Fecal Microbiota Transplantation — MCQs
A 40-year old woman presented to the surgical OPD with features suggestive of colitis. She was on prolonged treatment with clindamycin. Fecal sample was positive for toxin produced by this agent. Her condition improved on treatment with metronidazole. The clinical condition is associated with -
Antibiotic treatment of choice for treating cholera in an adult is a single dose of:
Sudha, a 20-year-old female, developed antibiotic-associated pseudomembranous colitis caused by Clostridium difficile. Among the following drugs, which is most likely to be effective in the treatment of this disease?
All of the following are true about ulcerative colitis except:
Which of the following is the BEST method for diagnosis of C. difficile infection?
What is the drug of choice for organism producing the following colonies?
A 35-year-old patient presents to the OPD 24 hours after a fight with a stranger in which he was bitten. GCS is 15/15 and following injury is noted on left forearm. He complains of extreme pain and tenderness in the injury. Swab from the injury was plated in chocolate agar and incubated in 10% carbon dioxide for 48 hours. Small colonies with pitting appearance were noted. Which of the following organism is responsible?
The acid-fast staining characteristic of Mycobacteria is due to which of the following cell wall constituents?
What is the causative agent of Primary Amoebic Meningoencephalitis?
Which of the following viruses has a double-stranded DNA genome?
Fecal Microbiota Transplantation Indian Medical PG Practice Questions and MCQs
Question 1: A 40-year old woman presented to the surgical OPD with features suggestive of colitis. She was on prolonged treatment with clindamycin. Fecal sample was positive for toxin produced by this agent. Her condition improved on treatment with metronidazole. The clinical condition is associated with -
- A. Listeria monocytogenes
- B. Bacillus anthracis
- C. Clostridium difficile (Correct Answer)
- D. Acinetobacter baumannii
Explanation: ***Clostridium difficile*** - The history of **clindamycin use**, followed by **colitis symptoms**, a **positive fecal toxin test**, and improvement with **metronidazole**, are classic indicators of *Clostridium difficile* infection (CDI) [1]. - *C. difficile* produces toxins (Toxin A and Toxin B) that cause **pseudomembranous colitis**, often after antibiotic disruption of normal gut flora [1]. *Listeria monocytogenes* - This bacterium is primarily a cause of **foodborne illness**, leading to febrile gastroenteritis, meningitis, or sepsis, particularly in immunocompromised individuals, pregnant women, and neonates. - It is not typically associated with **antibiotic-associated colitis** or treated with metronidazole as a primary agent for bowel infection. *Bacillus anthracis* - This is the causative agent of **anthrax**, which can manifest as cutaneous, inhalational, or gastrointestinal forms. - **Gastrointestinal anthrax** causes severe abdominal pain, vomiting, bloody diarrhea, and fever, but it is rare and not linked to antibiotic use or toxin detection in stool in the context described. *Acinetobacter baumannii* - *Acinetobacter baumannii* is an important **opportunistic pathogen** often associated with hospital-acquired infections, such as pneumonia, urinary tract infections, and bloodstream infections, particularly in critically ill patients. - It is not a known cause of **antibiotic-associated colitis** due to toxin production, nor is metronidazole the primary treatment.
Question 2: Antibiotic treatment of choice for treating cholera in an adult is a single dose of:
- A. Co-trimoxazole
- B. Doxycycline (Correct Answer)
- C. Furazolidone
- D. Tetracycline
Explanation: ***Doxycycline***- **Doxycycline** is the recommended first-line antibiotic for cholera in adults due to its effectiveness in reducing stool volume and duration of diarrhea, and it is often given as a **single oral dose**.- Its broad-spectrum activity and good oral bioavailability make it a practical choice for treating **Vibrio cholerae** infections, especially in outbreak settings.*Co-trimoxazole*- While **co-trimoxazole (trimethoprim-sulfamethoxazole)** can be effective against some strains of Vibrio cholerae, resistance has become more common, limiting its use as a first-line agent.- Its efficacy as a single-dose treatment for cholera is generally less established compared to doxycycline.*Furazolidone*- **Furazolidone** has been used in the past for cholera treatment, but its use has declined due to concerns about side effects and the development of resistance.- It is not typically recommended as the first-line treatment for cholera in adults, particularly as a single dose.*Tetracycline*- **Tetracycline** is historically effective against cholera, but modern guidelines often prefer doxycycline due to its improved tolerability, once-daily dosing, and similar efficacy profile.- The older tetracyclines often require multiple doses per day, which can impact patient compliance compared to a single-dose regimen of doxycycline.
Question 3: Sudha, a 20-year-old female, developed antibiotic-associated pseudomembranous colitis caused by Clostridium difficile. Among the following drugs, which is most likely to be effective in the treatment of this disease?
