Practice exam: chat my love <3 Flashcards by Paloma Loya

Which of the following best describes the mechanism of action of neuraminidase inhibitors (e.g., oseltamivir, zanamivir)?

A) They prevent viral RNA synthesis by inhibiting RNA polymerase.
B) They block the M2 ion channel, preventing viral uncoating.
C) They inhibit the release of new viral particles by preventing cleavage of sialic acid residues.
D) They interfere with viral DNA replication by incorporating into the viral genome.

Correct answer: C
Explanation: Neuraminidase inhibitors prevent the influenza virus from releasing new virions by blocking neuraminidase, an enzyme that cleaves sialic acid residues on the host cell surface. This traps the virus and limits its spread.

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Influenza viruses can develop resistance to neuraminidase inhibitors primarily through:

A) Mutations in the neuraminidase enzyme.
B) Mutations in the hemagglutinin protein.
C) Increased expression of viral thymidine kinase.
D) Changes in host cell receptor affinity.

Correct answer: A
Explanation: Resistance to neuraminidase inhibitors occurs through mutations in the neuraminidase enzyme, reducing drug binding and effectiveness. Hemagglutinin mutations can alter viral entry but are not the primary cause of resistance to these drugs.

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How is acyclovir selectively toxic to herpes simplex virus (HSV) and varicella-zoster virus (VZV)?

A) It inhibits host DNA polymerase, affecting only infected cells.
B) It requires phosphorylation by viral thymidine kinase to become active.
C) It directly binds to viral capsid proteins, preventing replication.
D) It blocks neuraminidase activity, preventing viral release.

Correct answer: B
Explanation: Acyclovir is a prodrug that requires phosphorylation by viral thymidine kinase to become active. This step ensures selective toxicity, as the drug remains inactive in uninfected cells.

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Which of the following statements correctly compares acyclovir, valacyclovir, and famciclovir?

A) Valacyclovir is a prodrug of acyclovir with improved bioavailability.
B) Acyclovir has the highest oral bioavailability among the three.
C) Famciclovir is only effective against CMV infections.
D) Valacyclovir is directly active without conversion.

Correct answer: A
Explanation: Valacyclovir is a prodrug of acyclovir that improves oral bioavailability. Acyclovir has lower bioavailability and requires frequent dosing. Famciclovir is another prodrug, used for herpes viruses, not just CMV.

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Why are antiviral drugs for influenza not considered a replacement for vaccination?

A) Antivirals only work on influenza B, not influenza A.
B) Vaccination provides long-term immunity, while antivirals only shorten illness duration.
C) Antivirals are highly toxic and should only be used in emergency cases.
D) Vaccines are 100% effective, whereas antivirals are not.

Correct answer: B
Explanation: Vaccination provides long-term protection by stimulating an immune response. Antivirals reduce symptom duration and severity but do not prevent infection or provide lasting immunity.

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Which mutation can lead to acyclovir resistance in HSV?

A) Mutations in the viral hemagglutinin gene.
B) Deletions or mutations in the viral thymidine kinase gene.
C) Increased expression of neuraminidase.
D) Alterations in human DNA polymerase.

Correct answer: B
Explanation: HSV can develop resistance to acyclovir by mutating or deleting the thymidine kinase gene, preventing activation of the drug. Foscarnet, which does not require activation by thymidine kinase, is used for resistant strains.

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How does baloxavir marboxil differ from neuraminidase inhibitors in treating influenza?

A) It blocks viral entry into host cells.
B) It inhibits the cap-dependent endonuclease required for viral mRNA transcription.
C) It prevents viral uncoating by blocking the M2 ion channel.
D) It interferes with neuraminidase activity, similar to oseltamivir.

Correct answer: B
Explanation: Baloxavir marboxil inhibits cap-dependent endonuclease, an enzyme critical for viral RNA synthesis. This is a different mechanism from neuraminidase inhibitors, which prevent viral release.

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Which of the following is NOT a significant adverse effect of oseltamivir?

