Infectious Diseases Practice Questions

Q: Which of the following statements regarding giardiasis is false?

Bloody diarrhea. Bloody diarrhea - **Giardiasis** is caused by the flagellate **_Giardia lamblia_**, which colonizes the small intestine and disrupts nutrient absorption, leading to **non-bloody diarrhea** [1]. - The parasite does not invade the intestinal wall, so **bloody stools are not a typical feature**; their presence suggests other infectious agents or conditions [1]. *Diarrhea with steatorrhea* - **_Giardia lamblia_ infection** impairs fat absorption in the small intestine, leading to the characteristic **fatty, foul-smelling stools known as steatorrhea**. - This malabsorption is due to damage to the brush border of enterocytes and disruption of bile salt metabolism. *Metronidazole is the drug of choice* - **Metronidazole** is indeed the **first-line treatment** for giardiasis, highly effective against the parasitic trophozoites. - Other effective alternatives include **tinidazole** and **nitazoxanide**, depending on regional resistance patterns and patient factors. *Absence of fever* - **Giardiasis** typically causes **gastrointestinal symptoms** such as diarrhea, abdominal cramps, and bloating, without systemic signs like fever [1]. - The absence of fever helps differentiate giardiasis from invasive infections that cause inflammatory responses.

Q: Maximum infection of CMV is seen after what duration post-transplantation?

1-4 months. ***1-4 months*** - The period of **1 to 4 months post-transplantation** is considered the peak risk period for **cytomegalovirus (CMV) infection** and disease due to a combination of intense immunosuppression and viral reactivation/transmission dynamics during this time [1]. - This window allows sufficient time for the transplanted organ to establish itself and for immunosuppressive regimens to reach their full effect, which then creates an environment highly susceptible to opportunistic viral infections like CMV [1]. *Immediate* - **Immediate post-transplant** (first few days) complications are usually related to surgery, organ function, or hyperacute rejection. - While viral exposure can occur, clinically significant CMV infection usually requires a longer incubation period. * 6 months* - After 6 months, while CMV infection can still occur (late-onset CMV disease), the **overall risk is generally lower** compared to the 1-4 month period. - This is because immunosuppression regimens are often tapered, and the recipient's immune system may have partially recovered or developed some anamnestic response by this time.

Q: What is the cause of perihepatic fibrosis in Fitz-Hugh-Curtis syndrome?

Pelvic Inflammatory Disease. ***Pelvic Inflammatory Disease*** - Fitz-Hugh-Curtis syndrome is a complication of **Pelvic Inflammatory Disease (PID)**, where infection spreads from the pelvic organs to the liver capsule [1]. - The inflammation leads to **perihepatic fibrosis** and adhesions, often described as "violin string" adhesions [1]. *Bile Duct Injury* - **Bile duct injury** can cause inflammation and fibrosis of the liver, but it typically affects the intrahepatic or extrahepatic bile ducts directly, rather than the liver capsule. - This condition is often associated with surgical procedures or gallstones, and not directly linked to PID. *Chronic Alcoholism* - **Chronic alcoholism** is a well-known cause of liver fibrosis and cirrhosis, but it specifically damages hepatocytes and leads to diffuse scarring of the liver parenchyma. - It does not primarily cause localized perihepatic fibrosis in the manner seen in Fitz-Hugh-Curtis syndrome. *Viral Hepatitis* - **Viral hepatitis** (e.g., Hepatitis B or C) causes diffuse inflammation and fibrosis throughout the liver, leading to cirrhosis over time. - It does not typically result in the characteristic localized perihepatic adhesions of Fitz-Hugh-Curtis syndrome, which is an ascendant infection.

Q: Which of the following is the least common mode of transmission of HIV?

Transfusion of blood products. ***Transfusion of blood products*** - In countries with robust screening, **blood product transfusions** have become an extremely rare source of HIV transmission due to meticulous testing of donated blood [2]. - While historically a significant route, advancements in blood screening and donor selection have nearly eliminated this risk, making it the **least common** mode in many regions [2]. *Homosexual contact* - **Unprotected anal intercourse** between men has been, and remains, a predominant mode of HIV transmission globally, particularly in developed countries [1]. - The risk is high due to the **fragility of rectal mucosa** and the potential for trauma during intercourse. *Heterosexual contact* - **Unprotected heterosexual intercourse** is the most common mode of HIV transmission globally, especially in sub-Saharan Africa [1]. - The risk is influenced by the presence of **other sexually transmitted infections** (STIs) and viral load of the infected partner. *Intravenous drug use* - **Sharing contaminated needles and syringes** among intravenous drug users is a highly efficient way to transmit HIV [1]. - This mode facilitates direct transfer of infected blood from one individual to another.

