FMGE 2025 Practice Questions

Q: Which mosquito species is recognized as the principal secondary vector for Zika virus transmission globally?

Aedes albopictus. ***Aedes albopictus*** - This mosquito, commonly known as the **Asian tiger mosquito**, is recognized as the **principal secondary vector** for Zika virus transmission globally. - It is a competent vector capable of transmitting **Zika**, **Dengue**, and **Chikungunya** viruses across multiple continents including Asia, Europe, Africa, and the Americas. - While *Aedes aegypti* remains the primary vector, *Aedes albopictus* plays a significant role in Zika transmission, particularly in temperate regions where *Ae. aegypti* is less prevalent. - Its adaptability to diverse climates and ability to breed in natural and artificial water containers make it epidemiologically important. *Aedes polynesiensis* - This species is primarily known as a vector for **lymphatic filariasis** (*Wuchereria bancrofti*) in Pacific islands. - While it was involved in Zika virus transmission during the **French Polynesia outbreak (2013-2014)**, it is geographically restricted and not considered a principal vector for global Zika transmission. - Its role is limited to specific Pacific island populations. *Aedes australis* - This species is endemic to Australia and transmits **Ross River virus** and other Australian arboviruses. - It is **not** a recognized vector for Zika virus transmission. - Its geographical distribution and host preferences exclude it from the Zika transmission cycle. *Aedes mitchellae* - This species is not documented in major public health literature as a vector for Zika virus. - It belongs to a mosquito species complex with no established role in arboviral transmission to humans. - Epidemiologically insignificant for Zika virus transmission.

Q: A woman presents with sudden-onset high-grade fever, hypotension, diffuse rash, and a history of using a tampon for an extended period. What is the most likely diagnosis?

Toxic Shock Syndrome. Toxic Shock Syndrome - This diagnosis is defined by the sudden onset of **high fever**, **hypotension** (shock), and a **diffuse erythematous rash** (often described as sunburn-like), strongly supported by the history of prolonged **tampon use** (a common source for *Staphylococcus aureus* producing **TSST-1** superantigen). [1] - TSS is a life-threatening illness caused by toxins that induce massive cytokine release, leading rapidly to shock and potential multi-organ failure. [1] Septic shock - While TSS is a specific diagnosis within the broader category of **sepsis/septic shock**, the acute presentation with the classic **diffuse rash** and clear association with prolonged tampon use makes TSS the most accurate diagnosis. - Septic shock is a general condition of infection-induced circulatory failure but lacks the specific **sunburn-like rash** and classic toxin etiology that defines TSS. Pelvic Inflammatory Disease - PID typically presents with **lower abdominal pain**, **cervical motion tenderness**, and purulent vaginal discharge, rather than rapid-onset systemic shock and generalized diffuse rash. - Although PID is an ascending infection often causing fever, it rarely leads to the swift and profound **hypotension** and multi-organ dysfunction characteristic of TSS. Streptococcal pharyngitis - This infection primarily presents with **sore throat**, fever, and sometimes exudates on the tonsils; it is locally confined and generally does not cause sudden, severe **hypotension** or systemic collapse. - While *Streptococcus pyogenes* can also cause a toxic shock syndrome, simple pharyngitis lacks the multi-system involvement, hypotensive crisis, and definitive association with **tampon usage** seen in this presentation. [1]

Q: An AIDS-positive patient came with a history of fever, vomiting, and meningismus. Which of the following tests help in the rapid diagnosis of cryptococcal meningitis?

