Infectious Diseases Practice Questions

Q: Exanthems are caused by all except which of the following?

Malaria. ***Malaria*** - **Malaria** is a parasitic disease that affects red blood cells and typically causes symptoms like **fever, chills, and headache**, but does not present with a characteristic skin rash or exanthem [3]. - While skin manifestations like **petechiae or jaundice** can occur in severe cases, a widespread rash defining an exanthem is not typical [3]. *Typhoid* - **Typhoid fever**, caused by *Salmonella Typhi*, can present with a characteristic exanthem known as **"rose spots"** on the trunk and abdomen [3]. - These are small, erythematous macules that blanch on pressure and are an important diagnostic clue. *Measles* - **Measles**, caused by the measles virus, is well-known for its characteristic **maculopapular rash** (exanthem) that typically starts on the face and spreads downwards [1]. - This rash is often preceded by **Koplik spots** in the mouth [1]. *Rubella* - **Rubella** (German measles), caused by the rubella virus, also presents with a classic exanthem, which is a **fine, pinkish-red maculopapular rash** that begins on the face and neck and spreads to the trunk and extremities [2]. - The rash is typically milder and resolves more quickly than measles.

Q: Procalcitonin is considered a marker for:

Sepsis. **Sepsis** - **Procalcitonin** (PCT) levels significantly rise in response to bacterial infections and **sepsis**, making it a useful diagnostic and prognostic marker. - Its levels correlate with the severity of bacterial infection and can help differentiate bacterial from viral etiologies. *Medullary thyroid carcinoma* - **Medullary thyroid carcinoma** (MTC) is characterized by the production of **calcitonin**, a different hormone from procalcitonin, by the parafollicular C cells of the thyroid. - While calcitonin is a tumor marker for MTC, **procalcitonin** is not. *Vitamin D resistant rickets* - **Vitamin D resistant rickets** (also known as X-linked hypophosphatemia) is a genetic disorder characterized by impaired phosphate reabsorption in the kidneys [1]. - It is associated with low phosphate levels and bone deformities, but not with elevated procalcitonin [1]. *Parathyroid adenoma* - A **parathyroid adenoma** leads to primary hyperparathyroidism, characterized by excessive production of **parathyroid hormone (PTH)** [1]. - This results in hypercalcemia and hypophosphatemia, with no direct link to procalcitonin levels [1].

Q: Commonest cause for acute sinusitis is:

Acute rhinitis. **Acute rhinitis** - **Acute rhinitis**, commonly known as the common cold, is the most frequent precursor to acute sinusitis due to inflammation and obstruction of the ostia. - The **inflammation** and **edema** of the nasal passages in rhinitis can block the sinus drainage pathways, leading to fluid accumulation and secondary bacterial infection within the sinuses. *Swimming/Diving* - While **swimming** and **diving** can introduce water and pathogens into the sinuses, leading to sinusitis, they are not the most common cause overall. - **Pressure changes** and chemical irritants like chlorine can also contribute, but usually as an exacerbating factor rather than the primary etiology. *Nasal tumours* - **Nasal tumors** can cause chronic sinusitis by physically obstructing sinus drainage, but they are relatively rare and not the most common cause of acute sinusitis. - Symptoms typically develop **gradually** and may include unilateral nasal obstruction, epistaxis, or facial pain, which are distinct from acute inflammatory onset. *Deviated nasal septum* - A **deviated nasal septum** can predispose individuals to sinusitis by impairing mucociliary clearance and ventilation of the sinuses, but it is a predisposing factor rather than the direct cause of acute sinusitis itself. - Often contributes to **recurrent** or **chronic sinusitis** by creating anatomical blockages, but an acute infectious trigger is usually necessary for an acute episode.

Q: What should you do next for a 35-year-old man who is positive for HBsAg and HBeAg, discovered incidentally during blood donation screening, with normal SGOT and SGPT laboratory values?

HBV-DNA estimation. ***HBV-DNA estimation*** - The presence of **HBsAg** and **HBeAg** indicates **active viral replication**, necessitating quantification of HBV-DNA to assess viral load [1]. - Normal SGOT and SGPT suggest compensated liver function, but **viral load** is crucial for staging the disease and guiding future management [1]. *Observation* - While liver enzymes are normal, the presence of **HBsAg** and **HBeAg** indicates active hepatitis B infection, which warrants further investigation, not just observation [1]. - Undiagnosed and untreated chronic hepatitis B can lead to serious complications such as **cirrhosis** and **hepatocellular carcinoma** [1]. *Liver biopsy* - **Liver biopsy** is an invasive procedure typically reserved for cases where histological assessment is required to confirm **fibrosis** or **inflammation severity**, or when there's discordance between viral markers and clinical presentation. - It's not the initial step for a patient with normal transaminases and clear serological markers of active infection; **HBV-DNA estimation** is generally performed first [1]. *Interferon therapy* - **Interferon therapy** is a treatment for chronic hepatitis B, but initiating treatment requires a comprehensive assessment including **HBV-DNA levels**, in addition to liver enzyme levels and evaluation of liver damage [2]. - It would be premature to consider treatment without a **viral load** measurement and a full workup to determine the phase of infection and the need for therapy [2].

