Antimicrobial susceptibility of enteric bacteria recovered from feedlot cattle administered chlortetracycline in feed

Platt, Tammy M.; Loneragan, Guy H.; Scott, H. M.; Norby, Bo; Thomson, Daniel U.; Brown, Michael S.; Ives, Samuel E.; Brashears, Mindy M.

doi:10.2460/ajvr.69.8.988

Cited by 37 publications

(61 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Studies published in 2008 by Platt et al (28) and in 2013 by Kanwar et al (22) found that in-feed CTC increased fecal TET r E. coli detection in the short term. Similarly, in the current study, the TET r E. coli concentration from the fecal swab samples at 5 dpt for the CTC group was 2.39 log 10 CFU/swab higher than the control group concentration (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Platt et al (28) reported a transient reduction in the prevalence of fecal 3GC r E. coli following in-feed CTC treatment, while Kanwar et al (22) reported increased 3GC r E. coli occurrence when a veterinary 3GC, ceftiofur, was administered followed by in-feed CTC administration. In contrast to both studies, we found that fecal swab 3GC r E. coli prevalences did not differ significantly (P Ն 0.90) between groups on any sampling occasion (Fig.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Effects of In-Feed Chlortetracycline Prophylaxis in Beef Cattle on Animal Health and Antimicrobial-Resistant Escherichia coli

Agga

Schmidt

Arthur

2016

Appl Environ Microbiol

View full text Add to dashboard Cite

Concerns have been raised that in-feed chlortetracycline (CTC) may increase antimicrobial resistance (AMR), specifically tetracycline-resistant (TET r ) Escherichia coli and third-generation cephalosporin-resistant (3GC r ) E. coli. We evaluated the impact of a 5-day in-feed CTC prophylaxis on animal health, TET r E. coli, and 3GC r E. coli. A control group of cattle (n ‫؍‬ 150) received no CTC, while a CTC group (n ‫؍‬ 150) received in-feed CTC (10 mg/lb of body weight/day) from the 5th to the 9th day after feedlot arrival. Over 25% (38/150) of the animals in the control group developed illnesses requiring therapeutic treatment with antimicrobials critically important to human medicine. Only two animals (1.3%) in the CTC group required such treatments. Fecal swab and pen surface occurrences of generic E. coli (isolated on media that did not contain antimicrobials of interest and were not isolated based on any specific resistance), TET r E. coli, and 3GC r E. coli were determined on five sampling occasions: arrival at the feedlot, 5 days posttreatment (5 dpt), 27 dpt, 75 dpt, and 117 dpt. On 5 dpt, TET r E. coli concentrations were higher for the CTC group than the control group (P < 0.01). On 27 dpt, 75 dpt, and 117 dpt, TET r E. coli concentrations did not differ between groups. 3GC r E. coli occurrences did not differ between control and CTC groups on any sampling occasion. For both groups, generic, TET r , and 3GC r E. coli occurrences were highest on 75 dpt and 117 dpt, suggesting that factors other than in-feed CTC contributed more significantly to antimicrobial-resistant E. coli occurrence. IMPORTANCEThe occurrence of human bacterial infections resistant to antimicrobial therapy has been increasing. It has been postulated that antimicrobial resistance was inevitable, but the life span of the antimicrobial era has been prematurely compromised due to the misuse of antimicrobials in clinical and agricultural practices. Direct evidence relating the use of antimicrobials in livestock production to diminished human health outcomes due to antimicrobial resistance is lacking, and the U.S. Food and Drug Administration has taken an approach to maximize therapeutic efficacy and minimize the selection of resistant microorganisms through judicious use of antimicrobials. This study demonstrated that prophylactic in-feed treatment of chlortetracycline administered for 5 days to calves entering feedlots is judicious, as this therapy reduced animal morbidity, reduced the use of antimicrobials more critical to human health, and had no long-term impact on the occurrence of antimicrobial-resistant E. coli.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Effects of In-Feed Chlortetracycline Prophylaxis in Beef Cattle on Animal Health and Antimicrobial-Resistant Escherichia coli

Agga

Schmidt

Arthur

2016

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…However, Other studies in cattle have examined the coselective properties of chlortetracycline on E. coli displaying resistance to tetracycline and ceftiofur. In one study, the administration of chlortetracycline at 22 mg/kg to cattle decreased the recovery of ceftiofur-resistant E. coli (35). In a more recent study by the same research group, similar regimens of therapeutic chlortetracycline treatment in cattle greatly increased both the counts of ceftiofurresistant E. coli and the quantities of bla CMY-2 , a gene found on IncA/C plasmids conferring ceftiofur resistance (36).…”

