Which antibiotics are effective in treating E. coli septicemia in ducks? (Part 1)

Septicemia caused by Escherichia coli (E. coli) is a common bacterial disease that causes significant losses in industrial duck farming. The disease can occur at all ages but is most common in ducklings aged 3–25 days, with high mortality and rapid progression. The bacteria enter the body through the digestive tract, respiratory system, or navel, then spread into the bloodstream, causing septicemia and multiple organ inflammation such as in the liver, heart, and air sacs, leading to a severe decline in the health of the flock.
Currently, antimicrobial resistance in E. coli is increasingly rising, making treatment more challenging. Therefore, selecting appropriate products and establishing an effective treatment regimen are crucial factors in disease control. Fivevet currently provides a range of veterinary solutions to support the treatment of E. coli infections in ducks, helping reduce mortality, improve treatment efficacy, and ensure sustainable flock health.

Septicemia caused by Escherichia coli (E. coli) in ducks
I. Principles of drug use in the treatment of E. coli septicemia in ducks
Septicemia in ducks caused by E. coli is a bacterial disease; therefore, antibiotics are the primary treatment to control and eliminate the causative bacteria. In acute or severe cases, injectable antibiotics should be prioritized to rapidly achieve therapeutic concentrations in the bloodstream. For mild cases or when morbidity is low, oral antibiotics or medicated feed can be used for convenience and cost-effectiveness.
In addition to specific treatment, supportive measures should be implemented, including antipyretics, anti-inflammatory drugs, electrolytes, vitamins, and liver–kidney support products to improve the animal’s condition and recovery. At the same time, proper cleaning and disinfection of housing play a crucial role in reducing pathogen load and limiting the spread within the flock.
II. Main antibiotic groups for the treatment of E. coli septicemia in ducks
1. Fluoroquinolone group

Mechanism of action of the Fluoroquinolone group of antibiotics
Fluoroquinolones are a broad-spectrum group of antibiotics with strong activity against Gram-negative bacteria such as E. coli. They act by inhibiting the enzymes DNA gyrase and topoisomerase IV, thereby disrupting DNA replication and killing bacteria.
The advantages of fluoroquinolones include high bioavailability, good tissue penetration, and rapid onset of action, making them especially effective in acute infections in ducks. In veterinary medicine, enrofloxacin is widely used due to its strong efficacy and its ability to be metabolized into ciprofloxacin, which prolongs its effect. In addition, marbofloxacin is a newer-generation active ingredient with more stable efficacy, but its higher cost makes it less commonly used.
Currently, resistance of E. coli to fluoroquinolones is increasing due to target gene mutations and drug efflux mechanisms. Therefore, this group of antibiotics should be used appropriately, at the correct dose and indication, to improve treatment effectiveness and limit antimicrobial resistance.

Some products containing fluoroquinolone antibiotics
2. Tetracycline group

Mechanism of action of the Tetracycline group
Tetracyclines are a broad-spectrum group of antibiotics that exert a bacteriostatic effect by binding to the 30S ribosomal subunit and inhibiting protein synthesis. This group has the advantage of good oral absorption and ease of use in animal production.
However, due to long-term use, the rate of E. coli resistance to tetracyclines is currently quite high. The main resistance mechanisms involve drug efflux pumps and ribosomal protection proteins, with resistance genes capable of spreading via plasmids.
In practice, oxytetracycline is an older active ingredient with low cost but limited efficacy in severe infections. Doxycycline is a newer generation with better tissue penetration, especially in the lungs and air sacs, and is therefore often preferred, maintaining a certain level of treatment effectiveness.

Products containing tetracycline antibiotics
3. Aminoglycoside group

Mechanism of action of aminoglycoside antibiotics
Aminoglycosides are a group of antibiotics with strong bactericidal activity against Gram-negative bacteria. Their mechanism of action involves binding to the 30S ribosomal subunit, causing misreading of mRNA and disrupting bacterial protein synthesis. This group exhibits concentration-dependent killing but is poorly absorbed via the gastrointestinal tract; therefore, it is mainly administered by injection.
Currently, the rate of E. coli resistance to aminoglycosides is at a moderate level, mainly due to bacterial production of antibiotic-inactivating enzymes and reduced cell membrane permeability.
In clinical practice, gentamicin is commonly used due to its strong efficacy in severe infections, especially when combined with β-lactam antibiotics to enhance synergistic effects. Kanamycin shows moderate effectiveness, while streptomycin is now less commonly used due to high resistance rates. Neomycin primarily acts in the gastrointestinal tract and is therefore not suitable for treating septicemia in ducks.

Some products containing aminoglycoside antibiotics
The treatment of E. coli septicemia in ducks requires the appropriate selection of antibiotics, correct treatment protocols, and the implementation of supportive measures to enhance treatment efficacy and minimize losses in the flock. In the context of increasing antimicrobial resistance in E. coli, rational antibiotic use - preferably guided by antimicrobial susceptibility testing—combined with proper biosecurity management is essential for effective disease control.
In Part II of this article, Fivevet will further analyze additional antibiotic groups, principles of drug combinations, and important considerations to improve the effectiveness of treating E. coli septicemia in modern duck production.
Frequently Asked Questions:
1. Is antibiotic use mandatory for treating E. coli septicemia in ducks?
Yes. This is a bacterial disease caused by E. coli, so antibiotics are the primary treatment to control and eliminate the causative bacteria.
2. When should injectable antibiotics be used to treat E. coli septicemia in ducks?
Injectable antibiotics are typically preferred in acute cases, when ducks have high fever, loss of appetite, or severe infections, to quickly achieve therapeutic concentrations in the bloodstream.
3. Why should electrolytes and vitamins be supplemented during treatment?
Electrolytes, vitamins, and liver–kidney support products help improve immunity, reduce dehydration, support recovery, and enhance treatment effectiveness.
4. Should multiple antibiotics be used simultaneously to treat E. coli septicemia in ducks?
Overuse of multiple antibiotics at the same time is not recommended, as it may increase the risk of antimicrobial resistance and toxicity. Drug combinations should be based on mechanisms of action and appropriate indications.
5. What is the role of farm hygiene in controlling E. coli infection in ducks?
Proper cleaning and disinfection help reduce bacterial load in the environment, limit disease spread, and decrease the risk of recurrence within the flock.