Table 4

Accuracy of surface swabbing (including gastric aspiration) for diagnosing bacterial infection

Study		Year		Reference		Test definition		Incidence of infection		Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	Positive LR (95% CI)	Negative LR
Study		Year		Reference		Test definition		Incidence of infection		Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	Positive LR (95% CI)	Negative LR	Scanlon	1972	49	Ear swab culture	8/67	100	40	18	100	1.56 (1.19 to 2.03)	0.15 (0.01 to 2.23)
Scanlon	1972	49	Ear swab microscopy: ⩾1 PMN	8/67	88	95	70	98	17.21 (5.54 to 53.44)	0.13 (0.02 to 0.83)
Scanlon	1972	49	Gastric aspirate culture	8/67	88	61	23	97	2.25 (1.49 to 3.39)	0.21 (0.03 to 1.30)
Scanlon	1972	49	Gastric aspirate microscopy: >5 PMN/high power field	8/67	88	85	44	98	5.74 (2.98 to 11.05)	0.15 (0.02 to 0.93)
Scanlon	1971	50	Ear swab culture	6/28	100	47	43	100	1.79 (1.05 to 3.04)	0.16 (0.01 to 2.40)
Scanlon	1971	50	Ear swab microscopy: any PMN	6/21	100	93	86	100	14.32 (2.12 to 96.49)	0.08 (0.006 to 1.12)
Scanlon	1971	50	Ear swab microscopy: any organisms seen	6/21	83	67	50	91	2.50 (1.12 to 5.57)	0.25 (0.04 to 1.55)
El-Radhi	1983	22	Gastric aspirate culture (4–28 days old)	44/67	71	100	100	64	33.65 (2.13 to 519.75)	0.30 (0.19 to 0.47)
El-Radhi	1983	22	Gastric aspirate culture (<4 days old)	2/21	50	90	33	94	4.75 (0.71 to 32.00)	0.56 (0.14 to 2.25)
El-Radhi	1983	22	Gastric aspirate microscopy: >3 PMN/HPF (4–28 days)	44/67	82	87	92	71	6.27 (2.16 to 18.19)	0.21 (0.11 to 0.40)
El-Radhi	1983	22	Gastric aspirate microscopy: >3 PMN/HPF (<4 days old)	2/21	100	90	50	100	7.80 (1.83 to 33.32)	0.22 (0.02 to 2.67)
Boyle	1978	12	Gastric aspirate microscopy: any bacteria	7/90	71	78	28	97	3.29 (1.77 to 6.13)	0.37 (0.11 to 1.18)
Boyle	1978	12	Gastric aspirate smear: any PMN	7/90	71	72	18	97	2.58 (1.44 to 4.62)	0.40 (0.12 to 1.29)
Rigal	1990	45	Tracheal aspirate culture	2/11	50	22	13	67	0.64 (0.15 to 2.68)	2.25 (0.36 to 14.28)
Evans^4-151	1988	23	Axilla swab culture	Not given^4-151	53	86	9		3.7^4-151	0.55^4-151
Evans^4-151	1988	23	Ear canal swab culture	Not given^4-151	50	87	9		3.7^4-151	0.58^4-151
Evans^4-151	1988	23	ET tube aspirate and culture	Not given^4-151	59	74	7		2.3^4-151	0.56^4-151
Evans^4-151	1988	23	Gastric aspirate culture	Not given^4-151	48	77	5		2.1^4-151	0.68^4-151
Evans^4-151	1988	23	Nasopharyngeal swab culture	Not given^4-151	59	87	12		4.6^4-151	0.47^4-151
Evans^4-151	1988	23	Rectal swab culture	Not given^4-151	69	31	5		1.0^4-151	1.01^4-151
Evans^4-151	1988	23	Skin swab culture	Not given^4-151	0	84	0		0.0^4-151	1.19^4-151
Evans^4-151	1988	23	Umbilical swab culture	Not given^4-151	80	77	4		3.5^4-151	0.26^4-151
Leibovich	1987	36	Gastric aspirate microscopy: ⩾5 WC/HPF or any bacteria	8/140	75	68	13	98	2.36 (1.47 to 3.78)	0.37 (0.11 to 1.23)
Thomson	1992	56	Ear swab culture	9/134	78	90	35	98	7.48 (4.02 to 13.93)	0.2 (0.07 to 0.84)
Thomson	1992	56	Gastric aspirate culture	9/127	67	85	25	97	4.37 (2.33 to 8.19)	0.39 (0.15 to 0.99)
Thomson	1992	56	Gastric aspirate microscopy (pus cells)	9/127	89	49	12	98	1.75 (1.31 to 2.34)	0.2 (0.04 to 1.45)
Thomson	1992	56	Gastric aspirate microscopy (pus cells and organisms)	9/127	89	80	24	99	4.37 (2.86 to 6.69)	0.14 (0.02 to 0.89)
Thomson	1992	56	Nasal swab culture	9/130	56	95	46	97	11.20 (4.23 to 26.69)	0.4 (0.23 to 0.97)
Thomson	1992	56	Umbilical swab culture	9/136	78	92	41	98	9.89 (4.96 to 19.69)	0.2 (0.07 to 0.82)

↵4-151 The sensitivities, specificities, and positive predictive values relating to these tests are given in the paper and it is therefore possible to calculate the likelihood ratios. However, insufficient data are provided to calculate the negative predictive value or the confidence limits around any of the likelihood ratios. CI = confidence interval; HPF = high power field; LR = likelihood ratio; NPV = negative predictive value; PMN = polymorphonuclear leucocyte; PPV = positive predictive value; WC = white cell