Association between herd management practices and antimicrobial resistance in Salmonella spp. from cull dairy cattle in Central California

Richard Van Vleck Pereira, Deniece R. Williams, Paul Rossitto, John M Adaska, Emmanuel Okello, John Champagne, Terry W Lehenbauer, Xunde Li, Jennifer Chase, Tran Nguyen, Alda De Andrade E Pires, Edward R Atwill, Sharif S Aly

Research output: Contribution to journalArticle

Abstract

Background: In this study cull dairy cows from six California dairy herds were sampled seasonally over the course of a year. The objectives were to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp. shed in cull cow feces, and the factors associated with fecal shedding of AMR and multidrug resistant (MDR) Salmonella. Methods: Six dairy farms located in the San Joaquin Valley of California were identified and enrolled as a convenience sample. On each dairy, and once during each of the four seasons, 10 cull cows were randomly selected for fecal sampling on the day of their removal from the herd. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous 4 month's herd management and the specific cattle sampled. Fecal samples were submitted to the California Animal Health and Food Safety laboratory for Salmonella isolation. Antimicrobial resistance was evaluated using broth microdilution method and a gram-negative assay plate following Clinical Laboratory Standards Institute (CLSI) guidelines and breakpoint references. All statistical models were survey adjusted for number of animals on sampling day. Results: A total of 62 Salmonella were isolated from 60 of the 239 fecal samples collected. For 12% (95% confidence interval (CI) [3-20]) of fecal samples a multidrug resistant Salmonella was isolated. The survey-weighted results for the two most common drug classes for which isolates were resistant were tetracycline (39%; 95% CI [27-51]) and ampicillin (18%; 95% CI [9-27]). An important finding was the identification of cephalosporin as the third most common drug class for which isolates were resistant, with ceftriaxone (10%; 95% CI [2-17]) being the most common drug associated with resistance in that class. At the cow-level, reason for culling, prior treatment with antimicrobial drugs as the reason for culling was associated with higher odds of isolating an AMR Salmonella isolate. At theherd-level, percent of animals monthly culled on the farm as well as number of milking cows in the herd were associated with isolation of antimicrobial resistant Salmonella in cull cows. Discussion: Salmonella isolated from fecal samples from cull cows were resistant to important antimicrobials, such as ceftriaxone. The most common drug classes for which isolates were resistant were tetracyclines and beta-lactams, with ampicillin, ceftriaxone and ceftiofur being the three most common drugs within the latter. Cow and herd level factors were associated with isolating antimicrobial resistant Salmonella that should be further investigated for their potential role in promoting occurrence of AMR Salmonella. Our results also highlight the importance of monitoring dairy cattle sent to slaughter for shedding of Salmonella resistant to medically important antimicrobial drugs.

Original languageEnglish (US)
Article numbere6546
JournalPeerJ
Volume2019
Issue number3
DOIs
StatePublished - Jan 1 2019

Fingerprint

Salmonella
Dairies
Practice Management
antibiotic resistance
dairy cattle
herds
anti-infective agents
drugs
ceftriaxone
cows
Ceftriaxone
confidence interval
Pharmaceutical Preparations
Confidence Intervals
culling (animals)
Animals
sampling
Ampicillin
ampicillin
Farms

Keywords

  • Antimicrobial resistance
  • Cull cows
  • Dairy cattle
  • Salmonella

ASJC Scopus subject areas

  • Neuroscience(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Association between herd management practices and antimicrobial resistance in Salmonella spp. from cull dairy cattle in Central California. / Pereira, Richard Van Vleck; Williams, Deniece R.; Rossitto, Paul; Adaska, John M; Okello, Emmanuel; Champagne, John; Lehenbauer, Terry W; Li, Xunde; Chase, Jennifer; Nguyen, Tran; De Andrade E Pires, Alda; Atwill, Edward R; Aly, Sharif S.

In: PeerJ, Vol. 2019, No. 3, e6546, 01.01.2019.

Research output: Contribution to journalArticle

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keywords = "Antimicrobial resistance, Cull cows, Dairy cattle, Salmonella",
author = "Pereira, {Richard Van Vleck} and Williams, {Deniece R.} and Paul Rossitto and Adaska, {John M} and Emmanuel Okello and John Champagne and Lehenbauer, {Terry W} and Xunde Li and Jennifer Chase and Tran Nguyen and {De Andrade E Pires}, Alda and Atwill, {Edward R} and Aly, {Sharif S}",
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AU - Pereira, Richard Van Vleck

AU - Williams, Deniece R.

