A rapid and highly sensitive protocol for the detection of Escherichia coli O157:H7 based on immunochromatography assay combined with the enrichment technique of immunomagnetic nanoparticles

Figures & data

Figure 1 The sensitivity of Escherichia coli O157:H7 (1 × 10⁸ to 1 × 10² CFUs/mL) with IMPs+ICA.

Abbreviations: CFUs, colony-forming units; ICA, immunochromatographic assay; IMPs, immunomagnetic nanoparticles.

Figure 2 The specificity of IMP enrichment for Escherichia coli O157:H7. (A) E. coli O157:H7 will appear as aubergine colonies. (B) Non-E. coli O157:H7 will appear as blue-green colonies and no growth.

Table 1 Comparison of two detection methods for Escherichia coli O157:H7

Sample	Concentration (CFUs/mL)	N	ICA	Positive rate (%)	IMPs+ICA	Positive rate (%)
Milk	10^5	15	15	100	15	100
	10^4	15	0	0	15	100
	10^3	15	0	0	14	93.3
	0	5	0	0	0	0
Water	10^5	15	13	86.7	15	100
	10^4	15	0	0	15	100
	10^3	15	0	0	12	80.0
	0	5	0	0	0	0.0
Beef	10^5	15	12	80.0	15	100
	10^4	15	0	0	15	100
	10^3	15	0	0	13	86.7
	0	5	1	0	0	0

Abbreviations: CFUs, colony-forming units; ICA, immunochromatographic assay; IMPs, immunomagnetic nanoparticles.

Table 2 The sensitivity and specificity of the two detection methods for Escherichia coli O157:H7

Group	N	ICA		IMPs+ICA
		Sensitivity	Specificity	Sensitivity	Specificity
O157:H7	135	29.6%		95.5%
Control	15		93.3%		100%

Abbreviations: ICA, immunochromatographic assay; IMPs, immunomagnetic nanoparticles.