Table 1. Comparison of antimicrobial resistance patterns of MRSA isolates among medical students over the duration of clinical exposure.
| Antibiotic | Number and percentage (%) of resistant strains in 1st year students, first evaluation (n=112) | Number and percentage (%) of resistant strains in 1st year students, 6 months follow-up and 3rd year students with clinical exposure for 6 months (n=226) | Number and percentage (%) of resistant strains in 5th year students (30 months of clinical exposure) (n=119) | Statistical analysis |
|---|---|---|---|---|
| MRSA (n=7) | MRSA (n=60) | MRSA (n=59) | ||
| Oxacillin MIC range (mg/L)4 to <16 | 5 | 12 | 14 | p=0.081 |
| 16 to <128 | 2 | 32 | 25 | p=0.032, Chi(2)=18.74 |
| >128 | 0 | 16 | 20 | p=0.021, Chi(2)=24.34 |
| DOX | 0 (0%) | 12 (20%) | 39 (66.1%) | p=0.012, Chi(2)=26.21 |
| SXT | 0 (0%) | 6 (10%) | 12 (20%) | p=0.075 |
| DA | 0 (0%) | 6 (10%) | 24 (40.6%) | p=0.011, Chi(2)=22.31 |
| E | 0 (0%) | 6 (10%) | 26 (44.1%) | p=0.012, Chi(2)=28.11 |
| CIP | 0 (0%) | 18 (30%) | 44 (74.5%) | p=0.031, Chi(2)=18.31 |
| LEV | 0 (0%) | 12 (20%) | 24 (40.6%) | p=0.042, Chi(2)=14.73 |
| GEN | 2 (28.5%) | 11 (18.3%) | 32 (54.2%) | p=0.011, Chi(2)=19.21 |
| C | 1 (14.4%) | 4 (6.6 %) | 22 (37.2 %) | p=0.021, Chi(2)=21.32 |
| FA | 0 (0%) | 2 (3.3 %) | 18 (31%) | p=0.011, Chi(2)=32.74 |
C – chloramphenicol; CIP – ciprofloxacin; DA – clindamycin; DOX – doxycycline; E – erythromycin; FA – fusidic acid; GEN – gentamicin; LEV – levofloxacin; SXT – sulfamethoxazole-trimethoprim.
P<0.05 considered as significant; all MRSA isolates were susceptible to vancomycin, teicoplanin, linezolid and tigecycline.