AU - Rossitto, Paul

AU - Adaska, John M

AU - Okello, Emmanuel

AU - Champagne, John

AU - Lehenbauer, Terry W

AU - Li, Xunde

AU - Chase, Jennifer

AU - Nguyen, Tran

AU - De Andrade E Pires, Alda

AU - Atwill, Edward R

AU - Aly, Sharif S

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N2 - Background: In this study cull dairy cows from six California dairy herds were sampled seasonally over the course of a year. The objectives were to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp. shed in cull cow feces, and the factors associated with fecal shedding of AMR and multidrug resistant (MDR) Salmonella. Methods: Six dairy farms located in the San Joaquin Valley of California were identified and enrolled as a convenience sample. On each dairy, and once during each of the four seasons, 10 cull cows were randomly selected for fecal sampling on the day of their removal from the herd. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous 4 month's herd management and the specific cattle sampled. Fecal samples were submitted to the California Animal Health and Food Safety laboratory for Salmonella isolation. Antimicrobial resistance was evaluated using broth microdilution method and a gram-negative assay plate following Clinical Laboratory Standards Institute (CLSI) guidelines and breakpoint references. All statistical models were survey adjusted for number of animals on sampling day. Results: A total of 62 Salmonella were isolated from 60 of the 239 fecal samples collected. For 12% (95% confidence interval (CI) [3-20]) of fecal samples a multidrug resistant Salmonella was isolated. The survey-weighted results for the two most common drug classes for which isolates were resistant were tetracycline (39%; 95% CI [27-51]) and ampicillin (18%; 95% CI [9-27]). An important finding was the identification of cephalosporin as the third most common drug class for which isolates were resistant, with ceftriaxone (10%; 95% CI [2-17]) being the most common drug associated with resistance in that class. At the cow-level, reason for culling, prior treatment with antimicrobial drugs as the reason for culling was associated with higher odds of isolating an AMR Salmonella isolate. At theherd-level, percent of animals monthly culled on the farm as well as number of milking cows in the herd were associated with isolation of antimicrobial resistant Salmonella in cull cows. Discussion: Salmonella isolated from fecal samples from cull cows were resistant to important antimicrobials, such as ceftriaxone. The most common drug classes for which isolates were resistant were tetracyclines and beta-lactams, with ampicillin, ceftriaxone and ceftiofur being the three most common drugs within the latter. Cow and herd level factors were associated with isolating antimicrobial resistant Salmonella that should be further investigated for their potential role in promoting occurrence of AMR Salmonella. Our results also highlight the importance of monitoring dairy cattle sent to slaughter for shedding of Salmonella resistant to medically important antimicrobial drugs.

AB - Background: In this study cull dairy cows from six California dairy herds were sampled seasonally over the course of a year. The objectives were to determine the prevalence of antimicrobial resistant (AMR) Salmonella spp. shed in cull cow feces, and the factors associated with fecal shedding of AMR and multidrug resistant (MDR) Salmonella. Methods: Six dairy farms located in the San Joaquin Valley of California were identified and enrolled as a convenience sample. On each dairy, and once during each of the four seasons, 10 cull cows were randomly selected for fecal sampling on the day of their removal from the herd. In addition, study personnel completed a survey based on responses of the herd manager to questions related to the previous 4 month's herd management and the specific cattle sampled. Fecal samples were submitted to the California Animal Health and Food Safety laboratory for Salmonella isolation. Antimicrobial resistance was evaluated using broth microdilution method and a gram-negative assay plate following Clinical Laboratory Standards Institute (CLSI) guidelines and breakpoint references. All statistical models were survey adjusted for number of animals on sampling day. Results: A total of 62 Salmonella were isolated from 60 of the 239 fecal samples collected. For 12% (95% confidence interval (CI) [3-20]) of fecal samples a multidrug resistant Salmonella was isolated. The survey-weighted results for the two most common drug classes for which isolates were resistant were tetracycline (39%; 95% CI [27-51]) and ampicillin (18%; 95% CI [9-27]). An important finding was the identification of cephalosporin as the third most common drug class for which isolates were resistant, with ceftriaxone (10%; 95% CI [2-17]) being the most common drug associated with resistance in that class. At the cow-level, reason for culling, prior treatment with antimicrobial drugs as the reason for culling was associated with higher odds of isolating an AMR Salmonella isolate. At theherd-level, percent of animals monthly culled on the farm as well as number of milking cows in the herd were associated with isolation of antimicrobial resistant Salmonella in cull cows. Discussion: Salmonella isolated from fecal samples from cull cows were resistant to important antimicrobials, such as ceftriaxone. The most common drug classes for which isolates were resistant were tetracyclines and beta-lactams, with ampicillin, ceftriaxone and ceftiofur being the three most common drugs within the latter. Cow and herd level factors were associated with isolating antimicrobial resistant Salmonella that should be further investigated for their potential role in promoting occurrence of AMR Salmonella. Our results also highlight the importance of monitoring dairy cattle sent to slaughter for shedding of Salmonella resistant to medically important antimicrobial drugs.

KW - Antimicrobial resistance

KW - Cull cows

KW - Dairy cattle

KW - Salmonella

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