NEET-PG 2017 - Microbiology Practice Questions

Q: All are correct about the organism causing the following lesion except:

Reynold Braude phenomenon. ***Reynold Braude phenomenon*** - The **Reynolds-Braude phenomenon** is associated with **Staphylococcus aureus** and refers to the increased invasiveness of *S. aureus* in the presence of certain other bacteria. - This phenomenon is **not characteristic of *Candida albicans***, the organism responsible for the oral candidiasis (thrush) shown in the image. - **This is the correct answer** to this "except" question. *Gram positive yeast cells* - *Candida albicans* is a **Gram-positive yeast** that appears purple/blue on Gram staining. - It typically shows **budding yeast cells** and **pseudohyphae** on microscopy. - This statement is TRUE for *Candida albicans*. *Chlamydospores obtained on cornmeal agar* - **Chlamydospores** are thick-walled, large, round terminal spores that are characteristic of *Candida albicans*. - They are best demonstrated on **cornmeal agar with Tween 80** (or rice agar), which is the standard medium for their production. - The presence of chlamydospores is a key identifying feature that helps differentiate *C. albicans* from other *Candida* species. - This statement is TRUE for *Candida albicans*. *Creamy patches that on removal lead to red oozing patches* - The image shows **creamy white patches** on an inflamed oral mucosa, characteristic of **pseudomembranous candidiasis** (oral thrush). - These patches can be **scraped off**, revealing an **erythematous, bleeding** (red oozing) underlying surface. - This is a classic clinical presentation of oral candidiasis. - This statement is TRUE for *Candida albicans*.

Q: Which of the following is correct about the vegetative fungal spores?

A = Blastospores, B= Arthrospores, C= Chlamydospores. **A = Blastospores, B= Arthrospores, C= Chlamydospores** - Image A depicts **blastospores**, which are asexually produced spores formed by **budding** from a parent cell, giving them a distinct tear-drop or oval shape. - Image B illustrates **arthrospores**, which are formed by the **fragmentation** of a hyphal cell into barrel-shaped segments. - Image C shows **chlamydospores**, characterized by their **thick-walled**, resistant, and usually spherical or oval structure within a hypha. *A = Arthrospores, B= Blastospores, C= Chlamydospores* - This option incorrectly identifies image A as arthrospores, which are typically barrel-shaped and result from hyphal fragmentation, not the budding pattern seen in image A. - Image B is incorrectly labeled as blastospores, but the fragmentation pattern is characteristic of arthrospores. *A = Blastospores, B= Chlamydospores, C= Arthrospores* - While image A is correctly identified as blastospores, this option misidentifies image B as chlamydospores. - Image C does not show arthrospores; the thick-walled structure is characteristic of chlamydospores, not the barrel-shaped arthrospores. *A = Chlamydospores, B= Arthrospores, C= Blastospores* - This option incorrectly identifies image A as chlamydospores, which are thick-walled resistant structures, not the budding spores visible in the image. - It also incorrectly labels image C as blastospores; the thick-walled appearance is typical of chlamydospores, not budded blastospores.

Q: The image shows:

Robertson cooked meat broth. ***Robertson cooked meat broth*** - The image displays a glass jar containing a **meat-based medium** at the bottom, covered with a liquid, which is characteristic of Robertson cooked meat broth. - This medium is primarily used for the **cultivation of anaerobic bacteria**, as the meat particles create an anaerobic environment and provide nutrients. *Alkaline peptone water* - Alkaline peptone water is a **liquid enrichment medium** that appears as a clear, yellowish broth without any particulate matter like cooked meat. - It is specifically used for the enrichment of *Vibrio cholerae* due to its high pH. *Lowenstein Jensen media* - Lowenstein Jensen media is a **solid egg-based medium** that is typically green in color and typically slants in test tubes or petri dishes. - It is used for the isolation and culture of **mycobacteria**, and its appearance is distinctly different from the image. *Cary Blair medium* - Cary Blair medium is a **semisolid transport medium** used for the preservation of enteric bacteria in stool samples. - It appears as a clear or slightly opalescent gel in a tube and does not contain visible chunks of meat.