A) Nausea and vomiting
B) Neuropsychiatric symptoms (hallucinations, delirium)
C) Severe nephrotoxicity
D) Headache

Correct answer: C
Explanation: Oseltamivir can cause nausea, vomiting, headache, and in rare cases, neuropsychiatric effects, especially in pediatric patients. Severe nephrotoxicity is not a common adverse effect.

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A 45-year-old male presents with fever, altered mental status, and focal neurological deficits. MRI shows temporal lobe involvement, and HSV DNA is detected in the CSF. What is the best treatment?

A) Oseltamivir
B) Acyclovir
C) Amantadine
D) Foscarnet

Correct answer: B
Explanation: Herpes simplex encephalitis is a medical emergency requiring IV acyclovir, which inhibits viral DNA polymerase. Early treatment reduces mortality and neurological sequelae.

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A 72-year-old woman with COPD and diabetes develops flu symptoms. A rapid test confirms influenza A. What is the best treatment option?

A) No treatment, as influenza is self-limiting
B) Acyclovir
C) Oseltamivir within 48 hours
D) Foscarnet

Correct answer: C
Explanation: High-risk patients should receive oseltamivir within 48 hours to reduce complications. If resistant, baloxavir marboxil is an alternative.

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Which of the following best describes the mechanism of action of beta-lactam antibiotics?

A) Inhibition of bacterial ribosome subunits
B) Disruption of folic acid synthesis
C) Inhibition of transpeptidases (PBPs), preventing peptidoglycan cross-linking
D) Disruption of bacterial DNA by inhibiting topoisomerase

Correct answer: C
Explanation: Beta-lactams bind to PBPs, preventing cross-linking of peptidoglycan, leading to bacterial cell lysis.

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Which two major toxicities are most commonly associated with aminoglycosides?

A) Hepatotoxicity and neurotoxicity
B) Nephrotoxicity and ototoxicity
C) Cardiotoxicity and pancreatitis
D) Bone marrow suppression and hemolytic anemia

Correct answer: B
Explanation: Aminoglycosides cause nephrotoxicity (acute kidney injury) and ototoxicity (hearing loss, vestibular dysfunction).

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What is the primary mechanism of resistance to vancomycin in Enterococcus species?

A) Production of beta-lactamases
B) Mutation of DNA gyrase
C) Modification of D-Ala-D-Ala target to D-Ala-D-Lac
D) Increased efflux pump activity

Correct answer: C
Explanation: Enterococci modify their peptidoglycan precursor from D-Ala-D-Ala to D-Ala-D-Lac, reducing vancomycin binding.

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Which beta-lactam has extended Gram-negative coverage, including Pseudomonas?

A) Amoxicillin
B) Piperacillin
C) Penicillin G
D) Cefazolin

Correct answer: B
Explanation: Piperacillin (often combined with tazobactam) has extended Gram-negative coverage, including Pseudomonas.

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Which antibiotic class is most strongly associated with Clostridioides difficile infections?

A) Beta-lactams
B) Tetracyclines
C) Fluoroquinolones
D) Lincosamides (clindamycin)

Correct answer: D
Explanation: Clindamycin disrupts normal gut flora, allowing C. difficile overgrowth.

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Which of the following antibiotic classes is most effective against Legionella, Mycoplasma, and Chlamydia?

A) Beta-lactams
B) Macrolides
C) Aminoglycosides
D) Carbapenems

Correct answer: B
Explanation: Macrolides (azithromycin, clarithromycin) target 50S ribosomes, making them effective against atypical pneumonia pathogens.

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Which antibiotic is NOT typically used for methicillin-resistant Staphylococcus aureus (MRSA)?

A) Vancomycin
B) Daptomycin
C) Cefepime
D) Linezolid

Correct answer: C
Explanation: Cefepime lacks reliable MRSA coverage, while vancomycin, daptomycin, and linezolid are effective.

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Which of the following is a major black box warning for fluoroquinolones?

A) Rhabdomyolysis
B) QT prolongation and tendon rupture
C) Agranulocytosis
D) Hepatic failure

Correct answer: B
Explanation: Fluoroquinolones (e.g., ciprofloxacin, levofloxacin) can cause QT prolongation and increase the risk of Achilles tendon rupture, especially in older adults

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Which antibiotic is most appropriate for treating carbapenem-resistant Enterobacterales (CRE)?

