Antimicrobial Agents Practice Questions

Q: All are effective against Tinea versicolor except :

Griseofulvin. ***Griseofulvin*** - **Griseofulvin** is primarily effective against **dermatophytes** (tinea infections of the skin, hair, and nails) by interfering with fungal cell division. - It has **no significant activity** against *Malassezia globosa* and *Malassezia furfur*, the yeasts responsible for Tinea versicolor. *Clotrimazole* - **Clotrimazole** is an azole antifungal that inhibits ergosterol synthesis, a key component of the fungal cell membrane. - It is an effective **topical treatment** for Tinea versicolor due to its broad-spectrum antifungal activity against *Malassezia* species. *Ketoconazole* - **Ketoconazole** is another azole antifungal that works by impairing ergosterol synthesis. - It is effective in both **topical** (shampoos, creams) and **oral** forms for treating Tinea versicolor. *Fluconazole* - **Fluconazole** is a systemic azole antifungal that inhibits lanosterol 14-alpha-demethylase, an enzyme involved in ergosterol synthesis. - It is an effective **oral treatment** for widespread or recurrent Tinea versicolor, demonstrating good activity against *Malassezia* species.

Q: Leprosy is made non-infectious by Rifampicin in:

2 weeks. ***2 weeks*** - Rifampicin is a potent bactericidal drug against **Mycobacterium leprae**, rapidly reducing the bacterial load and rendering the patient **non-infectious within approximately 2 weeks of initiation**. - This quick action is crucial for **breaking the chain of transmission** in leprosy, allowing patients to resume normal social activities with a lower risk of spreading the disease. *3 weeks* - While treatment duration for leprosy can extend to months or years, the specific action of Rifampicin in rendering a patient non-infectious is known to occur earlier, typically before 3 weeks. - The goal is rapid reduction in infectivity, which Rifampicin achieves quicker than 3 weeks. *4 weeks* - Four weeks (one month) is a longer duration than required for Rifampicin to effectively render a patient non-infectious, as its bactericidal action is much faster. - Delaying isolation or protective measures for this long would be unnecessary, given Rifampicin's rapid effect. *1 week* - Although Rifampicin acts rapidly, **a full week may not be sufficient for complete cessation of infectivity**, though significant reduction occurs within this timeframe. - The widely accepted timeframe for reliable non-infectivity is closer to 2 weeks for leprosy.

Q: Griseofulvin is used in –

Tinea capitis. ***Tinea capitis*** - **Griseofulvin** is an oral antifungal agent specifically effective against **dermatophytes**, which cause **tinea infections**, including **tinea capitis**. - It works by interfering with **microtubule function**, inhibiting fungal cell division and growth. *P. versicolor* - **P. versicolor (Malassezia furfur)** is the causative agent of **pityriasis versicolor**, a superficial fungal infection. - While Griseofulvin is active against dermatophytes, it is **not the primary treatment** for pityriasis versicolor; topical antifungals or oral azoles like fluconazole are usually preferred. *Candidiasis* - **Candidiasis** is caused by **Candida species**, primarily **Candida albicans**. - Griseofulvin has **no significant activity** against Candida; other antifungals like azoles, polyenes, or echinocandins are used for Candidiasis. *All of the options* - This option is incorrect because Griseofulvin is effective only against **dermatophytes** and not against *P. versicolor* or Candidiasis. - Its narrow spectrum of activity makes it unsuitable for all the conditions listed.

Q: Which one of the following antibiotic is not recommended for lactating mothers?

Quinolones. ***Quinolones*** - **Quinolones** are generally **not recommended** for lactating mothers due to concerns about potential harm to the infant's developing **cartilage** and **joints**. - They have been associated with **arthropathies** and **tendinopathies** in animal studies and young patients, leading to caution in this population. *Aminoglycoside* - **Aminoglycosides** are typically considered **safe** in lactation because they have **poor oral absorption** by the infant, meaning very little drug reaches the infant's systemic circulation. - While they can be excreted into breast milk, the amount absorbed by the infant is usually **negligible**, reducing risk of toxicity. *Cephalosporins* - **Cephalosporins** are generally considered **safe** for lactating mothers as they are excreted into breast milk in **low concentrations** and have a good safety profile for infants. - Potential side effects in the infant are usually minor, such as **diarrhea** or **thrush**, and serious adverse events are rare. *Anti tubercular drugs* - Most **first-line anti-tubercular drugs** (e.g., isoniazid, rifampicin, ethambutol, pyrazinamide) are generally **considered compatible** with breastfeeding. - While they do pass into breast milk, the benefits of treating **maternal tuberculosis** and preventing transmission to the infant usually outweigh the theoretical risks.

