Antimicrobial resistance profile and prevalence of extended-spectrum beta-lactamases (ESBL), AmpC beta-lactamases and colistin resistance (mcr) genes in Escherichia coli from swine between 1999 and 2018

Abstract

The frequent usage of antibiotics in livestock has led to the spread of resistant bacteria within animals and their products, with a global warning in public health and veterinarians to monitor such resistances. This study aimed to determine antibiotic resistance patterns and genes in pig farms from Spain during the last twenty years. Susceptibility to six antibiotics commonly used in pig production was tested by qualitative (disk diffusion) and quantitative (minimum inhibitory concentration, MIC) methods in 200 strains of Escherichia coli which had been isolated between 1999 and 2018 from clinical cases of diarrhoea in neonatal and post-weaned piglets. Results showed resistance around 100% for amoxicillin and tetracycline since 1999, and a progressive increase in ceftiofur resistance throughout the studied period. For colistin, it was detected a resistance peak (17.5% of the strains) in the 2011-2014 period. Concerning gentamicin, 11 of 30 strains with intermediate susceptibility by the disk diffusion method were resistant by MIC. Besides, the most frequent antimicrobial resistance genes were the extendedspectrum beta-lactamase (ESBL) bla CTX-M (13.5% of strains, being CTX-M-14, CTX-M-1 and CTX-M-32 the most prevalent genomes, followed by CTX-M-27, CTX-M-9 and CTX-M-3), AmpC-type beta-lactamase (AmpC) bla CMY-2 (3%) and colistin resistance genes mcr-4 (13%), mcr-1 (7%) and in less proportion mcr-5 (3%). Interestingly, these mcr genes were already detected in strains isolated in 2000, more than a decade before their first description. However, poor concordance between the genotypic mcr profile and the phenotypical testing by MIC was found in this study. These results indicate that although being a current concern, resistance genes and therefore antimicrobial resistant phenotypes were already present in pig farms at the beginning of the century.

Prevalence of Virulence Genes and Antimicrobial Resistances in E. coli Associated with Neonatal Diarrhea, Postweaning Diarrhea, and Edema Disease in Pigs from Austria

“…Therefore, observed high resistance levels in our investigations might be the result of a widespread use of tetracyclines, as already assumed before [21]. In recent Spanish investigations using agar disk diffusion testing, resistances of clinical porcine E. coli isolates were also more frequently detected against amoxicillin and tetracycline than against ceftiofur, gentamicin, and enrofloxacin [22]. It can be assumed that resistances of porcine E. coli towards tetracyclines emerged, when antimicrobials were also used as growth promoters.…”

Prevalence of ESβL, AmpC and Colistin-Resistant E. coli in Meat: A Comparison between Pork and Wild Boar

“…The most common genes encoding ESβL in animals are bla CTX-M1 and bla CTX-M14 , followed by bla TEM-52 and bla SHV-12 , while the gene mainly associated with resistance in AmpC-type β-lactamases is bla CMY-2 [ 7 ]. In enteric bacteria of domestic animals and large game animals in Europe, bla CTX-M1 is one of the most prevalent ESβL genes [ 36 , 46 , 47 ] and is also frequently found among Enterobacteriaceae recovered from the meat of farm animals [ 48 , 49 ]. In the present study, the E. coli isolated from both pork meat products and fresh wild boar meat frequently harboured bla CTX-M1 , but only bla CTX-M2 and bla TEM prevalence showed a statistically significant difference between pork and wild boar samples.…”

Antimicrobial Susceptibility Pattern of Porcine Respiratory Bacteria in Spain

“…The measurement of antimicrobial susceptibility is carried out by MIC determination that is more reproducible and comparable between laboratories [11] than disk diffusion techniques due to concerns about disk quality, performance issues [18,19] and variability intrinsically associated to some antimicrobials for the disk diffusion technique [20]. The MIC is the lowest antimicrobial concentration that inhibits in vitro the growth of the target bacteria in specific conditions of in vitro incubation.…”

“…The MIC is the lowest antimicrobial concentration that inhibits in vitro the growth of the target bacteria in specific conditions of in vitro incubation. In this study, the antimicrobial susceptibility has been determined using international guidelines on antimicrobial susceptibility determination [21,22] that cannot be directly compared with other studies only based on disk diffusion techniques [20]. This methodology does not emulate the natural biophase in which bacteria grow in vivo, such as blood, interstitial or intracellular fluid.…”