NEET-PG 2019 - Microbiology Practice Questions

Q: Contact isolation is done for:

MRSA. ***MRSA*** - **Methicillin-resistant *Staphylococcus aureus* (MRSA)** is transmitted primarily through direct contact with infected patients or contaminated environmental surfaces, necessitating **contact isolation** measures. - These measures include the use of **gloves and gowns** upon entering the patient's room to prevent spread. *Mumps* - Mumps is a viral infection primarily transmitted via **respiratory droplets**, requiring **droplet isolation** rather than contact isolation. - The virus spreads through coughing and sneezing, necessitating measures like wearing a surgical mask. *Diphtheria* - Diphtheria, caused by *Corynebacterium diphtheriae*, is spread through **respiratory droplets** from close contact with an infected person, requiring **droplet isolation**. - This typically involves wearing a mask and sometimes eye protection. *Typhoid* - Typhoid fever is a **fecal-oral disease** caused by *Salmonella Typhi*, transmitted through contaminated food and water. - While proper hand hygiene is crucial, it generally does not require specific isolation precautions beyond **standard precautions** in a hospital setting for most patients.

Q: Which vaccine requires annual updates due to frequent antigenic changes?

Influenza. ***Influenza*** - The influenza virus undergoes frequent **antigenic drift** and **antigenic shift**, which are changes in its surface proteins (hemagglutinin and neuraminidase). - These constant changes necessitate annual updates to the influenza vaccine to match the circulating strains predicted for the upcoming flu season. *Measles* - The measles virus is **antigenically stable**, meaning it does not frequently change its surface proteins. - Due to its stability, a highly effective and long-lasting vaccine can be produced, and annual updates are not required. *Rubella* - The rubella virus is also **antigenically stable**, similar to measles. - A single vaccine, usually given as part of the MMR (Measles, Mumps, Rubella) vaccine, provides long-term immunity without the need for annual revision. *BCG* - The Bacillus Calmette-Guérin (BCG) vaccine targets *Mycobacterium tuberculosis* and is not subject to frequent antigenic changes. - It is a live-attenuated vaccine that provides long-lasting immunity, and annual boosters or updates are not necessary.

Q: A 9 years old child presented to OPD with complaints of high grade fever, vomiting, one episode of seizure. CSF examination was done and Gram staining of the culture showed the following finding. What is the probable causative agent?

Gram-positive diplococci (e.g., Streptococcus pneumoniae). ***Gram-positive diplococci (e.g., Streptococcus pneumoniae)*** - The image displays small, purple (Gram-positive) cocci arranged in pairs (**diplococci**). - *Streptococcus pneumoniae* is a common cause of **bacterial meningitis** in children, and its characteristic morphology on Gram stain is Gram-positive diplococci. *Gram-negative coccobacilli (e.g., Haemophilus influenzae)* - While *Haemophilus influenzae* can cause meningitis in children, its Gram stain morphology would show **pink-stained coccobacillary forms**, not purple cocci. - The bacteria in the image are clearly cocci, not coccobacilli, and stain Gram-positive (purple). *Gram-negative diplococci (e.g., Neisseria meningitidis)* - *Neisseria meningitidis* is a significant cause of meningitis and appears as **Gram-negative (pink) diplococci**. - The organisms in the image are stained purple, indicating they are Gram-positive. *Gram-positive cocci in chains (e.g., Streptococcus pyogenes)* - *Streptococcus pyogenes* typically forms **chains of Gram-positive cocci**, which is not the predominant arrangement seen in the image. - Although it is Gram-positive, the characteristic arrangement in the image is diplococci, not chains.