A) Meropenem
B) Colistin
C) Vancomycin
D) Piperacillin-tazobactam

Correct answer: B
Explanation: Colistin (polymyxins) is often used as a last resort for carbapenem-resistant bacteria.

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What is the treatment of choice for primary syphilis?

A) Ceftriaxone
B) Azithromycin
C) Doxycycline
D) Benzathine penicillin G

Correct answer: D
Explanation: Benzathine penicillin G is the first-line treatment for Treponema pallidum.

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A 55-year-old man with acute leukemia presents with fever, hypotension, and neutropenia. Blood cultures show Gram-negative rods. What is the best empiric antibiotic regimen?

A) Ceftriaxone
B) Piperacillin-tazobactam + tobramycin
C) Vancomycin + meropenem
D) Linezolid

Correct answer: B
Explanation: Neutropenic fever requires broad-spectrum Gram-negative coverage, including Pseudomonas. Piperacillin-tazobactam plus an aminoglycoside is appropriate.

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An 80-year-old woman presents with fever, headache, and altered mental status. Lumbar puncture shows increased WBCs and low glucose. Which empiric antibiotics should be started?

A) Ceftriaxone + vancomycin + ampicillin
B) Piperacillin-tazobactam + clindamycin
C) Doxycycline + azithromycin
D) Meropenem + colistin

Correct answer: A
Explanation: Empiric treatment for bacterial meningitis in the elderly includes ceftriaxone (for S. pneumoniae, N. meningitidis), vancomycin (for resistant S. pneumoniae), and ampicillin (for Listeria monocytogenes).

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A 45-year-old woman with diabetes presents with fever and dysuria. Urine culture shows E. coli producing extended-spectrum beta-lactamase (ESBL). What is the best treatment?

A) Ceftriaxone
B) Nitrofurantoin
C) Meropenem
D) Amoxicillin-clavulanate

Correct answer: C
Explanation: ESBL-producing E. coli are resistant to most beta-lactams except carbapenems. Meropenem is first-line.

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A 34-year-old male IV drug user presents with fever and new-onset heart murmur. Blood cultures grow Staphylococcus aureus. What is the best empiric therapy?

A) Vancomycin
B) Nafcillin
C) Cefazolin
D) Doxycycline

Correct answer: A
Explanation: IV drug users have a high risk of MRSA, requiring vancomycin. If MSSA is confirmed, nafcillin or cefazolin is preferred.

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What is the primary mechanism of action of tenofovir in the treatment of Hepatitis B? A) Protease inhibition B) Reverse transcriptase inhibition C) NS5A inhibition D) RNA-dependent RNA polymerase inhibition

Correct answer: B Explanation: Tenofovir is a nucleotide analog that inhibits HBV reverse transcriptase, preventing viral replication.

How does pegylated interferon-α primarily exert its antiviral effects against HBV and HCV? A) Directly inhibits viral protease activity B) Increases degradation of viral mRNA C) Enhances host immune response via JAK-STAT pathway D) Blocks NS5B polymerase

Correct answer: C Explanation: Pegylated IFN-α stimulates the JAK-STAT pathway, boosting antiviral gene expression to suppress viral replication.

Which of the following statements about DAAs for Hepatitis C is false? A) NS5A inhibitors prevent viral replication and assembly. B) NS5B inhibitors block RNA polymerase activity. C) Protease inhibitors target the NS3/4A enzyme. D) Ribavirin is an essential component of all modern HCV regimens.

Correct answer: D Explanation: Ribavirin is not required for modern regimens. DAAs alone can achieve high cure rates without ribavirin.

Which antiviral agent is most prone to resistance development in chronic Hepatitis B treatment? A) Lamivudine B) Tenofovir C) Entecavir D) Interferon-α

Correct answer: A Explanation: Lamivudine has a high resistance rate (>70% at 5 years) due to HBV polymerase mutations.

