Antibiotics - Tetracyclines and Glycylcyclines

Tetracyclines are a group of broad-spectrum antibiotics, which were originally derived from soil-dwelling Streptomyces bacteria.

These medications can be used to treat a wide variety of bacterial infections, including central nervous system infections like meningitis, respiratory infections like community-acquired pneumonia, gastrointestinal infections like cholera, skin conditions like acne, and genitourinary infections like chlamydia and syphilis.

In addition, tetracyclines can be used to treat rare infections like rocky mountain spotted fever, anthrax, lyme disease, and tularemia.

Tetracyclines are very effective against gram-positive bacteria like Bacillus anthracis and Clostridium spp, as well as some gram-negative bacteria like Shigella spp, Escherichia coli, Rickettsia spp, Borrelia burgdorferi, Helicobacter pylori, and Neisseria meningitidis, and finally some atypical bacteria like Mycoplasma pneumoniae, Chlamydia trachomatis, Vibrio cholerae, and Francisella tularensis.

However, some of these bacteria developed resistance against tetracyclines in time. So as a solution, tetracyclines were modified into a newer generation of antibiotics called glycylcyclines.

These are commonly used in complicated skin infections and intra abdominal infections. Glycylcyclines are very effective against some gram-positive bacteria like Streptococcus pyogenes, Clostridium perfringens, both methicillin susceptible and methicillin resistant Staphylococcus aureus; and gram-negative bacteria like Klebsiella pneumoniae.

Now, according to the duration of action and half-life, tetracyclines are divided into two groups. Short acting tetracyclines, like tetracycline itself, have a half-life of around 8 hours, while long acting ones like doxycycline and minocycline have a half-life of 16 to 22 hours.

These medications can be administered both orally or intravenously. On the other hand, glycylcyclines are only administered intravenously.

The main drug in this category is tigecycline, which has a half-life of around 42 hours. Once administered, both tetracyclines and glycylcyclines work by entering the bacteria and completely shutting down their protein synthesis.

This ultimately leads to a bacteriostatic effect, meaning they stop bacterial growth without killing the bacteria.Now, common side effects associated with both the tetracyclines and glycylcyclines include headache and dizziness, as well as abdominal pain, nausea, vomiting, esophageal irritation and diarrhea.

In addition, they cause phototoxicity, so clients are much more likely to get sunburned. Some clients may also develop a skin rash or injection site reactions, as well as hypersensitivity reactions like exfoliative dermatitis, Stevens-Johnson syndrome, or anaphylaxis.

Another important side effect is superinfection due to fungal overgrowth in the mouth, most commonly Candida; or bacterial overgrowth in the bowel, which can rarely, but potentially, cause a Clostridioides difficile infection or CDI for short.

In addition, these medications can accumulate in teeth, causing permanent yellow or brown discoloration. If taken during pregnancy after the fourth month of gestation, these medications can cause staining of the baby's deciduous teeth, but not their permanent teeth.

On the other hand, if these medications are used in children younger than 8 years, they can cause discoloration of permanent teeth.

Additionally, these medications can accumulate in the bone, so children can have delayed bone growth. Lastly, the metabolic products of tetracycline can be nephrotoxic.

With these side effects, there are some contraindications to be kept in mind. Tigecycline has a boxed warning against their use when an alternative antibiotic is suitable, as this medication has increased mortality risk compared to other appropriate treatments.

This is also why it should never be considered a prophylactic treatment option. Now, both tetracyclines and glycylcyclines should not be used during pregnancy and breastfeeding, as well as in children younger than 8 years.

They should also be used cautiously in clients with pre-existing hepatic or renal disease. In addition, they should not be combined with certain medications, such as theophylline or warfarin, as they can dangerously increase their effects and toxicity.

Finally, tetracyclines should not be taken orally together with antacids, as well as multivitamins or mineral supplements like iron, magnesium, or calcium, since they can form an insoluble chelate that prevents their intestinal absorption.

Okay, when caring for a client who has been prescribed a tetracycline like doxycycline for Lyme disease, first perform a baseline assessment of their current symptoms, including fever, chills, headache, stiff neck, muscle or joint pain, as well as the presence of a bull’s eye lesion.

Then, review recent laboratory test results including renal and liver function; as well as enzyme-linked immunosorbent, or ELISA for short, and western blot results.

Finally, confirm a negative pregnancy test for clients assigned female at birth who can become pregnant.Alright, moving on to client education.

Explain to your client that their medication helps treat their infection and resolve their current symptoms. Then, instruct them to take their medication twice a day with a full glass of water on an empty stomach, at least one hour before or two hours after meals.

Additionally, advise your client to remain upright for at least 30 minutes after administration and to avoid taking their medication at bedtime to avoid esophageal irritation.

Also, advise them to avoid consuming dairy products or any product containing calcium, magnesium, iron, or zinc within 2 hours of taking their medication.

Lastly, emphasize the importance of completing the entire course of their medication, even if they start to feel better.

Next, review some side effects that your client could experience. If your client experiences gastrointestinal discomfort like nausea, vomiting, or diarrhea; encourage increased fluid intake, as well as small, frequent meals.

Let them know that because their medication can cause photosensitivity, they should avoid sunlight as much as possible and wear protective clothing along with sunscreen when spending time outside.

Also, to help prevent discoloration of the teeth, encourage frequent oral care. On the other hand, stress the importance of notifying their healthcare provider immediately if they notice symptoms of an oral Candida albicans infection, like white patches on the inner cheeks, tongue or roof of the mouth; symptoms of Clostridioides difficile infection, like fever, abdominal pain, and severe or bloody diarrhea; as well as symptoms of esophageal injury, like dysphagia or retrosternal pain.

Lastly, remind your clients assigned female at birth who can become pregnant to use a reliable birth control method during therapy.

Finally, while your client is being treated with doxycycline, monitor for the development of side effects, as well as evaluate for the therapeutic effect of infection resolution and an absence of Lyme disease symptoms.

Alright, as a quick recap …. Tetracyclines and glycylcyclines are antibiotics that stop bacterial growth by entering bacteria and inhibiting protein synthesis.

They are used to treat infections of the respiratory, genitourinary, gastrointestinal, integumentary, and central nervous systems.

Common side effects include gastrointestinal disturbances, headaches, dizziness, and photosensitivity; as well as more severe side effects like hypersensitivity reactions and superinfections.

Other severe side effects include discoloration of teeth and delayed bone growth in children. When caring for a client who is prescribed a tetracycline, nursing considerations include performing a baseline assessment, monitoring for side effects, and evaluating for the therapeutic response.

Client education is focused on safe self-administration, learning to recognize side effects, as well as when to