Q: Flask shaped ulcers in colon are caused by:-

Entamoeba histolytica. ***Entamoeba histolytica*** - *Entamoeba histolytica* is a protozoan parasite that invades the **colonic mucosa**, leading to characteristic **flask-shaped ulcers**. - These ulcers are formed as the trophozoites penetrate the epithelium and spread laterally through the submucosa, creating a narrow neck at the mucosal surface and a wider base below. *Giardia lamblia* - *Giardia lamblia* causes **giardiasis**, primarily affecting the **small intestine** and leading to malabsorption and diarrhea. - It typically does not cause invasive disease or ulcer formation in the colon, instead, it attaches to the intestinal villi. *Enterobius vermicularis* - *Enterobius vermicularis* is an intestinal nematode (pinworm) that causes **enterobiasis**, commonly manifesting as **perianal itching**, especially at night. - It is a non-invasive parasite and does not cause ulcers in the colon. *H. Pylori* - *H. pylori* is a bacterium primarily associated with infections of the **stomach** and **duodenum**, causing gastritis, peptic ulcers, and increasing the risk of gastric cancer. - It does not colonize the colon or cause flask-shaped ulcers.

Q: A neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?

Togaviridae family (includes Rubella virus). ***Togaviridae family (includes Rubella virus)*** - The classic triad of **congenital rubella syndrome (CRS)** includes **cataracts**, **deafness**, and **cardiac defects** (e.g., patent ductus arteriosus, pulmonary artery stenosis). - Rubella virus is a member of the **Togaviridae family** and causes significant fetal damage if the mother is infected during the first trimester. *Flaviviridae family (includes Zika virus)* - While congenital Zika syndrome can cause severe birth defects, it is primarily associated with **microcephaly**, intracranial calcifications, and ocular abnormalities, not typically the classic rubella triad. - **Deafness** and **linear cataracts** are not characteristic features of congenital Zika infection. *Bunyaviridae family (includes Rift Valley fever virus)* - Rift Valley fever virus is primarily transmitted by mosquitoes and causes **febrile illness** in humans and livestock, with potential for **hemorrhagic fever** or **encephalitis**. - It is not known to cause congenital abnormalities resembling cataracts, deafness, and cardiac defects in neonates. *Arenaviridae family (includes Lassa fever virus)* - Lassa fever virus causes a severe **hemorrhagic fever** in humans, primarily through contact with infected rodents or person-to-person transmission. - It is not associated with congenital malformations such as cataracts, deafness, and cardiac defects.

Q: Flask-shaped ulcers in the intestine are caused by which of the following?

Entamoeba histolytica. ***Entamoeba histolytica*** - *Entamoeba histolytica* is a protozoan that causes **amoebiasis**, which is characterized by **flask-shaped (bottle-shaped) ulcers** in the colon - this is the **pathognomonic feature** of intestinal amoebiasis. - The trophozoites invade the intestinal mucosa and submucosa, creating a **narrow neck at the mucosal surface** and a **wider base in the submucosa**, giving them their unique flask-like appearance. - These ulcers are most commonly found in the **cecum and ascending colon**. *TB* - Intestinal tuberculosis typically causes **transverse ulcers** (perpendicular to the bowel axis) due to lymphatic spread and caseous necrosis, often in the ileocecal region. - These ulcers are usually associated with **granulomas** and acid-fast bacilli, which are histologically distinct from flask-shaped ulcers. *Giardia* - *Giardia lamblia* (or *intestinalis*) is a flagellate that causes **giardiasis**, primarily adhering to the small intestinal villi and causing malabsorption and diarrhea. - It is **non-invasive** and does not penetrate the intestinal wall or cause ulcer formation; its pathology is mainly due to **mucosal inflammation** and villous blunting. *Typhoid* - Typhoid fever, caused by *Salmonella Typhi*, commonly leads to **longitudinal ulcers** (parallel to the bowel axis) in the **Peyer's patches** of the ileum due to bacterial invasion and necrosis of lymphoid tissue. - These ulcers may perforate but do not present with the flask-shaped morphology characteristic of amoebiasis.

Q: A person working in an abattoir presented with malignant pustule on hand. What is the causative agent?

