. 2008 Feb 1;74(6):1757–1766. doi: 10.1128/AEM.02740-07

TABLE 1.

Murine virulence of human and animal serotype Typhimurium isolates from clinical specimen submissions

Strain^a	Serotype	Site^b	Host	Yr of isolation	Location^c	Virulence (CI) in i.p. infection^d	Virulence plasmid^e	spvB^e	pef^e	Source^a
Serotype Typhimurium animal GI and extraintestinal isolates
11	Typhimurium	GI	Chicken	2003	U.S.	0.95	+	+	+	CA AHFSL
UK-1	Typhimurium	NGI	Chicken	1988	NY	2.4	+	+	+	R. Curtiss III
F98	Typhimurium	GI	Chicken	1991	England	0.46	+	+	+	R. Curtiss III
TY1212	Typhimurium	NGI	Cow	2001	CA	0.44	+	+	−	CA AHFSL
(97)-1332	Typhimurium	NGI	Dog	1997	CA	41.2	+	+	+	UC—Davis
(05)-6192	Typhimurium	GI	Horse	2005	CA	2.2	+	+	+	UC—Davis
(05)-4360	Typhimurium	NGI	Horse	2005	CA	1.22	+	+	+	UC—Davis
(03)-1516	Typhimurium	NGI	Horse	2003	ID	0.02	+	+	+	UC—Davis
(04)-8740	Typhimurium	GI	Horse	2004	CA	3.01	+	+	+	UC—Davis
131	Typhimurium	GI	Sheep	2005	VIC	0.54	+	+	+	University of Sydney
146	Typhimurium	GI	Sheep	2005	SA	2.0	+	+	+	University of Sydney
148	Typhimurium	NGI	Sheep	2005	SA	0.33	+	+	+	University of Sydney
150	Typhimurium	NGI	Sheep	2005	VIC	0.95	+	+	+	University of Sydney
222	Typhimurium	GI	Sheep	2005	WA	0.73	+	+	+	University of Sydney
227	Typhimurium	GI	Sheep	2005	WA	0.32	+	+	+	University of Sydney
230	Typhimurium	GI	Sheep	2005	WA	2.32	+	+	+	University of Sydney
250	Typhimurium	GI	Sheep	2005	WA	0.23	+	+	+	University of Sydney
(04)-9639	Typhimurium var. 5−	GI	Cow	2004	CA	11.3	+	+	+	UC—Davis
(04)-8511	Typhimurium var. 5−	GI	Cow	2004	CA	0.68	+	+	−	UC—Davis
(04)-4985	Typhimurium var. 5−	GI	Cow	2004	CA	2.8	+	+	−	UC—Davis
12	Typhimurium var. 5−	GI	Turkey	2000	U.S.	1.8	+	+	−	CA AHFSL
Serotype Typhimurium human fecal isolates from gastroenteritis patients
69	Typhimurium	Feces	Human	2005	CA	<0.0003	−	−	−	MCPHL
5	Typhimurium	Feces	Human	2005	CA	<0.0003	−	−	−	MCPHL
3h	Typhimurium	Feces	Human	2006	Western U.S.	0.24	+	+	+	PCMC
5h	Typhimurium	Feces	Human	2006	Western U.S.	22.2	+	+	+	PCMC
6h	Typhimurium	Feces	Human	2006	Western U.S.	0.82	+	+	+	PCMC
9h	Typhimurium	Feces	Human	2006	Western U.S.	<0.001	−	−	−	PCMC
10h	Typhimurium	Feces	Human	2006	Western U.S.	0.003*	+	+	+	PCMC
11h	Typhimurium	Feces	Human	2006	Western U.S.	<0.001	−	−	−	PCMC
12h	Typhimurium	Feces	Human	2006	Western U.S.	1.2	+	+	+	PCMC
13h	Typhimurium	Feces	Human	2006	Western U.S.	1.1	+	+	+	PCMC
F1	Typhimurium	Feces	Human	2007	Western U.S.	0.0009	−	−	−	UPHL
F2	Typhimurium	Feces	Human	2007	Western U.S.	0.072	+	+	+	UPHL
F3	Typhimurium	Feces	Human	2007	Western U.S.	0.1	+	+	+	UPHL
F4	Typhimurium	Feces	Human	2007	Western U.S.	0.36	+	+	+	UPHL
F5	Typhimurium	Feces	Human	2007	Western U.S.	0.004	−	−	−	UPHL
F6	Typhimurium	Feces	Human	2007	Western U.S.	0.0003	−	−	−	UPHL
F7	Typhimurium	Feces	Human	2007	Western U.S.	0.05	+	+	+	UPHL
F8	Typhimurium	Feces	Human	2007	Western U.S.	0.0006	−	−	−	UPHL
F9	Typhimurium	Feces	Human	2007	Western U.S.	5.2	+	+	+	UPHL
F10	Typhimurium	Feces	Human	2007	Western U.S.	0.008*	+	+	+	UPHL
F11	Typhimurium	Feces	Human	2007	Western U.S.	0.05	+	+	+	UPHL
F12	Typhimurium	Feces	Human	2007	Western U.S.	1.1	+	+	+	UPHL
F13	Typhimurium	Feces	Human	2007	Western U.S.	0.001	−	−	−	UPHL
F14	Typhimurium	Feces	Human	2007	Western U.S.	0.05	+	+	+	UPHL
1h	Typhimurium var. 5−	Feces	Human	2006	Western U.S.	<0.001*	+	+	+	PCMC
4h	Typhimurium var. 5−	Feces	Human	2006	Western U.S.	0.007	−	−	−	PCMC
7h	Typhimurium var. 5−	Feces	Human	2006	Western U.S.	3.9	+	+	+	PCMC
8h	Typhimurium var. 5−	Feces	Human	2006	Western U.S.	1.3	+	+	+	PCMC
630	Typhimurium var. 5−	Feces	Human	2005	CA	0.05	+	+	+	MCPHL
Serotype Typhimurium human blood isolates from bacteremic patients
B1	Typhimurium	Blood	Human	2000	Western U.S.	0.001*	+	+	+	UPHL
B2	Typhimurium	Blood	Human	2001	Western U.S.	3.2	+	+	+	UPHL
B3	Typhimurium	Blood	Human	2001	Western U.S.	4	+	+	+	UPHL
B4	Typhimurium	Blood	Human	2001	Western U.S.	15.5	+	+	+	UPHL
B5	Typhimurium	Blood	Human	2001	Western U.S.	0.003*	+	+	+	UPHL
B6	Typhimurium	Blood	Human	2002	Western U.S.	3.3	+	+	+	UPHL
B7	Typhimurium	Blood	Human	2002	Western U.S.	0.49	+	+	−	UPHL
B8	Typhimurium	Blood	Human	2002	Western U.S.	0.50	+	+	+	UPHL
B9	Typhimurium	Blood	Human	2003	Western U.S.	5.2	+	+	+	UPHL
B10	Typhimurium	Blood	Human	2003	Western U.S.	0.003*	+	+	+	UPHL
B11	Typhimurium	Blood	Human	2003	Western U.S.	1.1	+	+	+	UPHL
B12	Typhimurium	Blood	Human	2004	Western U.S.	0.33	+	+	−	UPHL