Section: Discussionmentioning

confidence: 95%

In Vivo Transmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

Johnson

Singer

Isaacson

et al. 2015

Appl Environ Microbiol

View full text Add to dashboard Cite

c IncA/C plasmids are broad-host-range plasmids enabling multidrug resistance that have emerged worldwide among bacterial pathogens of humans and animals. Although antibiotic usage is suspected to be a driving force in the emergence of such strains, few studies have examined the impact of different types of antibiotic administration on the selection of plasmid-containing multidrug resistant isolates. In this study, chlortetracycline treatment at different concentrations in pig feed was examined for its impact on selection and dissemination of an IncA/C plasmid introduced orally via a commensal Escherichia coli host. Continuous low-dose administration of chlortetracycline at 50 g per ton had no observable impact on the proportions of IncA/C plasmid-containing E. coli from pig feces over the course of 35 days. In contrast, high-dose administration of chlortetracycline at 350 g per ton significantly increased IncA/C plasmid-containing E. coli in pig feces (P < 0.001) and increased movement of the IncA/C plasmid to other indigenous E. coli hosts. There was no evidence of conjugal transfer of the IncA/C plasmid to bacterial species other than E. coli. In vitro competition assays demonstrated that bacterial host background substantially impacted the cost of IncA/C plasmid carriage in E. coli and Salmonella. In vitro transfer and selection experiments demonstrated that tetracycline at 32 g/ml was necessary to enhance IncA/C plasmid conjugative transfer, while subinhibitory concentrations of tetracycline in vitro strongly selected for IncA/C plasmid-containing E. coli. Together, these experiments improve our knowledge on the impact of differing concentrations of tetracycline on the selection of IncA/C-type plasmids.

show abstract

“…MDR data usually are presented in tabular or graphical formats without any analytical statistics (Scott et al, 2005;Alali et al, 2008) which do not allow for the analysis of risk factors on the occurrence of MDR. Some analytical analysis involving linear regression (Platt et al, 2008) and Poisson regression (Varga et al, 2009) models were applied to MDR data, without considering the natural ordering of the data structure. In a prospective cohort study conducted in calves to investigate risk factors for MDR in fecal E. coli (Berge et al, 2005), cumulative multinomial logistic regression was used.…”

Section: Tablementioning

confidence: 99%

“…Analysis of MDR data is mostly descriptive and is presented as frequency distribution in bar graphs or tables (Scott et al, 2005;Lowrance et al, 2007;Alali et al, 2008;Platt et al, 2008;Tadesse et al, 2012;FDA, 2013) sometimes combined with univariate analysis using a 2 test on binary classified MDR data. Such univariate analysis does not allow for simultaneous evaluation of more than one risk factor on the occurrence of MDR.…”

Section: Introductionmentioning

confidence: 99%

Use of generalized ordered logistic regression for the analysis of multidrug resistance data

Agga

Scott

2015

Preventive Veterinary Medicine

Self Cite

View full text Add to dashboard Cite

a b s t r a c tStatistical analysis of antimicrobial resistance data largely focuses on individual antimicrobial's binary outcome (susceptible or resistant). However, bacteria are becoming increasingly multidrug resistant (MDR). Statistical analysis of MDR data is mostly descriptive often with tabular or graphical presentations. Here we report the applicability of generalized ordinal logistic regression model for the analysis of MDR data. A total of 1,152 Escherichia coli, isolated from the feces of weaned pigs experimentally supplemented with chlortetracycline (CTC) and copper, were tested for susceptibilities against 15 antimicrobials and were binary classified into resistant or susceptible. The 15 antimicrobial agents tested were grouped into eight different antimicrobial classes. We defined MDR as the number of antimicrobial classes to which E. coli isolates were resistant ranging from 0 to 8. Proportionality of the odds assumption of the ordinal logistic regression model was violated only for the effect of treatment period (pre-treatment, during-treatment and post-treatment); but not for the effect of CTC or copper supplementation. Subsequently, a partially constrained generalized ordinal logistic model was built that allows for the effect of treatment period to vary while constraining the effects of treatment (CTC and copper supplementation) to be constant across the levels of MDR classes. Copper (Proportional Odds Ratio [Prop OR] = 1.03; 95% CI = 0.73-1.47) and CTC (Prop OR = 1.1; 95% CI = 0.78-1.56) supplementation were not significantly associated with the level of MDR adjusted for the effect of treatment period. MDR generally declined over the trial period. In conclusion, generalized ordered logistic regression can be used for the analysis of ordinal data such as MDR data when the proportionality assumptions for ordered logistic regression are violated.Published by Elsevier B.V.

show abstract

Antimicrobial susceptibility of enteric bacteria recovered from feedlot cattle administered chlortetracycline in feed

Cited by 37 publications

References 22 publications

Effects of In-Feed Chlortetracycline Prophylaxis in Beef Cattle on Animal Health and Antimicrobial-Resistant Escherichia coli

Effects of In-Feed Chlortetracycline Prophylaxis in Beef Cattle on Animal Health and Antimicrobial-Resistant Escherichia coli

In Vivo Transmission of an IncA/C Plasmid in Escherichia coli Depends on Tetracycline Concentration, and Acquisition of the Plasmid Results in a Variable Cost of Fitness

Use of generalized ordered logistic regression for the analysis of multidrug resistance data

Contact Info

Product

Resources

About