker.com/clipart-29067.html Voss, A, et al. Emerg Infect Dis. 2005 Dec;11(12):1965-6.

12.  Jan 2005 – 2 nd pig farmer found colonized Different region  Feb 2005 – Son of swine veterinarian colonized  Admitted to hospital, nurse colonized  Veterinarian colonized  No clinical signs www.stealstreet.com

13.  Regional farmer’s meeting  26 pig farmers screened – throat and nares  6/26 (23%) MRSA colonized  Frequency >760x higher than Dutch population www.cutcaster.com Voss, A, et al. Emerg Infect Dis. 2005 Dec;11(12):1965-6.

14.  Pulsed-field gel electrophoresis (PFGE) Digestion with restriction endonuclease (SmaI) Separation of DNA fragments by electric pulses Current gold standard

15.  Pulsed-field gel electrophoresis (PFGE) Digestion with restriction endonuclease (SmaI) Separation of DNA fragments by electric pulses Current gold standard www.bio.davidson.edu/courses/genomics/method/pulse_field.html

16.  Multi-locus sequence typing (MLST) Sequencing of 7 housekeeping genes Grouped into clonal complexes (CC)  spa-typing – Staphylococcal protein A gene (spa) Profile of repeats within gene  SCCmec typing mec complex – contains mecA gene ccr complex – responsible for mobility

17.  Non-typeable by standard PFGE  Almost all strains in CC398 (ST398)  General absence of PVL and other virulence factors  Virulence/resistance obtained through mobile genetic elements (MGE’s) Staphylococcal chromosomal cassette (SCC) Plasmids via bacteriophages (transduction)  Conjugative plasmids, transformation, transposons and staphylococcal pathogenicity islands (SaPIs) uncommon

18.  Five SCCmec types based on differences in mecA and ccrC genes www.staphylococcus.net

19.  Types I-III often larger, common in HA-MRSA  Types IV, V more common in CA-MRSA  Type IV predominates in human medicine  MRSA ST398: type V www.staphylococcus.net

20.  38 kb type V SCCmec  mecA – confers methicillin resistance  The ccrC gene encodes recombinase Relatively stable Schijffelen et al. BMC Genomics 2010, 11:376

21. GENEFUNCTION/PHENOTYPE ampAApramycin resistance blaZβ-lactam resistance cfrmultiple-antibiotic resistance copAcopper resistance dfrGtrimethoprim resistance dfrKtrimethoprim resistance erm (A)macrolide/lincosamide resistance erm(C)macrolide/lincosamide resistance erm(B)macrolide/lincosamide resistance erm(T)macrolide/lincosamide resistance fexA chloramphenicol/florfenicol resistance mecAmethicillin resistance tet(K)tetracycline resistance tet(L)tetracycline resistance tet(M)tetracycline resistance vga(A)virginiamycin resistance vga(C)virginiamycin resistance  Plasmids form accessory genome  Convey resistance or virulence  Lacking from most MRSA ST398 isolates  Multiple-abx resistance Tetracyclines – always Macrolides, lincosamides, etc +/- fluoroquinolones

22.  Predominant MRSA strain in swine Other recent reports limited to human strains  Most reports from Europe The Netherlands Germany Belgium  Limited reports elsewhere Canada Singapore USA www.netherlands.world-guides.com

23.  Carriage rates vary considerably 10% in Denmark (n=100) 24.9% in Canada (n=285) ~40% in The Netherlands, Germany  Farm prevalence 66% in Denmark (n=3) 45% in Canada (n=20) 68% in Belgium (n=50)  Study differences 81% vs 23% MRSA (+) farms in The Netherlands www.prlog.org

24.  Survey of 2 production systems in IA, IL Comprise ~90,000 animals  Nasal swabs from 299 swine, 20 workers  MRSA prevalence 49% in swine (147/299) 45% in workers (9/20)  MRSA (+) only on Farm A 70% in swine (147/209) 64% in workers (9/14) Smith, TC, et al, PLoS One. 2009;4(1):e4258 www.needalittleadvice.com

