Baseline characteristics of enrolled patients
| Characteristic | Clinical values | Full analysis set (n=400) |
| Age (years) | Mean (SD) | 63.1 (13.3) |
| Median, [range] and (IQR) | 63.0 [26-99] (54.0, 73.0) | |
| Sex | Male | 316 (79.0%) |
| Female | 84 (21.0%) | |
| Ethnicity | White | 377 (94.3%) |
| Other | 23 (5.7%) | |
| Site of recruitment | Hospital ward | 53 (13.3%) |
| Outpatient clinic | 319 (79.8%) | |
| Community clinic | 28 (7.0%) | |
| Diabetes type | Type 1 | 58 (14.5%) |
| Type 2 | 342 (85.5%) | |
| Duration of diabetes (years) | n Missing | 3 |
| Mean (SD) | 16.8 (11.0) | |
| Median, [range] and (IQR) | 15.0 [0.04–57) (9.0, 23.0) | |
| Diabetes treatment details | Oral hypoglycaemic agent | 107 (27.8%) |
| Insulin | 168 (43.6%) | |
| Oral hypoglycaemic agent and insulin | 109 (28.3%) | |
| Other | 1 (0.3%) | |
| None | 15 (3.8%) | |
| Number of foot ulcers | 1 | 268 (67.0%) |
| ≥2 | 132 (33.0%) | |
| Duration of index ulcer (months) | n Missing | 4 |
| Mean (SD) | 5.58 (12.28) | |
| Median,[range] and (IQR) | 1.84 [0.1–144.0] (0.69, 6.00) | |
| Aetiology of index ulcer | Ischaemic | 14 (3.5%) |
| Neuropathic | 202 (50.5%) | |
| Ischaemic and neuropathic | 182 (45.5%) | |
| Missing | 2 (0.5%) | |
| Antimicrobial dressing on ulcer | Yes | 241 (60.3%) |
| No | 154 (38.5%) | |
| Missing | 5 (1.3%) | |
| Patient already on systemic antibiotics | Yes | 187 (46.8%) |
| No | 194 (48.5%) | |
| Missing | 19 (4.8%) | |
| Patient on antibiotics immediately after sampling | Yes | 374 (93.5%) |
| No | 26 (6.5%) | |
| Grade (Wagner scale)* | Grade 1 | 136 (34.0%) |
| Grade 2 | 134 (33.5%) | |
| Grade 3 | 122 (30.5%) | |
| Grade 4 | 7 (1.8%) | |
| Grade 5 | 1 (0.3%) |
*Grade 1—superficial diabetic ulcer (partial or full thickness); grade 2—ulcer extension ligament, tendon, joint capsule, or deep fascia without abscess or osteomyelitis; grade 3—deep ulcer with abscess, osteomyelitis or joint sepsis; grade 4—gangrene localised to portion of forefoot or heel; grade 5—extensive gangrenous involvement of the entire foot.