TABLE 1.

Percentage of X. cheopis fleas that remained infected and the CFU per infected flea at different time points after infection with different Y. pseudotuberculosis and one Y. pestis strain

Species	Strain	Serotype	% Fleas infecteda			CFU/infected fleab
			1 day	7 days	28 days	1 day	7 days	28 days
Y. pseudotuberculosis	IP32953	O1b	55	60	40	9.5 × 102 ± 9.6 × 102	1.4 × 103 ± 7.7 × 102	3.4 × 103 ± 3.2 × 103
	K163	O1b	45	25	15	3.4 × 103 ± 5.2 × 10	2.1 × 103 ± 2.1 × 103	6.5 × 101 ± 2.3 × 101
	PB1	O1b	54 (13/24)	57 (28/49)	55 (30/55)	2.2 × 104 ± 4.8 × 104	3.1 × 104 ± 3.4 × 104	2.9 × 104 ± 2.2 × 104
	IP32951	O2	55	55	42 (5/12)	7.4 × 103 ± 5.6 × 103	2.8 × 103 ± 3.8 × 103	2.3 × 103 ± 2.1 × 103
	K170	O2c	55	50	35	3.6 × 103 ± 3.5 × 103	1.3 × 103 ± 1.0 × 103	1.9 × 103 ± 3.6 × 103
	IP32984	O3	11 (2/18)	0	0	1.5 × 102 ± 0	0	0
	YPIII	O3	12 (7/57)	5 (3/60)	0 (0/60)	1.2 × 103 ± 1.9 × 103	2.6 × 103 ± 2.2 × 103	0
	YPIII(pCH16)	O3	59 (23/39)	40 (24/60)	50 (30/60)	3.0 × 103 ± 5.4 × 103	2.7 × 104 ± 3.5 × 104	9.0 × 103 ± 8.3 × 103
	K171	O3	0	8 (3/39)	0 (0/40)	0	4.0 × 103 ± 4.8 × 103	0
	K171(pCH16)	O3	43 (6/14)	56 (24/43)	54 (30/56)	5.7 × 104 ± 8.8 × 104	1.5 × 104 ± 3.1 × 104	1.7 × 104 ± 2.1 × 104
	IP31411	O4	5	5	0	2.0 × 101c	2.7 × 102c	0
	K174	O4a	35	30	44 (4/9)	8.5 × 103 ± 1.5 × 104	5.6 × 102 ± 6.5 × 102	5.5 × 102 ± 6.6 × 102
	K175	O4b	45	60	50	4.9 × 103 ± 1.3 × 104	1.3 × 103 ± 2.1 × 103	3.6 × 103 ± 4.8 × 103
	IP32821	O5	95	80	15	1.1 × 103 ± 1.3 × 103	2.0 × 103 ± 2.2 × 103	6.0 × 101 ± 6.0 × 101
	K177	O5a	40	50	35	1.2 × 104 ± 1.0 × 104	1.2 × 104 ± 6.1 × 103	2.0 × 104 ± 8.8 × 103
	IP31553	O6	50	20	0	1.4 × 103 ± 1.7 × 103	3.0 × 102 ± 4.7 × 102	0
	K186	O9	25	45	10	4.3 × 103 ± 4.4 × 103	1.8 × 103 ± 2.6 × 103	5.4 × 103 ± 2.1 × 102
	K199	Unknown	45	50	55	1.4 × 104 ± 1.2 × 104	3.5 × 103 ± 6.3 × 103	4.0 × 103 ± 5.1 × 103
	PB1 ΔddhD-wzz	Rough	NDd	26 (5/19)	45	NDd	4.6 × 104 ± 2.2 × 104	1.6 × 104 ± 1.4 × 104
	PB1 ΔddhD-wzz(pHMS1.2)	Rough	70	60	55	2.6 × 103 ± 2.3 × 103	3.5 × 103 ± 3.9 × 103	2.3 × 103 ± 2.3 × 103
Y. pestis	KIM6+	Rough	81	89	54	4.9 × 104 ± 3.1 × 104	4.0 × 103 ± 1.1 × 105	4.0 × 105 ± 6.8 × 104

^aResults are for 20 fleas except where noted [e.g., (13/24)].

^bResults are expressed as means±standard deviations.

^cOnly a single flea in the sample was infected.

^dND, not determined.