25.  Isolates tested by PFGE Non-typeable by smaI, typeable by EagI  MLST revealed clonal isolates Not related to common IA isolates MRSA ST398  Isolates PVL negative  Workers and swine apparently unaffected www.thepigpage.com

26.  Early Belgian study (Willems, 2007) : risk for piglets > sows or fattening pigs  Canadian study (Weese, et al, 2009) : Low prevalence in piglets (<10%) Prevalence peaked at 64% (42 d) Dropped to 41% at study end (70 d)  Other studies show no effect www.thisisstaffordshire.co.uk

27.  Similar results in USA study Smith, TC, et al, PLoS One. 2009;4(1):e4258

28.  LA-MRSA first detected in mastitic milk  Few published reports of MRSA (+) cattle MRSA (+) milk/nasal swab samples in France (Alves, et al., 2009)  MRSA ST398 found in mastitic milk in S. Korea (Lee 2006, Moon 2007) Quarter level prevalence very low (<0.2%) www.farmville.wikia.com

29.  MRSA ST398 never detected in US milk  357 isolates of S. aureus from 24 NC dairy herds (Anderson, et al., 2006) No MRSA isolates  Comprehensive study by NAHMS 2009 (Virgin, et al., 2009)  542 bulk milk tank samples (17 states) No MRSA www.scientificamerican.com

30.  Due to elaboration of enterotoxins Symptoms generally mild Often undiagnosed  One report of MRSA food poisoning (Jones, et al., 2002) Contaminated coleslaw Isolate from hospital origin  No reports of LA-MRSA food intoxication www.mylot.com

31.  MRSA ST398 never detected in US food  Spain survey (Lozano, et al., 2009) : 318 raw meat samples Chicken, pork, veal, lamb, poultry, rabbit, game 2 MRSA ST398 (+) samples: pork and veal www.venere.com

32.  Dutch survey (de Boer, et al., 2009) : 2217 raw meat samples beef, pork, veal, lamb/mutton, chicken, turkey, fowl and game Incidence highest in poultry and veal Also found in turkey, lamb and sheep meat www.thefreedictionary.com

33.  Apparent capacity to transfer with close animal contact Especially swine workers  Also demonstrated in veal farming Lone report of LA-MRSA carriage  Unknown mechanism  No increased risk for dairy/beef farmers www.Ft.com

34.  Pig health conference in Denmark  Nasal/throat swab from 272 registrants  34 (12.5%) MRSA (+) from 9 countries 31/34 MRSA ST398 Wulf, et al., Clin Microbiol Infect. 2008 Jan;14(1):29-34 www.bacontoday.com

35.  Survey of US Veterinary Teaching Hosp.  70 S. aureus isolates, 9/70 MRSA  9 (+)’s: 4 EQ, 4 CN, 1 FE  No MRSA ST398

36.  Prevalent colonizer of swine Less common in other livestock  Poor host specificity Capable of transfer to humans Higher prevalence in livestock workers  Reports of associated disease rare  Potential to acquire virulence or resistance factors

37. www.clker.com

38.  Veterinary University of Austria 140 swabs of wounds/incisions 25 (+) MRSA, 7 MRSA ST398 All contracted after admission  Faculty of Vet Medicine, Ghent University 110 horses screened 12 (+) MRSA ST398 1 infected wound www.itstrulyrandom.com

39.  Cultured from foot ulcer (The Netherlands 2008) 5 other patients colonized No pig or cattle contact  3687 MRSA isolates – Canadian D-labs (2010) 5 MRSA ST398 samples No livestock contact  12 yr old Spanish girl Skin lesion (2010) Near pig farm 2 types isolated  Croatian pig farmer bitten on arm (2008) Complicated soft tissue infection www.northernvirginiamag.com