Antimicrobial Susceptibility of Enterotoxigenic Escherichia coli from Diarrhoeic Neonatal Calves in Spain

Simple Summary

Neonatal calf diarrhoea, a worldwide concern for cattle production, can be caused by viral, bacterial and protozoan enteropathogens: the enterotoxigenic Escherichia coli (ETEC) is one of the most important. The use of antimicrobials for treating neonatal calf diarrhoea cases is still a common practice among veterinary surgeons, although its use is only justified in bacterial infections evolving towards a systemic disease. Since the indiscriminate use of antimicrobials for treating diarrhoeic calves increases the risk for the appearance of antimicrobial resistances, restrictions on the use of antimicrobials in veterinary practice were implemented. The aim of this study was to characterize the antimicrobial susceptibility of ETEC strains obtained from diarrhoeic calves. Our results are alarming since all ETEC strains were resistant to three or more families of antimicrobials; in addition, a high number of strains were resistant to most first-line antimicrobials used in veterinary practice. Only ceftiofur, cefoperazone, cefquinome and gentamicin presented efficacy against most ETEC strains. Thus, empirical treatment of calf scours caused by ETEC is usually ineffective. Our results reveal that performing antimicrobial susceptibility tests in each NCD outbreak is needed for establishing an effective treatment and avoiding the emergence of new resistance mechanisms.

Abstract

Enterotoxigenic Escherichia coli (ETEC) is one of the major pathogens involved in neonatal calf diarrhoea (NCD) causing high economic losses in dairy farms. Antibiotic treatment is common in cases of systemic illness caused by NCD, but antimicrobial susceptibility tests (AST) are usually not performed. Thus, the aim of this study was to characterize the antimicrobial susceptibility of ETEC strains obtained from calves with diarrhoea between 2018–2020. Faecal samples (n = 420) were analyzed to detect the typical ETEC virulence factors F5 and STa. Positive samples were cultured to identify and isolate ETEC strains (n = 41) and ASTs were performed. Our results are alarming since ETEC strains resistant to three or more families of antimicrobials were detected in all isolates. Only four antibiotics (ceftiofur, cefoperazone, cefquinome and gentamicin) presented efficacy against more than 90% of the ETEC strains, while the other ten antibiotics were effective against less than 40% of the strains. In addition, a high number of strains were resistant to most first-line antimicrobials used in veterinary practice. For this reason, when ETEC infection is suspected, an AST must always be performed to select the most appropriate antimicrobial in each case and to avoid the emergence of new resistance mechanisms.

Gentamicin- and Ciprofloxacin-Resistant Enterobacteriaceae in Cattle Farms in Israel: Risk Factors for Carriage and the Effect of Microbiological Methodology on the Measured Prevalence

Our objectives were to establish a methodology for surveillance of ciprofloxacin-resistant Enterobacteriaceae and gentamicin-resistant Enterobacteriaceae (CPRE and GNRE, respectively) in cattle and to study the prevalence and risk factors for carriage of these bacteria in a national survey. This was a point prevalence study conducted from July to October 2013 in Israel. Stool samples were collected from 1,226 cows in 123 sections of 40 farms of all production types. The number of CPRE- and GNRE-positive cows was highest in quarantine stations and fattening farms and was lowest in pasture farms (p < 0.01). The number of CPRE- and GNRE-positive cows was lowest in dairy farm sections containing adult cows (>25 months) and highest in calves (<4 months) (p < 0.001). In bivariate analysis, other variables that were significant risk factors for CPRE and GNRE carriage included fewer troughs, crowding, lack of manure cleaning, and recent arrival of new calves. Antimicrobial prophylaxis was given almost exclusively to calves and was associated with a higher prevalence of carriers (p < 0.001). Compared to the use of nonselective media (MacConkey agar alone), the use of selective media (MacConkey agar with 10 μg/ml of ciprofloxacin or 5 μg/ml of gentamicin) increased the sensitivity of screening for CPRE and GNRE by 6.6- and 13.5-fold, respectively. CPRE and GNRE were identified in 609 (49.7%) and 840 (68.5%) samples, respectively. This study provides novel data regarding both the epidemiology of CPRE and GNRE carriage in livestock and the microbiological methodology for their surveillance.

