TABLE 6.
Results for throat culture-negative/Xpert Xpress Strep A-positive samples (n = 17)d
| Test result | Age (yrs) | Gender | Ethnicity | Indication | Pretreated antibiotics <14 days | Throat swab <14 days | Streptococcal serology | Type of growth on throat culture (gradee) | Xpert CT value | BioGX CT value |
|---|---|---|---|---|---|---|---|---|---|---|
| Positive by BioGX (n = 10)a | 2 | Male | Pacific | Pharyngitis | No | No | Not done | MOF (2) | 33.7 | 33.2 |
| 2.9 | Male | Pacific | Tonsillitis, scarlet fever | Yes , co-trimoxazole for 3 days prior, 1 day of i.v. penicillin prior | Yes, GAS (3 days prior) | Not done | MOF (2) | 31.3 | 31.9 | |
| 5 | Male | New Zealand Māori | Tonsillitis | No | No | Not done | MOF (2) | 33.4 | 31.1 | |
| 6 | Male | Pacific | Pharyngitis | No | Yes, GAS (1 day prior) | Not done | SAGA (1), GCS (FC), MOF (2) | 32.6 | 31 | |
| 9 | Female | Pacific | Recurrent pharyngitis | No | No | Not done | MOF (2), Haemophilus parahaemolyticus (2) | 35.2 | 34.1 | |
| 10 | Female | Pacific | PSGN | Yes , amoxicillin for 4 days prior | Yes, GAS (3 days prior) | Positive | MOF (2) | 35.7 | 39.3 | |
| 10 | Female | Pacific | Possible ARF: chorea, acute on chronic carditis | No | No | Positive | MOF (2), H. parahaemolyticus | 29.2 | 30.5 | |
| 16 | Female | Pacific | Pharyngitis | Yes , erythromycin for 2 days prior | Yes, GAS (1 day prior) | Negative | MOF (1), Corynebacterium urealyticum (2) | 23.2 | 25 | |
| 29 | Female | Pacific | Tonsillitis | Yes , i.m. penicillin given 2 days prior | No | Not done | MOF (2) | 26.1 | 25.5 | |
| 33 | Female | New Zealand Māori | Pharyngitis | No | No | Not done | MOF (2), H. parahaemolyticus (FC) | 32.1 | 33.5 | |
| Total | 9.5 (5.25–14.5)c | 6/10 (60%) female | 8/10 (80%) Pacific | 1/10 ARF, 1/10 PSGN, 1/10 scarlet fever | 4/10 (40%) | 4/10 (40%) positive GAS | 2/10 (20%) positive | 1/10 GCS/SAGA | 31.25 | 31.51 |
| Negative twice by BioGX (n = 7)b | 3.4 | Female | Pacific | Pharyngitis | No | No | Not done | MOF (1) | 39.4 | |
| 3.9 | Male | Pacific | Pharyngitis | No | No | Not done | GGS (FC), MOF (1) | 39.3 | ||
| 6 | Male | Pacific | PSGN | Yes (2/7 prior cefuroxime) | No | Positive | MOF (2), Neisseria flava/Neisseria perflava/Neisseria subflava (2) | 38.2 | ||
| 6 | Male | New Zealand European | Pharyngitis | No | No | Not done | MOF (2) | 38.5 | ||
| 9 | Male | Pacific | Pharyngitis | No | No | Not done | MOF (3), Kingella kingae (FC) | 35.3 | ||
| 13 | Female | New Zealand Māori | Pharyngitis | No | No | Not done | MOF (1), N. subflava (FC) | 36 | ||
| 22 | Female | Pacific | Pharyngitis | No | No | Not done | MOF (1) | 39.5 | ||
| Total | 6 (3.78–10)c | 3/7 (42.9%) Female | 5/7 (71.4%) Pacific | 1/7 PSGN | 1/7 (14.3%) | 0/7 | 1/7 (14.3%) positive | 1/7 GGS | 38.0 |
a
There were 5/10 true positives according to clinical data.
b
There was 1/7 true positive according to clinical data.
c
Data represent median (IQR).
d
Abbreviations: PSGN, poststreptococcal glomerulonephritis; ARF, acute rheumatic fever; GAS, group A streptococcus; CT, cycle threshold; MOF, mixed oropharyngeal flora; SAGA, S. agalactiae; GCS, group C streptococcus; GGS group G streptococcus; i.m., intramuscular; i.v., intravenous.
e
FC, few colonies; 1, light; 2, moderate; 3, heavy.