Longitudinal antimicrobial susceptibility trends of canine Staphylococcus pseudintermedius.

Antimicrobial resistance within Staphylococcus pseudintermedius poses a significant risk for the treatment of canine pyoderma and as a reservoir for resistance and potential zoonoses, but few studies examine long-term temporal trends of resistance. This study assesses the antimicrobial resistance prevalence and minimum inhibitory concentration (MIC) trends in S. pseudintermedius (n=1804) isolated from canine skin samples at the Cornell University Animal Health Diagnostic Center (AHDC) between 2007 and 2020. Not susceptible (NS) prevalence, Cochran-Armitage tests, logrank tests, MIC50 and MIC90 quantiles, and survival analysis models were used to evaluate resistance prevalence and temporal trends to 23 antimicrobials. We use splines as predictors in accelerated failure time (AFT) models to model non-linear temporal trends in MICs. Multidrug resistance was common among isolates (47%), and isolates had moderate to high NS prevalence to the beta-lactams, chloramphenicol, the fluoroquinolones, gentamicin, the macrolides/lincosamides, the tetracyclines, and trimethoprim-sulfamethoxazole. However, low levels of NS to amikacin, rifampin, and vancomycin were observed. Around one third of isolates (38%) were found to be methicillin resistant S. pseudintermedius (MRSP), and these isolates had a higher prevalence of NS to all tested antimicrobials than methicillin susceptible isolates. Amongst the MRSP isolates, one phenotypically vancomycin resistant isolate (MIC >16 µg/mL) was identified, but genomic sequence data was unavailable. AFT models showed increasing MICs across time to the beta-lactams, chloramphenicol, the fluoroquinolones, gentamicin, and the macrolides/lincosamides, and decreasing temporal resistance (decreasing MICs) to doxycycline was observed amongst isolates. Notably, ATF modeling showed changes in MIC distributions that were not identified using Cochran-Armitage tests on prevalence, MIC quantiles, and logrank tests. Increasing resistance amongst these S. pseudintermedius isolates highlights the need for rational, empirical prescribing practices and increased antimicrobial resistance (AMR) surveillance to maintain the efficacy of current therapeutic agents. AFT models with non-linear predictors may be a useful, breakpoint-independent, surveillance tool alongside other modeling methods and antibiograms.

Serotype and anti-microbial resistance trends among bovine Salmonella isolates from samples submitted to a veterinary diagnostic laboratory in central New York, 2007-2021.

AIMS: Salmonella enterica is a leading cause of acute enteritis in people, and dairy cattle are an important reservoir of this pathogen. The objective of this study was to analyse serotype and anti-microbial resistance trends of Salmonella isolated from dairy cattle in the United States between 2007 and 2021. METHODS AND RESULTS: We collected data for bovine Salmonella isolates obtained from samples submitted to Cornell University's Animal Health Diagnostic Center (AHDC). We analysed 5114 isolates for serotype trends, and a subset of 2521 isolates tested for anti-microbial susceptibility were analysed for resistance trends. The most frequently identified serotypes were Salmonella Cerro, Dublin, Typhimurium, Montevideo, 4,[5],12:i:-, and Newport. Among these serotypes, a Cochran-Armitage trend test determined there was a significant increase in the proportion of isolates serotyped as Salmonella Dublin (p < 0.0001) and Montevideo (p < 0.0001) over time. There was a significant decrease in the proportion of isolates serotyped as Salmonella Cerro (p < 0.0001), Typhimurium (p < 0.0001), and Newport (p < 0.0001). For the anti-microbial resistance (AMR) analysis, we found an overall increase in the proportion of multi-drug-resistant isolates over time (p = 0.009). There was a significant increase in the proportion of isolates resistant to ampicillin (p = 0.007), florfenicol (p = 0.0002), and ceftiofur (p < 0.0001) and a marginal increase in resistance to enrofloxacin (p = 0.05). There was a significant decrease in the proportion of isolates resistant to spectinomycin (p = 0.0002), trimethoprim/sulphamethoxazole (p = 0.01), sulphadimethoxine (p = 0.003), neomycin (p < 0.0001), and gentamicin (p = 0.0002). CONCLUSIONS: Our results provide evidence of an increase in resistance to key anti-microbial agents, although the observed trends were driven by the sharp increase in the proportion of Salmonella Dublin isolates over time.

