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Escherichia coli resistance data for each included study sorted by continent Each circle represents one study, and the size of each circle reflects how many isolates were included in the study. The colour of the circle illustrates resistance only (red circle) or resistance merged with intermediate (blue circle). The dashed lines indicate, for each antibiotic, the weighted arithmetic mean of %R (red dashed line) or %R+I (blue dashed line). The exact percentages these lines represent are listed in Appendix E. Numbers written to the left of the antibiotic names reflect the number of studies for a certain drug/continent combination.
Source publication
Abstract In this opinion, the antimicrobial‐resistant bacteria responsible for transmissible diseases that constitute a threat to the health of pigs have been assessed. The assessment has been performed following a methodology based on information collected by an extensive literature review and expert judgement. Details of the methodology used for...
Citations
... The identification of isolates for respiratory pathogens and enteric pathogens was carried out through matrix assisted laser desorption ionization-time of flight (MALDI-TOF Biotyper System, Bruker Daltonics, Bremen, Germany), as previously described (25). The individual isolates were stored at −80 • C in a brain-heart infusion (CM1135, Oxoid) with 30% glycerol (G9012, Sigma-Aldrich). ...
Monitoring the antimicrobial susceptibility of last-resource antimicrobials for veterinary pathogens is urgently needed from a one-health perspective. The objective of this study was to analyze the antimicrobial susceptibility trends of Spanish porcine bacteria to quinolones, cephalosporins, and polymyxins. Isolates of Actinobacillus pleuropneumoniae, Pasteurella multocida, and Escherichia coli were isolated from sick pigs from 2019 to 2022. An antimicrobial susceptibility test was determined based on the minimal inhibitory concentration (MIC) following an internationally accepted methodology. The MIC categorization was based on distributing the range of MIC values in four categories, with category one being the most susceptible (lowest MIC value) and category four the least susceptible (highest MIC value). Moreover, clinical susceptibility (susceptible/non-susceptible) was also determined according to the CLSI and EUCAST clinical breakpoints. A logistic and multinomial logistic regression model was used to analyze the susceptibility data for dichotomized and categorized MIC data, respectively, for any pair of antimicrobial/microorganism. In general terms, the antimicrobial susceptibility of pig bacteria to these antimicrobials remained stable or increased in the last four years in Spain. In the case of A. pleuropneumoniae and quinolones, a significant temporal trend was observed where isolates from 2020 had significantly increased odds of being more susceptible than isolates from 2019. In the case of E. coli and polymyxins, a significant temporal trend was observed where isolates from 2020 and 2021 had significantly increased odds of being more susceptible than isolates from 2019 and 2020, respectively. Finally, significant odds of being less susceptible were only observed for cephalosporins and E. coli for 2020 versus 2019, stagnating for the rest of study period. These results provide sound data on critically important antimicrobials in swine medicine.
... On the other hand, many non-infectious predisposing factors are also involved in PRDC, such as poor environmental conditions, density, stressors, season of the year, genetic background, and production flow (all in-all out versus continuous flow) [7][8][9]. If preventive medicine programs, such as improving environmental conditions, decrease density and stressors, combined with vaccination against the major viral and bacterial infectious etiologic factors [10] are not in place or fail, the use of antimicrobials with therapeutic or metaphylactic purpose in pigs may be necessary to control the relevant pathogens involved in respiratory disorders [11][12][13][14], contributing to most of the pig antimicrobial consumption [12,15]. ...
... On the other hand, many non-infectious predisposing factors are also involved in PRDC, such as poor environmental conditions, density, stressors, season of the year, genetic background, and production flow (all in-all out versus continuous flow) [7][8][9]. If preventive medicine programs, such as improving environmental conditions, decrease density and stressors, combined with vaccination against the major viral and bacterial infectious etiologic factors [10] are not in place or fail, the use of antimicrobials with therapeutic or metaphylactic purpose in pigs may be necessary to control the relevant pathogens involved in respiratory disorders [11][12][13][14], contributing to most of the pig antimicrobial consumption [12,15]. ...
