Impact of Ceftiofur Administration in Steers on the Prevalence and Antimicrobial Resistance of Campylobacter spp.

Abstract

Bacterial resistance to ceftiofur raises health concerns due to ceftiofur’s extensive veterinary usage and structural similarity with the human antibiotic ceftriaxone. Ceftiofur crystalline-free acid (CCFA) and ceftiofur hydrochloride (CHCL) are ceftiofur types used therapeutically in cattle, but their potential impacts on Campylobacter prevalence and antimicrobial resistance remain unclear. In this study two groups of steers were each treated with CCFA or CHCL. In vivo active drug concentrations were measured and fecal samples were analyzed for Campylobacter for up to 42 days post-treatment. Following administration, the colonic concentration of ceftiofur initially increased then dropped to pre-treatment levels by day 8. The estimated prevalence of Campylobacter spp. was significantly (p = 0.0009) higher during the first week after CCFA treatment than after CHCL treatment (81.3% vs. 45.2%). Campylobacter jejuni predominated overall, with other Campylobacter spp. mainly identified in the first week after CCFA treatment. No treatment impacts were noted on ceftiofur minimum inhibitory concentration (MIC) for C. jejuni (10–20 μg/mL). More C. jejuni genotypes were detected in CCFA-treated than CHCL-treated steers. These findings suggest that ceftiofur did not significantly impact Campylobacter prevalence or ceftiofur MIC. However, CHCL may be preferable due to the lower likelihood of temporary increases in Campylobacter prevalence.

Genomic Analysis Reveals That Isolation Temperature on Selective Media Introduces Genetic Variation in Campylobacter jejuni from Bovine Feces

“…This suggests that new alleles detected only at one temperature are more likely to be encountered in strains isolated at 42 • C. Neighbor-net SplitsTree analysis based on wgMLST showed that the five ST8221 strains were closely related, as were the six strains of ST8567, with a large distance between the two STs (Figure 4A). This agrees with the previous finding that ST8221 and ST8567 were both novel STs and only shared one allele in the seven-locus MLST scheme [9]. In spite of the close relatedness among the ST8221 strains, however, those isolated at 42 • C tended to exhibit higher variation (Figure 4B), with similar findings for the strains of ST8567 (Figure 4C).…”

“…The 18 C. jejuni strains that were selected to examine the temperature impact on the genome sequence were isolated during our previous study that assessed the effect of ceftiofur treatment of steers on Campylobacter [9]. All strains were isolated as previously described by selective enrichments of the fecal samples in Bolton broth at 37 • C following by plating of 0.1 mL of the enrichment on mCCDA plates that were incubated at 37 • C or 42 • C [9]. The strain panel included eight paired strains, i.e., one strain that had been isolated on mCCDA at 37 • C and another isolated on mCCDA at 42 • C from each of the four fecal samples.…”

“…Pathogens 2022, 11, 678 2 of 13 study regarding the impact of ceftiofur on Campylobacter in cattle, fecal samples from steers that were treated with ceftiofur crystalline-free acid (CCFA) were enriched in Bolton broth at 37 • C and then incubated on the selective medium modified charcoal-cefoperazonedeoxycholate agar (mCCDA) at both 37 • C and 42 • C [9]. The estimated prevalence of C. jejuni was found to be significantly higher at 42 • C than 37 • C [9].…”

“…Besides the two novel STs 8221 and 8567, the three dominant C. jejuni STs from the feces of the cattle in our ceftiofur study included ST21, which belongs to the same clonal complex (CC21) as ST8567 [9]. Analysis of the five available ST21 genomes (Table 1) The mechanisms underlying the observed higher prevalence of variable new alleles at 42 • C remain to be elucidated.…”

“…Besides the two novel STs 8221 and 8567, the three dominant C. jejuni STs from the feces of the cattle in our ceftiofur study included ST21, which belongs to the same clonal complex (CC21) as ST8567 [9]. Analysis of the five available ST21 genomes (Table 1) revealed that the number of loci with new alleles was similar between strains from different temperatures (ranging from 71 to 80) (Figure 3B) and lower than noted with ST8567 for which new alleles ranged from 111 to 122 (Figure 2).…”