Q: Ichthyosis is a side effect of -

Clofazimine. ***Clofazamine*** - **Clofazimine** is an antimycobacterial drug used to treat **leprosy**, and one of its characteristic skin-related side effects is **ichthyosis**, presenting as dry, scaly skin. - It accumulates in fatty tissues and the reticuloendothelial system, causing a range of skin pigmentation changes from red-brown to black, often associated with generalized dryness and scaling. *Capreomycin* - **Capreomycin** is an injectable antibiotic primarily used for **multi-drug resistant tuberculosis (MDR-TB)**. - Its main side effects involve **nephrotoxicity** and **ototoxicity**, not ichthyosis. *Letrozole* - **Letrozole** is an **aromatase inhibitor** used in the treatment of **hormone-receptor-positive breast cancer** in postmenopausal women. - Common side effects include **hot flashes**, **arthralgia**, and **fatigue**, but not ichthyosis. *Cephalosporin* - **Cephalosporins** are a class of **beta-lactam antibiotics** widely used for bacterial infections. - While they can cause various side effects like **allergic reactions** (rash, anaphylaxis), **gastrointestinal upset**, and **nephrotoxicity** at high doses, ichthyosis is not a recognized side effect.

Q: Drug that is contraindicated in renal failure is:

Streptomycin. ***Streptomycin*** - **Streptomycin** is primarily cleared renally, and its accumulation in **renal failure** can lead to significant **ototoxicity** and **nephrotoxicity**. - Its use in patients with compromised kidney function is contraindicated or requires significant dose reduction and careful monitoring. *Isoniazid* - **Isoniazid** is metabolized mainly by the liver, and only a small portion is excreted unchanged by the kidneys, making it relatively safe in **renal failure** with slight dose adjustments. - While it can cause **hepatotoxicity**, its renal excretion is not a primary concern. *Ethambutol* - Although **Ethambutol** is primarily eliminated renally, its dose can be adjusted in **renal failure** to prevent toxicity, most notably **optic neuritis**. - It is not outright contraindicated, but careful monitoring of renal function and visual acuity is necessary. *Rifampicin* - **Rifampicin** is extensively metabolized by the liver and is largely excreted through bile and feces, with only a small fraction excreted renally. - Therefore, it can be used safely in patients with **renal failure** without significant dose adjustment.

Q: Pseudotumor Cerebri in Infants is seen with?

Tetracyclines. ***Tetracyclines***- **Tetracyclines**, particularly in infants, are a known cause of **pseudotumor cerebri**, also known as **idiopathic intracranial hypertension (IIH)**. - This condition involves increased **intracranial pressure (ICP)**, leading to symptoms like **headache**, **visual disturbances**, and **papilledema**. *Aminoglycosides*- **Aminoglycosides** are primarily associated with **ototoxicity** (hearing loss) and **nephrotoxicity** (kidney damage) [1]. - They are not typically linked to the development of **pseudotumor cerebri**. *NSAIDS*- **NSAIDs** (Nonsteroidal Anti-inflammatory Drugs) are more commonly associated with **gastrointestinal ulcers** and **renal impairment**. - While they can have neurological side effects in some cases, **pseudotumor cerebri** is not a characteristic or common adverse effect. *Macrolides*- **Macrolides** like erythromycin or azithromycin are generally well-tolerated and are primarily associated with **gastrointestinal upset** and **QT prolongation**. - There is no significant evidence linking **macrolide use** to the development of **pseudotumor cerebri**.

Q: Which of the following is true about Mafenide?

May cause metabolic acidosis. ***May cause metabolic acidosis*** - Mafenide acetate is a **carbonic anhydrase inhibitor**, which can disrupt the kidney's ability to excrete acid. - This leads to an accumulation of hydrogen ions in the body, resulting in **metabolic acidosis**. - This is an **important adverse effect** that requires monitoring in burn patients. *Can penetrate eschars* - **This statement is actually TRUE** - Mafenide acetate has excellent eschar penetration, which is one of its key advantages over silver sulfadiazine. - However, the metabolic acidosis is more commonly emphasized as a distinguishing adverse effect in exams. - Both statements are medically accurate, but metabolic acidosis is the more clinically significant feature to remember. *Can be used orally* - **Mafenide acetate** is a topical agent specifically designed for application to burn wounds. - It is **not formulated for oral administration** and would cause systemic toxicity if used in that manner. *Doesn't cause burning sensation when applied to raw surface* - Mafenide acetate is well-known for causing a **significant burning sensation and pain** when applied to burn wounds. - This local discomfort can be a major challenge for patient compliance and pain management.

