3 Antimicrobials in Food Animals: Objectives

What is the most critical initial step in antimicrobial stewardship?

What is the primary challenge in evaluating the effectiveness of low-dose chlortetracycline (CTC) administered in cattle feed?

A client proposes administering 350 mg of chlortetracycline per day to their 1400 lb cows via feed. What is the estimated daily systemic exposure of CTC, given an assumed bioavailability of 20%?

Comparing in-vivo drug concentrations to minimum inhibitory concentration (MIC) values has inherent caveats. Why are simple comparisons often inappropriate?

For tetracyclines, which pharmacokinetic/pharmacodynamic (PK/PD) parameter is believed to be most closely related to efficacy?

What is an estimated AUC24 for a cow with a mean chlortetracycline concentration of 0.01 µg/ml over 24 hours?

Considering EUCAST MIC distributions, tetracycline may be effective against approximately what percentage of Mannheimia haemolytica and Pasteurella multocida strains at 350 mg/hd?

When writing a Veterinary Feed Directive (VFD) for chlortetracycline (CTC) to control bacterial pneumonia in beef cattle, which factor dictates the required drug level in feed?

A producer is feeding 2 lbs of a supplement containing chlortetracycline (CTC) per cow per day. To deliver 350 mg of CTC per day, what g/ton inclusion rate is required in the supplement?

Why is it important to adjust g/ton inclusion rates for in-feed drugs based on the dry matter content of the ration?

If a chlortetracycline (CTC) label specifies a g/ton inclusion rate at 90% dry matter, how should the rate be adjusted if the feed being used has a dry matter content of 45%?

Which statement accurately describes the effect of decreasing dry matter percentage on the required as-fed g/ton inclusion rate for a medicated feed?

Which factor should be carefully considered to guide appropriate antimicrobial use, particularly in cases of lameness?

A feedlot is experiencing a lameness outbreak in 250 out of 15,000 head of cattle. Initial treatments for foot rot are ineffective. What should be the next step?

What are the primary bacterial pathogens associated with infectious pododermatitis (foot rot) in cattle?

Which antimicrobial is NOT typically used for the treatment of foot rot?

What is the estimated number needed to treat for lincomycin paste in the treatment of papillomatous digital dermatitis?

What is the estimated number needed to treat for oxytetracycline paste in the treatment of papillomatous digital dermatitis?

When plasma concentrations are compared to MIC values, what scenario does this represent?

A client wants to put 350 mg of a drug in 4 oz of medicated mineral, what should the doctor do?

Which feed ingredient has typically low dry matter?

According to the VFD for cattle, what is the drug concentration of Aureomycin for growing cattle for reduction of the incidence of liver abscesses?

According to the VFD for cattle, what is the length of duration for treating growing cattle with Aureomycin for reduction of the incidence of liver abscesses?

What is meant when the client says, “The foot rot is resistant now”?

Which method involves a bandage for 2 days?

What is considered when a veterinarian is selecting an antibiotic?

Besides antimicrobial intervention, what must the vet consider?

If the client is having problems with pneumonia, but has not mentioned it to you before, what step are you on?

Which feedstuff has a dry matter range of 32-40%?

Which feedstuff can cause producers to do an analysis of their inclusions and final feed?

What does moving from the as-fed g/ton inclusion rate up towards 90% dry matter do?

What is the g/ton amount needed to treat if 100 g/ton is at 90% dry matter? the feed has 45% dry matter.

Where do you go when there is a responsibility for appropriate diagnostics and establishment of an accurate and functional case definition?

When is it possible to be below 50% dry matter content?

Which disease is associated with Fusobacterium necrophorum?

What happens when the veterinarian responds 'yes' to step 1 in the antimicrobial stewardship diagram?

A cattle producer is considering adding chlortetracycline (CTC) to their feed for disease prevention based on advice from a feed dealer, without consulting a veterinarian. Which principle of antimicrobial stewardship is MOST directly violated by this scenario?

