Tema 42. Antibióticos o fármacos indicados para las enfermedades bacterianas.

Summary

This video script covers the use of various antibiotics such as ciprofloxacin, levofloxacin, ofloxacin, and their role in treating infections, especially urinary and respiratory tract infections. It also discusses the treatment of tuberculosis with first-line drugs like isoniazid, rifampicin, and second-line options for resistant strains. The script highlights the mechanisms, absorption, metabolism, and potential side effects of these drugs, including their interactions with other medications. Furthermore, it emphasizes the rising issue of antibiotic resistance, particularly in tuberculosis and the challenges posed by HIV in controlling the disease.

Takeaways

• 😀 Fluoroquinolones, such as ciprofloxacin, levofloxacin, and others, are effective against both gram-positive and gram-negative bacteria, with ciprofloxacin being the most widely used.
• 😀 These antibiotics are particularly effective against enterobacteria and species resistant to penicillins, cephalosporins, and aminoglycosides.
• 😀 Ciprofloxacin has a high incidence of resistance in staphylococci but is well-absorbed orally and concentrates in tissues like the kidneys, prostate, and lungs.
• 😀 The fluoroquinolone class can have side effects such as digestive disturbances and skin reactions, but they are generally mild and reversible.
• 😀 Isoniazid is an important first-line drug in tuberculosis treatment, inhibiting the synthesis of mycolic acids in the cell walls of Mycobacterium tuberculosis.
• 😀 Rifampicin is another key first-line drug in tuberculosis therapy, effective against a broad range of bacteria and also used in the treatment of leprosy.
• 😀 Rifampicin’s resistance is commonly caused by mutations in the RNA polymerase enzyme and can develop rapidly if not combined with other drugs.
• 😀 The treatment of tuberculosis involves a two-phase regimen: an initial two-month phase with multiple drugs, followed by a continuation phase lasting four months.
• 😀 Ethambutol, while useful in treating tuberculosis, has the significant side effect of optic neuritis, requiring regular vision checks during treatment.
• 😀 Pyrazinamide is effective against intracellular mycobacteria, but can cause side effects like gout, gastrointestinal issues, and hepatotoxicity at high doses or prolonged use.

Q & A

What are fluoroquinolones, and how do they work?

Fluoroquinolones are a group of broad-spectrum antibiotics that are effective against both gram-positive and gram-negative bacteria. They work by inhibiting bacterial DNA synthesis, leading to the death of the bacteria. They are especially effective against enterobacteria and strains resistant to penicillins, cephalosporins, and aminoglycosides.

What is the most commonly used fluoroquinolone, and why?

The most commonly used fluoroquinolone is ciprofloxacin. It is widely used because of its effectiveness against a broad range of bacteria, including resistant strains, and its good absorption and distribution in tissues like the kidney, prostate, and lungs.

How do fluoroquinolones differ in terms of absorption and excretion?

Fluoroquinolones vary in their absorption and excretion properties. For example, ciprofloxacin and norfloxacin are primarily eliminated via hepatic metabolism and renal excretion, while ofloxacin is mainly excreted through urine. Some, like ofloxacin, can cross the blood-brain barrier, whereas others cannot.

What are the common side effects of fluoroquinolones?

The most common side effects of fluoroquinolones are gastrointestinal disturbances, skin rashes, and sometimes more serious effects like tendonitis or neuropathy. Ciprofloxacin, in particular, can interact with theophylline, potentially causing toxicity.

What role does HIV play in the resurgence of tuberculosis?

The rise of HIV has contributed significantly to the resurgence of tuberculosis (TB), especially in sub-Saharan Africa. HIV weakens the immune system, making individuals more susceptible to TB infections, which has led to an increase in TB cases and deaths in certain regions.

What are the first-line drugs used to treat tuberculosis?

The first-line drugs used to treat tuberculosis include isoniazid, rifampicin, rifabutin, ethambutol, and pyrazinamide. These drugs are highly effective against the TB bacteria and are usually administered in combination to reduce the risk of resistance.

How does isoniazid work to treat tuberculosis?

Isoniazid works by inhibiting the synthesis of mycolic acids, which are critical components of the cell wall of mycobacteria. This action is bacteriostatic but can be bactericidal against actively replicating bacteria. It is particularly effective against intracellular TB bacteria.

What are the possible side effects of isoniazid?

The common side effects of isoniazid include allergic skin reactions, hepatotoxicity, and neurological issues, particularly in malnourished individuals. In addition, it can interact with antiepileptic drugs, leading to toxicity.

Why is rifampicin important in the treatment of tuberculosis?

Rifampicin is a key drug in TB treatment because it is one of the most effective antitubercular agents. It works by inhibiting bacterial RNA polymerase, preventing bacterial RNA synthesis. It is also effective against many other bacteria and even leprosy.

What is the second-line treatment for drug-resistant tuberculosis?

For drug-resistant tuberculosis, second-line drugs are used. These include medications like clarithromycin, ciprofloxacin, streptomycin, capreomycin, and cycloserine. These drugs are used when first-line treatments fail or cannot be used due to side effects or resistance.