Task 9
A. Define selectively toxic. A1. Explain why being selectively toxic is an important feature of antimicrobial agents.
Selectively toxic means the therapeutic agent used can inhibits or kills microbial cells but not the host's cells. The therapeutic agent must interact with some microbial function or structure that is absent or differs from the host cell. This is important so that only the pathogenic microorganisms gets killed or inhibited, without harming the normal flora or causing harm to the host (Fridkin, 2014).
B. Explain broad- and narrow-spectrum antimicrobials. B1. Explain the pros and cons of each spectrum.
Broad spectrum antimicrobials are drugs that are effective against a variety of both gram-positive and gram-negative bacteria. It can be used on a broad range of bacteria. They are very powerful, very flexible drugs that can used to treat bacterial infections when the infecting bacterium has not yet been identified eg ampicillin, streptomycin. They attack without discrimination as to if it is a pathogenic bacteria or good bacteria. Broad spectrum can lead to superinfection by opportunist microorganism such as candida causing yeast infection. If broad-spectrum antibiotics are not used appropraitely it can cause great damage to the normal microbata., drug toxicity, allergic reactions to, and even lead to resistant strains of the microbe. Narrow-spectrum antibiotics, on the other hand, attack a specific bacterium i.e. just gram-positive or just gram-negative bacteria, or only a few, and can prevent the widespread of collateral damage to the body’s good bacteria. Novobiocin is a narrow-spectrum antibiotic that works actively against gram-positive bacteria but also against a few gram-negative bacteria. Narrow-spectrum antibiotics are also less likely to encourage superinfection however, the identity of the bacterium needs to be known in advance