Table 1.
Percentage of bacterial isolates non-susceptible to specified antimicrobial agents among older versus younger inpatients at Maryland and Chicago between 1999 and 2005
| Non-susceptible (%) |
||||||
|---|---|---|---|---|---|---|
| University of Maryland |
University of Chicago |
|||||
| ≥65 years | <65 years | P | ≥65 years | <65 years | P | |
| S. aureus (methicillin) (n = all isolates) | 1172 | 5051 | 1380 | 2786 | ||
| all isolates | 51.9 | 48.8 | 0.055 | 50.9 | 40.9 | <0.001* |
| isolates from ICU patients only | 48.7 | 37.0 | <0.001* | 49.3 | 40.9 | 0.002* |
| all isolates (>80 versus ≤80 years old) | 49.8 | 49.3 | 0.874 | 52.1 | 43.4 | 0.002* |
| isolates from bloodstream only | 50.2 | 50.6 | 0.238 | 48.3 | 38.9 | 0.004* |
| Enterococcus (vancomycin) (n) | 1775 | 3960 | 702 | 1137 | ||
| all isolates | 16.5 | 19.4 | 0.009* | 20.2 | 25.0 | 0.019* |
| isolates from ICU patients only | 18.4 | 18.9 | 0.779 | 26.1 | 23.4 | 0.409 |
| all isolates (>80 versus ≤80 years old) | 16.0 | 18.7 | 0.184 | 17.0 | 23.9 | 0.032* |
| isolates from bloodstream only | 27.0 | 28.7 | 0.598 | 24.0 | 30.5 | 0.047* |
| Pseudomonas (fluoroquinolones) (n) | 877 | 1966 | 805 | 1201 | ||
| all isolates | 30.1 | 30.3 | 0.931 | 26.2 | 24.0 | 0.257 |
| isolates from ICU patients only | 24.7 | 29.2 | 0.118 | 27.2 | 22.7 | 0.131 |
| all isolates (>80 versus ≤80 years old) | 28.6 | 30.3 | 0.610 | 25.8 | 24.8 | 0.761 |
| isolates from bloodstream only | 30.7 | 24.0 | 0.253 | 26.8 | 24.8 | 0.764 |
| Pseudomonas (imipenem) (n) | 866 | 1977 | 800 | 1199 | ||
| all isolates | 5.9 | 9.5 | 0.002* | 15.8 | 16.3 | 0.759 |
| isolates from ICU patients only | 7.8 | 11.8 | 0.046* | 21.6 | 12.7 | <0.001* |
| all isolates (>80 versus ≤80 years old) | 5.8 | 8.6 | 0.171 | 12.4 | 16.4 | 0.149 |
| isolates from bloodstream only | 2.7 | 11.6 | 0.024* | 18.3 | 18.6 | 0.963 |
| Klebsiella (third-generation cephalosporin)a (n) | 765 | 1577 | 883 | 1048 | ||
| all isolates | 5.2 | 4.8 | 0.619 | 6.3 | 7.3 | 0.430 |
| isolates from ICU patients only | 2.3 | 6.1 | 0.019* | 8.3 | 5.1 | 0.073 |
| all isolates (>80 versus ≤80 years old) | 2.2 | 5.1 | 0.080 | 5.9 | 7.0 | 0.528 |
| isolates from bloodstream only | 6.3 | 7.9 | 0.571 | 6.9 | 8.6 | 0.589 |
| Klebsiella (fluoroquinolone)b (n) | 882 | 1778 | 883 | 1047 | ||
| all isolates | 5.1 | 5.3 | 0.840 | 7.5 | 8.1 | 0.600 |
| isolates from ICU patients only | 3.5 | 6.8 | 0.044* | 9.6 | 6.3 | 0.089 |
| all isolates (>80 versus ≤80 years old) | 3.2 | 5.4 | 0.167 | 5.9 | 8.1 | 0.222 |
| isolates from bloodstream only | 7.9 | 7.3 | 0.816 | 12.5 | 10.8 | 0.622 |
| E. coli (fluoroquinolone)b (n) | 1573 | 3588 | 1788 | 2718 | ||
| all isolates | 17.6 | 13.5 | 0.000* | 12.1 | 8.3 | <0.0001* |
| isolates from ICU patients only | 14.9 | 12.1 | 0.150 | 12.2 | 7.4 | 0.007* |
| all isolates (>80 versus ≤80 years old) | 16.7 | 14.6 | 0.234 | 11.7 | 9.5 | 0.065 |
| isolates from bloodstream only | 29.0 | 20.1 | 0.040* | 13.7 | 12.4 | 0.656 |
| E. coli (third-generation cephalosporin)a (n) | 1462 | 3274 | 1788 | 2719 | ||
| all isolates | 4.9 | 3.0 | 0.001* | 3.3 | 3.0 | 0.544 |
| isolates from ICU patients only | 4.6 | 3.4 | 0.328 | 6.5 | 2.2 | <0.0001* |
| all isolates (>80 versus ≤80 years old) | 4.3 | 3.5 | 0.397 | 3.0 | 3.1 | 0.860 |
| isolates from bloodstream only | 9.2 | 5.8 | 0.340 | 2.8 | 4.6 | 0.315 |
aCeftriaxone at Chicago and cefepime at Maryland.
bCiprofloxacin at Chicago and any fluoroquinolone at Maryland.
*P < 0.05, Fisher's exact test.