Sampling considerations for herd-level measurement of faecal 
<i>Escherichia coli</i> antimicrobial resistance in finisher pigs

Dunlop, R.; McEwen, Scott A.; Meek, A H; Friendship, Robert; Black, W. D.; Clarke, Robert C.

doi:10.1017/s0950268899002411

Cited by 30 publications

(30 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Dunlop et al (1999) attributed much of the variability in E. coli AR prevalence within each farm to within-pig and within-pen differences rather than between-pen, within-room, and between-room components. However, they examined individual pig samples, and ours were composites collected across pens within production group.…”

Section: Discussionmentioning

confidence: 99%

Patterns of Antimicrobial Resistance Among CommensalEscherichia coliIsolated from Integrated Multi-Site Housing and Worker Cohorts of Humans and Swine

Scott

Campbell

Harvey

et al. 2005

Foodborne Pathogens and Disease

View full text Add to dashboard Cite

We examined antimicrobial resistance (AR) phenotypes among commensal Escherichia coli isolated from fecal matter of humans and swine housed in a semi-closed and uniquely integrated multi-site farrow-to-plate operation. Aggregate cohorts of humans consisted of (1) "control" groups of consumers, (2) groups of swine workers, and (3) groups of slaughter-plant workers. Analyses of cross-sectional AR data from 472 human and 376 swine isolates are presented. AR phenotypes among these isolates were compared by (1) host species, (2) facility location, (3) facility type, (4) housing (human) or production (swine) cohort, and (5) sample collection period and time of day. There were significant (p < 0.05) differences in isolates among host-species with swine uniformly at greater risk for (1) AR to four specific antimicrobials (kanamycin, streptomycin, sulfamethoxazole, tetracycline), and (2) multiple resistance phenotypes (p < 0.0001). Facility type and unit location were more often associated with AR differences among swine isolates than among human isolates. Swine production group was significantly associated with AR prevalence (p < 0.05) for nine antimicrobials; in general, purchased boars, suckling piglets, weaned piglets, and lactating sows were at higher risk of AR. There was no significant (p > 0.05) association of human occupational/consumer cohort with AR prevalence. Several unique AR phenotypes were detected in each of the human- and swine-intake groups. These data establish baseline characteristics for an on-going 3-year longitudinal study designed to further characterize AR phenotype and genotype in this population. Host-, facility-, and cohort-specific data demonstrate that sufficient prevalence differences exist to permit the future quantification of AR transmission, should it occur. Based on these cross-sectional data, occupational exposure to either swine-rearing or swine-slaughter facilities does not appear to be associated with the prevalence of phenotypic resistance among the commensal fecal E. coli isolated from this integrated system.

show abstract

Section: Discussionmentioning

confidence: 99%

Patterns of Antimicrobial Resistance Among CommensalEscherichia coliIsolated from Integrated Multi-Site Housing and Worker Cohorts of Humans and Swine

Scott

Campbell

Harvey

et al. 2005

Foodborne Pathogens and Disease

View full text Add to dashboard Cite

show abstract

“…One study of antimicrobial resistance in swine found that the precision of resistance estimates did not improve noticeably when more than 5 colonies were selected per swine fecal sample. 2 Another study demonstrated clustering of antimicrobial resistant phenotypes among isolates from feedlot cattle fecal samples and suggested that fewer than 5 isolates per sample is a reasonable guideline. 9 Wagner et al 9 suggested increasing the number of fecal samples, if possible, to increase the total number of isolates being tested for susceptibility.…”

Section: Discussionmentioning

confidence: 99%

Short-Term Repeatability of Measurements of Antimicrobial Susceptibility of Escherichia Coli Isolated from Feces of Feedlot Cattle

