Tylosin
Encyclopedia
Tylosin is a macrolide
Macrolide
The macrolides are a group of drugs whose activity stems from the presence of a macrolide ring, a large macrocyclic lactone ring to which one or more deoxy sugars, usually cladinose and desosamine, may be attached. The lactone rings are usually 14-, 15-, or 16-membered...

-class antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

 used in veterinary medicine. It has a broad spectrum of activity against gram positive organisms and a limited range of gram negative organisms. It is found naturally as a fermentation product of Streptomyces fradiae
Streptomyces fradiae
Streptomyces fradiae is a species of actinobacteria. It produces the antibiotics neomycin, tylosin and fosfomycin ....

.

Tylosin is used in veterinary medicine to treat bacterial infections in a wide range of species and has a high margin of safety. It has also been used as a growth promotant in some species, and as a treatment for colitis in companion animals.

Mode of action

Like other macrolides, tylosin has a bacteriostatic effect on susceptible organisms, caused by inhibition of protein synthesis through binding to the 50S
50S
50S is the larger subunit of the 70S ribosome of prokaryotes. It is the site of inhibition for antibiotics such as macrolides, chloramphenicol, clindamycin, and the pleuromutilins. It includes the subunits 5S and 23S.-Structure:...

 subunit of the bacterial ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....

.

Spectrum of activity

Tylosin has a wide spectrum of activity against gram positive bacteria including Staphylococci, Streptococci, Corynebacteria, and Erysipelothrix. It has a much narrower gram negative spectrum of activity, but has been shown to be active against Campylobacter coli, and certain spirochaete
Spirochaete
Spirochaetes belong to a phylum of distinctive Gram-negative bacteria, which have long, helically coiled cells...

s. It has also been shown to be extremely active against Mycoplasma species isolated from both mammalian and avian hosts.

Clinical use

Tylosin has been used to treat a variety of different diseases throughout the world. Differing formulations and licensing conditions will mean that it may not be a recognized method of treatment for certain conditions in certain countries. In general, tylosin is licensed for the treatment of infections caused by organisms susceptible to the drug, but it has also been used as a treatment of colitis
Colitis
In medicine, colitis refers to an inflammation of the colon and is often used to describe an inflammation of the large intestine .Colitides may be acute and self-limited or chronic, i.e...

 in small animals, as a growth promotant in food producing animals, and as a way of reducing epiphora (tear staining) around the eyes of white faced dogs. No marketing authority exists for the use of tylosin as a tear stain remover and thus it is not legal to use it for such purposes- the exception being as a Prescription Only Medicine of last resort by vets under the Cascading Rule (UK) or the Extra Label rule (US).

Examples of bacterial infections that could potentially be treated with tylosin include respiratory infections, metritis
Metritis
Metritis is inflammation of the wall of the uterus, whilst endometritis is inflammation of the functional lining of the uterus, called the endometrium Although these terms can apply to any species of mammal, in humans the term Pelvic Inflammatory Disease is more often used for metritis...

, and acute mastitis
Mastitis
Mastitis is the inflammation of breast tissue. S. aureus is the most common etiological organism responsible, but S. epidermidis and streptococci are occasionally isolated as well.-Terminology:...

 in cattle; mastitis in sheep and goats; enteritis
Enteritis
In medicine, enteritis, from Greek words enteron and suffix -itis , refers to inflammation of the small intestine. It is most commonly caused by the ingestion of substances contaminated with pathogenic microorganisms. Symptoms include abdominal pain, cramping, diarrhea, dehydration and fever...

, pneumonia
Pneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...

, erysipelas
Erysipelas
Erysipelas is an acute streptococcus bacterial infection of the deep epidermis with lymphatic spread.-Risk factors:...

, and infectious arthritis
Arthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....

 in swine; and soft tissue infections in small animals.
While tylosin may be one appropriate therapeutic choice in theory for the conditions listed above, there are many other antibiotics that may be preferable for treating a specific infection, and Tylosin will not be the first choice.

It is also used as a growth promoter for a variety of terrestrial and aquatic animals grown for human consumption(Hirsch et al. 1999)

Available forms

Tylosin is available in injectable, intramammary, and oral formulations with different product ranges available in different countries.

Precautions and contraindications

Administration of tylosin should be avoided in animals with a known hypersensitivity to the product, or to other macrolides.

Oral administration can result in diarrhoea and gastrointestinal disturbance. This is particularly true of horses, such that it can be fatal. Tylosin also has a foul taste that is difficult to disguise.

The injectable formulations of tylosin can cause pain, inflammation, and itchiness around the injection site.

Since tylosin has a relatively poor spectrum of activity against gram negative organisms, it may not be a sensible therapeutic choice in the treatment of infections caused by unknown, potentially unsusceptible organisms.

Drug interactions

Tylosin may increase digitalis blood levels and thus its toxicity, and may be antagonistic to chloramphenicol
Chloramphenicol
Chloramphenicol is a bacteriostatic antimicrobial that became available in 1949. It is considered a prototypical broad-spectrum antibiotic, alongside the tetracyclines, and as it is both cheap and easy to manufacture it is frequently found as a drug of choice in the third world.Chloramphenicol is...

 or lincosamides.

Colorimetric assays of serum ALT and AST may be falsely elevated by macrolide antibiotics.
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