FMGE 2018 - Microbiology PYQs Practice Questions

Q: Hydrops fetalis in a fetus can be due to:

Parvovirus B19. ***Parvovirus B19*** - **Parvovirus B19** infection in a fetus can lead to severe **anemia** and **hydrops fetalis** because the virus targets **erythroid progenitor cells**, impairing red blood cell production. - The resulting severe anemia causes **high-output cardiac failure**, leading to widespread edema, ascites, pleural effusions, and pericardial effusions, which characterize hydrops fetalis. *Epstein-Barr virus* - While **Epstein-Barr virus (EBV)** can infect the fetus, it is more commonly associated with conditions like **lymphoproliferative disorders** or **hepatosplenomegaly**, not typically hydrops fetalis as a primary manifestation. - EBV infection in pregnancy is often asymptomatic or causes mild illness and is not a common cause of severe fetal anemia or hydrops. *Human papilloma virus* - **Human papilloma virus (HPV)** is known to cause **genital warts** and is associated with **cervical cancer**, but it does not cause hydrops fetalis. - Vertical transmission of HPV can occur, leading to conditions like **recurrent respiratory papillomatosis** in the infant, but it does not affect red blood cell production or fluid balance in the fetus in a way that would cause hydrops. *Influenza Virus* - **Influenza virus** infection during pregnancy can lead to complications such as **preterm delivery** or **low birth weight**, but it is not a direct cause of hydrops fetalis. - The influenza virus primarily affects the respiratory system and does not directly target fetal erythroid cells or cause the severe anemia necessary for hydrops. [Practice more Microbiology PYQs on OnCourse]

Q: Babesiosis is most commonly transmitted by:

Ticks. **_Ticks_** - Babesiosis is a **tick-borne illness** caused by *Babesia* parasites, primarily *Babesia microti* in North America. - The main vector is the **deer tick** (*Ixodes scapularis*), which also transmits **Lyme disease**. *Rats* - Rats are known reservoirs for various diseases (e.g., **hantavirus**, **leptospirosis**), but they are not the primary vectors for babesiosis. - While *Babesia microti* can infect rodents, **direct transmission** to humans from rats is not the most common route. *Sand fly* - Sand flies are vectors for diseases like **leishmaniasis** and **Bartonellosis**. - They are not associated with the transmission of *Babesia* parasites. *Pigs* - Pigs can be reservoirs for certain zoonotic diseases (e.g., **cysticercosis**, **trichinellosis**). - They do not typically serve as vectors for babesiosis transmission to humans. [Practice more Microbiology PYQs on OnCourse]

Q: Biological indicator for determining efficacy of autoclaving is

Bacillus stearothermophilus. ***Bacillus stearothermophilus*** - *Bacillus stearothermophilus* (now *Geobacillus stearothermophilus*) is a **thermoduric spore-forming bacterium** used as a biological indicator for **autoclave efficacy**. - Its spores are highly **resistant to heat**, making them ideal for challenging the sterilization process. *Pseudomonas aeruginosa* - *Pseudomonas aeruginosa* is a **Gram-negative bacterium** known for causing hospital-acquired infections, but it is **not used as a biological indicator** for autoclaving. - It is **less resistant to heat** and sterilization methods compared to bacterial spores. *Clostridium perfringens* - *Clostridium perfringens* is a **spore-forming anaerobic bacterium** associated with gas gangrene and food poisoning. - While it forms spores, its **heat resistance profile is different** from that of *Bacillus stearothermophilus*, and it is not the standard biological indicator for autoclaving. *Salmonella typhi* - *Salmonella typhi* is a **Gram-negative bacterium** that causes typhoid fever. - It is a **pathogen but not a spore-former**, and therefore, it is easily killed by autoclaving and not suitable as a biological indicator for monitoring sterilization effectiveness. [Practice more Microbiology PYQs on OnCourse]

Q: Classical complement is activated by:

