Growing Agricultural Education: Embracing Health and Safety

Growing Agricultural Education: Embracing Health and Safet

Serotypes and Antimicrobial Resistance in <i>Salmonella enterica</i> Recovered from Clinical Samples from Cattle and Swine in Minnesota, 2006 to 2015

<div><p>Salmonellosis remains one of the leading causes of foodborne disease worldwide despite preventive efforts at various stages of the food production chain. The emergence of multi-drug resistant (MDR) non-typhoidal <i>Salmonella enterica</i> represents an additional challenge for public health authorities. Food animals are considered a major reservoir and potential source of foodborne salmonellosis; thus, monitoring of <i>Salmonella</i> strains in livestock may help to detect emergence of new serotypes/MDR phenotypes and to gain a better understanding of <i>Salmonella</i> epidemiology. For this reason, we analyzed trends over a nine-year period in serotypes, and antimicrobial resistance, of <i>Salmonella</i> isolates recovered at the Minnesota Veterinary Diagnostic Laboratory (MVDL) from swine (n = 2,537) and cattle (n = 1,028) samples. Prevalence of predominant serotypes changed over time; in swine, <i>S</i>. Typhimurium and <i>S</i>. Derby decreased and <i>S</i>. Agona and <i>S</i>. 4,5,12:i:- increased throughout the study period. In cattle, <i>S</i>. Dublin, <i>S</i>. Montevideo and <i>S</i>. Cerro increased and <i>S</i>. Muenster became less frequent. Median minimum inhibitory concentration (MIC) values and proportion of antibiotic resistant isolates were higher for those recovered from swine compared with cattle, and were particularly high for certain antibiotic-serotype combinations. The proportion of resistant swine isolates was also higher than observed in the NARMS data, probably due to the different cohort of animals represented in each dataset. Results provide insight into the dynamics of antimicrobial resistant <i>Salmonella</i> in livestock in Minnesota, and can help to monitor emerging trends in antimicrobial resistance.</p></div

Proportional similarity index (with bootstrapped 95% confidence intervals) of the top four bovine and top four porcine serotypes based on resistance to the 13 core antimicrobials.

<p>Proportional similarity index (with bootstrapped 95% confidence intervals) of the top four bovine and top four porcine serotypes based on resistance to the 13 core antimicrobials.</p

Relationship between serotype and antimicrobial resistance in <i>Salmonella</i> isolates recovered from swine and cattle at the MVDL, 2006–2015.

<p>Percentage of isolates recovered from swine (a) and cattle (b) samples resistant to ampicillin (A), ceftiofur (C), enrofloxacin (E), florfenicol (F), gentamicin (G), neomycin (N), oxytetracycline (O), spectinomycin (Sp), sulfadimethoxine (Sul), spectomycin (Sp) and trimethorpim/ sulfamethoxazole (Ts) belonging to the four most prevalent serotypes in each species plus <i>Salmonella</i> I 4,5,12:i:- serotype in swine per year.</p

Resistotype richness in <i>Salmonella</i> isolates recovered from swine and cattle at the MVDL in 2006–2015.

<p>Sample-based rarefaction curves comparing the estimated mean resistotype richness in porcine and bovine samples from Minnesota at different sampling efforts (95% confidence intervals are indicated by a dotted line).</p

<i>Salmonella</i> serotypes recovered from cattle samples at the MVDL in 2006–2015.

<p>Number of isolates with a given serotype recovered from cattle samples per year (solid line, right axis) and percentage of these isolates belonging to the four predominant serotypes identified per year (dotted lines, left axis).</p

Evolution in antimicrobial resistant <i>Salmonella</i> isolates recovered from swine at the MVDL in 2006–2015.

<p>Proportion of <i>Salmonella</i> isolates recovered from swine samples that were resistant to ampicillin (A), ceftiofur (C), enrofloxacin (E), florfenicol (F), gentamicin (G), neomycin (N), oxytetracycline (O), sulfadimethoxine (Sul), spectomycin (Sp) and trimethorpim/ sulfamethoxazole (Ts).</p

Time associated odds ratio quantifying the change in the probability of obtaining a response equal to or lower than each MIC level measured for each antimicrobial per year obtained using a cumulative logistic regression model (values below 1 indicate a decreasing probability of finding isolates with lower MIC values).

<p>Time associated odds ratio quantifying the change in the probability of obtaining a response equal to or lower than each MIC level measured for each antimicrobial per year obtained using a cumulative logistic regression model (values below 1 indicate a decreasing probability of finding isolates with lower MIC values).</p

Median number of antimicrobials to which isolates recovered from swine (black bars) and cattle (dashed bars) samples were resistant to per year.

<p>Median number of antimicrobials to which isolates recovered from swine (black bars) and cattle (dashed bars) samples were resistant to per year.</p

Number and proportion of <i>Salmonella</i> isolates resistant to different antimicrobials recovered from swine and cattle samples between 2006 and 2015.

<p>Number and proportion of <i>Salmonella</i> isolates resistant to different antimicrobials recovered from swine and cattle samples between 2006 and 2015.</p