et al. 2003

View full text Add to dashboard Cite

Abstract. Short-term stability of measurements of antimicrobial susceptibility of Escherichia coli isolated from feces of feedlot cattle is important in developing monitoring and surveillance programs. Frequent evaluations (i.e., daily) are resource intensive and in some situations may be impractical for long-term sampling protocols. Consequently, a point-in-time measurement will need to be used to represent conditions in the perisampling period. In this study, 30 fecal samples were collected from each of 6 cattle pens on a commercial cattle feedlot on 2 occasions separated by 48 hours. Escherichia coli was isolated from single and pooled samples. The isolates were tested for antimicrobial susceptibility against a panel of 17 antimicrobials. Resistance to 5 antimicrobials (ampicillin, nalidixic acid, streptomycin, sulfamethoxazole, and tetracycline) was detected in single and pooled samples from both sampling periods (days 1 and 3). The prevalence of isolates resistant to these 5 antimicrobials was 2% or higher in all treatment combinations except for pools obtained from day 3 samples. Lower levels of resistance to 6 more antimicrobials were detected inconsistently across the single and pooled samples. Logistic models constructed for the antimicrobials to which the E. coli isolates were most commonly resistant demonstrated that there were no significant differences between periods (P Ͼ 0.10) and between single and pooled samples (P Ͼ 0.20). The distribution of the number of antimicrobials to which isolates were resistant was consistent for the single samples across periods, but there appeared to be a lower prevalence of any resistance in day 1 pooled samples. A larger number of resistant phenotypes were detected in the single samples than in the pooled samples, and resistant phenotypes with prevalence of less than 2% were detected inconsistently across periods and single and pooled samples. Resistance to individual antimicrobials was consistent by all measures when the prevalence was at least 2%. Inconsistent results were obtained for antimicrobials to which resistance rarely occurred. The apparent inconsistencies do not appear to be related to external factors but rather to sampling intensity. Short-term stability is a plausible assumption under sampling strategies that are designed to detect specific levels of prevalence. However, when resistance levels fall below these levels, there will likely be fluctuations in the presence or absence of rare resistant phenotypes and in their prevalence and central tendency measures.

show abstract

“…In many previous investigations, the clustered nature of data has often been ignored in the data analysis. Dunlop et al 15 considered the variation in tetracycline and gentamicin resistance between pigs within pens, the variance between pens within rooms, and between rooms within a farm for sampling consideration. In the single farm included in that study, the between-pig within-pen variation constituted the overwhelming majority of the variance (97.5%).…”

Section: Subtherapeutic Chlortetracycline and Resistance In The Aerobmentioning

confidence: 99%

The Effect of Subtherapeutic Chlortetracycline on Antimicrobial Resistance in the Fecal Flora of Swine

Funk

LeJeune

Wittum

et al. 2006

Microbial Drug Resistance

View full text Add to dashboard Cite

The aims of this research were to determine the association between inclusion of subtherapeutic chlortetracycline in the diets of swine and the prevalence and antimicrobial resistance of Salmonella; define the association between inclusion of subtherapeutic chlortetracycline and antimicrobial resistance in the aerobic Gram-negative fecal flora of swine; and estimate the proportion of total model variance attributable to farm, pig, and colony level effects. There was no association between subtherapeutic chlortetracycline exposure and Salmonella prevalence. There were increased odds for an aerobic Gram-negative fecal isolate to be resistant to ampicillin, ceftriaxone, and tetracycline if isolated from a pig that received chlortetracycline. There was a positive association between inclusion of subtherapeutic chlortetracycline in the diet and resistance to multiple antimicrobials. The proportion of total variance associated with farm, pig, and colony varied based on the resistance phenotype. Because farm-level variance contributed a small proportion to total variance in all models, effects of antimicrobial use interventions observed in this study may be predictive of anticipated impact of interventions on most swine farms. Resources for future investigations may be better allocated to sampling more pigs and more bacterial colonies per pig in relationship to the number of farms.

show abstract

Sampling considerations for herd-level measurement of faecal Escherichia coli antimicrobial resistance in finisher pigs

Cited by 30 publications

References 27 publications

Patterns of Antimicrobial Resistance Among CommensalEscherichia coliIsolated from Integrated Multi-Site Housing and Worker Cohorts of Humans and Swine

Patterns of Antimicrobial Resistance Among CommensalEscherichia coliIsolated from Integrated Multi-Site Housing and Worker Cohorts of Humans and Swine

Short-Term Repeatability of Measurements of Antimicrobial Susceptibility of Escherichia Coli Isolated from Feces of Feedlot Cattle

The Effect of Subtherapeutic Chlortetracycline on Antimicrobial Resistance in the Fecal Flora of Swine

Contact Info

Product

Resources

About