Antimicrobial Agents Practice Questions

Q: DOC for Herpes simplex encephalitis:

Acyclovir. ***Acyclovir*** - **Acyclovir** is the drug of choice for treating **Herpes simplex encephalitis (HSE)** due to its potent antiviral activity against **herpes simplex virus (HSV)**. - It works by inhibiting viral DNA synthesis, thereby reducing viral replication and decreasing morbidity and mortality associated with HSE. *Amphotericin B* - **Amphotericin B** is an **antifungal medication** primarily used for severe systemic fungal infections. - It has no antiviral activity against **HSV** and is therefore ineffective in treating **Herpes simplex encephalitis**. *Inosine pranobex* - **Inosine pranobex** is an **immunomodulatory agent** that is sometimes used for viral infections, but it is not the drug of choice for acute, life-threatening conditions like **Herpes simplex encephalitis**. - Its effectiveness for **HSE** is not established, and it cannot replace potent antiviral therapy. *Intravenous immunoglobulins* - **Intravenous immunoglobulins (IVIG)** are used for immune deficiencies or certain autoimmune and inflammatory conditions. - While they can provide passive immunity, **IVIG** are not a primary treatment for acute viral infections like **HSE** and do not directly inhibit viral replication.

Q: Which of the following drugs can cause hypertrophic pyloric stenosis?

Erythromycin. ***Erythromycin*** - **Erythromycin** use in infants, particularly during the first few weeks of life, has been associated with an increased risk of developing **hypertrophic pyloric stenosis**. - The mechanism is believed to involve the drug's properties as a **motilin receptor agonist**, which may affect the development or function of the pyloric sphincter. *Nifedipine* - **Nifedipine** is a calcium channel blocker primarily used for cardiovascular conditions like hypertension and angina. - It works by relaxing smooth muscles and is not linked to the development of **pyloric stenosis**. *Vancomycin* - **Vancomycin** is an antibiotic used for severe bacterial infections, particularly against Gram-positive bacteria. - It is not associated with the development of **hypertrophic pyloric stenosis**. *Phenylpropanolamine* - **Phenylpropanolamine** is a sympathomimetic drug previously used as a decongestant and anorectic. - It primarily affects alpha-adrenergic receptors and has no established link to **pyloric stenosis**.

Q: According to current WHO guidelines, the first-line drug of choice for managing uncomplicated vivax malaria is:

Chloroquine. ***Chloroquine*** - **Chloroquine plus primaquine** remains the **WHO first-line treatment** for uncomplicated *P. vivax* malaria in areas where chloroquine resistance has not been established. - Chloroquine is highly effective against the blood stages of *P. vivax* with **rapid parasite clearance** and excellent tolerability. - In the majority of endemic regions, *P. vivax* remains **chloroquine-sensitive**, making it the preferred first-line agent. - Primaquine is added to eliminate hypnozoites and prevent relapse, but chloroquine remains the primary blood schizonticide. - Only in areas with **documented chloroquine resistance** (parts of Papua New Guinea, Indonesia) does WHO recommend switching to **artemisinin-based combination therapy (ACT)**. *Artesunate* - Artesunate is the cornerstone of **ACTs for *P. falciparum* malaria**, not monotherapy for vivax. - For vivax, artesunate-based ACTs are reserved for **chloroquine-resistant areas** or when used as combination therapy. - While effective, it is **not the first-line choice** globally for uncomplicated vivax malaria where chloroquine remains effective. *Artemether* - Artemether (typically as artemether-lumefantrine) is another ACT option. - Like artesunate, it is used for vivax malaria only in **chloroquine-resistant regions** or for *P. falciparum*. - Not the standard first-line for uncomplicated vivax malaria per WHO guidelines. *Clindamycin* - Clindamycin is used as an **adjunct therapy** in combination with quinine for severe malaria or in special populations (e.g., pregnant women). - It is **never used as monotherapy** and is not a first-line option for uncomplicated vivax malaria.