Q: Which of the following is not considered an opportunistic infection in AIDS?

Rubella. ***Rubella*** - Rubella, or **German measles**, is a relatively mild viral infection that typically affects children and is not considered an **opportunistic infection** in immunocompromised individuals like those with AIDS [1]. - While it can cause congenital rubella syndrome in infants whose mothers are infected during pregnancy, it does not disproportionately affect or cause severe disease in AIDS patients due to their compromised immunity [1]. *Candidiasis* - **Oropharyngeal** and **esophageal candidiasis** are common opportunistic infections in AIDS patients, often indicating significant immune suppression [2,3]. - The fungus *Candida albicans* can proliferate unchecked when the **CD4 count** is low [2]. *Kaposi's sarcoma* - This is a **cancer** caused by the **human herpesvirus 8 (HHV-8)**, which is a classic AIDS-defining illness [3]. - Its presence indicates severe immunodeficiency and was a hallmark of the early AIDS epidemic [3]. *Cytomegalovirus infection* - **Cytomegalovirus (CMV)** can cause severe and widespread disease in AIDS patients, including **retinitis**, **colitis**, and **encephalitis** [2]. - It becomes a significant risk when the **CD4 count** drops below 100 cells/mm³ [2].

Q: What is the therapy of choice for pseudomembranous enterocolitis?

Vancomycin. ***Vancomycin*** - **Oral vancomycin** is indicated for pseudomembranous enterocolitis, particularly for severe or recurrent cases, as it achieves high luminal concentrations in the colon to target *C. difficile* [1]. - Vancomycin works by inhibiting **bacterial cell wall synthesis**, effectively eradicating the toxigenic *C. difficile* strains responsible for the condition [1]. *Penicillin* - **Penicillin** is ineffective against *C. difficile* because *C. difficile* is a Gram-positive anaerobic bacterium producing toxins, and penicillin does not have the appropriate spectrum of activity. - In fact, many cases of pseudomembranous enterocolitis are triggered by prior **antibiotic use**, including penicillins, which disrupt the normal gut flora [2]. *Ampicillin* - Similar to penicillin, **ampicillin** is a broad-spectrum penicillin derivative and is not considered a treatment for *C. difficile* infection [3]. - Ampicillin can commonly be one of the **antibiotics that precipitates** the development of pseudomembranous enterocolitis by altering the normal gut microbiota [2]. *Erythromycin* - **Erythromycin**, a macrolide antibiotic, is not effective against *C. difficile* and is not used in the treatment of pseudomembranous enterocolitis. - Like other broad-spectrum antibiotics, erythromycin can **disrupt the normal gut flora**, potentially contributing to the overgrowth of *C. difficile* [2].

Q: In a patient where only Anti-HBsAg is positive in the serum, with all other viral markers being negative, this indicates

Immunized person with hepatitis B vaccine. ***Immunized person with hepatitis B vaccine*** - The presence of **Anti-HBsAg** (Hepatitis B surface antibody) as the *only* positive marker indicates immunity to hepatitis B [1]. - This immunity is most commonly acquired through **vaccination**, which introduces HBsAg to the immune system, leading to anti-HBsAg production without actual infection [1]. *Acute hepatitis infection* - Acute hepatitis B infection would typically show positive **HBsAg** (Hepatitis B surface antigen) and **Anti-HBc IgM** (hepatitis B core antibody, IgM class) [1]. - Anti-HBsAg is generally *not* present during acute infection, as it signals resolution or immunity rather than active disease [1]. *Chronic hepatitis infection* - A chronic hepatitis B infection would involve persistent **HBsAg** positivity for more than six months, often accompanied by **Anti-HBc IgG** and sometimes **HBeAg** [1]. - The isolated presence of Anti-HBsAg rules out chronic infection [1]. *Chronic carrier state* - A chronic carrier state is characterized by persistent presence of **HBsAg** in the blood, indicating ongoing viral replication or presence [1]. - The absence of HBsAg and the sole presence of anti-HBsAg would contradict a chronic carrier state [1].

