The first antibiotic was penicillin, which was discovered by Alexander Fleming. Sulfa drugs were used before penicillin and have antibiotic properties but are not considered as antibiotics.
Correct Answer: Penicillin
Most antimicrobials are effective against bacteria and are generally known as antibiotics. Viruses cause many more infections than bacteria, but there are very few effective antiviral drugs.
Correct Answer: Bacteria
All of the antibiotics listed target the bacterial cell wall except streptomycin, which targets protein synthesis.
Correct Answer: Streptomycin
There are only two totally selectively toxic targets, the bacterial cell wall and bacterial metabolic pathways. Of the answers listed only penicillin, which attacks the cell wall, is selectively toxic and therefore has the fewest side effects.
Bacteriostatic means inhibition of cell growth but not killing of the cell. All of the listed possibilities would result in the death of the cell – they are bacteriocidal.
Correct Answer: None of the choices
Amphotericin B is an antifungal agent. All the others are antibiotics.
Correct Answer: Amphotericin B
Although fungi produce some antibiotics, the majority are derived from bacteria.
Correct Answer: Produced by bacteria
Antibiotic treatment of tuberculosis involves a combination of Rifampin, isoniazid and ethambutol.
Correct Answer: Sulfonamide
Penicillin targets peptidoglycan found in the bacterial cell wall. Mycoplasma does not have a cell wall therefore penicillin would not affect this organism. Penicillium is the fungi that produces penicillin therefore it would not be affected. This leaves Neisseria and Streptococcus as possibilities. Gram-positive organisms have greater amounts of peptidoglycan than Gram-negative cells and since Streptococcus is a Gram-positive cell, it will be more susceptible to penicillin.
Correct Answer: Streptococcus pyogenes
All of the antibiotics listed here are produced by Streptomyces bacteria except bacitracin.
Correct Answer: Bacitracin
Broad spectrum antibiotics act against a wide range of bacteria.
Correct Answer: React with Gram-positive bacteria, Gram-negative bacteria, and Pseudomonas
Bacteriostatic agents inhibit bacterial growth but do not kill them.
Correct Answer: Inhibits bacterial growth but does not kill the organism
Penicillin and ampicillin are both beta-lactam antibiotics and therefore contain the same core, β-lactam, ring structure. Ampicillin is a synthetic form of penicillin, made with a different side chain.
Correct Answer: The side chains affixed to the core ring structure
β-lactamase is the enzyme that breaks one of the bonds in the beta lactam ring, which is the core ring structure of penicillin. This inactivates the drug.
Correct Answer: An enzyme that cleaves the ring structure of penicillin
All choices are targets except the glycocalyx.
Correct Answer: The glycocalyx
Monobactam antibiotics have a different ring structure to penicillin, consisting of a β-lactam ring on its own.
Correct Answer: No core structure
Protein synthesis is a selectively toxic target for antibiotics because bacteria (being prokaryotes) have different ribosomes to humans (being eukaryotes).
Correct Answer: A selective target
In the list of choices all of them recognize the bacterial ribosome except penicillin which targets the bacterial cell wall.
Sulpha drugs target the metabolic pathway involved in the production of folic acid.
Correct Answer: Folate
In order to prevent the continuation of the infection all the viral particles that could continue to infect host cells must be eliminated.
Correct Answer: Must eliminate all viral particles to be effective
Acyclovir is used against Herpes virus and is a nucleoside analog of guanine that selectively blocks the replication of viral DNA.
Correct Answer: Blocks viral DNA replication
Bacitracin targets bacteria while the others listed are used against fungi.
None of the listed antimicrobials are used for protozoan infections.
Penicillin prevents the cross-linking of the NAG and NAM units and prevents the formation of an intact cell wall during cell growth.
Correct Answer: True
Isoniazid is very effective against Mycobacteria because it inhibits the production of mycolic acid.
Correct Answer: False
The plasma membrane in bacteria is a prime target for antibiotics because any disruption of this membrane will destroy the bacteria’s ability to survive.
The synthetic forms of erythromycin, known as azithromycin and clarithromycin, have expanded spectra. They are used for respiratory infections because they are less toxic.
Rifampin is used only in combination therapy because resistance develops rapidly if the antibiotic is used alone.
Chloroquinine is an antimalarial which destroys the blood stage of Plasmodium by destroying infected red blood cells.
Correct Answer: Chloroquine
Azoles such as imidazole and triazole inhibit the production of ergosterol, which is vital component of the fungal plasma membrane.
Correct Answer: Azoles
Mebendazole disrupts microtubule formation in parasitic worms, which affects the motility of the worm.
Correct Answer: Mebendazole
The antifungal flucytosine interferes with DNA and RNA synthesis. This drug is taken up preferentially by fungi but has a high level of toxicity toward kidney and bone marrow that limits its use.
Correct Answer: Flucytosine