Which of the following drugs is a direct-acting NS5A inhibitor used in HCV therapy? A) Sofosbuvir B) Ledipasvir C) Ribavirin D) Simeprevir

Correct answer: B Explanation: Ledipasvir is an NS5A inhibitor, essential for HCV replication and assembly.

Which of the following patients is at highest risk for HBV reactivation? A) An HIV-positive patient on antiretroviral therapy B) A rheumatoid arthritis patient receiving rituximab C) A patient with resolved HBV (anti-HBs positive) undergoing surgery D) A pregnant woman with chronic HBV

Correct answer: B Explanation: Rituximab (anti-CD20 therapy) is strongly associated with HBV reactivation, even in resolved HBV cases.

Sofosbuvir should be avoided in which of the following situations? A) Pregnancy B) Co-administration with amiodarone C) Renal failure (GFR < 60) D) Cirrhosis

Correct answer: B Explanation: Sofosbuvir + amiodarone can cause severe bradycardia and should be avoided.

What is the primary endpoint of HCV treatment? A) Reduction of liver enzyme levels B) HCV RNA undetectable at 12 weeks post-treatment C) Decreased liver fibrosis score D) Prevention of hepatocellular carcinoma

Correct answer: B Explanation: The sustained virologic response (SVR12), defined as undetectable HCV RNA 12 weeks after therapy, indicates cure.

Which antiviral is preferred for preventing perinatal transmission of HBV in pregnant women? A) Lamivudine B) Entecavir C) Tenofovir D) Pegylated interferon

Correct answer: C Explanation: Tenofovir is the first-line option due to its low resistance and safety profile in pregnancy.

Why is ribavirin contraindicated in pregnancy? A) It causes severe hepatotoxicity in the fetus. B) It interferes with DNA polymerase activity in fetal cells. C) It has teratogenic effects. D) It causes maternal thrombocytopenia.

Correct answer: C Explanation: Ribavirin is highly teratogenic and requires at least 6 months of contraception post-exposure.

A 62-year-old man with HCV-related cirrhosis presents with jaundice, ascites, and encephalopathy. His MELD score is 18. He is HCV RNA positive, genotype 1b. Which is the best treatment option? A) Sofosbuvir-ledipasvir B) Pegylated interferon + ribavirin C) No treatment—wait until after liver transplant D) Grazoprevir-elbasvir

Correct answer: A Explanation: Sofosbuvir-ledipasvir is a preferred regimen for compensated and decompensated cirrhosis. Interferon is contraindicated in cirrhosis.

A 55-year-old woman with rheumatoid arthritis on methotrexate and prednisone starts rituximab for refractory disease. One month later, she presents with severe fatigue, jaundice, and ALT of 750 U/L. Serology: HBsAg: negative Anti-HBc IgG: positive Anti-HBs: negative HBV DNA: 10⁵ IU/mL What is the next step? A) Stop rituximab and monitor LFTs B) Start entecavir immediately C) Treat with pegylated interferon D) Order an anti-HBc IgM test

Correct answer: B Explanation: This is HBV reactivation (due to rituximab) in a previously resolved HBV patient (anti-HBc positive). Entecavir or tenofovir is required.

A 50-year-old man with HBV cirrhosis receives a liver transplant. What is the best long-term strategy to prevent HBV recurrence? A) Lifelong tenofovir + hepatitis B immune globulin (HBIG) B) Interferon therapy for 6 months C) Pegylated interferon + ribavirin D) No treatment—new liver is not at risk

Correct answer: A Explanation: Lifelong antiviral therapy (tenofovir or entecavir) + HBIG is needed to prevent HBV reinfection.

What is the key difference between nucleoside reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs)? A) NRTIs inhibit viral entry, while NNRTIs block integration into host DNA. B) NRTIs require phosphorylation to be active, while NNRTIs do not. C) NNRTIs inhibit protease activity, while NRTIs block viral budding. D) NNRTIs directly compete with nucleotides at the active site, while NRTIs do not.

Correct answer: B Explanation: NRTIs require intracellular phosphorylation to become active and incorporate into viral DNA, causing chain termination. NNRTIs do not require phosphorylation and instead bind directly to reverse transcriptase, causing allosteric inhibition.