Occurrence and Spread of Quinolone-Resistant Escherichia coli on Dairy Farms

Quinolone-resistant Escherichia coli (QREC) is common in feces from young calves, but the prevalence and genetic diversity of QREC in groups of cattle of other ages and the farm environment are unknown. The aims of the study were to obtain knowledge about the occurrence of QREC on dairy farms, the genetic diversity of QREC within and between farms, and how these relate to the number of purchased animals and geographic distances between farms. We analyzed the within-sample prevalence of QREC in individual fecal samples from preweaned dairy calves and postpartum cows and in environmental samples from 23 Swedish dairy farms. The genetic diversity of the QREC isolates on 10 of these farms was assessed. In general, QREC was more prevalent in the dairy farm environment and in postpartum cows if QREC was commonly found in calves than if QREC was rare in calves. In particular, we found more QREC organisms in feed and water troughs and in environments that may come into contact with young calves. Thus, the results suggest that QREC circulates between cattle and the farm environment and that calves are important for the maintenance of QREC. Some genotypes of QREC were widespread both within and between farms, indicating that QREC has spread within the farms and likely also between farms, possibly through purchased animals. Farms that had purchased many animals over the years had greater within-farm diversity than farms with more closed animal populations. Finally, animals on more closely located farms were more likely to share the same genotype than animals on farms located far apart.

IMPORTANCE

This study investigates the occurrence of a specific type of antimicrobial-resistant bacterium on dairy farms. It contributes to increased knowledge about the occurrence and spread of these bacteria, and the results pave the way for actions or further studies that could help mitigate the spread of these bacteria on dairy farms and in the community as a whole.

Dynamics of extended-spectrum cephalosporin resistance in pathogenic Escherichia coli isolated from diseased pigs in Quebec, Canada

The aim of this study was to investigate the evolution with time of ceftiofur-resistant Escherichia coli clinical isolates from pigs in Québec, Canada, between 1997 and 2012 with respect to pathotypes, clones and antimicrobial resistance. Eighty-five ceftiofur-resistant E. coli isolates were obtained from the OIE (World Organisation for Animal Health) Reference Laboratory for Escherichia coli. The most prevalent pathovirotypes were enterotoxigenic E. coli (ETEC):F4 (40%), extraintestinal pathogenic E. coli (ExPEC) (16.5%) and Shiga toxin-producing E. coli (STEC):F18 (8.2%). Susceptibility testing to 15 antimicrobial agents revealed a high prevalence of resistance to 13 antimicrobials, with all isolates being multidrug-resistant. blaCMY-2 (96.5%) was the most frequently detected β-lactamase gene, followed by blaTEM (49.4%) and blaCTX-M (3.5%). Pulsed-field gel electrophoresis (PFGE) applied to 45 representative E. coli isolates revealed that resistance to ceftiofur is spread both horizontally and clonally. In addition, the emergence of extended-spectrum β-lactamase-producing E. coli isolates carrying blaCTX-M was observed in 2011 and 2012 in distinct clones. The most predominant plasmid incompatibility (Inc) groups were IncFIB, IncI1, IncA/C and IncFIC. Resistance to gentamicin, kanamycin and chloramphenicol as well as the frequency of blaTEM and IncA/C significantly decreased over the study period, whereas the frequency of IncI1 and multidrug resistance to seven antimicrobial categories significantly increased. These findings reveal that extended-spectrum cephalosporin-resistant porcine E. coli isolates in Québec belong to several different clones with diverse antimicrobial resistance patterns and plasmids. Furthermore, blaCMY-2 was the major β-lactamase gene in these isolates. From 2011, we report the emergence of blaCTX-M in distinct clones.

Type II and type IV topoisomerase mutations in clinical isolates of Morganella morganii harbouring the qnrD gene

Introduction

The aim of this study was to show the emergence of the qnrD gene among fluoroquinolone-resistant Morganella morganii isolate. The occurrence of mutations in DNA gyrase (gyrA and gyrB) and topoisomerase IV (parC,parE) genes was also investigated in this strain.

