Antimicrobial Susceptibility Testing of Porcine Bacterial Pathogens: Investigating the Prospect of Testing a Representative Drug for Each Antimicrobial Family

Abstract

Antimicrobial susceptibility testing is necessary to carry out antimicrobial stewardship but a limited number of drugs belonging to each antimicrobial family has to be tested for technical limitations and economic resources. In this study, we have determined the minimal inhibitory concentration, using microdilution following international standards (CLSI), for 490 Actinobacillus pleuropneumoniae, 285 Pasteurella multocida, 73 Bordetella bronchiseptica, 398 Streptococcus suis and 1571 Escherichia coli strains from clinical cases collected in Spain between 2018 and 2020. The antimicrobial susceptibility pattern was deciphered using a principal component analysis for each bacterium and a matrix correlation (high > 0.8, medium 0.5–0.8 and low < 0.5) was obtained for each pair of antimicrobials. No significant associations were observed between MIC patterns for different antimicrobial families, suggesting that co-selection mechanisms are not generally present in these porcine pathogens. However, a high correlation was observed between the fluroquinolones (marbofloxacin and enrofloxacin) for all mentioned pathogens and for ceftiofur and cefquinome for E. coli and S. suis. Moreover, a significant association was also observed for tetracyclines (doxycycline and oxytetracycline) and B. bronchiseptica and tildipirosin/tulathromycin for P. multocida. These results suggest that generally, a representative drug per antimicrobial class cannot be selected, however, for some drug–bug combinations, MIC values from one representative drug could be extrapolated to the whole antimicrobial family.

Susceptibility Trends of Respiratory and Enteric Porcine Pathogens to Last Resource Antimicrobials

“…In this case, we have used a multinominal logistic model based on distributing the range of MIC values into four categories (from 1 to 4) that include two MIC values in each category, being category 1 the most susceptible (lowest MIC value) and 4 the less susceptible (highest MIC value), as suggested by other authors with a similar database for E. coli [48]. Finally, the antimicrobial panel was selected to represent commonly used compounds for the treatment of pig diseases in practice [31,32], and not focused on monitoring antimicrobial resistance in surveillance programs. This is a clear limitation of this study since antimicrobials tested herein were not the same for all the porcine pathogens.…”

Mobile colistin resistance (MCR), extended-spectrum beta-lactamase (ESBL) and multidrug resistance monitoring in Escherichia coli (commensal and pathogenic) in pig farming: need of harmonized guidelines and clinical breakpoints

“…On the other hand, E. coli is commonly used as an indicator bacteria on the "One-Health" surveillance of antimicrobial resistance (AMR) by the European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC) (EFSA (European Food Safety Authority) and ECDC (European Centre for Disease Prevention and Control), 2019). On top of that, there is a global consensus on the need for efficient antimicrobial stewardship programs in pigs to reduce the selection of resistant bacteria (Verliat et al, 2021;Bosman et al, 2022;Vilaró et al, 2022). Here, we aimed to gain knowledge on the diagnosis and clinical difficulties in the veterinary sector when providing the best antibiotic therapy option.…”

“…The goal of in vitro AST is to inform clinicians whether an antimicrobial is appropriate for the infection caused by a specific isolate. Furthermore, there is no successful option of empiric treatment for E. coli due to their heterogeneous MIC profile, so optimization to minimize resistance selection should be based on AST for each clinical case (Cortés et al, 2010;García-Meniño et al, 2019Vilaró et al, 2022). However, we report here the lack of standardized breakpoints for many antimicrobials of common use in livestock.…”

“…Nevertheless, it is outstanding the correlation obtained for flumequine applying CASFM VET and ECOFF (64.2% resistant and 76.4% N-WT, respectively), in comparison with data on enrofloxacin (31.1% resistant and 76.4% N-WT, respectively). Besides, resistance prevalence to marbofloxacin is expected to correlate with enrofloxacin (Vilaró et al, 2022). In our previous study (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017), where the CLSI2020 clinical breakpoints were applied, a high percentage of isolates implicated in colibacillosis exhibited quinolone/fluoroquinolone resistance: 82.3% to nalidixic acid, 56.5% to ciprofloxacin and 48.4% to levofloxacin.…”

Detection of antibiotic-resistant canine origin Escherichia coli and the synergistic effect of magnolol in reducing the resistance of multidrug-resistant Escherichia coli

“…The above antibiotics are commonly used in veterinary clinical treatment of E. coli infection. Susceptibility to ceftiofur and cefquinome was determined in reference to previous research ( 23 ). All drugs were diluted 2-fold in MHB and mixed with an equal volume of bacterial suspension in a 96-well microtiter plate.…”