Which of the following is a major long-term adverse effect of tenofovir disoproxil fumarate (TDF)? A) Hepatotoxicity B) Lactic acidosis C) Nephrotoxicity and decreased bone mineral density D) Hyperlipidemia

Correct answer: C Explanation: TDF is associated with renal toxicity (Fanconi syndrome) and osteopenia due to phosphate wasting. Tenofovir alafenamide (TAF) has less renal and bone toxicity.

Which of the following is currently a recommended first-line regimen for treatment-naïve HIV patients? A) Efavirenz + lamivudine + zidovudine B) Dolutegravir + abacavir + lamivudine (only if HLA-B*5701 negative) C) Raltegravir + tenofovir disoproxil fumarate + ritonavir-boosted darunavir D) Lopinavir/ritonavir + emtricitabine + tenofovir alafenamide

Correct answer: B Explanation: Dolutegravir + abacavir + lamivudine (Triumeq) is a recommended first-line regimen, but only if the patient is HLA-B*5701 negative (to avoid abacavir hypersensitivity).

Which of the following best describes the drug interaction profile of protease inhibitors (PIs) like darunavir? A) They are potent CYP3A4 inhibitors, leading to increased drug levels of co-administered medications. B) They induce CYP3A4, leading to decreased efficacy of co-administered drugs. C) They have minimal drug interactions. D) They are excreted unchanged in urine, avoiding hepatic metabolism.

Correct answer: A Explanation: Protease inhibitors are CYP3A4 inhibitors, often requiring pharmacokinetic boosting with ritonavir or cobicistat. This increases drug levels but also raises the risk of toxicity.

Which regimen is currently FDA-approved for HIV pre-exposure prophylaxis (PrEP)? A) Tenofovir alafenamide + lamivudine B) Dolutegravir + lamivudine C) Emtricitabine + tenofovir disoproxil fumarate D) Efavirenz + zidovudine

Correct answer: C Explanation: Emtricitabine + tenofovir disoproxil fumarate (Truvada) is FDA-approved for PrEP to prevent HIV infection in high-risk individuals.

A 45-year-old man with HIV has been on antiretroviral therapy (ART) for 8 years. His regimen includes dolutegravir + tenofovir disoproxil fumarate + emtricitabine. His recent HIV viral load is 120,000 copies/mL (previously undetectable), and his CD4 count has declined from 600 to 320. Resistance testing reveals mutations in the integrase and NRTI resistance pathways. What is the best next step? A) Continue the current regimen and repeat viral load in 4 weeks. B) Switch to ibalizumab + optimized ART regimen based on resistance testing. C) Discontinue ART and monitor CD4 count. D) Increase dolutegravir to twice daily.

Correct answer: B Explanation: This patient has virologic failure with resistance to integrase inhibitors and NRTIs. Ibalizumab, a monoclonal antibody that blocks viral entry, is used in multidrug-resistant HIV along with an optimized regimen.

A 28-year-old man presents with fever, sore throat, generalized lymphadenopathy, and a maculopapular rash. He had unprotected sex with multiple partners in the past month. Initial HIV ELISA is negative, but HIV RNA PCR shows 250,000 copies/mL. What is the best next step? A) Start immediate ART (Bictegravir/TAF/Emtricitabine) B) Repeat HIV ELISA in 2 weeks C) Start antibiotics for presumed bacterial pharyngitis D) Reassure the patient and send him home

Correct answer: A Explanation: This is acute retroviral syndrome (ARS), where HIV ELISA can be falsely negative due to lack of seroconversion. HIV RNA PCR confirms early infection, requiring immediate ART initiation.

What is the mechanism of action of amphotericin B? A) Inhibits fungal ergosterol synthesis B) Binds to ergosterol, creating membrane pores and causing ion leakage C) Inhibits β-glucan synthesis, disrupting the fungal cell wall D) Inhibits microtubule function, preventing mitosis

Correct answer: B Explanation: Amphotericin B binds to ergosterol, forming pores in the fungal membrane, leading to leakage of ions and cell death.