- A. Metronidazole (Correct Answer)
- B. Ampicillin
- C. Clindamycin
- D. Chloramphenicol
Explanation: ***Metronidazole*** - Among the options listed, **Metronidazole** is the most effective for treating **Clostridioides difficile infection (CDI)**. - It works by disrupting bacterial DNA synthesis and is highly effective against **anaerobic bacteria** like *C. difficile*. - **Note:** Current guidelines (IDSA/SHEA 2021) recommend **oral vancomycin or fidaxomicin as first-line therapy**, with metronidazole reserved for situations where preferred agents are unavailable. However, among the drugs listed here, metronidazole remains the correct choice. *Ampicillin* - **Ampicillin** is a penicillin-class antibiotic and is **ineffective** against *Clostridioides difficile*. - It is one of the antibiotics that can **trigger** antibiotic-associated pseudomembranous colitis by disrupting normal gut flora and promoting *C. difficile* overgrowth. *Clindamycin* - **Clindamycin** is notorious for being a common cause of **antibiotic-associated pseudomembranous colitis** due to *Clostridioides difficile*. - It would **exacerbate** rather than treat the condition, making it an inappropriate choice. *Chloramphenicol* - **Chloramphenicol** is a broad-spectrum antibiotic that is **not effective** for treating *Clostridioides difficile* infection. - Its use is limited due to significant side effects, including **bone marrow suppression** (aplastic anemia), and it is not a recommended treatment for CDI.
Question 4: All of the following are true about ulcerative colitis except:
- A. Surgery is required in a subset of severe cases.
- B. Extra-intestinal problems of UC are managed medically
- C. The highest risk of UC requiring surgery in 1st year
- D. Steroid dependent cases need surgery (Correct Answer)
Explanation: ***Steroid dependent cases need surgery*** - While **steroid dependency** in ulcerative colitis (UC) indicates a need for alternative or escalate medications, it does not automatically necessitate surgery [1]. - Many steroid-dependent patients can be managed effectively with **immunomodulators** or **biologic therapies**, avoiding surgery. *Surgery is required in a subset of severe cases.* - **Severe ulcerative colitis** that is refractory to medical therapy, or complicated by toxic megacolon, perforation, or severe bleeding, often requires surgical intervention [1]. - This statement is true, as surgery can be curative for UC by removing the affected colon [1]. *Extra-intestinal problems of UC are managed medically* - **Extra-intestinal manifestations** of ulcerative colitis, such as arthritis, skin lesions (erythema nodosum), and eye inflammation (uveitis), are typically managed with medications specific to those conditions, often in conjunction with UC treatment [1], [2]. - This statement is true, as these manifestations rarely require surgical intervention themselves. *The highest risk of UC requiring surgery in 1st year* - The risk of surgery in ulcerative colitis is indeed highest in the **first year after diagnosis**, particularly for patients presenting with severe disease. - This initial period often determines the disease course and responsiveness to medical treatment.
Question 5: Which of the following is the BEST method for diagnosis of C. difficile infection?
- A. Toxin gene detection by polymerase chain reaction (PCR) (Correct Answer)
- B. Enzyme-linked immunosorbent assay (ELISA)
- C. Culture
- D. Glutamate dehydrogenase (GDH) antigen detection
Explanation: ***Toxin gene detection by polymerase chain reaction (PCR)*** - **Nucleic acid amplification tests (NAAT/PCR)** for toxin genes (tcdA and tcdB) have the **highest sensitivity and specificity** among single-test methods, making them the preferred standalone diagnostic test. - Provides **rapid results** (2-4 hours), allowing for timely diagnosis and management of **Clostridioides difficile infection** (CDI). - **Clinical note:** While NAAT is highly sensitive, guidelines recommend **two-step algorithms** (GDH or NAAT + toxin EIA) to distinguish colonization from active infection in certain clinical settings. *Enzyme-linked immunosorbent assay (ELISA)* - **ELISA** for toxins A and B has **moderate specificity** but **lower sensitivity** (70-85%) compared to NAAT, potentially missing cases with lower toxin levels. - While it detects actual toxin production, the sensitivity limitation makes it suboptimal as a standalone test. *Culture* - **Culture** can detect the presence of *C. difficile* organism but **does not confirm toxin production**, meaning colonization cannot be distinguished from active disease without additional testing. - It is **time-consuming** (2-5 days), which delays diagnosis and treatment. - Useful for **epidemiological studies and strain typing** but not for routine diagnosis. *Glutamate dehydrogenase (GDH) antigen detection* - **GDH detection** is highly sensitive (>95%) for the presence of *C. difficile* organism, but has **low specificity** as it detects both toxigenic and non-toxigenic strains. - Best used as a **screening test** in two-step algorithms; a **positive GDH test must be confirmed** with toxin detection (EIA or NAAT).
