NEET-PG 2024 - Microbiology PYQs Practice Questions

Q: A child presented with perianal itching. The swab specimen is shown in the image. What is the diagnosis?

Enterobius. ***Enterobius*** - The image shows **D-shaped** (plano-convex) and **transparent eggs**, which are characteristic of *Enterobius vermicularis* (**pinworm** or **threadworm**). - **Perianal itching**, especially at night, is the hallmark symptom due to the female worm migrating to the perianal region to lay eggs. *Ascaris* - *Ascaris lumbricoides* eggs are typically **round to oval**, with a thick, mamillated (bumpy) outer shell, or smooth in the case of decorticated eggs, which is different from the eggs pictured. - Infection with *Ascaris* can cause pulmonary symptoms (Loeffler's syndrome) and intestinal obstruction, but not typically perianal itching. *Trichiura* - *Trichuris trichiura* (**whipworm**) eggs are distinctly **barrel-shaped** with prominent **polar plugs** at each end, which is not seen in the image. - Whipworm infection is often associated with bloody diarrhea, rectal prolapse, and growth retardation, not primarily perianal itching. *Ancylostoma* - *Ancylostoma duodenale* and *Necator americanus* (hookworms) eggs are typically **oval** with a **thin shell** and segmented embryo (morula stage) within, which lacks the distinct D-shape and transparency of the pictured eggs. - Hookworm infection primarily causes iron-deficiency anemia and can lead to cutaneous larva migrans, not perianal itching as a primary symptom. [Practice more Microbiology PYQs on OnCourse]

Q: A frequent traveler presented with 4 days of continuous fever, abdominal pain, and bradycardia. What is the best diagnostic test to confirm the pathogen?

Blood culture. ***Blood culture*** - **Blood culture** is the most sensitive and specific test for confirming **typhoid fever** in the first week of illness. - The presence of **continuous fever** (step-ladder pattern), **abdominal pain**, and **relative bradycardia** in a traveler strongly suggests typhoid fever caused by *Salmonella Typhi*. *Widal test* - The **Widal test** detects antibodies against *Salmonella Typhi* antigens and is often positive later in the disease course. - It has **limited sensitivity and specificity**, especially in endemic areas or with prior vaccination, leading to false positives and negatives. *Urine culture* - **Urine culture** has a low yield for *Salmonella Typhi*, as bacteria are intermittently shed in urine, usually later in the disease. - It's primarily useful for diagnosing **urinary tract infections** or in chronic carriers of typhoid. *Stool culture* - **Stool culture** yield is higher in the later stages of typhoid fever, as *Salmonella Typhi* is shed in feces. - Its sensitivity is lower than blood culture in the early acute phase when bacteremia is most prominent. [Practice more Microbiology PYQs on OnCourse]

Q: An adult patient with a military background is admitted with a rash, fever, altered sensorium, and a deficiency of the membrane attack complex. What is the most likely etiological agent?

Neisseria meningitidis. ***Neisseria meningitidis*** - A deficiency in the **membrane attack complex (MAC)**, particularly **C5-C9 components**, predisposes individuals to recurrent infections with encapsulated bacteria, especially *N. meningitidis*. - *N. meningitidis* is a common cause of **meningitis**, presenting with **fever, altered sensorium**, and often a **petechial rash** due to disseminated intravascular coagulation (DIC), which align with the patient's symptoms. *Klebsiella pneumoniae* - While *K. pneumoniae* can cause severe infections, including pneumonia and meningitis, it is not specifically associated with **MAC deficiency**. - Its infections more commonly manifest as **severe pneumonia** or **urinary tract infections** in immunocompromised patients. *Haemophilus influenzae* - *H. influenzae* can cause meningitis and other invasive infections, especially in children, but it is not typically linked to **MAC deficiency**. - The classic presentation involving **rash** and severe systemic symptoms as described is more characteristic of **meningococcal disease**. *CMV* - **Cytomegalovirus (CMV)** is a herpesvirus that causes a wide range of diseases, particularly in immunocompromised individuals. - However, CMV infections are primarily associated with **cellular immunity defects** rather than a deficiency in the **membrane attack complex** of the complement system. [Practice more Microbiology PYQs on OnCourse]

Q: A patient was admitted with bloody diarrhea after consumption of oysters. The organism exhibits the Kanagawa phenomenon. What is the correct organism?