Q: A patient who has developed fever and oral lesions after a trip to Bangkok is diagnosed as:

Enterovirus infection (HFMD). ***Enterovirus infection (HFMD)*** - **Hand, foot, and mouth disease (HFMD)**, commonly caused by **enteroviruses** such as Coxsackievirus A16 and enterovirus 71, presents with fever and characteristic oral lesions (enanthems) as well as skin eruptions on the hands and feet [1]. - The patient's recent travel to **Bangkok**, an endemic area for HFMD, further supports this diagnosis alongside the presentation of fever and oral lesions [2]. *Bacterial skin infection* - While bacteria can cause skin infections, they are less likely to manifest with typical **oral lesions** in conjunction with fever as the primary symptoms, unless it's a specific syndrome like Scarlet fever, which presents differently. - Bacterial infections often present with **pus**, **cellulitis**, or **abscess formation**, which are not indicated in the question's description [3]. *Viral skin infection* - Many viral infections can cause skin rashes, but the specific combination of **fever** and distinct **oral lesions** (enanthems) points more specifically towards enteroviral infections like HFMD, rather than a general viral skin infection [1]. - Other viral skin infections like **chickenpox** or **measles** have distinct patterns of rash and symptoms that differ from the described oral lesions [2]. *Autoimmune blistering disorder* - **Autoimmune blistering disorders** like pemphigus or bullous pemphigoid typically present with chronic **blister formation** and erosions, usually without acute onset fever or a recent travel history connection. - These conditions are not primarily infectious and do not typically resolve spontaneously within a short period like many viral infections.

Q: Duration of treatment in paucibacillary leprosy is?

6 months. ***6 months*** [1] - The World Health Organization (WHO) recommends a **6-month multidrug therapy (MDT)** regimen for paucibacillary (PB) leprosy [1]. - This regimen typically includes **rifampicin** and **dapsone** [1]. *9 months* - This duration is **not the standard WHO recommendation** for paucibacillary leprosy. - Longer durations (e.g., 12 months) are typically reserved for multibacillary leprosy [1]. *2 years* - A 2-year treatment duration is **excessive** for paucibacillary leprosy. - This longer period is usually associated with **multibacillary leprosy** [1] or specific relapse cases. *Till symptoms subside* - Treatment for leprosy is based on a **fixed-duration regimen**, not on symptom resolution [1]. - Stopping treatment once symptoms subside can lead to **relapse** and drug resistance.

Question 1

Which of the following statements regarding giardiasis is false?

Accepted Answer

Bloody diarrhea

Answer

Metronidazole is the drug of choice

Answer

Absence of fever

Answer

Diarrhea with steatorrhea

Question 2

Maximum infection of CMV is seen after what duration post-transplantation?

Accepted Answer

1-4 months

Answer

Immediate

Answer

< 1 month

Answer

> 6 months

Question 3

Which of the following statements regarding the management of a nurse who got an accidental prick from an HIV-infected needle is true? Select the correct option.

Accepted Answer

Follow-up HIV testing is performed only at 6 months post-exposure.

Answer

Post-exposure prophylaxis should be started within 72 hours of exposure.

Answer

Viral markers are checked at the time of the prick.

Answer

Lamivudine is used as monotherapy in post-exposure prophylaxis.

Question 4

What is the cause of perihepatic fibrosis in Fitz-Hugh-Curtis syndrome?

Accepted Answer

Pelvic Inflammatory Disease

Answer

Bile Duct Injury

Answer

Chronic Alcoholism

Answer

Viral Hepatitis

Question 5

Which of the following is the least common mode of transmission of HIV?

Accepted Answer

Transfusion of blood products

Answer

Homosexual contact

Answer

Heterosexual contact

Answer

Intravenous drug use

Question 6

Which of the following is not considered an opportunistic infection in AIDS?

Accepted Answer

Rubella

Answer

Candidiasis

Answer

Kaposi's sarcoma

Answer

Cytomegalovirus infection

Question 7

What is the therapy of choice for pseudomembranous enterocolitis?

Accepted Answer

Vancomycin

Answer

Penicillin

Answer

Ampicillin

Answer

Erythromycin

Question 8

In a patient where only Anti-HBsAg is positive in the serum, with all other viral markers being negative, this indicates

Accepted Answer

Immunized person with hepatitis B vaccine

Answer

Acute hepatitis infection

Answer

Chronic hepatitis infection

Answer

Chronic carrier state

Question 9

A patient who has developed fever and oral lesions after a trip to Bangkok is diagnosed as:

Accepted Answer

Enterovirus infection (HFMD)

Answer

Bacterial skin infection

Answer

Viral skin infection

Answer

Autoimmune blistering disorder

Question 10

Duration of treatment in paucibacillary leprosy is?

Accepted Answer

6 months

Answer

9 months

Answer

2 years

Answer

Till symptoms subside

Infectious Diseases — MCQs

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