TABLE 1.
Demographics and clinical features of patients with SAB and microbial characterization of bacterial isolates according to low versus elevated vancomycin MIC
| Variablea | Low MIC (n = 108) | Elevated MIC (n = 134) | P valueb |
|---|---|---|---|
| Demographics | |||
| Age (median [IQR]) (yr) | 64 (44.5–77.5) | 67.5 (50–76) | 0.886 |
| Male sex | 81 (75.0) | 91 (67.9) | 0.227 |
| Caucasian ethnicity | 91 (84.3) | 110 (82.1) | 0.655 |
| Hospital onset | 48 (44.4) | 74 (55.2) | 0.095 |
| Device-associated (no./total evaluablec [%]) | 47/103 (45.6) | 65/129 (50.4) | 0.471 |
| MRSA | 34 (31.5) | 70 (52.2) | 0.001 |
| Vancomycin treatment | 51 (47.2) | 79 (59.0) | 0.069 |
| Relapse (no./total infected [%]) | 8/103 (7.77) | 9/130 (6.9) | 0.806 |
| Persistent bacteremia (no./total evaluablec [%]) | 5/82 (6.1) | 8/115 (7.0) | 0.811 |
| Clinical features | |||
| DNR order (no./total evaluablec [%]) | 34/95 (35.8) | 51/122 (41.8) | 0.368 |
| ICU admission (no./total evaluablec [%]) | 34/107 (31.8) | 40/132 (30.3) | 0.807 |
| Infective endocarditis | 8 (7.4) | 8 (6.0) | 0.655 |
| Sepsis syndrome | 14 (13.0) | 18 (13.4) | 0.915 |
| Pneumonia | 7 (6.5) | 7 (5.2) | 0.677 |
| Osteoarticular | 7 (6.5) | 9 (6.7) | 0.942 |
| Skin and skin structure | 13 (12.0) | 23 (17.2) | 0.265 |
| Disease severity | |||
| APACHE II score (median [IQR]) | 15 (10–19) | 15.5 (11–20) | 0.577 |
| SAPS II score (median [IQR]) | 26 (19–35) | 27 (20–37) | 0.354 |
| Charlson comorbidity index (median [IQR]) | 1 (0–2) | 2 (1–3) | 0.097 |
| Pitt bacteremia score (median [IQR]) | 3 (1–3) | 3 (1–3) | 0.845 |
| Genotype (n)d | |||
| CC8 (69) | 11 (10.2) | 58 (43.3) | <0.001 |
| CC5 (26) | 7 (6.5) | 19 (14.2) | 0.055 |
| CC22 (20) | 20 (18.5) | 0 (0) | <0.001 |
| CC45 (18) | 9 (8.3) | 9 (6.7) | 0.634 |
| CC30 (15) | 8 (7.4) | 7 (5.2) | 0.484 |
| CC1 (14) | 6 (5.6) | 8 (6.0) | 0.891 |
| CC15 (11) | 2 (1.9) | 9 (6.7) | 0.071 |
| CC88 (11) | 11 (10.2) | 0 (0) | <0.001 |
| CC188 (11) | 10 (9.3) | 1 (0.7) | 0.002 |
| agr type (n) | |||
| I (146) | 64 (59.3) | 82 (61.2) | 0.760 |
| II (45) | 14 (13.0) | 31 (23.1) | 0.043 |
| III (48) | 29 (26.9) | 19 (14.2) | 0.014 |
| IV (3) | 1 (0.9) | 2 (1.5) | 0.692 |
| agr dysfunction present | 45 (41.7) | 79 (59.0) | 0.007 |
| Polysaccharide capsule | |||
| cap5 | 42 (38.9) | 27 (20.1) | 0.001 |
| cap8 | 64 (59.3) | 107 (80.0) | <0.001 |
| Antimicrobial resistance gene (antibiotic) | |||
| blaZ (penicillin) | 84 (77.8) | 124 (92.5) | 0.002 |
| ermA (erythromycin) | 10 (9.3) | 63 (47.0) | <0.001 |
| aacA-aphD (gentamicin) | 3 (2.8) | 58 (44.3) | <0.001 |
| mupR (mupirocin) | 0 (0) | 1 (0.8) | 0.368 |
| tetK (tetracycline) | 2 (1.9) | 39 (30.0) | <0.001 |
| fosB (fosfomycin) | 42 (38.9) | 107 (79.9) | <0.001 |
| qacA (quaternary ammonia compounds) | 12 (11.3) | 50 (37.3) | <0.001 |
| Leukocidins or exotoxins | |||
| PVL | 5 (71.4) | 2 (28.6) | 0.148 |
| tst | 7 (46.7) | 8 (53.3) | 0.870 |
| Enterotoxins | |||
| sea | 19 (19.4) | 79 (80.6) | <0.001 |
| seb | 11 (10.9) | 4 (3.0) | 0.015 |
| sec | 23 (21.3) | 2 (1.5) | <0.001 |
| seg | 50 (46.7) | 40 (30.1) | 0.008 |
| Exfoliative toxin etA | 2 (1.9) | 1 (0.8) | 0.435 |
| Adhesion factors | |||
| clfA | 22 (27.9) | 57 (72.2) | <0.001 |
| cna | 63 (41.2) | 90 (58.8) | 0.216 |
| Miscellaneous | |||
| ACME locus | 5 (21.7) | 18 (78.3) | 0.020 |
| sak | 99 (46.1) | 116 (53.9) | 0.210 |
| CHIPS | 61 (57.0) | 46 (43.0) | 0.001 |
| isaB | 68 (54.4) | 57 (45.6) | 0.002 |
| splA | 67 (37.0) | 114 (63.0) | 0.001 |
Data are represented as number (%), unless otherwise indicated. IQR, interquartile range; MRSA, methicillin-resistant S. aureus. DNR, do not resuscitate; ICU, intensive care unit; APACHE, Acute Physiology and Chronic Health Evaluation; SAPS, Simplified Acute Physiology Score; ACME, arginine catabolic mobile element; CHIPS, chemotaxis inhibiting protein of S. aureus.
P values are uncorrected for multiple analyses (as described in Materials and Methods).
“Total evaluable” represents the total number of patients for whom the indicated variable was recorded.
The most common genotypes are recorded. The remaining isolates belonged to CC6 (5), CC7 (2), CC9 (2), CC12 (5), CC20 (6), CC25 (2), CC50 (1), CC59 (3), CC78 (4), CC80 (1), CC93 (3), CC97 (3), CC101 (5), CC361 (2), CC398 (2), unassigned CC on DNA microarray (1; mapped to CC188 on phylogram).