One of the most prominent broad spectrum antibiotic groups, tetracycline antibiotics are widely prescribed by doctors for arresting bacterial infection of various types. Let’s find out more about this antibiotics group.
Although commonly believed to be anti-bacterial agents, antibiotics have a broader scope as they are equally effective against various other microbes besides bacteria, such as certain fungi. Antibiotics are classified under two primary categories – broad spectrum antibiotics and narrow spectrum antibiotics – based upon their microbicidal scope. Broad spectrum antibiotics, as the name suggests, are potent against a very wide variety of pathogenic bacteria (both gram positive and gram negative) and microbes.
Narrow spectrum antibiotics, on the other hand, are effective in fighting only very specific families of disease-causing bacteria. The tetracycline group belongs to the family of broad spectrum antibiotics. Although these days, tetracycline uses are going on a downward curve in terms of their popularity due to increased bacterial resistance, these types of antibiotics are still among the first line of attack for the initial stages of some of the most common bacterial or microbial infections. Let’s learn more about tetracycline antibiotics from the subsequent paragraphs.
Facts about the Tetracycline Group
Tetracyclines are so-called owing to their molecular structure which consists of four rings of hydrocarbons (tetra = four; cycl = ring). These antibiotics are effective in slowing down the growth and propagation of bacterial cells by inhibiting protein synthesis and preventing aminoacyl-tRNA from binding to the mRNA-ribosome complex.
In other words, these antibiotics work by stunting the growth of bacterial cells by inhibiting genetic translation in the pathogenic microbes. However, microbial cells become resistant to this effect of these antibiotics soon enough by inactivating the action of tetracyclines through the production of certain enzymes. Various bacteria also take resort of the efflux process and expel toxins and antibiotic compounds outside the bacterial cells. Ribosomal protection is also one of the few means by which bacteria resist antibiotics.
The most common uses of tetracycline antibiotics are for treating bacterial infections that occur in the respiratory tract, sinuses, urinary tract, intestines, middle ear and certain skin infections such as rosacea and acne. Tetracycline is also often used for treating gonorrhea. Despite the fact that pathogenic bacteria develop resistance to antibiotics of the tetracycline group very easily, antibiotics belonging to this group are still considered the first choice in the treatment of various other microbial infections caused by various pathogens such as Rickettsia, chlamydia, brucellosis, spirochetes, Bacillus anthracis, Yersinia pestis, Francisella tularensis and Legionella. Tetracyclines are also considered effective in reducing the severity of choleric symptoms as well as the duration of the ailment.
The most common antibiotics that fall under the aegis of this group are tetracycline, oxytetracycline, doxycycline, chlortetracycline, demeclocycline, methacycline and minocycline. The dosage to be administered depends upon the severity of the infection and the quantity prescribed by the doctor. However, the most common parameter for deciding the daily dosage of most of these antibiotics depends upon how long an antibiotic remains in the patient’s blood stream.
For instance, in case of doxycycline, 1 mg usually remains in the blood stream for 12 hours when first administered and from the second dose onwards, the duration between two doses increases by 24 hours. Therefore, on day 1, two doses of doxycycline, 1 mg each, will be administered with a gap of 12 hours between them. From the third dose onwards, the gap between two doses increases from 12 hours to 24 hours, which means that only one dose of 1 mg doxycycline would be administered in a day.
Tetracyclines should not be taken immediately before or after eating. This is true especially in case of the short acting tetracyclines like chlortetracycline, tetracycline, demeclocycline, oxytetracycline, and methacycline as they have greater tendency towards water solubility which makes them bind to food particles, ruining the chances of their complete absorption. This reduces their efficacy to a great extent. Also, since these antibiotics bind with various food nutrients like iron, calcium, magnesium, etc. it is advisable not to take any supplements of these nutrients, antacids, laxatives and dairy products immediately before or after consuming these antibiotics.
Tetracycline Side Effects
Although relatively safe, the most commonly reported tetracycline side effects include mild to moderate allergic reactions, sensitivity to sun exposure, upset stomach and, very rarely, severe headaches and problems related to eyesight. Since the tetracycline group of antibiotics have a tendency to cause discoloration of teeth in the tooth developmental stage, it is advised not to administer these antibiotics to children younger than 8 years. Also, these antibiotics are not recommended to women who are past the first 18 weeks of their pregnancy. Chemical driven liver damage, although rare, has been reported as a side effect on the event of very long-term or overuse of antibiotics.
The tetracycline group of antibiotics consists of a total of 11 antibiotics including the ones mentioned in this article. Besides conditions such as late pregnancy, lactation and infancy, antibiotics on the tetracycline group are also not recommended for people who are already suffering from diabetes, liver and kidney diseases.
When under an antibiotics course, no dose should be missed as this causes the infection to relapse, ruining the progressive effects of the previously consumed doses. Also, missing doses gives the pathogens more time to develop resistance to these antibiotics and in such a case, recovery may take a longer time than is usual.