NEET-PG 2018 - Microbiology PYQs Practice Questions

Q: Which organism is the most common cause of acute bacterial prostatitis?

E.coli. ***E.coli*** - **E.coli** is the most common cause of **acute bacterial prostatitis**, accounting for a significant majority of cases. - It is a **gram-negative rod** commonly found in the gastrointestinal tract and can ascend into the urinary tract and prostate. *Enterococcus* - While **Enterococcus species** can cause urinary tract infections and, less commonly, prostatitis, they are a distant second to E.coli in frequency. - They are **gram-positive cocci** and are often associated with catheter-associated infections or healthcare-acquired infections. *Streptococcus viridans* - **Streptococcus viridans** group bacteria are typically commensals of the oral cavity and are more known for causing **endocarditis** or dental infections. - They are not a common cause of acute bacterial prostatitis. *Peptostreptococcus* - **Peptostreptococcus** is a genus of **anaerobic gram-positive cocci** commonly found in the normal flora of the mouth, gastrointestinal tract, and vagina. - They are typically involved in **polymicrobial anaerobic infections** but are not a primary or common cause of acute bacterial prostatitis. [Practice more Microbiology PYQs on OnCourse]

Q: Which of the following organisms is MOST associated with histamine production in scombroid fish poisoning?

Morganella morganii. ***Morganella morganii*** - ***Morganella morganii*** is the **MOST commonly implicated organism** in **scombroid fish poisoning** - It produces the enzyme **histidine decarboxylase**, which converts **histidine** (abundant in scombroid fish like tuna, mackerel, bonito) to **histamine** - When fish are stored at improper temperatures (>15°C), *M. morganii* proliferates and produces large amounts of **histamine** - Other histamine-producing bacteria include *Klebsiella*, *Proteus*, *Enterobacter*, and *Photobacterium* species - Symptoms mimic an **allergic reaction**: flushing, headache, palpitations, urticaria, diarrhea *Staphylococcus* - ***Staphylococcus aureus*** causes **staphylococcal food poisoning** through preformed **enterotoxins** (not histamine) - Associated with protein-rich foods left at room temperature - Causes rapid-onset nausea, vomiting, and abdominal cramps - **Not a significant cause** of scombroid fish poisoning *Salmonella* - ***Salmonella*** species cause **gastroenteritis** through direct infection and invasion of intestinal mucosa - Symptoms include **diarrhea**, **fever**, and **abdominal cramps** with longer incubation period (6-72 hours) - **Not associated** with histamine production or scombroid poisoning *P. aeruginosa* - ***Pseudomonas aeruginosa*** is an **opportunistic pathogen** causing hospital-acquired infections - Associated with wound infections, pneumonia, and UTIs in immunocompromised patients - **Not a cause** of foodborne histamine poisoning [Practice more Microbiology PYQs on OnCourse]

Q: What is the Australian antigen for hepatitis B?

HBsAg. ***HBsAg*** - **HBsAg** stands for **Hepatitis B surface antigen**, which was originally discovered by Baruch Blumberg in 1965 and was initially called the **Australia antigen** due to its discovery in the serum of an Australian aboriginal. - Its presence indicates an **active hepatitis B infection**, either acute or chronic. *HBeAg* - **HBeAg** (Hepatitis B e-antigen) is a marker of **viral replication** and **infectivity**. - It is distinct from HBsAg and indicates a high level of **transmissibility** of the virus. *HBDAg* - **HBDAg** is not a standard or recognized antigen for hepatitis B. - The correct antigen for hepatitis D is **HDAg** (Hepatitis D antigen), which is only found in individuals co-infected with hepatitis D virus and hepatitis B virus. *HBV DNA* - **HBV DNA** refers to the viral genetic material of the hepatitis B virus. - While its presence indicates active viral replication and is used to monitor **viral load**, it is not an antigen but rather the **viral genome** itself. [Practice more Microbiology PYQs on OnCourse]

Q: Cutaneous larva migrans is caused by which organism?

Ancylostoma braziliense. ***Ancylostoma braziliense*** - This **hookworm** species commonly found in dogs and cats is the most frequent cause of **cutaneous larva migrans** in humans. - The larvae penetrate the skin but cannot complete their life cycle in humans, instead migrating aimlessly creating **serpiginous tracks**. *Strongyloides* - **_Strongyloides stercoralis_** causes **strongyloidiasis**, which presents with a rapidly advancing (up to 10 cm/hr) migratory rash known as **larva currens**, and not the slower cutaneous larva migrans. - It differs from cutaneous larva migrans in its ability to complete its life cycle in humans, leading to **autoinfection**. *Toxocara canis* - **_Toxocara canis_** is the causative agent of **visceral larva migrans** and **ocular larva migrans**, not cutaneous larva migrans. - In visceral larva migrans, larvae migrate through internal organs, causing symptoms like **hepatomegaly** and **eosinophilia**. *Necator americanus* - This is a human hookworm that can cause **iron deficiency anemia** due to chronic blood loss in the intestines. - While its larvae can penetrate the skin, causing a transient itchy rash known as **ground itch**, they do not cause the prolonged, migratory cutaneous larva migrans. [Practice more Microbiology PYQs on OnCourse]

Question 1

Which organism is the most common cause of acute bacterial prostatitis?

Accepted Answer

E.coli

Answer

Enterococcus

Answer

Streptococcus viridans

Answer

Peptostreptococcus

Question 2

Which of the following organisms is MOST associated with histamine production in scombroid fish poisoning?

Accepted Answer

Morganella morganii

Answer

P. aeruginosa

Answer

Staphylococcus

Answer

Salmonella

Question 3

Identify the organism related to the blood smear image.

Accepted Answer

Plasmodium falciparum

Answer

Salmonella Typhi

Answer

Toxoplasma gondii

Answer

Treponema pallidum

Question 4

What is the Australian antigen for hepatitis B?

Accepted Answer

HBsAg

Answer

HBeAg

Answer

HBDAg

Answer

HBV DNA

Question 5

Cutaneous larva migrans is caused by which organism?

Accepted Answer

Ancylostoma braziliense

Answer

Strongyloides

Answer

Toxocara canis

Answer

Necator americanus

Question 6

Which fungus is most commonly associated with orbital cellulitis in patients with diabetic ketoacidosis?

Accepted Answer

Rhizopus

Answer

Candida

Answer

Mucor

Answer

Aspergillus

Question 7

Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?

Accepted Answer

Enterovirus type 70

Answer

Enterovirus type 68

Answer

Enterovirus type 69

Answer

Enterovirus type 71

Question 8

Urea breath test is used for diagnosis of:

Accepted Answer

H. pylori

Answer

E. coli

Answer

Lactobacillus

Answer

Campylobacter jejuni

Question 9

Whole blood is used as a sample for which of the following tests?

Accepted Answer

Interferon Gamma Release Assay (IGRA)

Answer

Genexpert

Answer

Blood Culture for Bacteria

Answer

Serological Test for Viruses

Question 10

Sabin Feldman dye test is used for diagnosis of which of the following condition?

Accepted Answer

Toxoplasmosis

Answer

Botulism

Answer

Sarcoidosis

Answer

Yellow fever

NEET-PG 2018 — Microbiology