Which of the following best describes a major pharmacokinetic issue with azole antifungals? A) They induce CYP3A4, leading to decreased drug levels of co-administered medications. B) They inhibit CYP3A4, increasing levels of other drugs and causing toxicity. C) They have minimal drug interactions. D) They are renally excreted and require dose adjustment in renal failure.

Correct answer: B Explanation: Azoles (fluconazole, itraconazole, voriconazole, etc.) inhibit CYP3A4, leading to increased levels of drugs like warfarin, statins, and benzodiazepines, raising toxicity risks.

Which of the following antifungal agents inhibits β-glucan synthase, disrupting fungal cell wall synthesis? A) Voriconazole B) Caspofungin C) Flucytosine D) Amphotericin B

Correct answer: B Explanation: Caspofungin (and other echinocandins like micafungin and anidulafungin) inhibit β-glucan synthase, preventing fungal cell wall synthesis.

What is the first-line treatment for invasive pulmonary aspergillosis? A) Fluconazole B) Itraconazole C) Voriconazole D) Amphotericin B

Correct answer: C Explanation: Voriconazole is the first-line therapy for invasive pulmonary aspergillosis. Amphotericin B is reserved for resistant cases.

Flucytosine is primarily used in combination with amphotericin B to treat: A) Candida esophagitis B) Cryptococcal meningitis C) Dermatophytosis D) Invasive mucormycosis

Correct answer: B Explanation: Flucytosine is used with amphotericin B for cryptococcal meningitis due to its synergistic effect. Major toxicity: bone marrow suppression.

A diabetic patient with ketoacidosis develops black necrotic nasal lesions and fever. What is the best initial treatment? A) Fluconazole B) Amphotericin B C) Itraconazole D) Caspofungin

Correct answer: B Explanation: Mucormycosis (Rhizopus spp.) is an aggressive fungal infection seen in diabetic ketoacidosis. Liposomal amphotericin B is first-line treatment.

Terbinafine is used for onychomycosis. How does it work? A) Inhibits ergosterol synthesis by blocking lanosterol demethylase B) Inhibits squalene epoxidase, preventing ergosterol synthesis C) Inhibits microtubule formation, blocking fungal mitosis D) Disrupts glucan synthesis, weakening the fungal cell wall

Correct answer: B Explanation: Terbinafine inhibits squalene epoxidase, leading to toxic squalene accumulation and fungal cell death.

A 55-year-old man undergoing chemotherapy for leukemia develops fever, hemoptysis, and pleuritic chest pain. A CT scan shows nodular lung infiltrates with surrounding ground-glass opacity ("halo sign"). He is started on voriconazole. One week later, he complains of visual disturbances and hallucinations. What is the most likely cause of his symptoms? A) Chemotherapy-induced encephalopathy B) Voriconazole toxicity C) Progressive invasive aspergillosis D) Amphotericin B nephrotoxicity

Correct answer: B Explanation: Voriconazole toxicity can cause visual hallucinations, photopsia ("flashing lights"), and neurotoxicity. Monitoring drug levels is crucial in long-term therapy.

A 32-year-old man with HIV (CD4 count: 40) presents with headache, confusion, and photophobia. CSF analysis shows: WBC: 40 (lymphocytes) Glucose: 30 mg/dL Protein: 80 mg/dL India ink stain: Positive What is the best initial therapy? A) Fluconazole monotherapy B) Amphotericin B + flucytosine C) Itraconazole D) Caspofungin

Correct answer: B Explanation: Amphotericin B + flucytosine is the first-line treatment for cryptococcal meningitis in HIV. Fluconazole is used for maintenance therapy after induction.

A 65-year-old man in the ICU for septic shock develops persistent fever despite broad-spectrum antibiotics. Blood cultures grow Candida glabrata. He was initially started on fluconazole, but repeat cultures remain positive. What is the best next step? A) Increase fluconazole dose B) Switch to caspofungin C) Start voriconazole D) Switch to amphotericin B

Correct answer: B Explanation: Candida glabrata has high fluconazole resistance, so echinocandins (caspofungin, micafungin) are preferred.