A veterinarian is asked to write a Veterinary Feed Directive (VFD) for chlortetracycline (CTC) for a herd experiencing a recent increase in undifferentiated respiratory disease. If the veterinarian proceeds directly to writing the VFD without further investigation, what is the MOST significant potential consequence in terms of antimicrobial stewardship?

A feedlot nutritionist formulates two rations for finishing cattle: Ration X with 35% dry matter and Ration Y with 90% dry matter. If both rations are designed to deliver 350 mg of chlortetracycline (CTC) per head per day, how will the grams of CTC per ton (g/ton) inclusion rate differ between Ration X and Ration Y to achieve the same daily drug dosage?

A veterinarian intends to prescribe chlortetracycline (CTC) in feed for a calf with a Mannheimia haemolytica infection. Based on the provided EUCAST MIC distribution data for tetracycline against Mannheimia haemolytica, and assuming a target AUC24/MIC ratio of ≥25 is desired for 50% target attainment, what is the MOST critical factor to consider regarding the likelihood of therapeutic success using a low-dose CTC feed regimen?

When evaluating the potential efficacy of a low-dose chlortetracycline (CTC) in feed for treating bovine respiratory disease (BRD), why is comparing in-vivo plasma drug concentrations to in-vitro Minimum Inhibitory Concentrations (MICs) a complex and often limited approach?

Considering the pharmacokinetic/pharmacodynamic (PK/PD) relationship for tetracyclines, and the concept of AUC24:MIC ratio, which statement BEST explains why achieving a high AUC24:MIC ratio is important for therapeutic success with chlortetracycline (CTC)?

A feedlot veterinarian calculates that a chlortetracycline (CTC) feed medication regimen results in a mean plasma concentration of 0.02 µg/mL over 24 hours in treated cattle. If the target pathogen has a MIC of 0.008 µg/mL, what is the approximate AUC24:MIC ratio achieved with this regimen?

Based on the EUCAST MIC distribution data, if a producer uses a chlortetracycline (CTC) feed regimen at 350 mg/head/day, against which of the following bacterial pathogens (commonly associated with BRD) is this treatment MOST likely to have the LOWEST probability of clinical efficacy?

When writing a Veterinary Feed Directive (VFD) for chlortetracycline (CTC) to manage bacterial pneumonia in beef cattle, and selecting the appropriate drug level in feed, which of the following factors should be considered the MOST important for responsible antimicrobial use?

If a chlortetracycline (CTC) label specifies a g/ton inclusion rate of 200 g/ton at 90% dry matter, and a feedlot is using feed with a dry matter content of 60%, what as-fed g/ton inclusion rate of CTC is required to achieve the same drug concentration on a dry matter basis?

A veterinarian is investigating a lameness outbreak in a feedlot and suspects papillomatous digital dermatitis (PDD) rather than foot rot. Which clinical finding would MOST strongly support a diagnosis of PDD over foot rot in cattle?

In a feedlot experiencing a lameness outbreak diagnosed as papillomatous digital dermatitis (PDD), and initial treatments with systemic antibiotics typically used for foot rot have failed, what is the MOST appropriate next step in managing this outbreak from an antimicrobial stewardship perspective?

Based on the provided treatment success data for papillomatous digital dermatitis (PDD), which of the following treatments demonstrates the HIGHEST Number Needed to Treat (NNT), indicating the LEAST efficient treatment in terms of positive case outcome per treatment?

In the context of antimicrobial stewardship, if a client requests a Veterinary Feed Directive (VFD) for chlortetracycline (CTC) in feed for 'prevention of pneumonia' in their cattle without a recent diagnosis, and mentions they are using 'dried distillers grain and cracked corn mixed feed' with 'baled hay', what is the MOST critical piece of information the veterinarian needs to determine regarding the feed to accurately calculate the g/ton inclusion rate for the VFD?