GTC Microbiology test 4 UPDATED Exam
Questions and CORRECT Answers
What do we call antibiotic that kill gram negative and gram postive bacteria? - Correct
Answer- Broad spectrum
What do we call it when we give the patient 2 or 3 different antibiotics at once? why would
we do that? - Correct Answer- Combination therapy. It makes it more difficult for a pathogen
to develop resistance
If a drug has a low chemotherapeutic index, what does that mean? Is that good or bad? -
Correct Answer- Drugs that have a low chemotherapy index often inhibit pathways or attack
structures found in host cells. Low chemotherapy index is bad. Drugs often have a high
therapeutic index if the target of the drug is a structure or pathway not found in the host
organism.
A drug has a low selective toxicity. Is that good or bad? - Correct Answer- Selective toxicity
is the ability of a chemical or drug to kill a microorganism with out harming its host. A low
selective toxicitiy is bad.
Name four major methods by which antibiotics work. - Correct Answer- a. Inhibit cell wall
synthesis
b. inhibit protein synthesis
c. inhibit nucleic acid synthesis
d. inhibit folic acid syntheses
Penicillin is made by a - Correct Answer- fungus
Who discovered it - Correct Answer- Fleming
How does it harm bacteria - Correct Answer- Penicillin is in a group of beta-lactam drugs that
work by inhibiting the peptide cross-linkages between the NAM-NAG layers of the
peptidoglycan cell wall. Results in faulty cell wall and lysis of bacteria
,What are two problems with penicillins? - Correct Answer- Overuse leads to resistance;
narrow spectrum; many are allergic
What types of microorganisms are affected by penicillin? - Correct Answer- Primarily staph
and strep infection also syphillus
What do we mean by semisynthetic penicillins?
Are they only good for gram positve microorganisms? - Correct Answer- Altered natural
beta-lactams create semisynthetic derivatives of penicillin. These are synthetic and more
expensive. They have a broader spectrum than penicillin due to their modified chemical
structure
Why do they add clavulinic acid to penicilliin? - Correct Answer- This inactivates the
penicillinase made by bacteria
What is beta-lactamase? - Correct Answer- A bacterial enzyme produced by some bacteria
that provide resistance to beta-lactam antibiotics. Also known as penicillinase
Cephalasporins are described as first generation, second generation, and third generation.
What is the difference? - Correct Answer- 1st generation are generally used for gram+.
narrow spectrum. 2nd generation are more broad they kill enterics (gram- and some gram+).
3rd generation kills pseudomonas and is broad spectrum killing gram- and even more gram+
How do these work? - Correct Answer- They work like penicillin by inhibiting cell wall
synthesis. They do this by inhibiting the cross linkages between NAM & NAG layers of
peptidoglycan cell wall. They are resistant to beta lactamase enzyme
Why are these drugs better for some people than penicillin? - Correct Answer- They are
active against more organisms and do not cause as many allergic reactions
Name four other drugs that inhibit the synthesis of the cell wall? - Correct Answer-
Cephalosporin, carbapenems, bacitracin, vancomycin
Which of these drugs is used to treat MRSA? - Correct Answer- Vancomycin
, Which of these drugs is for topical application? - Correct Answer- Bacitracin
Name a drug that inhibits the cell wall synthesis in Mycobacteria. - Correct Answer-
isoniazid, ethambutol
Why can we give drugs that disrupt ribosomes? Wouldn't that affect human ribosomes: -
Correct Answer- The drugs only affect the 30s ribosome in prokaryotic cells. Human cells are
not affected because they have 40s and are eukaryotic
Aminoglycosides are effective against gram ______ bacteria. - Correct Answer- negative
What are some side effects of aminoglycosides? - Correct Answer- Toxicity, hearing loss,
kidney damage
Tetracycline is considered a ________ antibiotic. - Correct Answer- broad spectrum
Tetracycline is effective against intracellular bacteria such as: - Correct Answer- chlamydia,
rickettsia
Tetracycline is effective against bacteria without a cell wall such as: - Correct Answer-
mycoplasma
What is the problem with tetracycline in children? - Correct Answer- discolors teeth and
affects their bones
What is special about chloramphenicol? - Correct Answer- Broad spectrum, it gets through
the blood brain barrier and is great for treating meningititis
What about the problem associated with it? How serious is that? - Correct Answer- Toxicity
in children-->aplastic anemia. Suppress the immune system. Very serious causes suppression
of bone marrow and loss of production of WBC and RBC. Only used if absolutely necessary.
Which patients get erythromycin? - Correct Answer- Patients who are allergic to penicillin.