Metronidazole is used to treat Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis. What is its mechanism of action? A) Binds to tubulin, disrupting microtubule formation B) Generates reactive free radicals, leading to DNA strand breaks C) Inhibits dihydrofolate reductase, blocking folate synthesis D) Interferes with heme metabolism, causing toxic accumulation in the parasite

Correct answer: B Explanation: Metronidazole is reduced by anaerobic organisms, generating free radicals that cause DNA damage and parasite death.

A patient is diagnosed with severe Plasmodium falciparum malaria. What is the preferred treatment? A) Chloroquine B) Artesunate (IV) C) Mefloquine D) Atovaquone-proguanil

Correct answer: B Explanation: IV artesunate is the first-line therapy for severe falciparum malaria, while atovaquone-proguanil is used for uncomplicated cases. Chloroquine is ineffective due to widespread resistance.

Ivermectin is used to treat all of the following except: A) Strongyloides stercoralis B) Onchocerca volvulus C) Ascaris lumbricoides D) Plasmodium vivax

Correct answer: D Explanation: Ivermectin is effective against nematodes (Strongyloides, Onchocerca) and some ectoparasites (scabies, lice) but not against malaria (Plasmodium spp.).

Albendazole is used to treat helminth infections by: A) Inhibiting microtubule polymerization, leading to parasite death B) Blocking folic acid synthesis C) Disrupting oxidative phosphorylation D) Inducing membrane depolarization

Correct answer: A Explanation: Albendazole inhibits β-tubulin polymerization, disrupting parasite microtubules and preventing nutrient uptake.

Which drug is first-line for chloroquine-resistant Plasmodium falciparum malaria? A) Artemether-lumefantrine B) Primaquine C) Pyrimethamine-sulfadoxine D) Ivermectin

Correct answer: A Explanation: Artemether-lumefantrine is the standard therapy for chloroquine-resistant malaria. Primaquine is used for Plasmodium vivax/ovale liver stages.

A patient with seizures and brain cysts (Taenia solium larvae) should be treated with: A) Ivermectin B) Albendazole + corticosteroids C) Praziquantel D) Metronidazole

Correct answer: B Explanation: Albendazole is the drug of choice for neurocysticercosis, often combined with corticosteroids to reduce inflammation from cyst destruction.

Permethrin, used for scabies and lice, acts by: A) Blocking GABA receptors, causing paralysis B) Inhibiting microtubule formation C) Disrupting sodium channels, leading to paralysis D) Inhibiting folic acid metabolism

Correct answer: C Explanation: Permethrin disrupts sodium channels in ectoparasites, leading to paralysis and death.

A 28-year-old pregnant woman (third trimester) returns from Nigeria with high fever, chills, and sweating. Blood smear confirms Plasmodium falciparum with parasitemia >10%. She has mild hypotension and jaundice. What is the best treatment? A) Chloroquine B) IV artesunate C) Primaquine D) Mefloquine

Correct answer: B Explanation: IV artesunate is the first-line therapy for severe malaria, including in pregnancy (2nd & 3rd trimester). Primaquine is contraindicated in pregnancy due to hemolysis risk.

A 45-year-old HIV-positive man presents with fever, weight loss, hepatosplenomegaly, and pancytopenia. Bone marrow biopsy shows Leishmania donovani amastigotes inside macrophages. What is the best treatment? A) Amphotericin B B) Metronidazole C) Mefloquine D) Ivermectin

Correct answer: A Explanation: Liposomal amphotericin B is the first-line therapy for visceral leishmaniasis, especially in immunocompromised patients.

A 68-year-old man on chronic corticosteroids for rheumatoid arthritis presents with severe diarrhea, cough, and sepsis. Stool and sputum microscopy show larvae of Strongyloides stercoralis. What is the best treatment? A) Ivermectin B) Albendazole C) Metronidazole D) Praziquantel

Correct answer: A Explanation: Ivermectin is the treatment of choice for Strongyloides hyperinfection syndrome, which occurs in immunosuppressed patients.