Urine lateral flow assay for cryptococcal antigen. ***Urine lateral flow assay for cryptococcal antigen*** - The **Cryptococcal Antigen (CrAg) lateral flow assay (LFA)**, performed on various body fluids (CSF, serum, or urine), allows for rapid diagnosis, often yielding results in 10 minutes. - Detection of CrAg is highly sensitive in patients with extensive disease, such as those with AIDS and high fungal burdens, facilitating quick initiation of life-saving antifungal therapy. *India ink preparation of CSF* - Although relatively quick, the **India ink preparation** has low sensitivity (50-75%) in HIV-associated cryptococcal meningitis, leading to potential false-negative results. - This test identifies the yeast by visualizing the characteristic **capsule** against a black background, but its utility has largely been replaced by the more sensitive CrAg assay. *Blood culture* - Blood cultures confirm **cryptococcemia** (disseminated infection), which is common in AIDS patients with meningitis, but require several days (3–7 or more) for growth and identification. - Due to the prolonged incubation time, blood culture is unsuitable for the **rapid diagnosis** required to manage acute meningeal symptoms promptly. *CSF culture* - CSF culture remains the **gold standard** for definitive diagnosis, confirmation of viability, and performance of antifungal susceptibility testing. - Similar to blood culture, CSF culture takes multiple days (typically 2–7 days) to provide results, thus delaying immediate treatment needed for **meningitis**.

Q: A diabetic patient presents with whitish plaques in the oral cavity. A KOH mount confirms the presence of budding yeast with pseudohyphae. Which of the following is the most appropriate culture medium for isolation of this organism?

Sabouraud Dextrose Agar (SDA). ***Sabouraud Dextrose Agar (SDA)*** - SDA is the standard mycological culture medium used for the isolation of fungi, such as the yeast **_Candida albicans_** described in the clinical scenario. - Its **low pH** and high **dextrose** concentration inhibit the growth of most bacteria, making it selective for fungi. *Chocolate agar* - This is an enriched medium containing lysed red blood cells, primarily used for cultivating fastidious bacteria like **_Haemophilus influenzae_** and **_Neisseria_** species. - It is not a selective medium for fungi and would allow the overgrowth of oral bacteria, complicating the isolation of yeast. *Thayer-Martin medium* - This is a selective agar containing antibiotics, specifically designed to isolate pathogenic **_Neisseria_** species (**_N. gonorrhoeae_** and **_N. meningitidis_**) from samples with mixed flora. - The antibiotics in this medium inhibit the growth of gram-positive bacteria, most gram-negative bacteria, and yeast, making it unsuitable for this purpose. *Loeffler's serum slope* - This is an enrichment medium used for the cultivation of **_Corynebacterium diphtheriae_**, the causative agent of diphtheria. - It promotes the development of characteristic **metachromatic granules** within the bacteria and is not used for fungal isolation.

Q: A 30-year-old man develops profuse vomiting and diarrhea within 3 hours of consuming pre-packaged salad and milk at a picnic. There is no fever. Which of the following is the most likely causative organism?

Staphylococcus aureus. ***Staphylococcus aureus***- This organism produces a **heat-stable enterotoxin** that, when ingested (preformed toxin), causes rapid symptoms within 1 to 6 hours, fitting the **3-hour onset** without requiring bacterial multiplication in the host.- Symptoms are primarily profound **nausea and vomiting**, accompanied by diarrhea, and characteristically **without fever**, as this is a food intoxication rather than an invasive infection.*Clostridium perfringens*- Symptoms usually manifest after a longer incubation period of **8 to 16 hours**, as the toxin is produced *in vivo* after the bacteria are ingested.- The illness is dominated by **watery diarrhea** and abdominal cramps; vomiting is typically mild or absent.*Salmonella enterica*- This organism causes an **invasive infection** (or requires prolonged multiplication) and thus has a longer incubation period, typically **6 hours to 3 days**.- Gastroenteritis caused by *Salmonella* almost always presents with associated systemic symptoms, most notably significant **fever**.*Bacillus cereus*- *B. cereus* causes two syndromes: the **diarrheal form** (slower onset) and the **emetic form** (rapid 1–6-hour onset), which is mostly associated with contaminated **fried rice**.- While the emetic form fits the timeline, *Staphylococcus aureus* is the most common cause of rapid, non-febrile illness affecting both the stomach (vomiting) and intestines (diarrhea) related to cold, packaged foods like salads or milk.