Trends of feline Escherichia coli minimum inhibitory concentrations over 14 years illustrate the need for judicious antimicrobial use in cats.

OBJECTIVE: This study aims to assess the antimicrobial resistance (AMR) trends among Escherichia coli isolated from cats between 2008 and 2022, utilizing MIC data, within a one-health framework. SAMPLE: The study analyzed MIC results from 1,477 feline E coli isolates that were obtained from samples submitted to the Cornell University Animal Health Diagnostic Center, primarily from the northeastern US. METHODS: MIC values were categorized as susceptible or not susceptible using the Clinical and Laboratory Standards Institute breakpoints. Multidrug resistance (MDR) was analyzed using a Poisson regression model. Additionally, accelerated failure time models were employed to analyze MIC values. RESULTS: Out of the 1,477 E coli isolates examined, 739 (50%) showed susceptibility to all tested antimicrobials. Among the tested antimicrobials, cefazolin (69%) and ampicillin (74% for urinary tract isolates) exhibited the lowest susceptibility. Overall, 15% of isolates were not susceptible to cefovecin. E coli isolates were highly susceptible (> 95%) to antibiotics typically reserved for human use. Almost one-third of the isolates were classified as MDR, with nonurinary isolates more likely to exhibit an MDR pattern. A decrease in MICs for fluoroquinolones and gentamicin in recent years was identified. However, MICs for cephalexin increased from 2016 to 2022 and cefovecin from 2012 to 2019. CLINICAL RELEVANCE: This study highlights the challenge of AMR in feline medicine, emphasizing the importance of responsible antimicrobial use and surveillance to address E coli AMR. The related Currents in One Health by Cazer et al, JAVMA, December 2023, addresses additional feline antimicrobial stewardship topics.

Equine synovial sepsis laboratory submissions yield a low rate of positive bacterial culture and a high prevalence of antimicrobial resistance.

OBJECTIVE: To investigate (1) variables associated with the likelihood of obtaining a positive culture, (2) commonly isolated microorganisms, and (3) antimicrobial resistance patterns of isolates from horses with presumptive synovial sepsis. SAMPLES: Synovial fluid, synovium, and bone samples from equine cases with presumptive synovial sepsis submitted to the Cornell University Animal Health Diagnostic Center from 2000 to 2020 for microbial culture and antimicrobial sensitivity testing. PROCEDURES: Univariable and multivariable analyses were performed to determine the effect of variables on the likelihood of positive culture. Frequency distributions for isolated organisms and antimicrobial resistance were generated. Multidrug resistance patterns and associations were assessed with association rule mining. RESULTS: The positive culture rate for all samples was 37.4%, while the positive culture rate among samples confirmed to be septic by a combination of clinical pathological variables and case details was 43%. Blood culture vial submissions were 1.7 times more likely to yield a positive culture compared to samples submitted in a serum tube. Structure sampled, tissue submitted, and horse age were associated with a positive culture. Staphylococcus spp (23.7%), Streptococcus spp (22.4%), and Enterococcus spp (9.67%) were commonly isolated. Multidrug resistance prevalence decreased from 92% (2000 to 2009) to 76% (2010 to 2020) of gram-negative isolates and 60% (2000 to 2009) to 52% (2010 to 2020) of gram-positive isolates. CLINICAL RELEVANCE: The positive culture rate from synovial fluid submissions with traditional sampling and culture methods remains low and may be optimized by submitting samples in blood culture vials. Overall, antimicrobial resistance was frequently observed but did not increase from the first to second decade for most genera.