WHAT DOES “ANTIBIOTIC RANK” MEANS?
The use of antibiotics is critical to maintaining both human and animal health, ensuring food safety, and preventing the spread of zoonotic diseases. However, concerns about antibiotic resistance have prompted the need to rank veterinary antibiotics based on their importance, usage, and associated risks. This ranking or categorization serves as a tool to support veterinarians in making informed decisions about which antibiotics to use. The AMEG and AVA proposes to classify antibiotics in four different categories, which are: Category A (“Avoid”)/ Restricted: Antibiotic that is not authorized in veterinary medicine but authorized in human medicine in the EU. These drugs are vitally important to human health so should never be used in animals. Category B (“Restrict”)/ Tertiary/ 3rd line: Antibiotics that are of great importance to animal and human health especially for the treatment of multidrug resistant bacteria, and where resistance is more likely occur following use and/or is of great concern in veterinary and human healthcare. Category C (“Caution”)/ Secondary/ 2nd line: Antibiotics that are often broad-spectrum that are important for animal and human health and in which resistance is more likely to occur. For substances proposed for inclusion in this category, there are in general alternatives in human medicine in the EU but there are few alternative antibiotics in veterinary medicine for certain indications. Category D (“Prudence”)/ Primary/ 1st line: Antibiotics that are well established with good evidence of high efficacy and safety. Ideally, they should be narrow-spectrum. Source: Guidance for the rational use of antimicrobials (https://www.ava.com.au/siteassets/advocacy/gram-book—guidance-for-the-rational-use-of-antimicrobials.pdf) AMEG – EMA’s Antimicrobial Advice Ad Hoc Expert Group Report (https://www.ema.europa.eu/en/documents/report/categorisation-antibiotics-european-union-answer-request-european-commission-updating-scientific-advice-impact-public-health-and-animal-health-use-antibiotics-animals_en.pdf) OIE LIST OF ANTIMICROBIAL AGENTS OF VETERINARY IMPORTANCE (https://www.woah.org/app/uploads/2021/06/a-oie-list-antimicrobials-june2021.pdf)
Understanding Antibiotic Classifications: A Comprehensive Guide
Antibiotics are essential tools in modern medicine, used to combat bacterial infections that could otherwise lead to severe health issues or even death. To use these powerful drugs effectively, it’s crucial to understand the different classifications of antibiotics, which are based on their chemical structure, mechanism of action, and spectrum of activity. This article explores the main classifications of antibiotics, providing an overview of their uses and how they work. Beta-Lactam Antibiotics Examples: Penicillins, Cephalosporins, Carbapenems, Monobactams Mechanism of Action: Beta-lactam antibiotics work by inhibiting the synthesis of bacterial cell walls. They target the penicillin-binding proteins (PBPs) that are crucial for forming peptidoglycan, a key component of the bacterial cell wall. By disrupting this process, beta-lactams weaken the bacterial cell wall, leading to cell lysis and death. Uses: These antibiotics are widely used to treat a variety of infections, including respiratory tract infections, urinary tract infections, skin infections, and more. Penicillins are often the first line of defense against many common bacterial infections. Macrolides Examples: Erythromycin, Azithromycin, Clarithromycin Mechanism of Action: Macrolides inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit, preventing the translocation of peptides. This action effectively stops the bacteria from growing and multiplying. Uses: Macrolides are particularly useful for treating respiratory infections, such as pneumonia and bronchitis, as well as skin infections. They are also an alternative for patients allergic to penicillin. Tetracyclines Examples: Tetracycline, Doxycycline, Minocycline Mechanism of Action: Tetracyclines inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit. This prevents the attachment of aminoacyl-tRNA to the mRNA-ribosome complex, thereby halting protein synthesis and bacterial growth. Uses: Tetracyclines are used to treat a variety of infections, including skin infections, respiratory tract infections, and urinary tract infections. Aminoglycosides Examples: Gentamicin, Amikacin, Tobramycin Mechanism of Action: Aminoglycosides bind to the 30S subunit of bacterial ribosomes, leading to the misreading of mRNA. This causes the bacteria to produce faulty proteins, ultimately leading to cell death. Uses: These antibiotics are often used to treat serious infections caused by Gram-negative bacteria, such as sepsis, endocarditis, and complicated urinary tract infections. Due to their potential for toxicity, they are usually reserved for severe infections. Fluoroquinolones Examples: Ciprofloxacin, Levofloxacin. Mechanism of Action: Fluoroquinolones inhibit bacterial DNA gyrase and topoisomerase IV, enzymes critical for DNA replication and transcription. By disrupting these processes, fluoroquinolones prevent bacterial cell division and lead to cell death. Uses: Fluoroquinolones are used to treat a variety of infections, including respiratory tract infections, urinary tract infections, gastrointestinal infections, and skin infections. Sulfonamides Examples: Sulfamethoxazole, Sulfadiazine Mechanism of Action: Sulfonamides inhibit dihydropteroate synthase, an enzyme involved in folate synthesis in bacteria. Folate is necessary for DNA synthesis and cell division, so its inhibition leads to bacterial growth arrest. Uses: Sulfonamides are commonly used in combination with trimethoprim (e.g., as co-trimoxazole) to treat urinary tract infections, respiratory infections, and some types of diarrheas. Glycopeptides Examples: Vancomycin Mechanism of Action: Glycopeptides inhibit bacterial cell wall synthesis by binding to the D-alanyl-D-alanine termini of cell wall precursor units. This prevents the cross-linking of peptidoglycan chains, which is essential for bacterial cell wall strength and rigidity. Uses: Glycopeptides are used primarily to treat serious Gram-positive infections, especially those caused by methicillin-resistant Staphylococcus aureus (MRSA) and other resistant organisms. Oxazolidinones Examples: Linezolid, Tedizolid Mechanism of Action: Oxazolidinones inhibit protein synthesis by binding to the 50S subunit of the bacterial ribosome, preventing the formation of a functional initiation complex for protein translation. Uses: Oxazolidinones are used to treat serious infections caused by Gram-positive bacteria, including MRSA and vancomycin-resistant enterococci (VRE).