Background
Antimicrobial resistance is one of the most important health challenges in humans and animals. Antibiotic susceptibility determination is used to select the most suitable drug to treat animals according to its success probability following the European legislation in force for these drugs. We have studied the antibiotic susceptibility pattern (ASP) of Actinobacillus pleuropneumoniae (APP) and Pasteurella multocida (PM) isolates, collected during the period 2019–2022 in Spain. ASP was measured by determining minimum inhibitory concentration using standardized laboratory methods and its temporal trend was determined by logistic regression analysis of non-susceptible/susceptible isolates using clinical breakpoints.
Results
It was not observed any significant temporal trends for susceptibility of Actinobacillus pleuropneumoniae to ceftiofur, florfenicol, sulfamethoxazole/trimethoprim, tulathromycin and tildipirosin during the study period (p > 0.05). Contrarily, a significant temporal trend (p < 0.05) was observed for quinolones (enrofloxacin and marbofloxacin), tetracyclines (doxycycline and oxyteracycline), amoxicillin, tiamulin and tilmicosin. On the other hand, it was not observed any significant temporal trends for susceptibility of Pasteurella multocida to quinolones (enrofloxacin and marbofloxacin), amoxicillin, ceftiofur, florfenicol and macrolides (tildipirosin, tulathromycin and tilmicosin) during the study period (p > 0.05). Contrarily, a significant temporal trend (p < 0.05) was observed for tetracyclines (oxyteracycline), tiamulin and sulfamethoxazole/trimethoprim.
Conclusions
In general terms, pig pathogens (APP and PM) involved in respiratory diseases analysed herein appeared to remain susceptible or tended to increase susceptibility to antimicrobials over the study period (2019–2022), but our data clearly showed a different pattern in the evolution of antimicrobial susceptibility for each combination of drug and microorganism. Our results highlight that the evolution of antimicrobial susceptibility must be studied in a case-by-case situation where generalization for drug families and bacteria is not possible even for bacteria located in the same ecological niche.
... The use of antimicrobials with therapeutic or metaphylactic purpose in pigs may be necessary to control the relevant pathogens involved in respiratory and enteric disorders, contributing to most of the pig antimicrobial consumption [21][22][23]. Thus, porcine respiratory disease complex (PRDC) and post-weaning diarrhoea (PWD) are some of the most challenging diseases affecting the pig industry worldwide [24,25]. ...
... PWD is characterized by a profuse diarrhea, dehydration, significant mortality, and loss of body weight in surviving pigs [27][28][29]. When clinical signs appear, prescription of antimicrobials is in many cases the only solution to control the spread of the PRDC and PWD within the herd [21,22,[29][30][31]. Thus, it may be necessary to use last resource antimicrobials if no other option is available according to an antimicrobial stewardship program . ...
The objective of the study was to analyse the antimicrobial susceptibility trends of Spanish porcine bacteria to quinolones, cephalosporins and polymyxins. Isolates of Actinobacillus pleuropneumoniae, Pasteurella multocida, and Escherichia coli were isolated from sick pigs from 2019 to 2022. Antimicrobial susceptibility test was determined by minimal inhibitory concentration (MIC) following internationally accepted methodology. MIC categorization was based on distributing the range of MIC values in four categories being category one the most susceptible (lowest MIC value) and four the less susceptible one (highest MIC value). Moreover, clinical susceptibility (susceptible/resistant) was also determined according to CLSI and EUCAST clinical breakpoints. A logistic and multinomial logistic regression model was used to analyze the susceptibility data for dichotomized and categorized MIC data, respectively for any pair of antimicrobial/microorganism. In general terms, the antimicrobial susceptibility of pig bacteria to these antimicrobials remained stable or increased in the last four years in Spain. In the case of A. pleuropneumoniae and quinolones, it was observed a significant temporal trend where isolates from 2020 had significantly increased odds of being more susceptible than isolates from 2019. In the case of E. coli and polymyxins, a significant temporal trend was observed where isolates from 2020 and 2021 had significantly increased odds of being more susceptible than isolates from 2019 and 2020, respectively. Finally, a significant odd of being less susceptible was only observed for cephalosporins and E. coli for 2020 versus 2019, stagnating for the rest of study period. These results provide sound data on critical important antimicrobials in swine medicine.
