NEET-PG 2017 - Microbiology PYQs Practice Questions

Q: All are true about Helicobacter pylori on special stain preparation of stomach except:

S shaped non-flagellated bacteria. ***S shaped non-flagellated bacteria*** - *H. pylori* are generally **spiral-shaped** or **curved rods**, not typically S-shaped, and are characterized by their **polar flagella** which are essential for their motility in the viscous gastric mucus. - The presence of flagella is a key feature distinguishing *H. pylori* and enabling its survival in the stomach environment. *Steiner stain preparation* - The **Steiner silver stain** is commonly used to visualize *H. pylori* in gastric biopsies, demonstrating them as dark, helical organisms. - While effective, other stains like Giemsa or Warthin-Starry are also used, but Steiner stain is a valid method for detection. *Dormant stage is coccoid form* - Under stressful conditions, such as antibiotic exposure or prolonged culture, *H. pylori* can transform into a **coccoid form**. - This coccoid form is considered a **viable but non-culturable** dormant stage, potentially contributing to persistence and recurrence of infection. *Attaches but does not invade the cells* - *H. pylori* colonizes the **mucus layer** and attaches to the apical surface of gastric epithelial cells but generally **does not invade** the cells. - Its effects are mediated by toxins and enzymes released into the extracellular space, leading to inflammation and cellular damage without direct intracellular invasion. [Practice more Microbiology PYQs on OnCourse]

Q: A 19-year-old woman presents to the emergency department complaining of lesions on her vulva. They have been present for several months but are now beginning to interfere with intercourse. Which viral subtypes are responsible for most cases of this disease? (Recent Neet Pattern 2016-17)

Types 6 and 11. ***Types 6 and 11*** - Human Papillomavirus (HPV) **types 6 and 11** are responsible for approximately 90% of all cases of **genital warts (condyloma acuminata)**. - These types are considered low-risk HPV as they rarely lead to cancer but can cause significant discomfort and interfere with sexual activity due to their physical presence. *Types 6 and 18* - While **HPV type 6** is a common cause of genital warts, **HPV type 18** is a high-risk type primarily associated with **cervical cancer**, not typically with vulvar warts. - Combining a low-risk and a high-risk type in this manner does not accurately represent the primary cause of condyloma acuminata. *Types 11 and 16* - **HPV type 11** causes genital warts, but **HPV type 16** is a **high-risk HPV** type strongly associated with cervical and other anogenital cancers. - While both can cause lesions, type 16 is not a primary cause of benign genital warts; it's a major cause of malignancies. *Types 11 and 31* - **HPV type 11** is linked to genital warts, but **HPV type 31** is another **high-risk HPV** type associated with cervical cancer, not typically with benign vulvar warts. - Similar to the previous option, this combination incorrectly mixes a benign wart-causing type with a high-risk oncogenic type when addressing the cause of vulvar lesions. [Practice more Microbiology PYQs on OnCourse]

Q: Which is correct sequence of handwashing technique?

A → B → C. ***A → B → C*** - Follows the **WHO 6-step handwashing protocol** progression from **palm-to-palm with fingers interlaced** (step 3) to **backs of fingers against opposing palm** (step 4) to **rotational thumb rubbing** (step 5). - This sequence ensures **systematic cleaning** of all hand surfaces, moving from basic interdigital spaces to more complex finger positions before focusing on the thumb. *A → C → B* - Skips the **backs of fingers cleaning** (step 4) before proceeding to **thumb cleaning**, disrupting the systematic progression. - **Thumb cleaning** should come after thorough **interdigital cleaning** to ensure complete coverage of all finger surfaces. *B → A → C* - Begins with **backs of fingers to opposing palm**, which requires **fingers interlocked**, before completing basic **palm-to-palm interlacing**. - This reverses the **WHO protocol** by attempting advanced finger positioning before establishing proper **interdigital contact**. *C → B → A* - Starts with **thumb cleaning** before addressing **interdigital spaces**, completely reversing the systematic approach. - **Thumb cleaning** should be performed after **thorough finger and palm cleaning** to prevent recontamination of cleaned areas. [Practice more Microbiology PYQs on OnCourse]

Q: All are true about bacteria shown in the smear of pus below, except:

Most strains are inhibited in presence of 5 % NaCl. The image shows **Gram-positive cocci** arranged in clusters, which is characteristic of *Staphylococcus aureus*. Many pus cells (neutrophils) are also seen, indicating an inflammatory response, consistent with a bacterial infection. ***Most strains are inhibited in presence of 5 % NaCl*** - *Staphylococcus aureus* is known to be **halophilic**, meaning it **grows well** in the presence of high salt concentrations (e.g., 7.5% NaCl), which distinguishes it from many other bacteria. - Therefore, the statement that it is 'inhibited in the presence of 5% NaCl' is **incorrect**. *Produce black colonies on potassium tellurite blood agar* - *Staphylococcus aureus* **reduces tellurite** to metallic tellurium, resulting in the production of **black colonies** on potassium tellurite blood agar. - This is a characteristic feature used in the identification of *Staphylococcus aureus*, particularly on media like Baird-Parker agar. *Liquefy gelatin* - *Staphylococcus aureus* produces the enzyme **gelatinase**, which **hydrolyzes gelatin**, causing it to liquefy. - This is a biochemical characteristic used to differentiate *Staphylococcus aureus* from certain other staphylococcal species. *Seen in Job syndrome* - **Job syndrome** (Hyper-IgE syndrome) is characterized by recurrent severe **Staphylococcal infections** of the skin and lungs. - Patients with Job syndrome have impaired neutrophil chemotaxis and elevated IgE levels, making them highly susceptible to *Staphylococcus aureus* infections. [Practice more Microbiology PYQs on OnCourse]

Q: Which of the following toxins will produce the condition shown below?

ETA and ETB. ***ETA and ETB*** - The image shows a child with widespread **blistering and epidermal exfoliation**, characteristic of **Staphylococcal Scalded Skin Syndrome (SSSS)**. - SSSS is caused by **exfoliative toxins A (ETA)** and **exfoliative toxins B (ETB)** produced by *Staphylococcus aureus*, which target **desmoglein-1** in the stratum granulosum, leading to intraepidermal cleavage and skin peeling. *Leukocidin* - **Leukocidin** is a cytotoxin produced by *Staphylococcus aureus* that targets and destroys **leukocytes**, particularly neutrophils and macrophages. - It does not directly cause the widespread epidermal blistering and exfoliation seen in the image. *TSST-1* - **Toxic Shock Syndrome Toxin-1 (TSST-1)** is a superantigen produced by *Staphylococcus aureus* that causes **Toxic Shock Syndrome**, characterized by fever, rash, hypotension, and multi-organ failure. - While it can manifest with a diffuse erythematous rash followed by desquamation, it does not typically cause the prominent blistering and extensive epidermal peeling seen in the image. *Serum opacity factor* - **Serum opacity factor** is an enzyme produced by some strains of **Group A Streptococcus** (not *Staphylococcus aureus*) that degrades serum lipoproteins. - It is associated with **rheumatic fever** and **acute glomerulonephritis** but plays no direct role in skin blistering or exfoliation. [Practice more Microbiology PYQs on OnCourse]

Question 1

All are true about Helicobacter pylori on special stain preparation of stomach except:

Accepted Answer

S shaped non-flagellated bacteria

Answer

Steiner stain preparation

Answer

Dormant stage is coccoid form

Answer

Attaches but does not invade the cells

Question 2

A 19-year-old woman presents to the emergency department complaining of lesions on her vulva. They have been present for several months but are now beginning to interfere with intercourse. Which viral subtypes are responsible for most cases of this disease? (Recent Neet Pattern 2016-17)

Accepted Answer

Types 6 and 11

Answer

Types 6 and 18

Answer

Types 11 and 16

Answer

Types 11 and 31

Question 3

Which is correct sequence of handwashing technique?

Accepted Answer

A → B → C

Answer

A → C → B

Answer

B → A → C

Answer

C → B → A

Question 4

All are true about bacteria shown in the smear of pus below, except:

Accepted Answer

Most strains are inhibited in presence of 5 % NaCl

Answer

Produce black colonies on potassium tellurite blood agar

Answer

Liquefy gelatin

Answer

Seen in Job syndrome

Question 5

Which of the following toxins will produce the condition shown below?

Accepted Answer

ETA and ETB

Answer

Leukocidin

Answer

TSST-1

Answer

Serum opacity factor

Question 6

All are true about the bacteria shown in the figure except:

Accepted Answer

Urease positive

Answer

Pyrazinamidase test positive

Answer

C. gravis has daisy head colony

Answer

Heat labile toxin has affinity for myocardium

Question 7

All of the following are caused by the organism shown except:

Accepted Answer

Myonecrosis

Answer

Meningitis

Answer

Pneumonia

Answer

Hemorrhagic diarrhea

Question 8

What is the drug of choice for organism producing the following colonies?

Accepted Answer

Ciprofloxacin

Answer

Erythromycin

Answer

Ceftriaxone

Answer

No treatment with approx. 100% mortality

Question 9

What is the following pattern seen with *Clostridium perfringens* called?

Accepted Answer

Nagler's reaction

Answer

Reverse CAMP test

Answer

Stormy clot reaction

Answer

CAMP test

Question 10

Which of the bacteria is shown in this culture plate of nutrient agar? (Recent NEET Pattern 2016-17)

Accepted Answer

Pseudomonas

Answer

Plesiomonas

Answer

Burkholderia

Answer

Pasteurella

NEET-PG 2017 — Microbiology