Food Protection Trends - March/April 2025 - 108

A
60
40
20
Top Ten FSIS Cattle Serovars
Serovar
2015
B
100
125
50
75
25
2015
2016
2017
Year
Figure 1. Top 10 cattle Salmonella serovars from 2015 to 2020. Line plots of Salmonella serovar
trends over 6 years in cattle based on isolate counts from A, FSIS data and B, NCBI PD.
2018
2019
2020
2016
2017
Year
Top Ten NCBI Cattle Serovars
Serovar
Anatum
Cerro
Heidelberg
Dublin
Montevideo
Muenchen
Muenster
Typhimurium
Newport
I 4[5]12:i:2018
2019
2020
Anatum
Cerro
Dublin
Infantis
Kentucky
Montevideo
Muenster
Typhimurium
Newport
Muenchen
Cerro,
and Heidelberg overrepresented in NCBI cattle data
and (ii) Salmonella serovars Derby, Infantis, Johannesburg,
Montevideo, Muenchen, Muenster, and Reading
overrepresented in FSIS cattle data. Salmonella Heidelberg
(OR = 10.5) was the serovar most highly overrepresented
among the NCBI data, while Salmonella Johannesburg (OR
= 0.0752) was the most highly overrepresented among the
FSIS data (Table 3).
A chi-square test was performed to better understand
over- and underrepresentation of serovars in relation to
isolation sources (e.g., feces, ground beef), followed by post
hoc hypothesis testing with adjusted Pearson residuals for
the chi-square tests that yielded a significant P-value (Table
S5). An overall chi-square test on the NCBI cattle data set
was significant (P < 2e-16), indicating that serovars were
not randomly distributed among isolation sources. More
specifically, Salmonella Muenchen was highly overrepresented
in ground beef (ri
highly overrepresented in cattle feces (ri
= 10.85) (Fig. 4A). Salmonella Cerro was
= 13.42) and hide (ri
= 9.49) but underrepresented in cattle organs and tissues (ri
= −6.12) and boneless beef (ri
was overrepresented in cattle organs and tissues (ri
and boneless beef (ri
= −6.76). Salmonella Dublin
= 14.72)
= 7.01), while underrepresented in cattle
feces (ri
= −15.07) and ground beef (ri
Infantis was highly overrepresented in ground beef (ri
= 6.00).
= −7.00). Salmonella
=
9.16). Salmonella Typhimurium was overrepresented among
unspecified cattle isolates (ri
The associations between cattle serovars and certain
organs and tissue isolates on the basis of data from NCBI
are presented in Fig. S1. Our analyses found that Salmonella
Anatum was most highly overrepresented in cattle lymph
nodes (ri
cattle lungs (ri
overrepresented in stomach samples (ri
Dublin was overrepresented among cattle lung (ri
and liver samples (ri
among cattle intestines and lymph nodes (ri
=11.26) and most highly underrepresented in
= −4.66). Salmonella Derby was found to be
= 11.95). Salmonella
= 13.20)
= 6. 02), while it was underrepresented
= −9.33 and
−7.55, respectively). Similarly, Salmonella Heidelberg was
overrepresented among cattle liver samples (ri
= 6.27).
Serovar distribution in chicken
In chicken, the top 10 Salmonella serovars were Enteritidis,
Hadar, Heidelberg, Infantis, Kentucky, Montevideo, Schwarzengrund,
Typhimurium, Johannesburg, and I 4,[5],12:i:−
(Fig. 2A and Table S3). Over the inclusion period (2015 to
2020), Salmonella Kentucky consistently was the most freMarch/April
Food Protection Trends 108
Number of Isolates
Number of Isolates
Food Protection Trends - March/April 2025

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