Table 2.
Characteristics and clinical outcomes of hospitalized patients with CRPA, stratified by two definitions of heteroresistance (HR1 and HR2) to colistin
| Characteristic or outcome | HR1a |
HR2c |
|||||
|---|---|---|---|---|---|---|---|
| Total (N = 82) | Not heteroresistant (N = 77) | Heteroresistant (N = 5) | P valueb | Not heteroresistant (N = 58) | Heteroresistant (N = 24) | P valued | |
| Age category (years), n (%) | 0.7 | 0.2 | |||||
| 19–49 | 21 (26) | 19 (25) | 2 (40) | 18 (31) | 3 (13) | ||
| 50–64 | 24 (29) | 22 (29) | 2 (40) | 14 (24) | 10 (42) | ||
| 65–79 | 28 (34) | 27 (35) | 1 (20) | 20 (34) | 8 (33) | ||
| >79 | 9 (11) | 9 (12) | 0 (0) | 6 (10) | 3 (13) | ||
| Male (N = 81), n (%) | 45 (56) | 43 (57) | 2 (40) | 0.7 | 32 (56) | 13 (54) | 0.9 |
| Race (N = 79), n (%) | 0.4 | 0.7 | |||||
| Black | 47 (59) | 45 (61) | 2 (40) | 34 (62) | 13 (54) | ||
| White | 31 (39) | 28 (38) | 3 (60) | 20 (36) | 11 (46) | ||
| Other or multiracial | 1 (1) | 1 (1) | 0 (0) | 1 (2) | 0 (0) | ||
| CCI > 2, n (%) | 35 (43) | 34 (44) | 1 (20) | 0.4 | 28 (48) | 7 (29) | 0.11 |
| Residence 3 days prior to culture, n (%) | 0.7 | 0.8 | |||||
| Inpatient | 41 (50) | 38 (49) | 3 (60) | 29 (50) | 12 (50) | ||
| LTCF or LTACH | 17 (21) | 17 (22) | 0 (0) | 11 (19) | 6 (25) | ||
| Private residence | 24 (29) | 22 (29) | 2 (40) | 18 (31) | 6 (25) | ||
| Admitted to ICU in prior week, n (%) | 24 (29) | 23 (30) | 1 (20) | 1.0 | 20 (34) | 4 (17) | 0.11 |
| Culture source, n (%) | 1.0 | 0.16 | |||||
| Sterile site | 12 (15) | 11 (14) | 1 (20) | 11 (19) | 1 (4) | ||
| Lower respiratory tract | 28 (34) | 26 (34) | 2 (40) | 20 (34) | 8 (33) | ||
| Urine | 25 (30) | 24 (31) | 1 (20) | 14 (24) | 11 (46) | ||
| Wound | 17 (21) | 16 (21) | 1 (6) | 13 (22) | 4 (17) | ||
| Days from admission to discharge, median (IQR) | 16 (7–49) | 15 (6–44) | 21 (13–60) | 0.4 | 15 (6–44) | 19 (9–64) | 0.5 |
| Days from culture to discharge, median (IQR) | 10 (6–24) | 10 (6–24) | 17 (11–47) | 0.3 | 9 (5–20) | 16 (9–28) | 0.09 |
| 90 day mortality, n (%) | 17 (21) | 17 (22) | 0 (0) | 0.6 | 14 (24) | 3 (12) | 0.4 |
LTCF, long-term care facility; LTACH, long-term acute care hospital.
Patients with an isolate that met criteria for the HR1 definition: growth of a resistant subpopulation of cells at 4 and 8 mg/L of colistin at a frequency of least 1 × 10−6 the main population on antibiotic-free media.
Compared patients with an HR1 isolate with those that did not, using χ2 or Fisher’s exact test for categorical variables and Mann–Whitney U-test for continuous variables.
Patients with an isolate that met criteria for the HR2 definition: growth of a resistant subpopulation of cells at a colistin concentration at least 8× higher than the main population MIC, at a frequency of at least 1 × 10−7.
Compared patients with an HR2 isolate with those that did not, using χ2 or Fisher’s exact test for categorical variables and Mann–Whitney U-test for continuous variables.