Bacillus anthracis. **Bacillus anthracis** - The presence of a **malignant pustule** on the hand, especially in an individual working in an **abattoir** (exposure to animals/animal products), is highly characteristic of **cutaneous anthrax**. - **Bacillus anthracis** is a **spore-forming bacterium** that causes anthrax, and the cutaneous form typically presents as a painless ulcer that develops into a black eschar. *Clostridium botulinum* - This bacterium causes **botulism**, a severe **neuroparalytic disease** characterized by flaccid paralysis. - It does not cause cutaneous lesions like a malignant pustule and is typically associated with **food poisoning** or wound infections leading to toxin production. *Streptococcus pyogenes* - This bacterium is a common cause of various infections, including **strep throat**, **impetigo**, **erysipelas**, and **necrotizing fasciitis**. - While it can cause skin infections, it does not typically present as a "malignant pustule" with the characteristic eschar seen in anthrax. *Clostridium perfringens* - This bacterium is a common cause of **gas gangrene** (myonecrosis) and **food poisoning**. - While it can cause severe tissue infections, it does not present as a malignant pustule.

Q: A 9-year-old child presented to OPD with complaints of high-grade fever, vomiting, and one episode of seizure. CSF examination was done and Gram staining of the culture showed lanceolate-shaped gram-positive diplococci. What is the probable causative agent?

Streptococcus pneumoniae. ***Streptococcus pneumoniae*** - The description of **lanceolate-shaped gram-positive diplococci** in CSF is characteristic of *S. pneumoniae*. - This bacterium is a common cause of **bacterial meningitis** in children and can present with high fever, vomiting, and seizures. *Haemophilus influenzae* - This is a **gram-negative coccobacillus**, which would appear as small, pleomorphic rods rather than lanceolate-shaped diplococci on Gram stain. - While it causes meningitis, its Gram stain morphology is distinct from *S. pneumoniae*. *Streptococcus agalactiae* - *S. agalactiae* (Group B Streptococcus) is a **gram-positive coccus**, but it typically appears in **chains** and is a major cause of neonatal meningitis, not usually in a 9-year-old child. - Its morphology on Gram stain would not be described as lanceolate diplococci. *Neisseria meningitidis* - *N. meningitidis* is a **gram-negative diplococcus** and would appear as kidney-bean shaped or flattened paired cocci, not gram-positive. - Though a common cause of meningitis, the Gram stain morphology described rules it out.

Q: Rubella is caused by

Togavirus. ***Correct Answer: Togavirus*** - Rubella virus is classified under the genus *Rubivirus* within the family **Togaviridae** - Togaviruses are **enveloped, positive-sense, single-stranded RNA viruses** - Rubella causes German measles, characterized by mild fever and maculopapular rash - Important for congenital rubella syndrome when infection occurs during pregnancy *Incorrect: Paramyxovirus* - This family includes viruses like **measles (rubeola)** and **mumps** - Paramyxoviruses are enveloped, negative-sense, single-stranded RNA viruses - Different structural and genetic characteristics from rubella virus *Incorrect: Orthomyxovirus* - This family primarily consists of **influenza viruses** (types A, B, and C) - Orthomyxoviruses are enveloped, **negative-sense, segmented** RNA viruses - The segmented genome distinguishes them from rubella virus *Incorrect: Flavivirus* - This family includes **dengue virus**, **yellow fever virus**, and **Zika virus** - While flaviviruses are also enveloped, positive-sense, single-stranded RNA viruses, they belong to the family *Flaviviridae*, not Togaviridae - Different envelope proteins and replication strategies distinguish them from rubella virus

Q: A 35 year old man presented with dry cough and rusty colored sputum. He has a history of eating in a Chinese restaurant very often with consumption of crabs. What is the probable causative agent in this condition?