Question 6: What is the drug of choice for organism producing the following colonies?
- A. Erythromycin
- B. Ciprofloxacin (Correct Answer)
- C. Ceftriaxone
- D. No treatment with approx. 100% mortality
Explanation: ***Ciprofloxacin*** - The image displays characteristic **"Medusa head" colonies**, which are pathognomonic for *Bacillus anthracis* (anthrax). - **Ciprofloxacin** is a fluoroquinolone and is the **first-line drug of choice** for *Bacillus anthracis* infections (treatment and prophylaxis). - Other first-line options include **doxycycline**, and combination therapy is often used for systemic/inhalational anthrax. - Early antibiotic therapy significantly reduces mortality, though delayed treatment in inhalational anthrax carries high mortality risk. *Erythromycin* - Erythromycin is a **macrolide antibiotic** that is **not recommended** for *Bacillus anthracis* infections. - It has lower efficacy and is not considered effective against anthrax, especially in severe systemic forms. *Ceftriaxone* - Ceftriaxone is a **third-generation cephalosporin** that is **not recommended** for anthrax. - *Bacillus anthracis* produces **beta-lactamase enzymes** that confer resistance to many beta-lactam antibiotics. - Therefore, ceftriaxone would be ineffective as monotherapy. *No treatment with approx. 100% mortality* - This is **incorrect** as a treatment option since effective antibiotics are available. - While untreated inhalational anthrax has very high mortality (approaching 90-100%), **treatment exists and is effective**, especially when initiated early. - The drug of choice for anthrax is ciprofloxacin (or doxycycline), not "no treatment."
Question 7: A 35-year-old patient presents to the OPD 24 hours after a fight with a stranger in which he was bitten. GCS is 15/15 and following injury is noted on left forearm. He complains of extreme pain and tenderness in the injury. Swab from the injury was plated in chocolate agar and incubated in 10% carbon dioxide for 48 hours. Small colonies with pitting appearance were noted. Which of the following organism is responsible?
- A. Flavobacterium meningosepticum
- B. Capnocytophaga gingivalis
- C. Streptobacillus moniliformis
- D. Eikenella corrodens (Correct Answer)
Explanation: ***Eikenella corrodens*** - The context of a **human bite wound** and the characteristic **pitting of agar** by bacterial colonies are classic identifiers for *Eikenella corrodens*. - This organism is a common inhabitant of the **oral flora** and is frequently implicated in infections resulting from human bites. *Flavobacterium meningosepticum* - This organism is more commonly associated with **nosocomial infections**, particularly in newborns and immunocompromised patients, and severe infections like meningitis or sepsis, not typically human bite wounds. - While it can grow on chocolate agar, its colonial morphology does **not typically involve pitting** of the agar. *Capnocytophaga gingivalis* - This organism is also part of the normal oral flora and can cause infections related to human bites, especially in immunocompromised individuals. - However, while it can grow on chocolate agar, it characteristically exhibits **gliding motility** and ferments carbohydrates, but does not typically cause the striking **pitting** seen with *Eikenella corrodens*. *Streptobacillus moniliformis* - *Streptobacillus moniliformis* is associated with **rat bite fever** (Haverhill fever if contracted through contaminated food or water) and not typically human bite wounds. - It often produces **"fried egg" colonies** with a dense center and a lacy edge, which is distinct from the pitting observed here.
Question 8: The acid-fast staining characteristic of Mycobacteria is due to which of the following cell wall constituents?
- A. Mycolic acid (Correct Answer)
- B. Lipopolysaccharide
- C. Lipid A
- D. N-acetyl muramic acid
Explanation: **Explanation:** The acid-fastness of *Mycobacteria* is primarily attributed to the presence of **Mycolic acids** in their cell walls. Mycolic acids are long-chain (C60 to C90) fatty acids that form a thick, waxy, and hydrophobic layer. During the Ziehl-Neelsen (acid-fast) staining process, the primary stain (Carbol Fuchsin) is driven into the cell wall using heat or detergents. Once stained, this waxy layer resists decolorization by strong mineral acids (like 3% HCl in alcohol), hence the term "acid-fast." **Analysis of Incorrect Options:** * **Lipopolysaccharide (LPS):** This is a major component of the outer membrane of **Gram-negative bacteria** (e.g., *E. coli*). It acts as an endotoxin but does not confer acid-fastness. * **Lipid A:** This is the toxic moiety of the Lipopolysaccharide molecule. While it is a lipid, it is specific to Gram-negative endotoxins and not the waxy wall of Mycobacteria. * **N-acetyl muramic acid (NAM):** This is a basic building block of **peptidoglycan**, found in almost all bacterial cell walls. While Mycobacteria do have a peptidoglycan layer, it is not responsible for their unique staining properties. **NEET-PG High-Yield Pearls:** * **Acid-fast organisms:** Besides *Mycobacterium*, other acid-fast structures include *Nocardia* (weakly acid-fast), *Cystoisospora*, *Cryptosporidium* oocysts, and bacterial spores. * **Staining Technique:** The Ziehl-Neelsen stain is the "hot method," while the Kinyoun stain is the "cold method." * **Auramine-Rhodamine:** This is a fluorescent stain used for rapid screening of sputum smears; it is more sensitive than ZN staining. * **L-form bacteria:** Bacteria that lack a cell wall entirely (like *Mycoplasma*) will not stain with ZN or Gram stain.
