Insights on the performance of phenotypic tests versus genotypic tests for the detection of carbapenemase-producing Gram-negative bacilli in resource-limited settings

Kamel, Noha A.; Tohamy, Sally T.; Yahia, Ibrahim S.; Aboshanab, Khaled M.

doi:10.1186/s12866-022-02660-5

Table 1 Evaluation of sensitivity, specificity, positive predictive value and negative predictive value of phenotypic tests

From: Insights on the performance of phenotypic tests versus genotypic tests for the detection of carbapenemase-producing Gram-negative bacilli in resource-limited settings

Test	GNB	TP^a	FP^b	FN^c	TN^d	Sensitivity	Specificity	PPV	NPV
95% confidence interval [95% CI]
MHT	Enterobacterales (n = 28)	20	0	7	1	74% [53.40-88.12]	100% [5.46–100]	100% [79.95–100]	12.50% [0-53.32]
	Non glucose fermenting bacilli (n = 40) A. baumannii P. aeruginosa	23 16 6	0 0 0	14 8 0	3 2 1	62.16% [44.78–77.06] 66.66% [44.69–83.57] 50% [22.28–77.71]	100% [31–100] 100% [19.78–100] 100% [5.46–100]	100% [82.19–100] 100% [75.92–100] 100% [51.68–100]	17.64% [4.67–44.19] 20% [3.54–55.78] 14.28% [0.78-58]
	total tested = 68	43	0	21	4	65.62% [52.61–76.75]	100% [39.57–100]	100% [89.56–100]	15.38% [5.04–35.72]
m-CIM	Enterobacterales (n = 30)	15	0	14	1	51.72% [32.89–70.10]	100% [5.46–100]	100% [74.65–100]	6.66% [3.49–33.96]
	Non glucose fermenting bacilli (n = 41) A. baumannii P. aeruginosa	31 19 11	0 0 0	7 6 1	3 2 1	81.57% [65.10-91.67] 76% [49.65–85.50] 91.66% [62.08–99.60]	100% [31–100] 100% [19.78–100] 100% [5.46–100]	100% [86.27–100] 100% [79.07–100] 100% [67.85–100]	30% [8.09–64.63] 25% [4.45–64.42] 50% [2.66–97.33]
	total tested = 71	46	0	21	4	68.65%, [56.02–79.13]	100%, [39.57–100]	100%, [90.39–100]	16%, [5.25–36.91]
BCT	Enterobacterales (n = 30)	24	0	5	1	82.75% [63.51–93.47]	100% [5.46–100]	100% [82.82–100]	16.66% [1.05–70.12]
	Non glucose fermenting bacilli (n = 41) A. baumannii P. aeruginosa	36 23 12	1 0 1	2 2 0	2 2 0	94.74% [80.93–99.08] 92.56% [72.49–98.60] 100% [69.87–100]	66.66% [12.53–98.23] 100% [19.78–100] 0% [0-94.53]	97.29% [84.19–99.85] 100% [82.19–100] 92.30% [62.08–99.59]	50% [9.18–90.81] 50% [9.18–90.81] NA
	total tested = 71	60	1	7	3	89.55% [79.06–95.34]	75% [21.94–98.68]	98.36% [90.01–99.91]	30% [8.09–64.63]
CDT	Enterobacterales (n = 30)	18	0	11	1	62.07 [42.36–78.69]	100% [5.46–100]	100% [78.12–100]	8.33% [0-40.24]
	Non glucose fermenting bacilli (n = 41) A. baumannii P. aeruginosa	19 15 4	0 0 0	19 10 8	3 2 1	50% [33.65–66.34] 60% [38.89–78.18] 33.33% [11.27–64.56]	100% [31–100] 100% [19.78–100] 100% [5.46–100]	100% [79.07–100] 100% [74.65–100] 100% [39.57–100]	13.63% [3.58–35.96] 16.66% [2.94–49.11] 11.11% [0.58–49.32]
	total tested = 71	37	0	30	4	55.22%, [42.63–67.21]	100%, [39.57–100]	100%, [88.28–100]	11.76% [3.83–28.39]

TP^a, true positive, FP^b, False positive, FN^c, False negative, TN^d, true negative; Sensitivity = a/(a + c), Specificity = d/(b + d), PPV (Positive predictive value) = a/(a + b), NPV (Negative predictive value) = d/ (c + d); MHT, modified Hodge test, mCIM, modified carbapenem inactivation method, CDT, combined disk test by EDTA ; BCT, blue-carba test
* Non glucose fermenting included A. baumannii, P. aeruginosa and Stenotrophomonas maltophilia isolates

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