Methodology

95 clinical Enterobacteria were screened for harbouring the qnrD gene. The clinical isolate of M. morganii was recovered from urine from a patient hospitalized in the urology unit at Fattouma Bourguiba Hospital, Tunisia. Antibiotic susceptibility was tested with the agar disk diffusion method. Quinolone susceptibility was studied with microbroth dilution technique. The investigations of plasmid mediated quinolone resistance (PMQR) and topoisomerases mutations were performed by polymerase chain reaction and nucleotide sequencing.

Results

This isolate showed high level of resistance to quinolones. The MIC with microbroth dilution technique was 512 μg/ml for norfloxacin, 256 μg/ml for ofloxacin and ciprofloxacin and 64μg/ml for levofloxacin.

This strain was found to harbour the quinolone resistance determinant qnrD. In addition, this strain harboured two new gyrB mutations (S463A, S464Y) and one parC mutation (S80I).

Conclusions

This is the first report in Tunisia of qnrD determinant and tow new gyrB muations in M. morganii. The nosocomial infection due to this proteeae invites further study of its epidemiologic evolution.

Characterization of multi-antibiotic-resistant Escherichia coli Isolated from beef cattle in Japan

The emergence of multiple-antibiotic-resistance bacteria is increasing, which is a particular concern on livestock farms. We previously isolated 1,347 antimicrobial-resistant (AMR) Escherichia coli strains from the feces of beef cattle on 14 Japanese farms. In the present study, the genetic backgrounds and phylogenetic relationships of 45 AMR isolates were characterized by the chromosome phylotype, AMR phenotype, AMR genotype, and plasmid type. These isolates were classified into five chromosome phylotypes, which were closely linked to the farms from which they were isolated, suggesting that each farm had its own E. coli phylotype. AMR phenotype and plasmid type analyses yielded 8 and 14 types, all of which were associated with the chromosomal phylotype and, thus, to the original farms. AMR genotype analysis revealed more variety, with 16 types, indicating both inter- and intra-farm diversity. Different phylotype isolates from the same farm shared highly similar plasmid types, which indicated that plasmids with AMR genes could be transferred between phylotypes, thereby generating multi-antibiotic-resistant microorganisms. This ecological study demonstrated that the chromosome phylotype was strongly correlated with the farm from which they were isolated, while the AMR phenotype, genotype, and plasmid type were generally correlated with the chromosome phylotype and farm source.

Prevalence and molecular epidemiological characterization of antimicrobial-resistant Escherichia coli isolates from Japanese black beef cattle

We investigated the prevalence of antimicrobial-resistant Escherichia coli in Japanese black beef cattle from the three major production regions of Japan. We collected and examined 291 fecal samples from Japanese black beef cattle in Hokkaido, Chubu, and Kyushu. Of the 3,147 E. coli isolates, 1,397 (44.4%) were resistant to one or more antibiotics; these included 553 (39.8%) of 1,388 isolates from Hokkaido, 352 (54.4%) of 647 isolates from Chubu, and 492 (44.2%) of 1,112 isolates from Kyushu. The difference in resistance rates between the three regions was significant. The antibiotics with the highest rates of resistance were oxytetracycline and dihydrostreptomycin (35.8% each), followed by ampicillin (21.4%). Further, E. coli isolates from calves had higher resistance rates than those from growing cattle and mature cattle, and the calf isolates showed high rates of resistance to gentamicin (20.2%), enrofloxacin (9.4%), and ceftiofur (4.2%). In addition, the high degrees of similarity in the genotypes of the isolates and in the resistance patterns on each farm suggest that resistance bacteria and resistance genes were horizontally transferred. Most isolates, in each of the three regions, harbored resistance genes such as blaTEM, strA, strB, aphA1, aphAI-IAB, and catI. In contrast to the isolates from Kyushu, most of which harbored aacC2, tetB, and dfrA12, the isolates from Hokkaido and Chubu harbored a variety of resistance genes. Furthermore, the prevalence of genes for resistance to dihydrostreptomycin, gentamicin, chloramphenicol, and trimethoprim differed significantly between the regions. This is the first large-scale study describing and comparing antimicrobial-resistant bacteria from different regions in Japan. The results will contribute to improving food safety and promoting careful usage of antimicrobial agents.