Chapter 20 Microbiology Final Summer 2009

Explanation
The use of drugs to treat a disease is known as pharmacotherapy.

Explanation
An antibiotic is a substance produced by a microbe that, in small amounts, inhibits another microbe. Antibiotics are used to treat bacterial infections by killing or inhibiting the growth of bacteria. They can be naturally produced by certain microbes or synthesized in a laboratory. Antibiotics work by targeting specific components or processes within bacterial cells, disrupting their normal function and ultimately leading to their death or inhibition.

Explanation
Broad-spectrum antibiotics are effective against a wide range of both gram-positive and gram-negative bacteria. They are able to target and kill a variety of bacteria, regardless of their cell wall structure. This makes them versatile and useful in treating a wide range of bacterial infections.

Explanation
The three specific modes of action for protein synthesis inhibition are inhibiting nucleic acid synthesis, inhibiting the synthesis of essential metabolites, and injuring the plasma membrane. This means that the correct answer is the plasma membrane, which is one of the targets for protein synthesis inhibition.

Explanation
Natural penicillins prevent the cross-linking of NAG (N-acetylglucosamine) and NAM (N-acetylmuramic acid). These two molecules are essential components of the bacterial cell wall. By inhibiting the cross-linking process, natural penicillins weaken the cell wall, leading to the lysis and death of the bacteria.

Explanation
Penicillin works against bacterial cell wall synthesis.

Explanation
Streptomycin was the first antibiotic effective against gram-negative bacteria. It was discovered in 1943 and was widely used to treat infections caused by organisms such as tuberculosis and plague. Streptomycin works by inhibiting protein synthesis in bacteria, leading to their death. Its discovery revolutionized the field of medicine and paved the way for the development of other antibiotics to combat gram-negative infections.

Explanation
Tetracycline's causes discoloration of teeth, and liver damage in pregnancy. Tetracycline is an antibiotic medication that is commonly used to treat bacterial infections. However, when taken during pregnancy, it can cross the placenta and affect the developing baby's teeth, leading to discoloration. Additionally, tetracycline can also cause liver damage in pregnant women. Therefore, it is important for pregnant women to avoid taking tetracycline unless specifically prescribed by a healthcare professional.

Explanation
Triclosan is a chemical compound that inhibits fatty acid synthesis. Fatty acid synthesis is a process in which the body produces fatty acids, which are important for various cellular functions. Triclosan acts by inhibiting an enzyme called enoyl-acyl carrier protein reductase, which is involved in the synthesis of fatty acids. By inhibiting this enzyme, triclosan disrupts the production of fatty acids, leading to a decrease in lipid synthesis. This can have various effects on the body, including antimicrobial activity and potential use in personal care products.

Explanation
Sulfa drugs inhibit folic acid synthesis, which can result in spina bifida in infants.

Explanation
Amphotericin is considered the last chance drug for fungal infections due to its broad-spectrum antifungal activity. It is typically used as a last resort when other antifungal medications have failed or when the infection is severe and life-threatening. Amphotericin works by binding to the cell membrane of the fungus, causing it to become leaky and ultimately leading to its death. However, it is known to have significant side effects and is administered intravenously under close medical supervision.

Explanation
The disk-diffusion method is a technique used to assess the effectiveness of antibiotics. By placing antibiotic disks on a culture plate, the method measures the zone of inhibition, which indicates the ability of the antibiotic to inhibit the growth of bacteria. This allows researchers to determine how well the antibiotic works against specific bacteria strains.

Explanation
Antagonism refers to a situation where the combined effect of two drugs is less effective than the effect of either drug alone. In other words, when two drugs have opposite or competing actions, they can neutralize or diminish each other's effectiveness, resulting in antagonism. This can occur when the drugs interact with the same receptors or pathways in the body, leading to a reduced therapeutic effect.

Explanation
Intracellular pathogens are more difficult to treat with antibiotics because they live inside the host and utilize host mechanisms. These pathogens have evolved strategies to evade the immune system and can hide within host cells, making it harder for antibiotics to reach and eliminate them. Additionally, intracellular pathogens can manipulate host cellular processes to their advantage, further complicating treatment. Therefore, targeting intracellular pathogens requires specialized approaches that can effectively penetrate host cells and disrupt the pathogen's survival mechanisms.

Explanation
Vancomycin is the correct answer to the question. It is a drug that was discovered in Borneo and is considered the "last line" against antibiotic-resistant S. aureus. Vancomycin is a powerful antibiotic that is used when other antibiotics are ineffective due to bacterial resistance. It is commonly used to treat serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and other antibiotic-resistant bacteria.