MBPL3822 Chemotherapy CAT 1 | MCQ Quiz | OmpathStudy Kenya

Question 1

Which one of the following antibiotics is likely to be most effective agent in the treatment of an infection due to enterococci if used in conjunction with penicillin G? (Application question) Choices:

Accepted Answer

Gentamicin — Gentamicin, when used in combination with penicillin G, shows synergistic activity against enterococci. The penicillin disrupts the cell wall, allowing better penetration of the aminoglycoside (gentamicin) into the bacterial cell, resulting in enhanced bactericidal activity. ---

Question 2

Regarding the antibacterial action of gentamicin, which one of the following statements is the MOST accurate? (Application question) Choices:

Accepted Answer

Gentamicin continues to exert antibacterial effects even after plasma levels decrease below detectable levels — Gentamicin exhibits a post-antibiotic effect (PAE) , meaning it continues to suppress bacterial growth even after drug concentrations fall below the minimum inhibitory concentration (MI C). This is characteristic of concentration-dependent antibiotics like aminoglycosides. ---

Question 3

A 24-year-old woman is diagnosed with genital herpes simplex virus infection. Which agent is indicated for use in this diagnosis? Choices:

Accepted Answer

Valacyclovir — Valacyclovir, famciclovir, penciclovir, and acyclovir are all indicated for herpes simplex virus infection. Cidofovir and ganciclovir are used for CMV retinitis. Zanamivir is indicated for influenza. ---

Question 4

A 72-year-old man is admitted to the hospital from a nursing home with severe pneumonia. He was discharged from the hospital 1 week ago after open heart surgery. The patient has no known allergies. Which of the following regimens is most appropriate for empiric coverage of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa in this patient? Choices:

Accepted Answer

Vancomycin + cefepime + ciprofloxacin — Vancomycin provides adequate coverage against MRSA, and cefepime and ciprofloxacin provide adequate empiric coverage of Pseudomonas. Option B is incorrect because cefazolin does not have activity against Pseudomonas. Option C is incorrect because telavancin should be avoided if possible with drugs that prolong the QTc interval (ciprofloxacin). Daptomycin is inactivated by pulmonary surfactant and should not be used for pneumonia. ---

Question 5

Select the agent which evades acquired efflux and target-mediated resistance Choices:

Accepted Answer

Tigecycline — Tigecycline is the first glycylcycline to be launched and is one of the very few new antimicrobials with activity against Gram-negative bacteria. It evades acquired efflux and target-mediated resistance to classical tetracyclines, but not chromosomal efflux in Proteeae and Pseudomonas. It has shown equivalence to imipenem/cilastatin in intra-abdominal infections and is useful for treating multiresistant pathogens. ---

Question 6

Superinfections are more common with Choices:

Accepted Answer

Use of antibiotic combinations covering both gram positive and gram negative bacteria — Broad-spectrum antibiotics or antibiotic combinations that cover both gram-positive and gram-negative bacteria disrupt the normal flora more extensively, allowing opportunistic organisms (like C. difficile or Candida) to overgrow, leading to superinfections. ---

Question 7

Which one of the following drugs is most likely to be effective against multi-drug-resistant (MDR) strains of M tuberculosis, including those resistant to streptomycin? Choices:

Accepted Answer

Amikacin — Amikacin is an aminoglycoside that is often effective against MDR-TB strains, including those resistant to streptomycin. It is one of the second-line agents used in the treatment of drug-resistant tuberculosis due to its different resistance profile compared to streptomycin. ---

Question 8

A 77-year-old woman was started on antibiotics for pneumonia treatment. After 3 days of antibiotic therapy, the serum creatinine doubled. Which of the following antibiotics is most likely responsible for this increase in serum creatinine? Choices:

Accepted Answer

Tobramycin — Aminoglycosides such as tobramycin accumulate in the proximal tubular cells of the kidney and disrupt calcium-mediated transport processes. This results in kidney damage ranging from mild, reversible renal impairment to severe, potentially irreversible acute tubular necrosis. Nephrotoxicity is not commonly associated with tetracyclines, macrolides, or oxazolidinones. ---

Question 9

The persistent suppression of bacterial growth that may occur following limited exposure to some antimicrobial drugs is called Choices:

Accepted Answer

The post antibiotic effect — The post-antibiotic effect (PAE) is the continued suppression of bacterial growth after brief exposure to an antimicrobial agent, even after drug concentrations have fallen below the MIC. This is particularly notable with aminoglycosides and fluoroquinolones. ---

Question 10

Select the antibiotic whose dose must be reduced in patients with renal insufficiency Choices:

Accepted Answer

Tobramycin — Tobramycin (an aminoglycoside) is primarily eliminated by the kidneys through glomerular filtration. In patients with renal insufficiency, the drug can accumulate to toxic levels, so dose adjustment is necessary to prevent nephrotoxicity and ototoxicity. ---

Question 11

Isoniazid is a primary antitubercular agent that Choices:

Accepted Answer

Requires pyridoxine supplementation — Isoniazid can cause peripheral neuropathy by interfering with pyridoxine (vitamin B6) metabolism. Pyridoxine supplementation is given to prevent this adverse effect, especially in high-risk patients (diabetics, alcoholics, malnourished individuals, pregnant women). ---

Question 12

Linezolid would be a good choice for antibiotic treatment in which of the following patient scenarios? Choices:

Accepted Answer

Pneumonia caused by drug-resistant Streptococcus pneumoniae — Linezolid has excellent coverage against resistant gram-positive organisms including drug-resistant S. pneumoniae. It is not an optimal choice for treatment of bacteremia (static, not cidal). Linezolid also does not have gram-negative coverage against E. coli and P. aeruginosa. ---

Question 13

In the empiric treatment of severe bacterial infections of unidentified etiology, this drug, often used in combination with an aminoglycoside, provides coverage against many staphylococci Choices:

Accepted Answer

Nafcillin — Nafcillin is a penicillinase-resistant penicillin that provides excellent coverage against methicillin-sensitive Staphylococcus aureus (MSSA). It is often used in combination with aminoglycosides for empiric treatment of severe infections where staphylococcal involvement is suspected. ---

Question 14

Which of the following statements accurately describes the difference in spectrum of activity between erythromycin and azithromycin? Choices:

Accepted Answer

Azithromycin has better activity against respiratory pathogens such as Haemophilus influenzae and Moraxella catarrhalis but less potent activity against staphylococci and streptococci — Azithromycin has improved activity against gram-negative respiratory pathogens like H. influenzae and M. catarrhalis compared to erythromycin, but erythromycin has better activity against gram-positive organisms (staphylococci and streptococci). ---

Question 15

Regarding the lipid formulation of amphotericin B, which one of the following statements is accurate? (Application question) Choices:

Accepted Answer

They may decrease nephrotoxicity of amphotericin B — Lipid formulations of amphotericin B (liposomal, lipid complex) have the same spectrum of activity but significantly reduced nephrotoxicity compared to conventional amphotericin B. The lipid carrier preferentially delivers the drug to tissues rather than kidneys, reducing renal toxicity while maintaining antifungal efficacy. ---

Question 16

The mechanism of antibacterial action of tetracycline involves Choices:

Accepted Answer

Blockade of binding of aminoacyl-tRNA to bacterial ribosomes — Tetracyclines bind to the 30S ribosomal subunit and prevent the binding of aminoacyl-tRNA to the acceptor site on the ribosome, thereby inhibiting protein synthesis. This is a bacteriostatic mechanism. ---

Question 17

In which of the following groups do all four drugs warrant careful monitoring for drug-related seizures in high-risk patients? (Application question) Choices:

Accepted Answer

Penicillin G, imipenem, amphotericin B, metronidazole — All four drugs in this group (Penicillin G, imipenem, amphotericin B, and metronidazole) can lower the seizure threshold and cause seizures, especially in high-risk patients (those with renal impairment, CNS disorders, or receiving high doses). These drugs require careful monitoring for neurological adverse effects. ---

Question 18

Penicillins interfere with bacterial cell wall synthesis by Choices:

Accepted Answer

Inhibiting transpeptidases and carboxypeptidases which cross link the peptidoglycan residues — Penicillins are β-lactam antibiotics that inhibit bacterial transpeptidases (also called penicillin-binding proteins or PBPs), which are essential for cross-linking peptidoglycan chains in the bacterial cell wall. This weakens the cell wall and leads to bacterial cell lysis. ---