... Beta-Laktamase-bildende Staphylokokken-Stämme sind weit verbreitet und führen zu Resistenzen gegen Penicilline und Aminopenicilline [19], aber auch Resistenzen gegen Ceftiofur sind hinlänglich beschrieben [20]. Zugelassene Impfstoffe gegen St. hyicus stehen nicht zur Verfügung. ...
Zusammenfassung
Exsudative Epidermitis (EE) – meist, aber nicht ausschließlich ausgelöst durch Staphylococcus (St.) hyicus – ist ein verbreitetes Problem auf Ferkelerzeugerbetrieben. So auch in einem westdeutschen eigenremontierenden Betrieb mit 350 produktiven Sauen. Beginnend mit schwärzlich-schuppigen Hautläsionen bei einzelnen Saug- und Aufzuchtferkeln sowie Jung- und Altsauen, bestand bereits in der nächsten Absetzgruppe bei etwa 50% der Ferkel die klinische Verdachtsdiagnose der EE. Die Mortalitätsrate im Aufzuchtstall stieg bei betroffenen Ferkelgruppen auf 10%. Sowohl die (histo)pathologische Untersuchung als auch der wiederholte Nachweis von St. hyicus aus Hauttupfern sowie Tupfern aus anderen Organen bestätigten die klinische Verdachtsdiagnose. Neben St. hyicus konnte aus einzelnen Hauttupfern zudem St. chromogenes isoliert werden. In der weiterführenden Charakterisierung der St. hyicus-Stämme wurden ExhA und SHETA als beteiligte Toxine identifiziert, und die Isolate zeigten unter anderem Resistenzen gegen Penicilline und Aminopenicilline. Kurzfristig verbesserte eine bestandsweise antibiotische Therapie mit einem Trimethoprim-Sulfadiazin-haltigen Präparat in Kombination mit der individuellen Behandlung einzelner Tiere und dem Waschen mit einer jodhaltigen Lösung die klinische Symptomatik. Zur dauerhaften Reduktion des Einsatzes antibiotischer Mittel wurde sich für die Herstellung eines bestandsspezifischen Impfstoffs mit den isolierten St. hyicus- und St. chromogenes-Stämmen entschieden, welcher als Mutterschutzvakzine an die Sauen appliziert wurde. Zusätzlich wurde die externe und interne Biosicherheit anhand eines objektiven Fragebogens (Bio-check.UGentTM) evaluiert und angepasst. Die Kombination der Maßnahmen führte zu einer langfristigen Besserung des klinischen Geschehens. Das erneute Auftreten leichter Hautläsionen bei einzelnen Ferkeln konnte mit der Anpassung des bestandsspezifischen Impfstoffes durch neu gewonnene St. hyicus-Isolate zielführend in den Griff bekommen werden. Der Fallbericht verdeutlicht, wie mit der Kombination aus kontinuierlichem Monitoring, Einzeltier- und Gruppentherapie, Evaluierung der Biosicherheit und dem Einsatz einer angemessenen Immunprophylaxe selbst hartnäckige Fälle der EE auf ein Minimum reduziert werden können.
Abstract
A massive outbreak of exudative epidermitis (EE) occurred on a Western German piglet producing farm with 350 productive sows. Gilts are produced on site. In one group of piglets, more than 50% of suckling and nursery piglets were clinically affected; furthermore, gilts as well as sows showed localized blackish-squamous skin lesions in the neck area. Generalized infection in suckling and nursery piglets resulted in mortality rates of up to 10% per weaning group. Swabs of moist, affected areas of skin taken on the farm in addition to swab and organ samples collected during necropsy were examined via bacterial cultivation. Both Staphylococcus (St.) hyicus and St. chromogenes strains were detected in affected skin lesions, with St. hyicus also present in systemic localizations. Further characterization of the St. hyicus strains identified ExhA and SHETA as toxins involved, and isolates showed resistance to penicillin and aminopenicillin. In the short term, antibiotic treatment with trimethoprim-sulfadiazine of the whole age group combined with individual treatment of severely affected animals as well as washing with an iodine-containing solution improved the clinical signs. In order to reduce the antibiotic use, an autogenous vaccine against the isolated St. hyicus and St. chromogenes strains for gilts and sows was produced and applied as a basic immunization twice before farrowing. In addition, external and internal biosecurity was evaluated and adjusted using an objective questionnaire (Bio-check.UGentTM). The combination of taken measures resulted in a long-term improvement of the overall health status. Several months after the severe EE outbreak, the sporadic occurrence of new EE cases in individual piglets could be controlled by the adjustment of the autogenous vaccine with an additional St. hyicus isolate. The case report illustrates how the combination of continuous monitoring, individual and group antibiotic treatment, biosecurity evaluation, and the use of appropriate immune prophylaxis can improve the clinical picture of EE.