Q: Which of the following is correct about the media shown below?

Liquid paraffin layering over the broth prevents air entry. ***Liquid paraffin layering over the broth prevents air entry*** - The image depicts **Cooked Meat Medium (CMM)**, which is used primarily for cultivating **anaerobic bacteria**, particularly Clostridia species. - **Liquid paraffin layering** on top of the broth is a key feature of CMM that **creates anaerobic conditions** by preventing oxygen diffusion into the medium. - This technique, combined with the reducing substances from meat particles, ensures a truly anaerobic environment suitable for obligate anaerobes. *Saccharolytic bacteria turn meat black* - **Saccharolytic bacteria** primarily ferment carbohydrates and produce acid/gas, but do not typically cause blackening of meat. - Blackening in CMM is associated with **hydrogen sulfide (H2S) production** by proteolytic bacteria, not saccharolytic activity. *Proteolytic bacteria turn meat red* - This is incorrect. **Proteolytic bacteria** break down proteins and typically turn the meat particles **black** due to H2S production. - The digestion of meat proteins by proteolytic Clostridia results in darkening (blackening), not reddening of the medium. *Favor growth of microaerophilic bacteria* - CMM is designed for **anaerobic bacteria**, not microaerophiles. - **Microaerophilic bacteria** require low oxygen tension (5-10% O2) and are cultivated in specialized conditions like candle jars or microaerophilic atmosphere generators, not in CMM. - CMM provides an anaerobic environment through liquid paraffin seal and reducing agents from meat.

Q: The following diagram depicts blood smear of which species?

Plasmodium falciparum. ***Plasmodium falciparum*** - The image displays characteristic **crescent-shaped or banana-shaped gametocytes** (stages 16-20), which are **pathognomonic for *Plasmodium falciparum*** - The earlier stages (1-5) represent ring forms (multiple rings per RBC, delicate ring forms) - Subsequent stages (6-15) show maturation culminating in the distinct **crescentic gametocytes** - This morphology is the **key distinguishing feature** of P. falciparum *Plasmodium vivax* - Produces **oval-shaped gametocytes**, not crescent-shaped - Characterized by enlarged RBCs with **Schüffner's dots** - Shows amoeboid trophozoites, not seen in this smear *Plasmodium malariae* - Produces **oval to round gametocytes** - Characteristic **band forms** and **rosette-shaped schizonts** (8-12 merozoites) - Not crescent-shaped as shown in the image *Plasmodium ovale* - Produces **oval gametocytes** similar to P. vivax - RBCs show **fimbriated edges** and Schüffner's dots - Does not produce crescent-shaped gametocytes

Question 1

All are correct about the organism causing the following lesion except:

Accepted Answer

Reynold Braude phenomenon

Answer

Gram positive yeast cells

Answer

Chlamydospores obtained on cornmeal agar

Answer

Creamy patches that on removal lead to red oozing patches

Question 2

Which of the following is correct about the vegetative fungal spores?

Accepted Answer

A = Blastospores, B= Arthrospores, C= Chlamydospores

Answer

A = Arthrospores, B= Blastospores, C= Chlamydospores

Answer

A = Blastospores, B= Chlamydospores, C= Arthrospores

Answer

A = Chlamydospores, B= Arthrospores, C= Blastospores

Question 3

The image shows:

Accepted Answer

Robertson cooked meat broth

Answer

Alkaline peptone water

Answer

Lowenstein Jensen media

Answer

Cary Blair medium

Question 4

Which of the following is correct about the media shown below?

Accepted Answer

Liquid paraffin layering over the broth prevents air entry

Answer

Saccharolytic bacteria turn meat black

Answer

Proteolytic bacteria turn meat red

Answer

Favor growth of microaerophilic bacteria

Question 5

The following diagram depicts blood smear of which species?

Accepted Answer

Plasmodium falciparum

Answer

Plasmodium malariae

Answer

Plasmodium ovale

Answer

Plasmodium vivax

NEET-PG 2017 — Microbiology