Antimicrobial Agents Practice Questions

Q: Praziquantel is used for the treatment of

Schistosomiasis. ***Schistosomiasis*** - **Praziquantel** is the primary drug for treating all species of **schistosomiasis**, effectively killing adult worms [1], [2]. - It works by increasing the **calcium permeability** of the worm's cells, leading to muscle contraction and paralysis [2]. *Rhinosporidiosis* - **Rhinosporidiosis** is a fungal infection, and its treatment typically involves **surgical excision** of the lesions. - Antifungal agents like **dapsone** may be used as an adjuvant therapy, but praziquantel is not indicated. *Strongyloidiasis* - **Strongyloidiasis** is caused by the nematode *Strongyloides stercoralis*, and the preferred treatment is **ivermectin** [3]. - **Albendazole** is an alternative treatment option, but praziquantel is ineffective against this parasite [2], [3]. *Trichomoniasis* - **Trichomoniasis** is a sexually transmitted infection caused by the protozoan *Trichomonas vaginalis*. - It is effectively treated with **metronidazole** or **tinidazole**, while praziquantel has no activity against this protozoan.

Q: Prophylactic dose of Oseltamivir for infants (3-11 months) is?

3 mg/kg/day. ***3 mg/kg/day*** - The recommended **prophylactic dose of oseltamivir** for infants aged 3 to 11 months is **3 mg/kg once daily** for 10 days. - This dosage is essential for preventing **influenza** in this vulnerable age group when exposure is known or highly suspected. *5 mg/kg/day* - A dose of **5 mg/kg** is generally used for **treatment** of influenza in infants and children, not for prophylaxis. - This higher dose is administered twice daily for 5 days when a child is already symptomatic. *1 mg/kg/day* - This dosage is **too low** for either prophylactic or treatment use in infants and would likely be ineffective against influenza. - Sub-optimal dosing can lead to **treatment failure** and a higher risk of complications. *7 mg/kg/day* - This dosage is **higher than recommended** for prophylaxis and could potentially lead to increased adverse effects without offering additional benefit. - Higher doses are usually reserved for **severely immunocompromised** patients or specific treatment regimens, not standard prophylaxis.

Q: Which of the following is the chemoprophylaxis of choice in a person who is on a journey to endemic malarial region?

Atovaquone-proguanil. ***Atovaquone-proguanil*** - **First-line choice** for malaria chemoprophylaxis in travelers to endemic regions according to WHO and CDC guidelines - Highly effective against **drug-resistant *P. falciparum***, including chloroquine and mefloquine-resistant strains - **Excellent tolerability** with minimal side effects compared to other antimalarials - **Convenient dosing schedule**: started 1-2 days before travel and continued for only **7 days after** leaving the endemic area (shorter post-travel duration than alternatives) - Well-tolerated with few contraindications, making it suitable for most travelers *Doxycycline* - Effective alternative for malaria prophylaxis as a **tetracycline antibiotic** - Provides additional protection against **leptospirosis** and traveler's diarrhea - However, associated with **photosensitivity reactions** (sunburn risk), **GI upset**, and **esophageal irritation** - Contraindicated in **pregnancy** and **children <8 years** due to effects on teeth and bone - Requires daily dosing starting 1-2 days before until **4 weeks after travel** (longer duration) *Mefloquine* - Once-weekly dosing offers convenience for long-term travelers - Effective against most *P. falciparum* strains - Major limitation: significant **neuropsychiatric side effects** including anxiety, depression, dizziness, and rarely psychosis - Contraindicated in those with **psychiatric history**, seizure disorders, or cardiac conduction abnormalities - Must be started **2-3 weeks before travel** to assess tolerance *Chloroquine* - Historically the first-line agent but now limited by widespread **chloroquine resistance** - Only effective in few remaining areas with **chloroquine-sensitive *P. vivax*** or *P. falciparum* (parts of Central America, Middle East) - Well-tolerated with once-weekly dosing - Not appropriate for most endemic malarial regions in Africa, Southeast Asia, or South America

Q: Which of the following aminoglycosides is most cochleotoxic:-

Gentamycin. ***Gentamycin*** - **Gentamycin** is known to be the most **cochleotoxic** aminoglycoside, causing irreversible damage to the hair cells in the cochlea [1]. - This toxicity can lead to **permanent hearing loss** and **tinnitus** due to its selective accumulation in inner ear fluids [2]. *Streptomycin* - While streptomycin can cause ototoxicity, its primary adverse effect is vestibulo-toxicity, affecting **balance** more than hearing [2]. - It mainly targets the hair cells of the semicircular canals and otolithic organs, leading to **vertigo** and ataxia [3]. *Amikacin* - Amikacin is also an ototoxic aminoglycoside but is generally considered **less cochleotoxic** than gentamycin. - Its ototoxic effects are comparable to gentamicin, but it is often reserved for infections resistant to other aminoglycosides. *Minocycline* - Minocycline is a **tetracycline antibiotic**, not an aminoglycoside, and is not associated with significant ototoxicity. - Its side effects typically include photosensitivity, gastrointestinal upset, and **vestibular dysfunction** (dizziness, vertigo) in some patients, distinct from cochlear damage.