... Indeed, countries such as Denmark and the Netherlands, which both have had massive swine production in recent years, have achieved tremendous reductions in antimicrobial usage while sustaining peak production. Comparable results have been accomplished in Belgium, France, Sweden and the United Kingdom [7,46,48,50]. In contrast, in six countries, there were only increasing trends, and there were increasing trends in Belgium (despite the reduction in antibiotic use), Poland and Romania for three antimicrobials [48]. ...
... As a summary for the EU, the EFSA Animal Health and Welfare Panel (2021) revealed clinical swine E. coli isolates with a high proportion of resistance to numerous antibiotics, with a prevalence from 63% to 70% (to aminopenicillins, sulfonamides and tetracycline). However, lower rates of resistance to clinically critical antibiotics (fluoroquinolones and third-generation cephalosporins) were detected [50]. Likely, the latter was the first fruit of the recent Regulation (EU) 2019/61 on Veterinary Medicines and Regulation (EU) 2019/4 on Medicated Feed, stating that antibiotics shall not be applied routinely, nor for prophylaxis, unless in exceptional cases. ...
Escherichia coli (E. coli) is a ubiquitous microorganism with pathogenic and saprophytic clones. The objective of this study was to evaluate the presence, virulence, antibiotic resistance and biofilm formation of E. coli in three industrial farms in Bulgaria, as well as their adjacent sites related to the utilization of manure (feces, wastewater in a separator, lagoons, means of transport, and soils). The isolation of single bacterial cultures was performed via standard procedures with modifications, and E. coli isolates were identified via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and polymerase chain reaction (PCR). The disk diffusion method was used to assess antimicrobial resistance, and PCR was used to detect genes for antibiotic resistance (GAR) (qnr, aac(3), ampC, blaSHV/blaTEM and erm) and virulence genes (stx, stx2all, LT, STa, F4 and eae). The protocol of Stepanović was utilized to measure the biofilm formation of the isolates. A total of 84 isolates from different samples (n = 53) were identified as E. coli. Almost all demonstrated antimicrobial resistance, and most of them demonstrated resistance to multiple antibiotics from different classes. No virulence genes coding the Shiga toxin or enterotoxins or those associated with enteropathogenicity were detected. No GAR from those tested for quinolones, aminoglycosides and macrolides were found. However, all isolates that were resistant to a penicillin-class antibiotic (56) had β-lactamase-producing plasmid genes. All of them had ampC, and 34 of them had blaTEM. A total of 14 isolates formed strongly adherent biofilms. These results in a country where the use of antibiotics for growth promotion and prophylaxis in farms is highly restricted corroborate that the global implemented policy on antibiotics in human medicine and in animal husbandry needs revision.
... 126 In ruminants and pigs, amoxicillin/clavulanic acid is important for treatment of resistant infections caused by Mannheimia, Pasteurella and in particular Actinobacillus spp. 127,128 Resistance to aminopenicillins in respiratory pathogens from food-producing species in the EU generally remain low to moderate, although increasing rates have been demonstrated, e.g. in isolates from pigs in Spain and Italy and cattle in Germany. 127,128 In Pasteurella multocida and Mannheimia haemolytica from cattle, the mean levels of resistance to aminopenicillins in Europe were 15.3% and 12.3%, respectively. ...