Ag-Ab complex. ***Ag-Ab complex*** - The **classical complement pathway** is initiated by the binding of **C1q** to an antigen-antibody complex, specifically involving **IgM** or certain subclasses of **IgG**. - This binding triggers a cascade of events leading to the activation of the complement system, ultimately resulting in the **lysis of target cells**, **opsonization**, and **inflammation**. *C3 Convertase* - **C3 convertase** is an enzyme complex formed later in the complement cascade, responsible for cleaving C3 into C3a and C3b. - While essential for all complement pathways, it is a **downstream effector** and not the initial activator of the classical pathway. *C1* - **C1** is a complex protein that includes C1q, C1r, and C1s. While C1 plays a crucial role in the classical pathway, it is **activated by** the antigen-antibody complex, not an independent activator. - The activation sequence is: **Ag-Ab complex → C1q binding → C1 activation → cascade initiation**. Thus, the Ag-Ab complex is the primary trigger, and C1 is the responder. *IgA* - **IgA** primarily functions in mucosal immunity and is generally **not an activator** of the classical complement pathway. - Instead, IgA can activate the **alternative complement pathway** under specific circumstances, but not the classical pathway through direct binding to C1q. [Practice more Microbiology PYQs on OnCourse]

Q: In Plasmodium vivax malaria, relapse is caused by:

Hypnozoite. ***Hypnozoite*** - **Hypnozoites** are dormant forms of *Plasmodium vivax* and *P. ovale* that persist in the liver for months to years after initial infection. - These dormant hepatic stages can later reactivate, develop into merozoites, and cause a **relapse** of malaria symptoms even after successful treatment of the blood-stage infection. - Relapses are a defining feature of *P. vivax* malaria and require treatment with **primaquine** or **tafenoquine** for radical cure to eliminate hypnozoites. *Incorrect: Schizont* - **Schizonts** are stages where asexual reproduction occurs, either in liver cells (hepatic schizonts) or red blood cells (erythrocytic schizonts). - Erythrocytic schizonts cause acute malaria symptoms but do not cause delayed relapses as they are cleared by standard antimalarial treatments. - Hepatic schizonts complete their cycle within 1-2 weeks and do not remain dormant. *Incorrect: Sporozoite* - **Sporozoites** are the infective stage injected by the mosquito that travel to the liver to initiate infection. - They differentiate into either developing schizonts or dormant hypnozoites but do not directly cause relapses. - Sporozoites represent the initial infection, not the mechanism of relapse. *Incorrect: Gametocyte* - **Gametocytes** are the sexual stage found in human blood that are ingested by mosquitoes to continue the parasite lifecycle. - They are responsible for transmission to mosquitoes but do not cause human symptoms or relapses in the host. - Gametocytes do not remain dormant in the liver. [Practice more Microbiology PYQs on OnCourse]

Question 1

Hydrops fetalis in a fetus can be due to:

Accepted Answer

Parvovirus B19

Answer

Human papilloma virus

Answer

Influenza Virus

Answer

Epstein-Barr virus

Question 2

Babesiosis is most commonly transmitted by:

Accepted Answer

Ticks

Answer

Rats

Answer

Sand fly

Answer

Pigs

Question 3

Biological indicator for determining efficacy of autoclaving is

Accepted Answer

Bacillus stearothermophilus

Answer

Pseudomonas aeruginosa

Answer

Clostridium perfringens

Answer

Salmonella typhi

Question 4

Classical complement is activated by:

Accepted Answer

Ag-Ab complex

Answer

C3 Convertase

Answer

C1

Answer

IgA

Question 5

In Plasmodium vivax malaria, relapse is caused by:

Accepted Answer

Hypnozoite

Answer

Schizont

Answer

Sporozoite

Answer

Gametocyte

Question 6

Mark the false statement regarding testing of COVID-19.

Accepted Answer

First line screening assay: N gene assay.

Answer

Confirmatory assay: RdRp gene assay.

Answer

Peripheral ground glass opacities on CT is the hallmark feature.

Answer

Most predominant method of diagnosis of COVID-19 is PCR.

Question 7

Quellung reaction is seen with:

Accepted Answer

Pneumococcus

Answer

Gonococcus

Answer

Staphylococcus

Answer

Streptococcus

Question 8

Otomycosis is most commonly caused by:

Accepted Answer

Aspergillus fumigatus

Answer

Mucor

Answer

Actinomycetes

Answer

Candida albicans

Question 9

Most common cause of bacterial meningitis in post-neonatal period:

Accepted Answer

Streptococcus pneumoniae

Answer

Mycobacterium tuberculosis

Answer

Staphylococcus aureus

Answer

Klebsiella

Question 10

Which one of the following is a major component in activation of the complement alternative pathway?

Accepted Answer

C3

Answer

C2

Answer

C4

Answer

C1

FMGE 2018 — Microbiology