Table 1.
Individual data for 53 contamination suspect samples
| Sample no. |
Original culture profile | Repeat culture profilea | Unique spoligotype?b |
If nonunique spoligotype, unique RFLP?c |
Clinical follow-up achieved |
Follow-up culture resultd | Microbiologic assessment (reculture) |
Molecular assessment |
Clinical assessment (including follow-up investigations) |
Overall assessment | ||||||
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| MODS | MBBacT | LJ | MODS | MBBacT | LJ | MODS | MBBacT | LJ | 1 = Consistent with cross-contamination, 0 = regarded as excluding cross-contamination |
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| 1 | + | + | − | − | − | − | N | N e | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 2 | + | + | − | + | − | − | Y | − | N | NA | NA | NA | 0 | 0 | 1 | Not cross-contamination |
| 3 | + | + | − | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 1 | Not cross-contamination |
| 4 | + | + | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 5 | + | + | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 6 | + | − | − | − | − | − | N | Y | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 7 | + | − | − | + | − | − | N | N | Y | NA | NA | NA | 0 | 1 | 1 | Not cross-contamination |
| 8 | + | − | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 9 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 10 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 11 | + | − | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 12 | + | − | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 13 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 14 | + | − | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 15 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 16 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 17 | − | + | − | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 1 | Not cross-contamination |
| 18 | − | − | + | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 1 | Not cross-contamination |
| 19 | + | + | − | − | − | − | N | Y | Y | OT− | OT− | OT− | 1 | 0 | 0 | Not cross-contamination |
| 20 | + | + | − | − | − | − | N | Y | Y | OT− | OT− | OT− | 1 | 0 | 0 | Not cross-contamination |
| 21 | + | + | − | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 22 | + | + | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 0 | Not cross-contamination |
| 23 | + | + | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 0 | Not cross-contamination |
| 24 | + | − | + | + | − | − | N | Y | Y | NA | NA | NA | 0 | 0 | 0 | Not cross-contamination |
| 25 | + | − | − | − | − | − | N | Y | Y | OT− | OT− | OT− | 1 | 0 | 0 | Not cross-contamination |
| 26 | + | − | − | − | − | − | N | Y | Y | OT+ | NA | OT− | 1 | 0 | 0 | Not cross-contamination |
| 27 | + | − | − | − | − | − | N | N | Y | − | − | − | 1 | 1 | 0 | Not cross-contamination |
| 28 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 0 | Not cross-contamination |
| 29 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 0 | Not cross-contamination |
| 30 | + | − | − | − | − | − | Y | − | Y | NA | NA | NA | 1 | 0 | 0 | Not cross-contamination |
| 31 | + | − | + | − | − | − | Y | − | Y | + | + | + | 1 | 0 | 0 | Not cross-contamination |
| 32 | + | − | − | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 33 | + | − | − | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 34 | + | − | − | − | − | − | Y | − | Y | + | − | + | 1 | 0 | 0 | Not cross-contamination |
| 35 | + | − | − | − | − | − | Y | − | Y | + | + | + | 1 | 0 | 0 | Not cross-contamination |
| 36 | + | − | − | − | − | − | NA | − | Y | NA | NA | NA | 1 | NA | 0 | Not cross-contamination |
| 37 | − | + | − | − | − | − | N | Y | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 38 | − | − | + | − | − | − | N | Y | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 39 | − | − | + | − | − | − | Y | − | Y | − | − | − | 1 | 0 | 0 | Not cross-contamination |
| 40 | + | + | − | − | − | − | N | N | Y | − | − | − | 1 | 1 | 1 | Probable cross-contamination |
| 41 | + | + | − | − | − | − | Y | − | Y | OT− | OT− | OT− | 1 | 1f | 1 | Probable cross-contamination |
| 42 | + | + | − | − | − | − | Y | − | N | NA | NA | NA | 1 | 1f | 1 | Probable cross-contamination |
| 43 | + | − | − | − | − | − | Y | Y | Y | NA | NA | NA | 1 | 1g | 1 | Probable cross-contamination |
| 44 | + | − | − | − | − | − | Y | Y | Y | NA | NA | NA | 1 | 1g | 1 | Probable cross-contamination |
| 45 | + | − | − | − | − | − | N | N | Y | NA | NA | NA | 1 | 1 | 1 | Probable cross-contamination |
| 46 | + | − | − | − | − | − | N | N | Y | NA | NA | NA | 1 | 1 | 1 | Probable cross-contamination |
| 47 | + | − | − | − | − | − | N | N | Y | − | − | − | 1 | 1 | 1 | Probable cross-contamination |
| 48 | + | − | − | − | − | − | N | N | Y | NA | NA | NA | 1 | 1 | 1 | Probable cross-contamination |
| 49 | + | − | − | − | − | − | N | N | Y | − | − | − | 1 | 1 | 1 | Probable cross-contamination |
| 50 | + | − | − | − | − | − | N | N | Y | − | − | − | 1 | 1 | 1 | Probable cross-contamination |
| 51 | + | − | − | − | − | − | NA | − | Y | NA | NA | NA | 1 | NA | 1 | Probable cross-contamination |
| 52 | − | + | − | − | − | − | NA | − | Y | OT− | OT− | OT− | 1 | NA | 1 | Probable cross-contamination |
| 53 | − | − | + | − | − | − | NA | − | Y | − | − | − | 1 | NA | 1 | Probable cross-contamination |
Though evidence from 1 approach may have implied that cross-contamination was unlikely, in some instances, evidence to the contrary was regarded as superior (e.g., unique and different molecular fingerprints were observed for 2 cultures from the same participant in whom there was no clinical suspicion of disease—she had attended the NTP asymptomatically for an insurance screen). NA = not available.
+ = reculture of original sample positive; − = reculture of original sample negative.
Unique spoligotype for date of sample processing and 2 days at either side (5-day window); 4 patients had 2 samples with identical spoligotypes (11,12; 10,18; 32,33; 43,44) unique to each patient.
Strains with contemporary matching spoligotypes were also typed by RFLP to further aid discrimination; thus, “unique RFLP” refers to differentiation from strains with shared spoligotype.
All results are in duplicate (i.e., 2 samples processed); OT = follow-up sample taken on TB therapy.
Cultured strains from samples 45 and 1, but no other contemporarily processed samples shared identical spoligotypes and RFLP patterns; 45 probably cross-contaminated from 1.
Spoligotypes for 2 isolates from the same sample differ.
Although spoligotypes for these 2 samples from the same patient are temporally unique, they differ from each other, as do their RFLP patterns.