... 127,128 Resistance to aminopenicillins in respiratory pathogens from food-producing species in the EU generally remain low to moderate, although increasing rates have been demonstrated, e.g. in isolates from pigs in Spain and Italy and cattle in Germany. 127,128 In Pasteurella multocida and Mannheimia haemolytica from cattle, the mean levels of resistance to aminopenicillins in Europe were 15.3% and 12.3%, respectively. In the respiratory pathogens from pigs, the mean resistance levels for aminopenicillins were 10.4% for P. multocida. ...
... In the respiratory pathogens from pigs, the mean resistance levels for aminopenicillins were 10.4% for P. multocida. 127,128 In addition, aminopenicillins are useful in treating urinary infections or enteric infections caused by E. coli in food-producing animals. Resistance to aminopenicillins in E. coli can be at high to very high levels, depending on the animal species. ...
Aminopenicillins have been widely used for decades for the treatment of various infections in animals and humans in European countries. Following this extensive use, acquired resistance has emerged among human and animal pathogens and commensal bacteria. Aminopenicillins are important first-line treatment options in both humans and animals, but are also among limited therapies for infections with enterococci and Listeria spp. in humans in some settings. Therefore, there is a need to assess the impact of the use of these antimicrobials in animals on public and animal health.
The most important mechanisms of resistance to aminopenicillins are the β-lactamase enzymes. Similar resistance genes have been detected in bacteria of human and animal origin, and molecular studies suggest that transmission of resistant bacteria or resistance genes occurs between animals and humans. Due to the complexity of epidemiology and the near ubiquity of many aminopenicillin resistance determinants, the direction of transfer is difficult to ascertain, except for major zoonotic pathogens. It is therefore challenging to estimate to what extent the use of aminopenicillins in animals could create negative health consequences to humans at the population level. Based on the extent of use of aminopenicillins in humans, it seems probable that the major resistance selection pressure in human pathogens in European countries is due to human consumption. It is evident that veterinary use of these antimicrobials increases the selection pressure towards resistance in animals and loss of efficacy will at minimum jeopardize animal health and welfare.
... In Europe, the EFSA AHAW Panel (2021c) revealed clinical swine E. coli isolates with a high proportion of resistance to numerous antibiotics with a prevalence from 63% to 70% (namely to aminopenicillins, sulfonamides, and tetracycline) [77]. However, lower rates of resistance to clinically critical antibiotics (fluoroquinolones and third-generation cephalosporins) were detected. ...
Swine pathogenic infection caused by Escherichia coli, known as swine colibacillosis, represents an epidemiological challenge not only for animal husbandry but also for health authorities. To note, virulent E. coli strains might be transmitted, and also cause disease, in humans. In the last decades, diverse successful multidrug-resistant strains have been detected, mainly due to the growing selective pressure of antibiotic use, in which animal practices have played a relevant role. In fact, according to the different features and particular virulence factor combination, there are four different pathotypes of E. coli that can cause illness in swine: enterotoxigenic E. coli (ETEC), Shiga toxin-producing E. coli (STEC) that comprises edema disease E. coli (EDEC) and enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), and extraintestinal pathogenic E. coli (ExPEC). Nevertheless, the most relevant pathotype in a colibacillosis scenario is ETEC, responsible for neonatal and postweaning diarrhea (PWD), in which some ETEC strains present enhanced fitness and pathogenicity. To explore the distribution of pathogenic ETEC in swine farms and their diversity, resistance, and virulence profiles, this review summarizes the most relevant works on these subjects over the past 10 years and discusses the importance of these bacteria as zoonotic agents.
... This might be due to the very limited alternative antimicrobials for certain indications in certain EU countries and depending on susceptibility patterns to other Category B substances depending on resistance profile and disease/patient characteristics. In addition, the European Food Safety Agency (EFSA) assessments of animal diseases caused by bacteria resistant to antimicrobials noted high levels of resistance to first-line antimicrobials (e.g., aminopenicillins, potentiated sulphonamides, tetracyclines) in pathogenic E. coli from pigs, poultry, sheep, goats, and calves, suggesting their limited efficacy against these infections in many EU countries [46][47][48][49]. In pigs, high concentrations of in-feed zinc oxide have been extensively used to manage neonatal and weaning gastrointestinal infections [50,51], but this became prohibited in June 2022 due to its negative environmental impact and potential co-selection of resistance genes but might lead to more use again of colistin [52]. ...