Q: Drug of choice for roundworm

Albendazole. ***Albendazole*** - **Albendazole** is a broad-spectrum anthelminthic and is the drug of choice for treating common roundworm infections like *Ascaris lumbricoides*. - It works by inhibiting microtubule polymerization in parasitic worms, leading to their immobility and death. *Mebendazole* - **Mebendazole** is also an effective anthelminthic used for roundworm infections, but **albendazole** is generally preferred due to its single-dose efficacy and broader spectrum. - While effective, it may be used as an alternative if albendazole is not available or contraindicated. *Metronidazole* - **Metronidazole** is an antibiotic and antiprotozoal agent used primarily for anaerobic bacterial infections and parasitic protozoa like *Giardia* and *Trichomonas*. - It is **ineffective** against helminthic infections such as roundworms. *Praziquantel* - **Praziquantel** is primarily used to treat infections caused by **flukes** (trematodes) and **tapeworms** (cestodes). - It is **not effective** against roundworms (nematodes).

Q: Which strain is used in the Mumps vaccine?

Jeryl Lynn. **Jeryl Lynn** - The **Jeryl Lynn strain** is a live attenuated mumps virus strain commonly used in the development of the **mumps vaccine**, particularly in the **MMR vaccine**. - This strain was developed in the 1960s and has a proven track record of safety and efficacy in preventing mumps infection. *Oka* - The **Oka strain** is primarily associated with the **live attenuated varicella (chickenpox) vaccine**. - It is not used in the mumps vaccine, which targets a different viral pathogen. *Danish 1331* - Danish 1331 is a strain associated with a particular **Mycobacterium bovis Bacillus Calmette-Guérin (BCG)** vaccine for **tuberculosis**, not mumps. - BCG vaccines are used to prevent tuberculosis and are distinct from viral vaccines. *Edmonston Zagreb* - The **Edmonston-Zagreb strain** is a live attenuated measles vaccine strain, commonly used in some regions for the **measles, mumps, and rubella (MMR) vaccine**. - While it is part of the MMR vaccine, it specifically targets measles, not mumps.

Q: 'Savlon' contains:

Cetavlon and hibitane. ***Cetavlon and hibitane*** - Savlon is a well-known **antiseptic formulation** that contains both **cetrimide** (often marketed as Cetavlon) and **chlorhexidine gluconate** (referred to as hibitane) [1]. - **Cetrimide** is a quaternary ammonium compound acting as a **surfactant** and antiseptic [2], while **chlorhexidine** is a broad-spectrum antiseptic [1]. *Hibitane and chloroxylenol* - While **hibitane (chlorhexidine)** is a component of Savlon [1], **chloroxylenol** is not. - **Chloroxylenol** is the active ingredient in Dettol, another common antiseptic. *Cetavlon and chloroxylenol* - **Cetavlon (cetrimide)** is part of Savlon's formulation [2], but **chloroxylenol** is not. - These two active ingredients originate from different popular antiseptic products. *Chlorhexidine and chloroxylenol* - **Chlorhexidine** is a component of Savlon [1], but **chloroxylenol** is not. - This option incorrectly substitutes part of the Dettol formulation for a component of Savlon.

Q: All of the following drugs cause renal failure except?

Cefoperazone. ***Cefoperazone*** - **Cefoperazone** is a third-generation cephalosporin that is primarily eliminated by the liver and does not typically cause **nephrotoxicity**. - While all cephalosporins can potentially cause hypersensitivity reactions or interstitial nephritis in rare cases, cefoperazone is not known for direct renal tubular damage. *Amphotericin B* - **Amphotericin B** is a potent antifungal agent that frequently causes dose-dependent **nephrotoxicity** due to direct damage to renal tubular cells. - It can lead to acute kidney injury, electrolyte imbalances (e.g., **hypokalemia**, **hypomagnesemia**), and renal tubular acidosis. *Gentamicin* - **Gentamicin** is an aminoglycoside antibiotic known for its significant **nephrotoxic** potential, particularly with prolonged use or high doses. - It accumulates in renal cortical cells, leading to **proximal tubular necrosis** and acute tubular necrosis. *Cephaloridine* - **Cephaloridine** is a first-generation cephalosporin that was historically removed from the market due to its significant and dose-dependent **nephrotoxicity**. - It caused direct damage to the **renal tubules**, leading to acute kidney injury.

Q: Which of the following drugs are used topically for dermatophytes?

