Final answer:
Antibiotics are classified based on their spectrum of activity; narrow-spectrum antibiotics target specific types of bacteria, while broad-spectrum antibiotics are effective against a wide range of both gram-positive and gram-negative bacteria. Penicillin derivatives such as ampicillin and amoxicillin are examples of broad-spectrum antibiotics. The choice of antibiotics depends on various factors, including the type of bacteria, susceptibility to antibiotics, and the patient's immune status.
Step-by-step explanation:
Antibiotics can be categorized based on their spectrum of activity against bacteria. Narrow-spectrum antibiotics, such as isoniazid, are effective against a limited group of bacteria, for example, only gram-positive or only gram-negative bacteria. Broad-spectrum antibiotics, on the other hand, are active against a wider range of microbial species, including both gram-positive and gram-negative bacteria. Examples include penicillin derivatives like ampicillin and amoxicillin, which are effective against a variety of gram-positive bacteria and some gram-negative bacteria, such as Escherichia coli. The use of broad-spectrum antibiotics is common in polymicrobial infections or as empiric therapy when the exact pathogen has not been identified. Choosing an appropriate antibiotic therapy involves considering factors such as bacteriostatic versus bactericidal mechanisms, potential side effects, and minimizing the risk of antibiotic resistance. The selection should target the specific pathogen causing the infection, leveraging testing pathogen susceptibility to antibiotics while they grow in culture. For instance, life-threatening infections may require the use of bactericidal drugs, particularly in immunocompromised patients.