Vibrio parahaemolyticus. ***Vibrio parahaemolyticus*** - This organism is a common cause of **gastroenteritis** linked to consumption of **raw or undercooked seafood**, especially oysters, and is known for causing **bloody diarrhea**. - The **Kanagawa phenomenon** refers to the production of **thermostable direct hemolysin (TDH)** by *V. parahaemolyticus*, which is a key virulence factor causing hemolysis and is detectable by a specific agar assay. *Staphylococcus aureus* - While *S. aureus* can cause **food poisoning** through its toxins, it typically presents with **nausea, vomiting**, and **abdominal cramps**, not bloody diarrhea. - Food poisoning from *S. aureus* is usually rapid-onset (within hours) and is associated with **improperly handled foods**, particularly those requiring no cooking after preparation (e.g., salads, custards). *Campylobacter jejuni* - This bacterium is a common cause of **bacterial gastroenteritis** and can lead to **bloody diarrhea**, but it's typically acquired from **poultry** or contaminated water, not specifically oysters. - **Guillain-Barré syndrome** is a serious complication that can follow *C. jejuni* infection, which is not characteristic of *Vibrio* infections. *Salmonella typhi* - *Salmonella typhi* causes **typhoid fever**, a systemic illness characterized by **sustained fever, headache, malaise**, and can lead to a "rose spot" rash. - While it can cause gastrointestinal symptoms, **bloody diarrhea is not the predominant symptom**, and raw oyster consumption is not its typical mode of transmission; it's usually spread through contaminated food or water by asymptomatic carriers. [Practice more Microbiology PYQs on OnCourse]

Q: Desert rheumatism is caused by:

Coccidioides immitis. ***Coccidioides immitis*** - This fungus is the causative agent of **coccidioidomycosis**, also known as **Valley fever** or **desert rheumatism**, due to its prevalence in arid regions. - Infection most commonly occurs through inhalation of **arthroconidia** from disturbed soil in endemic areas. *Paracoccidioides brasiliensis* - This fungus causes **paracoccidioidomycosis** (South American blastomycosis), which is endemic to Latin America. - It typically manifests as chronic granulomatous disease affecting the lungs, skin, mucous membranes, lymph nodes, and internal organs. *Candida albicans* - This is a common opportunistic yeast responsible for various infections, from **superficial mucocutaneous candidiasis** (e.g., thrush, vaginal yeast infections) to severe invasive candidemia. - It is not associated with "desert rheumatism." *Cryptococcus neoformans* - This encapsulated yeast is a major cause of **cryptococcosis**, particularly in immunocompromised individuals. - It commonly causes **meningoencephalitis** and pulmonary disease, and is associated with bird droppings, but not "desert rheumatism." [Practice more Microbiology PYQs on OnCourse]

Question 1

A child presented with perianal itching. The swab specimen is shown in the image. What is the diagnosis?

Accepted Answer

Enterobius

Answer

Ascaris

Answer

Trichiura

Answer

Ancylostoma

Question 2

A frequent traveler presented with 4 days of continuous fever, abdominal pain, and bradycardia. What is the best diagnostic test to confirm the pathogen?

Accepted Answer

Blood culture

Answer

Widal test

Answer

Urine culture

Answer

Stool culture

Question 3

An adult patient with a military background is admitted with a rash, fever, altered sensorium, and a deficiency of the membrane attack complex. What is the most likely etiological agent?

Accepted Answer

Neisseria meningitidis

Answer

Klebsiella pneumoniae

Answer

Haemophilus influenzae

Answer

CMV

Question 4

A patient was admitted with bloody diarrhea after consumption of oysters. The organism exhibits the Kanagawa phenomenon. What is the correct organism?

Accepted Answer

Vibrio parahaemolyticus

Answer

Staphylococcus aureus

Answer

Campylobacter jejuni

Answer

Salmonella typhi

Question 5

Desert rheumatism is caused by:

Accepted Answer

Coccidioides immitis

Answer

Paracoccidioides brasiliensis

Answer

Candida albicans

Answer

Cryptococcus neoformans

Question 6

Broad-based budding yeasts are seen in:

Accepted Answer

Blastomycosis

Answer

Histoplasmosis

Answer

Candidiasis

Answer

Coccidioidomycosis

Question 7

A female patient presents with dysuria and frequency. A coagulase-negative, novobiocin-resistant Staphylococcus species (>10^4 CFU/mL) was grown in urine culture. What does this indicate?

Accepted Answer

UTI

Answer

Commensal

Answer

Contamination

Answer

Repeat culture needed

Question 8

Which viral infection is most likely responsible for triggering this aplastic crisis in the patient?

Accepted Answer

Parvovirus B19

Answer

Epstein-Barr Virus (EBV)

Answer

Hepatitis B Virus (HBV)

Answer

Cytomegalovirus (CMV)

Question 9

A patient was diagnosed with Escherichia coli O157:H7 infection. In this designation, what does the "H" stand for?

Accepted Answer

Flagella

Answer

Lipopolysaccharide (LPS)

Answer

Capsule

Answer

Fimbriae

Question 10

A woman presents with a chronic history of fever and lower limb swelling. The microscopic image of a parasite in her blood smear is shown. Identify the pathogen responsible for her condition.

Accepted Answer

Brugia

Answer

Mansonella

Answer

Wuchereria bancrofti

Answer

Loa loa

NEET-PG 2024 — Microbiology