All of the options. ***All of the options*** - **Terbinafine**, **Ciclopirox olamine**, and **Econazole** are all commonly used as topical antifungal agents for the treatment of dermatophyte infections. - These drugs target different aspects of fungal cell metabolism or structure to inhibit growth or kill the fungus. *Terbinafine* - It is an **allylamine antifungal** that inhibits **squalene epoxidase**, an enzyme involved in fungal ergosterol synthesis. - While effective topically, terbinafine can also be used orally for more extensive or recalcitrant infections, but the question specifically asks for topical use. *Cyclopirox olamine* - This is a **hydroxypyridone antifungal** that acts by chelating polyvalent metal cations, inhibiting essential enzymes in fungal cells. - It is often used for topical treatment of dermatophyte infections, including **tinea pedis** and **tinea corporis**, and is also used for onychomycosis. *Econazole* - It is an **imidazole antifungal** that inhibits the fungal cytochrome P450 enzyme 14α-demethylase, which is crucial for **ergosterol biosynthesis**. - Commonly available as a cream or solution, econazole is effective against a broad spectrum of fungi, including dermatophytes, and is used for various superficial fungal infections.

Q: Mechanism of action of terbinafine?

Inhibition of ergosterol synthesis. ***Inhibition of ergosterol synthesis*** - Terbinafine specifically inhibits **squalene epoxidase**, an enzyme involved in the **biosynthesis of ergosterol**, a crucial component of fungal cell membranes. - This inhibition leads to the accumulation of **squalene**, which is toxic to the fungal cell, and a deficiency of ergosterol, compromising membrane integrity and fungal growth. *Inhibition of microtubule formation* - This mechanism is characteristic of **griseofulvin**, another antifungal agent, which interferes with fungal mitosis by disrupting the assembly of microtubules. - Terbinafine does not target microtubule formation; its action is focused on the fungal cell membrane pathway. *Prevents formation of purine* - This mechanism is associated with drugs like **flucytosine**, which is converted into an active metabolite that interferes with fungal DNA and RNA synthesis by inhibiting purine and pyrimidine synthesis. - Terbinafine's fungicidal action is unrelated to purine metabolism. *Binds to ergosterol* - This mechanism describes **polyene antifungals** such as **amphotericin B** and **nystatin**, which directly bind to ergosterol in the fungal cell membrane, creating pores and leading to leakage of cellular contents. - Terbinafine does not directly bind to ergosterol but rather prevents its synthesis.

Question 1

DOC for Herpes simplex encephalitis:

Accepted Answer

Acyclovir

Answer

Amphotericin B

Answer

Intravenous immunoglobulins

Answer

Inosine pranobex

Question 2

Which of the following drugs can cause hypertrophic pyloric stenosis?

Accepted Answer

Erythromycin

Answer

Nifedipine

Answer

Vancomycin

Answer

Phenyl propanolamine

Question 3

According to current WHO guidelines, the first-line drug of choice for managing uncomplicated vivax malaria is:

Accepted Answer

Chloroquine

Answer

Clindamycin

Answer

Artesunate

Answer

Artemether

Question 4

Drug of choice for roundworm

Accepted Answer

Albendazole

Answer

Mebendazole

Answer

Metronidazole

Answer

Praziquantel

Question 5

Which strain is used in the Mumps vaccine?

Accepted Answer

Jeryl Lynn

Answer

Oka

Answer

Danish 1331

Answer

Edmonston Zagreb

Question 6

'Savlon' contains:

Accepted Answer

Cetavlon and hibitane

Answer

Hibitane and chloroxylenol

Answer

Cetavlon and chloroxylenol

Answer

Chlorhexidine and chloroxylenol

Question 7

All of the following drugs cause renal failure except?

Accepted Answer

Cefoperazone

Answer

Amphotericin B

Answer

Gentamicin

Answer

Cephaloridine

Question 8

Which of the following drugs are used topically for dermatophytes?

Accepted Answer

All of the options

Answer

Terbinafine

Answer

Cyclopirox olamine

Answer

Econazole

Question 9

Mechanism of action of terbinafine?

Accepted Answer

Inhibition of ergosterol synthesis

Answer

Inhibition of microtubule formation

Answer

Prevents formation of purine

Answer

Binds to ergosterol

Question 10

Paucibacillary leprosy treatment includes

Accepted Answer

Rifampicin 600 mg once a month for 6 months + Dapsone 100 mg daily for 6 months

Answer

Rifampicin 600 mg daily + Dapsone 100 mg daily for 6 months

Answer

Rifampicin 600 mg + Dapsone 100 mg + Clofazimine for 12 months

Answer

Dapsone 100 mg daily + Clofazimine 300 mg daily for 6 months

Antimicrobial Agents — MCQs

Antimicrobial Agents — MCQs

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