The use of bacterial DNA from saliva for the detection of GAS pharyngitis

Figures & data

Table 1. Comparison of demographic and clinical characteristics: patients with positive and negative throat cultures.

	Positive culture N = 56	Negative culture N = 44	P Value
Age, years (SD)	8.6 (±3)	8.1(±2.2)	0.41
Female, n (%)	28 (50%)	21 (43.7%)	0.69
GAS in the past 6 months, n (%)	12 (21.4%)	13 (27.1%)	0.45
GAS in the family, n (%)	12 (21.4%)	5 (10.4%)	0.15
Days of disease, days (SD)	1.4(±0.6)	1.5(±0.7)	0.89
Exudate, n (%)	29 (51.8%)	16 (33.3%)	0.11
Fever, n (%)	43 (76.8%)	29 (60.4%)	0.22
Cervical lymph node enlargement, n (%)	10 (17.9%)	10 (20.8%)	0.62
Empirical ABX treatment, n (%)	35 (62.5%)	15 (31.3%)	0.007

Table 2. Comparison of demographic and clinical characteristics: patients with positive throat cultures and positive PCR for GAS.

	Positive culture N = 56	Positive GAS PCR N = 48	P Value
Age, years (SD)	8.6 (±3)	8.5 (±2.8)	0.89
Female (%)	28 (50%)	23 (47.9%)	0.78
GAS in the last 6 months (%)	12 (21.4%)	11 (22.9%)	0.91
GAS in the family (%)	12 (21.4%)	10 (20.8%)	0.85
Days of disease, days (SD)	1.4(±0.6)	1.4 (±0.6)	0.93
Exudate (%)	29 (51.8%)	22 (45.8%)	0.54
Fever (%)	43 (76.8%)	37 (77.1%)	0.97
Cervical lymph node enlargement (%)	10 (17.9%)	7 (14.6%)	0.65
Empirical ABX treatment (%)	35 (62.5%)	32 (66.7%)	0.66

Table 3. Comparison of sensitivity and specificity of Saliva PCR vs. Bacterial cultures as a function of the number of days since manifestation of symptoms.

	All days	Day 1	Day 2–4
sensitivity	79%	75%	90%
specificity	91%	85%	100%
PPV	92%	86%	100%
NPV	77%	73%	85%

Figure 1. Receiver operating characteristics (ROC) Curve for saliva PCR for the diagnosis of GAS infection. Area under the curve (AUC) for saliva PCR was 0.85 (P < 0.001).