Salmonella human clinical isolates were recovered from specimens submitted to diagnostic laboratories in different outbreaks; fecal isolates derived from patients with gastroenteritis were obtained from UPHL, PCMC, and the MCPHL. Blood isolates derived from patients with bacteremia were obtained from UPHL. Salmonella animal clinical isolates were recovered from specimens submitted to diagnostic laboratories in different outbreaks or individual cases and were obtained from the following sources: the University of Sydney; the University of California, Davis (UC—Davis); and the CA AHFSL. Pathogenic serotype Typhimurium strains UK-1 and F98 (6, 33) were obtained from Roy Curtiss III, Arizona State University, Tempe, AZ. The pathogenic reference strain S. enterica serovar Typhimurium ATCC 14028 (CDC6516-60) was used in all studies.

Host site from which the specimen containing bacteria was obtained. Animal isolates were obtained from specimens from GI sites (e.g., intestinal specimens and feces) and NGI sites (e.g., spleen, liver, and urine specimens, etc.); human isolates were obtained from the feces and blood of gastroenteritis and bacteremic patients, respectively.

U.S., United States; VIC, Victoria, Australia; WA, Western Australia; SA, South Australia.

CIs for Salmonella test strains relative to the reference wild-type serotype Typhimurium strain 14028. BALB/c mice were i.p. infected with a 1:1 ratio of the test strain to the reference wild-type strain (MT2057, a virulent derivative of strain 14028) at a dose of ∼500 cells each. Five days postinfection, the bacterial cells were recovered from the spleens; the CI is the ratio of test strain cells to reference wild-type strain cells recovered. Three to five mice per challenge strain were tested. Isolates with a CI of <0.02 were designated as avirulent and were subsequently evaluated for virulence via the oral route of administration (in the oral LD₅₀ assay). All six virulence plasmid-containing Salmonella serotype Typhimurium human isolates that were avirulent via the i.p. route (in the CI assay) exhibited a reduction in virulence via the oral route of ≥1,000-fold relative to the reference wild-type strain 14028 (values for these isolates are indicated by an asterisk).

Salmonella virulence plasmids were detected via visual inspection of genomic DNA derived from Salmonella strains subjected to agarose gel electrophoresis (40). Strains containing Salmonella virulence plasmid candidates of the appropriate sizes were evaluated for the presence of virulence plasmid-associated markers spvB and pef, detected by PCR and hybridization analysis. + denotes a strong signal via hybridization and/or PCR; − denotes no detectable signal via PCR and hybridization analysis.