Polymyxin E (colistin) is a medically important active substance both in human and veterinary medicine. Colistin has been used in veterinary medicine since the 1950s. Due to the discovery of the plasmid-borne mcr gene in 2015 and the simultaneously increased importance in human medicine as a last-resort antibiotic, the use of colistin for animals was scrutinised. Though veterinary colistin sales dropped by 76.5% between 2011 to 2020, few studies evaluated real-world data on the use patterns of colistin in different European countries and sectors. A survey among veterinarians revealed that 51.9% did not use or ceased colistin, 33.4% decreased their use, 10.4% stabilised their use, and 2.7% increased use. The most important indications for colistin use were gastrointestinal diseases in pigs followed by septicaemia in poultry. A total of 106 (16.0%) responding veterinarians reported governmental/industry restrictions regarding colistin use, most commonly mentioning “use only after susceptibility testing” (57%). In brief, colistin was perceived as an essential last-resort antibiotic in veterinary medicine for E. coli infections in pigs and poultry, where there is no alternative legal, safe, and efficacious antimicrobial available. To further reduce the need for colistin, synergistic preventive measures, including improved biosecurity, husbandry, and vaccinations, must be employed.
... Data collection on AMR (and the associated resistome) in food animals is required to enhance animal health measures, to promote the rational use of antimicrobials, and to identify specific therapeutic challenges related to AMR [48]. According to the third joint inter-agency report on the integrated analysis of antimicrobial consumption and resistance in humans and food-producing animals (that is, the third JIACRA report), bacterial resistance from humans was associated with that from food animals, where the latter was in turn related to antimicrobial consumption in animals. ...
The aim of this study was metagenomics analyses of acquired antibiotic-resistance genes (ARGs) in the intestinal microbiome of two important food-animal species in Hungary from a One Health perspective. Intestinal content samples were collected from 12 domestic pigs (Sus scrofa) and from a common carp (Cyprinus carpio). Shotgun metagenomic sequencing of DNA purified from the intestinal samples was performed on the Illumina platform. The ResFinder database was applied for
detecting acquired ARGs in the assembled metagenomic contigs. Altogether, 59 acquired ARG types
were identified, 51 genes from domestic pig and 12 genes from the carp intestinal microbiome. ARG
types belonged to the antibiotic classes aminoglycosides (27.1%), tetracyclines (25.4%), β-lactams (16.9%), and others. Of the identified ARGs, tet(E), a blaOXA-48-like β-lactamase gene, as well as cphA4, ampS, aadA2, qnrS2, and sul1, were identified only in carp but not in swine samples. Several of the detected acquired ARGs have not yet been described from food animals in Hungary. The tet(Q), tet(W), tet(O), and mef(A) genes detected in the intestinal microbiome of domestic pigs had also been identified from free-living wild boars in Hungary, suggesting a possible relationship between the occurrence of acquired ARGs in domestic and wild animal populations.
... In the case of S. suis, disease outbreaks mainly occur after weaning when maternal antibodies wane. The mortality rate can be as high as 30%, but less severe manifestations of the disease include polyarthritis, meningitis, endocarditis or pneumonia during the nursery period [3,6,7]. Up to date, there is not registered vaccine for S. suis. ...
... PWD is characterized by a profuse diarrhea, dehydration, significant mortality and loss of body weight in surviving pigs [10,11]. When clinical signs appear, prescription of antimicrobials is the only solution to control the spread of the disease within the herd [6,7,12]. ...
... The use of antimicrobials with a therapeutic or metaphylactic purpose may be necessary to control the relevant pathogens involved in PRDC, S. suis infections and PWD [6,7,13,14]. In particular, the objective of antimicrobial therapy is to provide an effective drug to obtain a fast clinical recovery from the infection, reducing the probability of generating AMR bacteria [15]. ...
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.