Q: Receptor used for the entry of HIV virus into the host cell is?

CCR5. ***CCR5*** - HIV initially binds to the **CD4** receptor on the surface of T-helper cells, which triggers a conformational change in the viral envelope protein gp120. - This change exposes a binding site for a coreceptor, which is typically the chemokine receptor **CCR5** (or **CXCR4**), facilitating the fusion of the viral envelope with the host cell membrane and allowing viral entry. *CCR7* - **CCR7** is a chemokine receptor primarily involved in the homing of lymphocytes and dendritic cells to secondary lymphoid organs like lymph nodes. - It is not utilized by HIV as a coreceptor for entry into host cells. *CD6* - **CD6** is a cell surface receptor found on T cells that functions as a costimulatory molecule in T-cell activation and adhesion. - It plays no role in the binding or entry process of the HIV virus. *CD8* - **CD8** is a coreceptor molecule that defines cytotoxic T lymphocytes, which are essential for killing virally infected cells. - HIV primarily infects **CD4+** cells, not CD8+ cells, and CD8 does not serve as a viral entry receptor.

Q: Which organism is most commonly responsible for gas gangrene?

Clostridium perfringens. ***Clostridium perfringens*** - This **anaerobic, Gram-positive** rod is the most common cause of gas gangrene (or **myonecrosis**) due to its rapid production of potent toxins, especially $\alpha$-toxin (a **lecithinase**). - It is found ubiquitously in soil and the GI tract and typically infects deep penetrating wounds, leading to rapid tissue destruction and gas formation (crepitus). *Clostridium difficile* - This organism primarily causes **antibiotic-associated diarrhea** and **pseudomembranous colitis** due to the production of Toxin A (enterotoxin) and Toxin B (cytotoxin). - It is rarely involved in tissue infections or gas gangrene. *Clostridium tetani* - This bacterium is the causative agent of **tetanus**, a neurological disorder characterized by muscle spasms and locked jaw. - Tetanus symptoms are due to the production of the neurotoxin **tetanospasmin**, which blocks inhibitory neurotransmitters. *Clostridium botulinum* - This organism produces the potent **botulinum toxin**, which causes **flaccid paralysis** (botulism) by preventing the release of acetylcholine at the neuromuscular junction. - It is associated with food poisoning or infant botulism, not typically gas gangrene.

Q: A woman was bitten by a rabid dog. The dog developed symptoms and died within a week. What is the best method for post-mortem diagnosis of rabies in the dog?

DFAT. ***DFAT (Direct Fluorescent Antibody Test)*** - The **Direct Fluorescent Antibody Test (DFAT)** is the **gold standard** for post-mortem diagnosis of rabies in animals - It detects rabies viral antigen in **brain tissue** with high sensitivity and specificity - Provides **rapid results** (within hours) and is the WHO-recommended method for definitive diagnosis - Used worldwide as the standard confirmatory test for rabies in suspected animals *Detection of Negri bodies* - **Negri bodies** are pathognomonic eosinophilic cytoplasmic inclusions found in neurons (especially hippocampal pyramidal cells) - Detection has **low sensitivity** (only 50-80% of cases) and requires expert interpretation - While specific when present, their absence does not rule out rabies - Not reliable as the primary diagnostic method *Seller's staining* - **Seller's staining** is a classical histological technique specifically used to visualize Negri bodies - It is an **outdated method** with the same limitations as general Negri body detection - Has been largely replaced by more sensitive and specific methods like DFAT - Lower sensitivity compared to immunofluorescence techniques *Brain biopsy* - While brain tissue is the ideal specimen for rabies diagnosis, **brain biopsy** is not performed post-mortem - Post-mortem examination involves direct collection of brain tissue, not biopsy - For antemortem human diagnosis, less invasive methods (skin biopsy from nape of neck, corneal impressions) are preferred over brain biopsy

Q: HPV infection is most commonly associated with which type of cancer?

