Table 4.
Results in 25 Samples With Positive Molecular Testing and Negative Culture Results
| Sample | Cycle Threshold, No. of Cycles | β-Hemolytic Streptococci Isolated by Culture | Diagnosis | Positive Results of Streptococcal Serology (ASO or ADB) | Possible Explanation for Positive Results |
|---|---|---|---|---|---|
| 1 | 39 | GCS (grade 2+) | Monoarthritis | Yes | Cross-reactive with GCS |
| 2 | 37.5 | GGS (grade 3+) | Pharyngotonsillitis | Not done | Cross-reactive with GGS |
| 3 | 35.1 | None | Pharyngotonsillitis | Yes | True-positive |
| 4 | 32.6 | None | Pharyngotonsillitis | Not done | True-positive |
| 5 | 38.9 | None | Pharyngotonsillitis | Not done | True-positive (but note high cycle threshold) |
| 6 | 36.2 | None | Pharyngotonsillitis | Not done | True-positive |
| 7 | 36 | None | Pharyngotonsillitis | Not done | True-positive |
| 8 | 27.6 | None | Pharyngotonsillitis | Not done | True-positive |
| 9 | 33.9 | None | Pharyngotonsillitis | Not done | True-positive |
| 10 | 38.6 | None | Pharyngotonsillitis | Not done | True-positive (but note high cycle threshold) |
| 11 | 38.1 | None | Pharyngotonsillitis | Not done | True-positive (but note high cycle threshold) |
| 12 | 31.6 | None | Pharyngotonsillitis | Not done | True-positive |
| 13 | 32.5 | None | Pharyngotonsillitis | Not done | True-positive |
| 14 | 31 | None | Pharyngotonsillitis | Not done | True-positive |
| 15 | 31.6 | None | Otitis media and “viral” URTI | Not done | True-positive |
| 16 | 36.5 | None | Definite ARF | Yes | Persistent positive after recent infection |
| 17 | 32.2 | None | Definite ARF | Yes | Persistent positive after recent infection |
| 18 | 34.3 | None | Possible ARF | Yes | Persistent positive after recent infection |
| 19 | 39.2 | None | Possible ARF | Yes | Persistent positive after recent infection (but note high cycle threshold) |
| 20 | 37.2 | None | Possible ARF | Yes | Persistent positive after recent infection |
| 21 | 37.8 | None | Scarlet fever | Yes | Persistent positive after recent infection (but note high cycle threshold) |
| 22 | 42.1 | None | Fever after dental extraction; plaque and erythema of soft palate | Not done | Uncertain (note high cycle threshold) |
| 23 | 32.1 | None | Genitolabial abscess | Yes | Uncertain |
| 24 | 41.8 | None | Lower respiratory tract infection | Yes | Uncertain (note high cycle threshold) |
| 25 | 34.2 | None | Melioidosis | No | False-positive |
Abbreviations: ADB, anti-DNase B; ARF, acute rheumatic fever; ASO, antistreptolysin O; GCS, group C Streptococcus; GGS, group G Streptococcus; URTI, respiratory tract infection.