Comparison of three methods for identification of Gram-negative bacteria and Gram-positive bacteria_
| Method | Identification results | Total | p-value | |
|---|---|---|---|---|
| Gram-negative bacteria | Gram-positive bacteria | |||
| Conventional urine culture | 170 | 41 | 211 | p = 0.135 |
| Centrifugation-based MALDI-TOF MS | 140 | 19 | 159 | |
| Short-term culture combined with MALDI-TOF MS | 155 | 27 | 182 | |
Correlation between colony count and the MALDI-TOF MS identification_
| Germ | Centrifugation-based MALDI-TOF MS No. of cases (%) | Short-term culture combined with MALDI-TOF MS No. of cases (%) | p-value | ||
|---|---|---|---|---|---|
| Detected | Detected | ||||
| Yes | No | Yes | No | ||
| Gram-negative bacteria | |||||
| ≥ 105 CFU/ml | 133/147 (90.5%) | 14/147 (9.5%) | 137/147 (93.2%) | 10/147 (6.8%) | p = 0.394 |
| 104 ~ 105 CFU/ml | 5/15 (33.3%) | 10/15 (66.7%) | 12/15 (80.0%) | 3/15 (20.0%) | p = 0.027 |
| ≤ 104 CFU/ml | 2/8 (25.0%) | 6/8 (75.0%) | 6/8 (75.0%) | 2/8 (25.0%) | p = 0.132 |
| Total | 140/170 (82.4%) | 30/170 (17.6%) | 155/170 (91.2%) | 15/170 (8.8%) | p = 0.016 |
| Gram-positive bacteria | |||||
| ≥ 105 CFU/ml | 15/25 (60.0%) | 10/25 (40.0%) | 18/25 (72.0%) | 7/25 (28.0%) | |
| 104 ~ 105 CFU/ml | 3/12 (25.0%) | 9/12 (75.0%) | 8/12 (66.7%) | 4/12 (33.3%) | |
| ≤ 104 CFU/ml | 1/4 (25.0%) | 3/4 (75.0%) | 1/4 (25.0%) | 3/4 (75.0%) | |
| Total | 19/41 (46.3%) | 22/41 (53.7%) | 27/41 (65.9%) | 14/41 (34.1%) | p = 0.075 |
| Escherichia coli | |||||
| ≥ 105 CFU/ml | 81/87 (93.1%) | 6/87 (6.9%) | 84/87 (96.6%) | 3/87 (3.4%) | p = 0.494 |
| 104 ~ 105 CFU/ml | 2/11 (18.2%) | 9/11 (81.8%) | 9/11 (81.8%) | 2/11 (18.2%) | p = 0.009 |
| ≤ 104 CFU/ml | 1/2 (50.0%) | 1/2 (50.0%) | 2/2 (100.0%) | 0/2 (0.0%) | p = 1.000 |
| Total | 84/100 (84.0%) | 16/100 (16.0%) | 95/100 (95.0%) | 5/100 (5.0%) | p = 0.011 |
| Enterococcus faecalis | |||||
| ≥ 105 CFU/ml | 5/8 (62.5%) | 3/8 (37.5%) | 6/8 (75.0%) | 2/8 (25.0%) | |
| 104 ~ 105 CFU/ml | 2/5 (40.0%) | 3/5 (60.0%) | 3/5 (60.0%) | 2/5 (40.0%) | |
| ≤ 104 CFU/ml | 0/2 (0.0%) | 2/2 (100.0%) | 1/2 (50.0%) | 1/2 (50.0%) | |
| Total | 7/15 (46.7%) | 8/15 (53.3%) | 10/15 (66.7%) | 5/15 (33.3%) | p = 0.462 |
Comparison of MALDI scores between the two methods_
| Germ | Centrifugation-based MALDI-TOF MS | Short-term culture combined with MALDI-TOF MS | p-value | ||
|---|---|---|---|---|---|
| score ± SD | RSD | score ± SD | RSD | ||
| Gram-negative bacteria | 2.18 ± 0.25 | 11.4% | 2.14 ± 0.18 | 8.3% | p = 0.113 |
| Gram-positive bacteria | 2.10 ± 0.19 | 9.1% | 2.03 ± 0.23 | 11.2% | p = 0.282 |
| Total | 2.17 ± 0.24 | 11.2% | 2.09 ± 0.20 | 9.5% | p = 0.003 |
Identification results by conventional culture and two MALDI-TOF MS methods_
| Conventional urine culture (No. of cases) | Centrifugation-based MALDI-TOF MS | Short-term culture combined with MALDI-TOF MS | ||||
|---|---|---|---|---|---|---|
| Score > 1.7 (No. of cases) | Score > 2.0 (No. of cases) | Mean Score ± SD | Score > 1.7 (No. of cases) | Score > 2.0 (No. of cases) | Mean Score ± SD | |
| Escherichia coli (100) | 84 | 75 | 2.22 ± 0.16 | 95 | 87 | 2.17 ± 0.08 |
| Klebsiella pneumoniae (28) | 23 | 18 | 2.16 ± 0.21 | 26 | 22 | 2.18 ± 0.18 |
| Proteus mirabilis (10) | 10 | 8 | 2.18 ± 0.19 | 9 | 6 | 2.04 ± 0.15 |
| Enterobacter cloacae (9) | 8 | 7 | 2.14 ± 0.19 | 8 | 6 | 2.09 ± 0.18 |
| Pseudomonas aeruginosa (7) | 3 | 2 | 1.95 ± 0.13 | 5 | 5 | 2.24 ± 0.09 |
| Enterobacter aerogenes (4) | 3 | 3 | 2.27 ± 0.10 | 4 | 4 | 2.26 ± 0.10 |
| Citrobacter freundii (4) | 4 | 4 | 2.22 ± 0.12 | 4 | 4 | 2.23 ± 0.11 |
| Acinetobacter baumannii (3) | 2 | 1 | 2.14 ± 0.19 | 2 | 1 | 2.03 ± 0.18 |
| Stenotrophomonas maltophilia (3) | 1 | 1 | 2.09 | 0 | 0 | N/A |
| Morganella morganii (2) | 2 | 2 | 2.18 ± 0.16 | 2 | 1 | 2.22 ± 0.28 |
| Enterococcus faecalis (15) | 7 | 5 | 2.15 ± 0.19 | 10 | 6 | 2.03 ± 0.20 |
| Enterococcus faecium (14) | 8 | 6 | 2.08 ± 0.17 | 12 | 7 | 2.04 ± 0.24 |
| Staphylococcus aureus (2) | 1 | 0 | 2.20 | 2 | 1 | 1.96 ± 0.23 |
| Staphylococcus haemolyticus (2) | 0 | 0 | N/A | 1 | 1 | 2.22 |
| Staphylococcus epidermidis (2) | 0 | 0 | N/A | 1 | 0 | 1.76 |
| Streptococcus agalactiae (1) | 1 | 1 | 2.09 | 1 | 1 | 2.15 |
| Streptococcus gallicans (1) | 1 | 1 | 2.20 | 0 | N/A | N/A |
| Streptococcus anginae (1) | 1 | 0 | 1.75 | 0 | N/A | N/A |
| Staphylococcus saprophyticus (1) | 0 | 0 | N/A | 0 | 0 | N/A |
| Enterococcus avium (1) | 0 | 0 | N/A | 0 | 0 | N/A |
| Lactobacillus crispatus (1) | 0 | 0 | N/A | 0 | 0 | N/A |
| Total (211) | 159 | 135 | 182 | 153 | ||