Interactions of Neuropathogenic Escherichia coli K1 (RS218) and Its Derivatives Lacking Genomic Islands with Phagocytic Acanthamoeba castellanii and Nonphagocytic Brain Endothelial Cells

Table 2

RS218-derived islands (RDI’s) mutants and their interactions with Acanthamoeba castellanii. The number of E. coli K1 c.f.u. interacting with A. castellanii was considered as 100% and the results of mutants strains are expressed as the relative change.

Identity	A. castellanii
	Association	Invasion	Survival	Cyst survival
K1 (RS218)	100	100	100	100
Plasmid cured RS218	130.49 ± 25	26.19 ± 2*	75.19 ± 10*	25 ± 5*
RS218 in which black hole was filled with respective DNA from HB101	143.8 ± 19	32.74 ± 7*	147.84 ± 23	227.5 ± 23*
RDI 1	111 ± 12	96.42 ± 9	132.8 ± 14	93.75 ± 16
RDI 2	68.53 ± 7*	36.90 ± 3*	132.8 ± 11	63.75 ± 8*
RDI 4	246.53 ± 31	143.44 ± 20*	108.58 ± 15	55 ± 5*
RDI 9	52 ± 3*	76.19 ± 6*	65 ± 8*	10 ± 2*
RDI 10	45.9 ± 6*	51.78 ± 5*	63.66 ± 6*	8.75 ± 3*
RDI 12	83.62 ± 10	69 ± 11*	92.18 ± 10	158.75 ± 9
RDI 14	88.92 ± 15	81.54 ± 11	97.26 ± 9	165 ± 5
RDI 15	60.19 ± 8*	73.8 ± 12*	110.34 ± 18	136.25 ± 13
RDI 16	124.7 ± 18	116 ± 11	93.35 ± 7	60 ± 9*
RDI 17	49.95 ± 6*	83.92 ± 9	108.39 ± 16	172.5 ± 12*
RDI 18	117.97 ± 16	28.57 ± 2*	25.38 ± 3*	8.12 ± 1*
RDI 21	157 ± 14*	39.28 ± 4*	70.89 ± 6*	45 ± 3*
RDI 22	109.62 ± 9	38.69 ± 6*	9.76 ± 1*	16.25 ± 3*

(i) Association was calculated as follows: (number of bacterial c.f.u./number of amoebae) × 100 = bacterial association of A. castellanii.
(ii) Invasion was calculated as follows: (number of bacterial c.f.u./number of amoebae) × 100 = bacterial invasion of A. castellanii.
(iii) Survival was calculated as follows: (number of bacterial c.f.u./number of amoebae) × 100 = bacterial survival of A. castellanii.
(iv) Cyst survival was calculated as follows: (number of bacterial c.f.u./number of amoebae cysts) × 100 = bacterial survival of A. castellanii cysts.
*indicates a significant difference (P < 0.05 using paired t-test, one-tailed distribution) when data of mutant strains were compared with the wild type E. coli K1 data.