Q: Treatment of choice for chloroquine resistant malaria is :

Artemisinin-based combination therapies (ACTs). ***Artemisinin-based combination therapies (ACTs)*** - **ACTs** are the recommended first-line treatment for **uncomplicated Plasmodium falciparum malaria**, especially in areas with chloroquine resistance, due to their high efficacy and rapid action. - They combine an **artemisinin derivative** (which rapidly reduces parasite biomass) with a longer-acting partner drug (which provides sustained curative effect and prevents recrudescence), addressing resistance mechanisms. *Chloroquine* - **Chloroquine** is the treatment of choice for **chloroquine-sensitive malaria**, but it is ineffective against resistant strains. - Its widespread use led to the development of **drug resistance** in many regions, particularly for *Plasmodium falciparum*. *Primaquine* - **Primaquine** is primarily used for **radical cure** to prevent relapses in *Plasmodium vivax* and *Plasmodium ovale* malaria by targeting hypnozoites in the liver. - It is **not effective** as a sole agent for treating acute *Plasmodium falciparum* infections, particularly chloroquine-resistant ones. *Quinine* - **Quinine** has historically been used for treating malaria, including some resistant strains, but is now typically reserved for **severe malaria** or in specific combination regimens where ACTs are unavailable. - Its use can be associated with side effects such as **cinchonism** (tinnitus, headache, nausea) and a longer treatment course compared to ACTs.

Q: What is false about mafenide acetate?

Immunomodulatory action. ***Immunomodulatory action*** - Mafenide acetate is an **antimicrobial agent** primarily used topically for burn wound infections due to its broad spectrum of activity against Gram-positive and Gram-negative bacteria. - Its mechanism of action involves **inhibiting bacterial carbonic anhydrase** and folic acid synthesis, and it does not possess significant immunomodulatory properties. *Deeper penetration* - Mafenide acetate has a **low molecular weight** and is readily absorbed through eschar, allowing for **deeper penetration** into burn wounds compared to other topical agents. - This characteristic makes it effective in treating established burn wound infections but also contributes to its systemic absorption and potential side effects. *Painful* - Application of mafenide acetate can be **very painful** for patients due to its chemical composition and the disruption of nerve endings in burn wounds. - This significant side effect leads to patient discomfort and may necessitate pre-medication or alternative pain management strategies. *Metabolic acidosis* - Mafenide acetate is an inhibitor of **carbonic anhydrase**, which is crucial for acid-base balance, particularly in the kidneys. - Systemic absorption can lead to **metabolic acidosis** due to impaired bicarbonate reabsorption and increased acid excretion, requiring careful monitoring of electrolyte levels, especially in patients with large burn areas or renal dysfunction.

Question 1

All are effective against Tinea versicolor except :

Accepted Answer

Griseofulvin

Answer

Clotrimazole

Answer

Ketoconazole

Answer

Fluconazole

Question 2

Leprosy is made non-infectious by Rifampicin in:

Accepted Answer

2 weeks

Answer

3 weeks

Answer

4 weeks

Answer

1 week

Question 3

Griseofulvin is used in –

Accepted Answer

Tinea capitis

Answer

P. versicolor

Answer

Candidiasis

Answer

All of the options

Question 4

Which one of the following antibiotic is not recommended for lactating mothers?

Accepted Answer

Quinolones

Answer

Aminoglycoside

Answer

Cephalosporins

Answer

Anti tubercular drugs

Question 5

Ichthyosis is a side effect of -

Accepted Answer

Clofazimine

Answer

Capreomycin

Answer

Letrozole

Answer

Cephalosporin

Question 6

Drug that is contraindicated in renal failure is:

Accepted Answer

Streptomycin

Answer

Isoniazid

Answer

Ethambutol

Answer

Rifampicin

Question 7

Pseudotumor Cerebri in Infants is seen with?

Accepted Answer

Tetracyclines

Answer

Aminoglycosides

Answer

Macrolides

Answer

NSAIDs

Question 8

Which of the following is true about Mafenide?

Accepted Answer

May cause metabolic acidosis

Answer

Can penetrate eschars

Answer

Can be used orally

Answer

Doesn't cause burning sensation when applied to raw surface

Question 9

Treatment of choice for chloroquine resistant malaria is :

Accepted Answer

Artemisinin-based combination therapies (ACTs)

Answer

Chloroquine

Answer

Primaquine

Answer

Quinine

Question 10

What is false about mafenide acetate?

Accepted Answer

Immunomodulatory action

Answer

Deeper penetration

Answer

Painful

Answer

Metabolic acidosis

Antimicrobial Agents — MCQs

Antimicrobial Agents — MCQs

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