Q: A 65-year-old male presents with fever, chills, and a productive cough with rust-colored sputum. What is the most likely diagnosis?

Pneumococcal Pneumonia. Pneumococcal Pneumonia - This presentation with fever, chills, and rust-colored sputum is classic for pneumococcal pneumonia, caused by Streptococcus pneumoniae [1]. [2] - The rust color results from the presence of hemolyzed red blood cells from the inflamed alveoli [3]. TB - While TB can cause fever and cough, the sputum is typically mucoid or purulent, and sometimes hemoptysis (frank blood) is seen, but not usually rust-colored [4]. - TB symptoms tend to be more chronic, including night sweats and weight loss, which are not mentioned here. Klebsiella pneumonia - Klebsiella pneumoniae typically causes severe pneumonia, often in individuals with alcoholism or diabetes [1]. - It classically presents with currant jelly sputum, which is distinct from rust-colored sputum [2]. Pneumocystis pneumonia - Pneumocystis jirovecii pneumonia (PCP) primarily affects immunocompromised individuals, particularly those with HIV [4]. - Symptoms are usually more insidious, involving dyspnea, non-productive cough, and hypoxia, and sputum is not typically rust-colored [4].

Q: What is a condition directly associated with HIV/AIDS?

Enteropathy. ***Enteropathy*** - **HIV enteropathy** is a condition characterized by chronic diarrhea, malabsorption, and weight loss, frequently seen in HIV/AIDS patients [1]. - It results from the direct effects of HIV on the **gastrointestinal tract**, leading to mucosal damage and immune dysfunction [1]. *Hypertrophic cardiomyopathy* - While cardiac complications can occur in HIV/AIDS, **hypertrophic cardiomyopathy** is not a direct or defining association. - HIV-associated cardiac disease typically manifests as **dilated cardiomyopathy** or myocarditis, rather than hypertrophy. *Bronchial asthma* - **Bronchial asthma** is a chronic inflammatory airway disease that is not directly increased or caused by HIV infection. - Its prevalence in HIV-positive individuals is similar to the general population, without a causal link. *Peptic ulcer disease* - **Peptic ulcer disease** is primarily caused by *Helicobacter pylori* infection or NSAID use and is not a direct consequence of HIV/AIDS [1]. - Although immunosuppression might alter its presentation, HIV does not directly lead to ulcer formation.

Q: In which of the following conditions is glucocorticoid used?

Severe typhoid. ***Severe typhoid*** * **Glucocorticoids** (e.g., **dexamethasone**) are indicated in **severe typhoid fever** with altered mental status, delirium, stupor, coma, or shock, as they can reduce inflammation and improve neurological outcomes. * Their use in severe typhoid can decrease mortality by attenuating the systemic inflammatory response induced by *Salmonella Typhi*. *E. coli septicemia* * The use of **glucocorticoids** in **bacterial sepsis**, including *E. coli* septicemia, is generally controversial and not recommended unless there is confirmed or suspected **adrenal insufficiency**. * Routine use can increase the risk of secondary infections and other adverse effects without clear mortality benefit in immunocompetent patients. *Cerebral malaria* * **Glucocorticoids** are **contraindicated** in **cerebral malaria** because studies have shown they increase the risk of complications (e.g., gastrointestinal bleeding, seizures, hyperglycemia, infections) without improving neurological outcomes or survival. * Their use can worsen immune suppression in a disease already characterized by significant immune dysregulation. *Leishmaniasis* * **Glucocorticoids** are **not a primary treatment** for **leishmaniasis**, which is caused by a protozoan parasite and requires specific antileishmanial drugs. * While they might be used to manage severe inflammatory reactions in specific forms (e.g., post-kala-azar dermal leishmaniasis), they are not a standard therapeutic intervention and can even exacerbate the infection by suppressing the immune response.

Q: Fever and haemorrhagic rash are seen in all except which of the following?

Sand fly fever. ***Sand fly fever*** - **Sand fly fever**, also known as phlebotomus fever, is typically characterized by an acute onset of fever, headache, myalgia, and malaise. - While it can cause a rash, it is generally **non-hemorrhagic** and petechiae or purpura are uncommon. *Dengue fever* - **Dengue fever** is well-known for causing **hemorrhagic manifestations**, ranging from petechiae and purpura to severe bleeding [1]. - The classic presentation includes high fever, severe headache, retro-orbital pain, and a generalized rash which can become hemorrhagic [1]. *Lassa fever* - **Lassa fever** is a severe viral hemorrhagic fever caused by the Lassa virus [2]. - It often progresses to include a **hemorrhagic rash** along with organ damage and generalized bleeding tendencies [2]. *Rift Valley fever* - **Rift Valley fever** is another viral hemorrhagic fever that can cause a spectrum of symptoms including fever and, in severe cases, **hemorrhagic manifestations** such as petechiae, ecchymoses, and epistaxis. - Ocular and neurological complications are also characteristic of severe disease.

