10.  Bacterial strain typing: 1. understanding the epidemiology of MRSA 2. evaluating the effectiveness of infection control 3. evaluating the effectiveness of antimicrobial prescribing measures.

12. CHEF DR III

14. PFGE results using the standardized European protocol

15. PFGE results using the standardized European protocol and Matushek electrophoresis parameters

16. PFGE results using the standardized Canadian protocol

17. PFGE results for some isolates using the Matushek protocol. M= lambda concatemers, numbers represent the isolates. M 1 2 3 4 5 6 7 8 9 12 14 25 26 M

21. Number and percentage of the PFGE types (designated M1-M6 and uniques) PFGE type Number of isolates (%) M1187 (36.5) M2105 (20.5) M3 27 (5.3) M473 (14.3) M529 (5.7) M67 (1.4) Unique84 (16.4)

25. Figure shows the positive bands at 309 bp with 100 bp molecular weight markers. Isolate identification codes are indicated for each lane. MRSA ATCC 33591 (positive control) and MSSA ATCC 6538 (negative control) are included in the last 2 lanes of the gel.

26. PCR mecA detection No. of isolates No. (%) of isolates with the indicated result Ox-salt agar screen Ox disk diffusion Fox disk diffusion Fox E-test MIC of (µg/ml) PBP2' latex agglutination Growth No growth ResistantSensitiveResistantSensitive<8<8>32PositiveNegative Positive 39 36 (92.3 § ) 3 (7.7) 33 (84.6 § ) 6 (15.4) 33 (84.6 § ) 6 (15.4) 26 (66.7) 13 (33.3 § ) 36 (92.3 § ) 3 (7.7) Negative 24 13 (54.2) 11 (45.8 ¶ ) 5 (20.8) 19 (79.2 ¶ ) 3 (12.5) 21 (87.5 ¶ ) 18 (75 ¶ ) 6 (25) 5 (20.8) 19 (79.2 ¶ ) Evaluation of oxacillin-salt agar screen test, oxacillin and cefoxitin disk diffusion tests, cefoxitin E-test, and PBP2' latex agglutination methods for detection of methicillin resistance in 63 S. aureus isolates Ox=oxacillin, Fox=cefoxitin, PBP2'= penicillin binding protein 2' § = Sensitivity, ¶ = Specificity

28. PCR mecA detection No. of isolates No. (%) of isolates with the indicated result Modified Fox disk diffusion Modified Fox E-test MIC of (µg/ml) Resistant <21 Sensitive >22 <4<4>6>6 Positive 39 35(89.7 § )4(10.3) 35(89.7 § ) Negative 24 3(12.5)21(87.5 ¶ )22(91.7 ¶ )2(8.3) Evaluation of the revised cefoxitin disk diffusion and revised cefoxitin E-test breakpoints for detection of methicillin resistance in the 63 S. aureus isolates Ox=oxacillin, Fox=cefoxitin, PBP2'= penicillin binding protein 2‘ § = Sensitivity, ¶ = Specificity

31. AntibioticTotal susceptibility No. (%) (512) Inpatient isolates No. (%) (397) Outpatient isolates No. (%) (115) VAN512(100)397(100)115(100) Q/D512(100)397(100)115(100) LZD491(95.9)386(97.2)105(91.3) CHL413(80.7)302(76.1)111(96.5) GAT404(78.9)299(75.3)105(91.3) MUP394(77.0)292(73.6)102(88.7) GEN203(39.6)118(29.7)85(73.9) SXT173(33.8)85(21.4)88(76.5) FD22(4.3)15(3.8)7(6.1) FD = fusidic acid, GAT = gatifloxacin, GEN = gentamicin, LZD = linezolid, MUP = mupirocin, Q/D = quinupristin/dalfopristin, SXT = sulfa/trimethoprim, CHL = chloramphenicol, VAN = vancomycin

32. FD = fusidic acid, GAT = gatifloxacin, GEN = gentamicin, LZD = linezolid, MUP = mupirocin, Q/D = quinupristin/dalfopristin, SXT = sulfa/trimethoprim, CHL = chloramphenicol HospitalFDGATGENLZDMUPQ/DSXTCHL A (179)3.484.936.197.874.310020.168.7 B (72)1.488.944.484.773.610045.895.8 C (69)2.987.068.192.888.410066.791.3 D (64)3.156.39.410076.610012.585.9 E (74)9.552.729.794.671.610031.171.6 F (54)7.496.357.498.183.31005090.7

33. The numbers above the columns are the diameters of the zones

34. The numbers above the columns are the MICs in µg/mL

35. VAN= vancomycin, MIN= minocycline, GAT= gatifloxacin, GEN= gentamicin, LZD= linezolid, MUP= mupirocin, Q/D= quinupristin/dalfopristin, SXT= sulfamethoxazole/trimethoprim

36. Antibiotic Susceptibility PatternA (179)B (72)C (69)D (64)E (74)F (54) 1 GAT/LZD/MUP/QD/CHL22.333.315.929.74.124.5 2 GAT/LZD/QD12.80001.40 4 GAT/LZD/MUP/QD12.84.24.39.416.24.1 9 LZD/MUP/QD/CHL9.52.85.823.418.92.0 11 GAT/GEN/LZD/MUP/QD/C11.201.5008.2 16 GAT/GEN/LZD/MUP/QD/SXT/CHL10.12549.33.110.838.8 FD = fusidic acid, GAT = gatifloxacin, GEN = gentamicin, LZD = linezolid, MUP = mupirocin, Q/D = quinupristin/dalfopristin, SXT = sulfamethoxazole/trimethoprim, CHL = chloramphenicol. A-F represent the hospital codes

37. FD = fusidic acid, GAT = gatifloxacin, GEN = gentamicin, LZD = linezolid, MUP = mupirocin, Q/D = quinupristin/dalfopristin, SXT = Sulfamethoxazole/trimethoprim, CHL = chloramphenicol. Isolation period (No.) FDGATGENLZDMUPQ/DSXTCHL 1 (55) 3.696.414.598.285.510021.883.6 2 (206) 3.488.336.998.180.610030.672.3 3 (210) 5.283.851.493.875.610036.282.3 4 (41) 4.851.246.392.782.910039.082.9