Question 19

Which of the following statements about vancomycin is accurate? Choices:

Accepted Answer

It is not susceptible to penicillinase — Vancomycin is a glycopeptide antibiotic that is not affected by β-lactamases (penicillinases) because it has a completely different structure and mechanism of action from β-lactam antibiotics. It inhibits cell wall synthesis by binding to D-alanyl-D-alanine terminals, not to PBPs. ---

Question 20

A 36-year-old woman recently treated for leukemia is admitted to hospital with malaise, chills and high fever. Gram stain of blood reveals the presence of gram-negative bacilli. The initial diagnosis is bacteremia and parenteral antibiotics are indicated. The records of the patient reveal that she had a severe urticarial rash, hypotension, and respiratory difficulty following oral penicillin V about 6 months ago. The most appropriate drug regimen for empiric treatment is Choices:

Accepted Answer

Aztreonam — The patient has a documented severe penicillin allergy (anaphylaxis). Aztreonam is a monobactam that has no cross-reactivity with penicillins and can be safely used in penicillin-allergic patients. It provides good gram-negative coverage. Cephalosporins and carbapenems have potential cross-reactivity with penicillins and should be avoided in severe allergic reactions. ---

Question 21

Clarithromycin and erythromycin have very similar spectrums of antimicrobial activity. The major advantage of clarithromycin is that it Choices:

Accepted Answer

Is more active against Mycobacterium avium complex — Clarithromycin has greater intracellular activity than erythromycin against Mycobacterium avium complex (MAC), making it a preferred agent for MAC infections, particularly in HIV-infected individuals. Both drugs have similar spectrums against typical bacteria, but clarithromycin's enhanced activity against MAC is a key distinguishing feature. ---

Question 22

The primary mechanism underlying the resistance of gram-positive organisms to macrolide antibiotics is Choices:

Accepted Answer

Methylation of binding sites on the 50S ribosomal subunit — The most common mechanism of macrolide resistance in gram-positive bacteria is methylation of the 23S rRNA component of the 50S ribosomal subunit (mediated by erm genes). This modification prevents macrolide binding to the ribosome, conferring resistance. ---

Question 23

Which fluoroquinolone has markedly enhanced activity against gram positive bacteria and anaerobes? Choices:

Accepted Answer

Moxifloxacin — Moxifloxacin is a 4th generation fluoroquinolone with improved gram-positive coverage (including S. pneumoniae), maintains gram-negative coverage, and gains anaerobic coverage. This broader spectrum distinguishes it from earlier fluoroquinolones like ciprofloxacin. ---

Question 24

A 20-year-old woman presents to the emergency room with headache, stiff neck, and fever for 2 days and is diagnosed with meningitis. Which is the best agent for the treatment of meningitis in this patient? Choices:

Accepted Answer

Cefotaxime — Cefotaxime is a 3rd generation cephalosporin with excellent CSF penetration and broad coverage against common meningitis pathogens (S. pneumoniae, N. meningitidis, H. influenzae). Cefdinir and cefuroxime axetil are only available orally and not appropriate for serious CNS infections. Cefazolin has inadequate CSF penetration and spectrum. ---

Question 25

A 68-year-old man presents from a nursing home with fever, increased urinary frequency and urgency, and mental status changes. He has a penicillin allergy of anaphylaxis. Which of the following β-lactams is the most appropriate choice for gram-negative coverage of this patient's urinary tract infection? Choices:

Accepted Answer

Aztreonam — Aztreonam is a monobactam with no cross-reactivity with penicillins and can be safely given to penicillin-allergic patients, even those with anaphylaxis. Although cross-reactivity between cephalosporins/carbapenems and penicillins is low (<1-10%), the risk rarely outweighs the benefit in cases of documented anaphylaxis. Aztreonam provides good gram-negative coverage for UTI. ---

Question 26

Your 23-year-old female patient is pregnant and has gonorrhea. The past medical history includes anaphylaxis following exposure to amoxicillin. Worried about compliance, you would like to treat this patient with a single dose, so you chose Choices:

Accepted Answer

Spectinomycin — Spectinomycin is an aminocyclitol antibiotic that can be given as a single intramuscular dose for gonorrhea. It has no cross-reactivity with penicillins (safe in penicillin allergy) and is safe in pregnancy. Ceftriaxone and cefixime have potential cross-reactivity with penicillins. Ciprofloxacin and tetracycline are contraindicated in pregnancy. ---

Question 27

After 5 days of clindamycin treatment for a skin infection, a patient develops diarrhea (10 watery stools/day), severe abdominal pain, and fever. Which of the following organisms would you be concerned about as the causative pathogen of diarrhea? Choices:

Accepted Answer

Clostridium difficile — Clindamycin use has been strongly associated with Clostridium difficile-associated diarrhea (CDAD) or pseudomembranous colitis. Clindamycin disrupts normal colonic flora, allowing C. difficile to proliferate and produce toxins that cause severe diarrhea, abdominal pain, and fever. ---

Question 28

A 23-year-old man presents with acute appendicitis that ruptures shortly after admission. He is taken to the operating room for surgery, and postsurgical cultures reveal Escherichia coli and Bacteroides fragilis, susceptibilities pending. Which of the following provides adequate empiric coverage of these two pathogens? Choices:

Accepted Answer

Piperacillin/tazobactam — Piperacillin/tazobactam is a β-lactam/β-lactamase inhibitor combination that provides excellent coverage against both gram-negative aerobes (E. coli) and anaerobes (Bacteroides fragilis). While the other agents cover E. coli, only piperacillin/tazobactam provides adequate coverage against Bacteroides species, which are common in intra-abdominal infections. ---

Question 29

Beta-lactamase production by strains of Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae confers resistance against penicillin G. Which one of the following antibiotics is most likely to be effective against all strains of each of the above organisms? Choices:

Accepted Answer

Ceftriaxone — Ceftriaxone is a 3rd generation cephalosporin that is β-lactamase stable and has excellent activity against H. influenzae, M. catarrhalis, and N. gonorrhoeae, including β-lactamase-producing strains that are resistant to penicillin G and ampicillin. ---

Question 30

In which of the following cases would it be appropriate to use telavancin? Choices:

Accepted Answer

A 36-year-old man with cellulitis and abscess growing MRSA — Telavancin is approved for skin and skin structure infections caused by gram-positive organisms including MRSA. Option A is not appropriate due to QTc prolongation risk with amiodarone. Option B is not ideal because of baseline renal dysfunction (telavancin is nephrotoxic). Option D is inappropriate because telavancin can harm the fetus. Option C has no contraindications. ---

Question 31

Which type of antimicrobial drug combination is most likely to exhibit antagonism? Choices:

Accepted Answer

Bactericidal + Bacteriostatic for a marginally sensitive organism — Antagonism is most likely when combining bactericidal and bacteriostatic agents, especially for marginally sensitive organisms. Bactericidal drugs (like β-lactams) work best on actively dividing bacteria, but bacteriostatic drugs stop bacterial growth/division. This can reduce the effectiveness of the bactericidal agent. ---

Question 32

Important microbiological features of ciprofloxacin include the following except Choices:

Accepted Answer

Marked suppression of intestinal anaerobes — First generation fluoroquinolones such as ciprofloxacin and ofloxacin are inactive against most anaerobic bacteria. Therefore, they do not cause marked suppression of intestinal anaerobes. Ciprofloxacin does exhibit slow resistance development, bactericidal activity (MBC ≈ MIC), and a long post-antibiotic effect. ---

Question 33

Which of the following is NOT true of sulfonamides? Choices:

Accepted Answer

They are more likely to produce crystalluria in alkaline urine in which they are less soluble — This statement is NOT true. Sulfonamides are actually more soluble in alkaline urine and more likely to crystallize in acidic urine where they are less soluble. Alkalinization of urine is sometimes used to prevent sulfonamide crystalluria. The other statements are all true about sulfonamides. --- All questions from MBPL3822 Chemotherapy CAT 1 have been formatted! Total: 33 questions formatted with choices, answers, and explanations.

MBPL3822 Chemotherapy CAT 1 | MCQ Quiz | OmpathStudy Kenya

Questions, Answers & Explanations