Q: Which of the following is a chronic complication of malaria?

Splenomegaly. Splenomegaly - Chronic malaria, especially Plasmodium falciparum infections, leads to persistent erythrocytic sequestration in the spleen. - This prolonged immune response and destruction of infected red blood cells contribute to significant and often palpable enlargement of the spleen [1]. Nephrotic syndrome - While malaria can cause kidney complications, nephrotic syndrome is more commonly associated with specific types of malaria, particularly Plasmodium malariae, and is often considered a direct acute or subacute complication rather than a widespread chronic sequela of all malaria types. - The primary chronic complication that affects a broader range of malaria cases is splenomegaly. Pneumonia - Pneumonia is an acute respiratory infection that can occur as a co-infection or complication in severely ill malaria patients. - It is not considered a chronic complication of malaria itself, but rather an acute opportunistic infection or secondary issue. Hodgkin's disease - There is no direct, established link between chronic malaria infection and the development of Hodgkin's disease [2]. - While other infections (e.g., EBV) are associated with certain lymphomas, malaria is not known to be a direct causative agent or chronic complication leading to Hodgkin's lymphoma [2].

Q: Fecal leucocytes are absent in all of the following, except:

Campylobacter infection. ***Campylobacter infection*** - This infection causes **inflammatory diarrhea**, leading to the presence of **fecal leucocytes** as a response to intestinal tissue invasion. - The inflammatory process results in disruption of the intestinal mucosa, attracting **neutrophils** and other inflammatory cells to the stool. *Giardiasis* - **Giardia lamblia** infection typically causes **non-inflammatory diarrhea** by interfering with nutrient absorption in the small intestine. - Due to the non-invasive nature of the pathogen, **fecal leucocytes** are generally **absent** in the stool. *Cryptosporidiosis* - **Cryptosporidium parvum** primarily causes **non-inflammatory watery diarrhea** by adhering to and damaging the microvilli of the intestinal epithelium. - While it can cause flattening of the villi, it does not typically lead to significant tissue invasion or the presence of **fecal leucocytes**. *Clostridium perfringens infection* - This bacterium causes **food poisoning** mainly through the production of **toxins** that affect the intestinal lining. - The diarrhea is typically **non-inflammatory**, and **fecal leucocytes** are usually **absent** because there is no significant host immune cell invasion.

Question 1

Exanthems are caused by all except which of the following?

Accepted Answer

Malaria

Answer

Typhoid

Answer

Rubella

Answer

Measles

Question 2

Procalcitonin is considered a marker for:

Accepted Answer

Sepsis

Answer

Medullary thyroid carcinoma

Answer

Parathyroid adenoma

Answer

Vitamin D resistant rickets

Question 3

Commonest cause for acute sinusitis is:

Accepted Answer

Acute rhinitis

Answer

Swimming/Diving

Answer

Nasal tumours

Answer

Deviated nasal septum

Question 4

What should you do next for a 35-year-old man who is positive for HBsAg and HBeAg, discovered incidentally during blood donation screening, with normal SGOT and SGPT laboratory values?

Accepted Answer

HBV-DNA estimation

Answer

Observation

Answer

Liver biopsy

Answer

Interferon therapy

Question 5

A 65-year-old male presents with fever, chills, and a productive cough with rust-colored sputum. What is the most likely diagnosis?

Accepted Answer

Pneumococcal Pneumonia

Answer

TB

Answer

Klebsiella pneumonia

Answer

Pneumocystis pneumonia

Question 6

What is a condition directly associated with HIV/AIDS?

Accepted Answer

Enteropathy

Answer

Hypertrophic cardiomyopathy

Answer

Bronchial asthma

Answer

Peptic ulcer disease

Question 7

In which of the following conditions is glucocorticoid used?

Accepted Answer

Severe typhoid

Answer

E. coli septicemia

Answer

Cerebral malaria

Answer

Leishmaniasis

Question 8

Fever and haemorrhagic rash are seen in all except which of the following?

Accepted Answer

Sand fly fever

Answer

Dengue fever

Answer

Rift Valley fever

Answer

Lassa fever

Question 9

Which of the following is a chronic complication of malaria?

Accepted Answer

Splenomegaly

Answer

Nephrotic syndrome

Answer

Pneumonia

Answer

Hodgkin's disease

Question 10

Fecal leucocytes are absent in all of the following, except:

Accepted Answer

Campylobacter infection

Answer

Cryptosporidiosis

Answer

Clostridium perfringes infection

Answer

Giardiasis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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