Q: Empirical drug of choice for treatment of meningococcal meningitis is:-

Ceftriaxone. ***Ceftriaxone*** - As a **third-generation cephalosporin**, **Ceftriaxone** provides excellent coverage against common bacterial causes of meningitis, including *Neisseria meningitidis*. - It achieves high concentrations in the **cerebrospinal fluid (CSF)**, making it highly effective for CNS infections. *Cefotetan* - **Cefotetan** is a **second-generation cephalosporin** that has limited CSF penetration and less reliable coverage against common meningitis pathogens. - While it has activity against some gram-negative bacteria, it is not considered a first-line agent for empirical treatment of meningitis. *Cefoxitin* - **Cefoxitin** is also a **second-generation cephalosporin** with limited ability to cross the blood-brain barrier, making it unsuitable for treating meningitis. - Its spectrum of activity is more focused on anaerobic bacteria and some gram-negative organisms, not typically the main culprits in meningitis. *Gentamicin* - **Gentamicin** is an **aminoglycoside antibiotic** that has poor penetration into the CSF and is less effective as a monotherapy for meningitis. - It is often used in combination with other antibiotics, but not as an empirical monotherapy for suspected meningococcal meningitis.

Q: American Heart Association standard pediatric dose of amoxicillin for antibiotic prophylaxis, in cases of endocarditis is

50mg/kg. ***50mg/kg*** - The **American Heart Association (AHA)** guidelines recommend **50 mg/kg** of amoxicillin as the standard pediatric dose for antibiotic prophylaxis against infective endocarditis before certain dental procedures. - This dose is typically given orally, as a single dose, 30-60 minutes before the procedure. *20mg/kg* - This dose is lower than the recommended **AHA guideline** for infective endocarditis prophylaxis in children. - Administering this dose could result in **subtherapeutic levels**, failing to adequately prevent bacterial colonization and infection. *125mg/kg* - This dosage is significantly higher than the standard **AHA recommendation** for endocarditis prophylaxis. - Such a high dose could increase the risk of **adverse effects** without providing additional prophylactic benefit. *100mg/kg* - While higher than the standard 50mg/kg, this dose also exceeds the **AHA guidelines** for pediatric endocarditis prophylaxis. - Overdosing can lead to increased **gastrointestinal side effects** and other unwanted drug reactions.

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).

Question 1

Praziquantel is used for the treatment of

Accepted Answer

Schistosomiasis

Answer

Rhinosporidiosis

Answer

Strongyloidiasis

Answer

Trichomoniasis

Question 2

Prophylactic dose of Oseltamivir for infants (3-11 months) is?

Accepted Answer

3 mg/kg/day

Answer

5 mg/kg/day

Answer

1 mg/kg/day

Answer

7 mg/kg/day

Question 3

Which of the following is the chemoprophylaxis of choice in a person who is on a journey to endemic malarial region?

Accepted Answer

Atovaquone-proguanil

Answer

Doxycycline

Answer

Mefloquine

Answer

Chloroquine

Question 4

Which of the following aminoglycosides is most cochleotoxic:-

Accepted Answer

Gentamycin

Answer

Streptomycin

Answer

Amikacin

Answer

Minocycline

Question 5

Empirical drug of choice for treatment of meningococcal meningitis is:-

Accepted Answer

Ceftriaxone

Answer

Cefotetan

Answer

Cefoxitin

Answer

Gentamicin

Question 6

American Heart Association standard pediatric dose of amoxicillin for antibiotic prophylaxis, in cases of endocarditis is

Accepted Answer

50mg/kg

Answer

20mg/kg

Answer

125mg/kg

Answer

100mg/kg

Question 7

DOC for Herpes simplex encephalitis:

Accepted Answer

Acyclovir

Answer

Amphotericin B

Answer

Intravenous immunoglobulins

Answer

Inosine pranobex

Question 8

Which of the following drugs can cause hypertrophic pyloric stenosis?

Accepted Answer

Erythromycin

Answer

Nifedipine

Answer

Vancomycin

Answer

Phenyl propanolamine

Question 9

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 10

Drug of choice for roundworm

Accepted Answer

Albendazole

Answer

Mebendazole

Answer

Metronidazole

Answer

Praziquantel

Antimicrobial Agents — MCQs

Antimicrobial Agents — MCQs

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