Question 9: What is the causative agent of Primary Amoebic Meningoencephalitis?
- A. Endolimax nana
- B. Dientamoeba fragilis
- C. Naegleria fowleri (Correct Answer)
- D. Entamoeba histolytica
Explanation: ### Explanation **Correct Answer: C. Naegleria fowleri** **Primary Amoebic Meningoencephalitis (PAM)** is a rapidly fatal central nervous system infection caused by ***Naegleria fowleri***, often referred to as the "brain-eating amoeba." * **Pathogenesis:** It is a free-living thermophilic amoeba found in warm freshwater. Infection occurs when contaminated water is forcefully inhaled through the nose (e.g., during diving or swimming). The amoeba penetrates the **cribriform plate** and migrates along the olfactory nerves to the brain, causing acute hemorrhagic necrosis and purulent meningitis. * **Clinical Presentation:** It mimics acute bacterial meningitis but progresses much faster, usually leading to death within 7–10 days. **Why the other options are incorrect:** * **A. Endolimax nana:** This is a non-pathogenic commensal amoeba found in the human intestine. It does not cause disease and is considered an indicator of fecal-oral contamination. * **B. Dientamoeba fragilis:** Despite its name, it is a flagellate that causes mild gastrointestinal symptoms (diarrhea, abdominal pain) but never involves the CNS. * **C. Entamoeba histolytica:** This is the causative agent of amoebic dysentery and liver abscesses. While it can rarely cause a brain abscess (secondary to hematogenous spread), it does not cause Primary Amoebic Meningoencephalitis. **NEET-PG High-Yield Pearls:** * **Diagnostic Finding:** Wet mount microscopy of **CSF** showing motile trophozoites (look for pseudopodial movement). Note: Cysts are *not* seen in brain tissue or CSF. * **Drug of Choice:** **Amphotericin B** (often used in combination with Rifampicin and Miltefosine). * **Differential:** Contrast with *Acanthamoeba*, which causes **Granulomatous Amoebic Encephalitis (GAE)** in immunocompromised hosts and has a more subacute/chronic course.
Question 10: Which of the following viruses has a double-stranded DNA genome?
- A. Hepatitis A virus
- B. Hepatitis B virus (Correct Answer)
- C. Hepatitis C virus
- D. Hepatitis D virus
Explanation: **Explanation:** The classification of Hepatitis viruses based on their genomic structure is a high-yield topic for NEET-PG. **Correct Answer: B. Hepatitis B virus (HBV)** HBV is the only DNA virus among the major hepatitis viruses. It belongs to the *Hepadnaviridae* family. Its genome is unique: it is a **circular, partially double-stranded DNA (dsDNA)** molecule. During its replication cycle, it utilizes an enzyme called **reverse transcriptase** to convert an RNA intermediate back into DNA, a feature it shares with retroviruses. **Incorrect Options:** * **Hepatitis A virus (HAV):** A member of the *Picornaviridae* family, it has a **single-stranded positive-sense RNA (ssRNA+)** genome. It is typically transmitted via the fecal-oral route. * **Hepatitis C virus (HCV):** A member of the *Flaviviridae* family, it also possesses an **ssRNA+** genome. It is notorious for its high rate of progression to chronic infection. * **Hepatitis D virus (HDV):** Known as a "defective" virus, it has a **circular ssRNA** genome. It requires the presence of HBV (specifically the HBsAg coat) to replicate and cause infection. **High-Yield Clinical Pearls for NEET-PG:** 1. **DNA vs. RNA:** Remember the mnemonic: "All Hepatitis viruses are RNA, **except B** which is DNA." 2. **Morphology:** The infectious particle of HBV is known as the **Dane particle** (42 nm). 3. **Serology:** HBsAg is the first marker to appear in acute infection; Anti-HBs indicates immunity (via recovery or vaccination). 4. **HCV:** It lacks 3'-5' exonuclease activity in its RNA polymerase, leading to high antigenic variation (why there is no vaccine).
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