Paragonimus westermani. ***Paragonimus westermani*** - The key clinical features are **dry cough**, **rusty-colored sputum**, and a history of consuming **crabs**. These are classic indicators of **paragonimiasis**. - *Paragonimus westermani* is a **lung fluke** acquired by eating undercooked freshwater crabs or crayfish. *Pneumocystis jirovecii* - This fungus typically causes pneumonia in **immunocompromised individuals**, like those with HIV/AIDS. - While it can cause a dry cough, **rusty-colored sputum** is not a characteristic sign, and there's no mention of immunocompromise. *Strongyloides stercoralis* - This parasite primarily causes **gastrointestinal symptoms** (e.g., abdominal pain, diarrhea) and can lead to cutaneous manifestations (larva currens). - While lung involvement can occur in severe cases (hyperinfection), it does not typically present with **rusty sputum** or a direct association with crab consumption. *Diphyllobothrium latum* - This is the **fish tapeworm**, acquired by eating undercooked freshwater fish. - It primarily causes **gastrointestinal symptoms** such as abdominal pain and diarrhea, and is known for causing **vitamin B12 deficiency** leading to megaloblastic anemia, not pulmonary symptoms.

Question 1

Contact isolation is done for:

Accepted Answer

MRSA

Answer

Mumps

Answer

Diphtheria

Answer

Typhoid

Question 2

Which vaccine requires annual updates due to frequent antigenic changes?

Accepted Answer

Influenza

Answer

Measles

Answer

Rubella

Answer

BCG

Question 3

A 9 years old child presented to OPD with complaints of high grade fever, vomiting, one episode of seizure. CSF examination was done and Gram staining of the culture showed the following finding. What is the probable causative agent?

Accepted Answer

Gram-positive diplococci (e.g., Streptococcus pneumoniae)

Answer

Gram-negative coccobacilli (e.g., Haemophilus influenzae)

Answer

Gram-negative diplococci (e.g., Neisseria meningitidis)

Answer

Gram-positive cocci in chains (e.g., Streptococcus pyogenes)

Question 4

Flask shaped ulcers in colon are caused by:-

Accepted Answer

Entamoeba histolytica

Answer

Giardia lamblia

Answer

Enterobius vermicularis

Answer

H. Pylori

Question 5

A neonate was found to have cataract, deafness and cardiac defects. Which group of viruses was the mother infected with?

Accepted Answer

Togaviridae family (includes Rubella virus)

Answer

Flaviviridae family (includes Zika virus)

Answer

Bunyaviridae family (includes Rift Valley fever virus)

Answer

Arenaviridae family (includes Lassa fever virus)

Question 6

Flask-shaped ulcers in the intestine are caused by which of the following?

Accepted Answer

Entamoeba histolytica

Answer

TB

Answer

Giardia

Answer

Typhoid

Question 7

A person working in an abattoir presented with malignant pustule on hand. What is the causative agent?

Accepted Answer

Bacillus anthracis

Answer

Clostridium botulinum

Answer

Streptococcus pyogenes

Answer

Clostridium perfringens

Question 8

A 9-year-old child presented to OPD with complaints of high-grade fever, vomiting, and one episode of seizure. CSF examination was done and Gram staining of the culture showed lanceolate-shaped gram-positive diplococci. What is the probable causative agent?

Accepted Answer

Streptococcus pneumoniae

Answer

Haemophilus influenzae

Answer

Streptococcus agalactiae

Answer

Neisseria meningitidis

Question 9

Rubella is caused by

Accepted Answer

Togavirus

Answer

Paramyxovirus

Answer

Orthomyxovirus

Answer

Flavivirus

Question 10

A 35 year old man presented with dry cough and rusty colored sputum. He has a history of eating in a Chinese restaurant very often with consumption of crabs. What is the probable causative agent in this condition?

Accepted Answer

Paragonimus westermani

Answer

Pneumocystis jirovecii

Answer

Strongyloides stercoralis

Answer

Diphyllobothrium latum

NEET-PG 2019 — Microbiology