Questions and CORRECT Answers
What do we call antibiotic that kill gram negative and gram postive bacteria? - Correct
Answer- Broad spectrum
What do we call it when we give the patient 2 or 3 different antibiotics at once? why would
we do that? - Correct Answer- Combination therapy. It makes it more difficult for a pathogen
to develop resistance
If a drug has a low chemotherapeutic index, what does that mean? Is that good or bad? -
Correct Answer- Drugs that have a low chemotherapy index often inhibit pathways or attack
structures found in host cells. Low chemotherapy index is bad. Drugs often have a high
therapeutic index if the target of the drug is a structure or pathway not found in the host
organism.
A drug has a low selective toxicity. Is that good or bad? - Correct Answer- Selective toxicity
is the ability of a chemical or drug to kill a microorganism with out harming its host. A low
selective toxicitiy is bad.
Name four major methods by which antibiotics work. - Correct Answer- a. Inhibit cell wall
synthesis
b. inhibit protein synthesis
c. inhibit nucleic acid synthesis
d. inhibit folic acid syntheses
Penicillin is made by a - Correct Answer- fungus
Who discovered it - Correct Answer- Fleming
How does it harm bacteria - Correct Answer- Penicillin is in a group of beta-lactam drugs that
work by inhibiting the peptide cross-linkages between the NAM-NAG layers of the
peptidoglycan cell wall. Results in faulty cell wall and lysis of bacteria
,What are two problems with penicillins? - Correct Answer- Overuse leads to resistance;
narrow spectrum; many are allergic
What types of microorganisms are affected by penicillin? - Correct Answer- Primarily staph
and strep infection also syphillus
What do we mean by semisynthetic penicillins?
Are they only good for gram positve microorganisms? - Correct Answer- Altered natural
beta-lactams create semisynthetic derivatives of penicillin. These are synthetic and more
expensive. They have a broader spectrum than penicillin due to their modified chemical
structure
Why do they add clavulinic acid to penicilliin? - Correct Answer- This inactivates the
penicillinase made by bacteria
What is beta-lactamase? - Correct Answer- A bacterial enzyme produced by some bacteria
that provide resistance to beta-lactam antibiotics. Also known as penicillinase
Cephalasporins are described as first generation, second generation, and third generation.
What is the difference? - Correct Answer- 1st generation are generally used for gram+.
narrow spectrum. 2nd generation are more broad they kill enterics (gram- and some gram+).
3rd generation kills pseudomonas and is broad spectrum killing gram- and even more gram+
How do these work? - Correct Answer- They work like penicillin by inhibiting cell wall
synthesis. They do this by inhibiting the cross linkages between NAM & NAG layers of
peptidoglycan cell wall. They are resistant to beta lactamase enzyme
Why are these drugs better for some people than penicillin? - Correct Answer- They are
active against more organisms and do not cause as many allergic reactions
Name four other drugs that inhibit the synthesis of the cell wall? - Correct Answer-
Cephalosporin, carbapenems, bacitracin, vancomycin
Which of these drugs is used to treat MRSA? - Correct Answer- Vancomycin
, Which of these drugs is for topical application? - Correct Answer- Bacitracin
Name a drug that inhibits the cell wall synthesis in Mycobacteria. - Correct Answer-
isoniazid, ethambutol
Why can we give drugs that disrupt ribosomes? Wouldn't that affect human ribosomes: -
Correct Answer- The drugs only affect the 30s ribosome in prokaryotic cells. Human cells are
not affected because they have 40s and are eukaryotic
Aminoglycosides are effective against gram ______ bacteria. - Correct Answer- negative
What are some side effects of aminoglycosides? - Correct Answer- Toxicity, hearing loss,
kidney damage
Tetracycline is considered a ________ antibiotic. - Correct Answer- broad spectrum
Tetracycline is effective against intracellular bacteria such as: - Correct Answer- chlamydia,
rickettsia
Tetracycline is effective against bacteria without a cell wall such as: - Correct Answer-
mycoplasma
What is the problem with tetracycline in children? - Correct Answer- discolors teeth and
affects their bones
What is special about chloramphenicol? - Correct Answer- Broad spectrum, it gets through
the blood brain barrier and is great for treating meningititis
What about the problem associated with it? How serious is that? - Correct Answer- Toxicity
in children-->aplastic anemia. Suppress the immune system. Very serious causes suppression
of bone marrow and loss of production of WBC and RBC. Only used if absolutely necessary.
Which patients get erythromycin? - Correct Answer- Patients who are allergic to penicillin.