Oropharyngeal cancer. ***Oropharyngeal cancer*** - HPV (particularly HPV-16 and HPV-18) is strongly associated with oropharyngeal cancers, especially those affecting the **base of tongue and tonsils** [2], [3] - HPV-positive oropharyngeal cancers represent a distinct epidemiological entity with **better prognosis** compared to tobacco/alcohol-related cases - Among the options listed, oropharyngeal cancer is the **only HPV-associated malignancy** [3] - Note: Cervical cancer is the **most common HPV-related cancer overall** (not listed in options) [1], [3] *Incorrect: Esophageal cancer* - Primarily associated with **tobacco, alcohol, Barrett's esophagus, and chronic GERD** - Not significantly associated with HPV infection *Incorrect: Lung cancer* - Main risk factors include **smoking, radon exposure, asbestos, and air pollution** - No established HPV association *Incorrect: Stomach cancer* - Associated with **H. pylori infection, dietary factors (nitrosamines), and chronic gastritis** - Not linked to HPV infection **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1007-1008. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 739-741. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 219-220.

Question 1

Which mosquito species is recognized as the principal secondary vector for Zika virus transmission globally?

Accepted Answer

Aedes albopictus

Answer

Aedes polynesiensis

Answer

Aedes australis

Answer

Aedes mitchellae

Question 2

A woman presents with sudden-onset high-grade fever, hypotension, diffuse rash, and a history of using a tampon for an extended period. What is the most likely diagnosis?

Accepted Answer

Toxic Shock Syndrome

Answer

Septic shock

Answer

Pelvic Inflammatory Disease

Answer

Streptococcal pharyngitis

Question 3

An AIDS-positive patient came with a history of fever, vomiting, and meningismus. Which of the following tests help in the rapid diagnosis of cryptococcal meningitis?

Accepted Answer

Urine lateral flow assay for cryptococcal antigen

Answer

CSF culture

Answer

India ink preparation of CSF

Answer

Blood culture

Question 4

A diabetic patient presents with whitish plaques in the oral cavity. A KOH mount confirms the presence of budding yeast with pseudohyphae. Which of the following is the most appropriate culture medium for isolation of this organism?

Accepted Answer

Sabouraud Dextrose Agar (SDA)

Answer

Chocolate agar

Answer

Thayer-Martin medium

Answer

Loeffler's serum slope

Question 5

A 30-year-old man develops profuse vomiting and diarrhea within 3 hours of consuming pre-packaged salad and milk at a picnic. There is no fever. Which of the following is the most likely causative organism?

Accepted Answer

Staphylococcus aureus

Answer

Bacillus cereus

Answer

Salmonella enterica

Answer

Clostridium perfringens

Question 6

Receptor used for the entry of HIV virus into the host cell is?

Accepted Answer

CCR5

Answer

CD8

Answer

CD6

Answer

CCR7

Question 7

Which organism is most commonly responsible for gas gangrene?

Accepted Answer

Clostridium perfringens

Answer

Clostridium difficile

Answer

Clostridium tetani

Answer

Clostridium botulinum

Question 8

A woman was bitten by a rabid dog. The dog developed symptoms and died within a week. What is the best method for post-mortem diagnosis of rabies in the dog?

Accepted Answer

DFAT

Answer

Detection of Negri bodies

Answer

Brain biopsy

Answer

Seller’s staining

Question 9

A 25-year-old presents with painful vesicular lesions on the lips. A Tzanck smear from the lesion base shows multinucleated giant cells. What is the most likely causative agent?

Accepted Answer

Herpes simplex virus

Answer

Coxsackievirus A16

Answer

Human papillomavirus

Answer

Varicella-zoster virus

Question 10

HPV infection is most commonly associated with which type of cancer?

Accepted Answer

Oropharyngeal cancer

Answer

Esophageal cancer

Answer

Lung cancer

Answer

Stomach cancer

FMGE 2025

Community Medicine

Internal Medicine

Microbiology

Pathology