Infectious Diseases Practice Questions

Q: What is the most common site for extrapulmonary tuberculosis?

Lymph nodes. ***Lymph nodes*** - **Lymphatic involvement** is the most frequent manifestation of extrapulmonary tuberculosis (EPTB), particularly in immunocompromised individuals [1]. - It often presents as **painless lymphadenopathy**, commonly in the cervical region, and can be diagnosed via biopsy and culture [1]. *GIT* - **Gastrointestinal tuberculosis** is relatively rare compared to lymphatic involvement, though it can affect any part of the alimentary canal. - Symptoms are often non-specific, including abdominal pain, weight loss, and changes in bowel habits, which makes diagnosis challenging. *Pleura* - **Pleural tuberculosis** is a common form of EPTB, but it is less frequent than lymph node involvement. - It typically presents as a **pleural effusion** and is often diagnosed by analyzing pleural fluid or biopsy for evidence of *Mycobacterium tuberculosis* [2]. *Brain* - **Central nervous system (CNS) tuberculosis**, including tuberculous meningitis or tuberculoma, is a severe but less common form of EPTB [2]. - It carries significant morbidity and mortality and often requires a high index of suspicion for diagnosis [2].

Q: A 25 year old female, presents to the clinic with dysuria, urinary frequency and urgency. After a laboratory workup a diagnosis of cystitis is made. Which is the first line drug for the treatment for this patient?

Nitrofurantoin. ***Nitrofurantoin*** - **Nitrofurantoin** is the most widely recommended first-line antibiotic for uncomplicated **cystitis** due to its excellent efficacy against common urinary pathogens, especially **E. coli**. - It achieves high concentrations in the urine and has a low rate of resistance, making it an excellent choice for this condition. - It is preferred over other antibiotics due to antimicrobial stewardship principles and minimal impact on gut flora. *Cephalexin* - While generally effective against some urinary pathogens, **cephalexin** is typically reserved as a second-line agent for uncomplicated cystitis, particularly if there are contraindications to or resistance to first-line agents. - Its broad-spectrum activity may contribute to increased resistance development if used routinely as first-line. *Norfloxacin* - **Norfloxacin** is a **fluoroquinolone** that, while effective for UTIs and sometimes used in regional practice, is generally not recommended as the preferred first-line for uncomplicated cystitis due to concerns about increasing antibiotic resistance and potential for serious side effects (e.g., tendinitis, QT prolongation, CNS effects). - Current antimicrobial stewardship guidelines recommend reserving fluoroquinolones for more complicated urinary tract infections or when other first-line options are not suitable. *Amoxicillin* - **Amoxicillin** is generally not recommended as a first-line agent for cystitis due to high rates of **bacterial resistance**, particularly among **E. coli** strains, which are the most common cause of UTIs. - Its efficacy against common urinary pathogens is often lower compared to other first-line options.

Q: Most common heart valve involved in IV drug users is

Tricuspid Valve. ***Tricuspid Valve*** - The **tricuspid valve** is most commonly affected because intravenous (IV) drug users inject directly into the venous system, and the first valve the bacteria encounter as they return to the heart is the tricuspid valve. - This often leads to **right-sided endocarditis**, a common complication in this population. *Mitral valve* - The **mitral valve** is part of the left side of the heart and is less frequently affected in IV drug users as bacteria would need to traverse the pulmonary circulation first. - Mitral valve endocarditis is more common in non-IV drug users or in patients with pre-existing valvular disease. *Pulmonary valve* - While the **pulmonary valve** is also on the right side of the heart, it is located after the tricuspid valve in the blood flow path, making it less likely to be the initial site of bacterial seeding. [1] - **Infective endocarditis** of the pulmonary valve is extremely rare compared to the tricuspid valve. [1] *Aortic valve* - The **aortic valve** is on the left side of the heart and is typically affected by endocarditis that originates from systemic infections or in patients with underlying valvular abnormalities. - It is much less common for the aortic valve to be the primary site of infection in IV drug users compared to the tricuspid valve, as bacteria would have to bypass the pulmonary circulation and mitral valve first.

Q: The most common etiology of native valve endocarditis is

Streptococcus viridans. ***Streptococcus viridans*** - This group of bacteria is the **most common cause** of native valve endocarditis, accounting for about half of cases [1]. - They typically cause **subacute bacterial endocarditis** in patients with pre-existing heart valve damage [1]. *Enterococcus faecalis* - While a significant cause of endocarditis, particularly in the elderly and those with genitourinary or gastrointestinal procedures, it is **less common** than *Streptococcus viridans* for native valve infections overall [1]. - *Enterococci* are associated with **nosocomial infections** and are often resistant to multiple antibiotics. *Gram negative bacilli* - Gram-negative bacilli, such as *Pseudomonas aeruginosa* or *Escherichia coli*, are **uncommon causes** of native valve endocarditis. - When they do cause endocarditis, it is often associated with immunocompromised states, intravenous drug abuse, or prosthetic valves, and carries a **poor prognosis**. *Staphylococcus aureus* - *Staphylococcus aureus* is a common cause of endocarditis, especially in **intravenous drug users** and those with **prosthetic valves**, or in cases of acute endocarditis [1]. - However, for overall native valve endocarditis, its incidence is **lower than** *Streptococcus viridans*.

Q: Break bone fever is ?

Dengue fever. ***Dengue fever*** - **Dengue fever** is commonly known as **break bone fever** due to the severe muscle and joint pain it causes [1]. - This intense body pain is one of the characteristic symptoms, making the name highly descriptive of the patient's experience [1]. *Kala azar* - **Kala azar**, or visceral leishmaniasis, is characterized by **prolonged fever**, significant **weight loss**, **splenomegaly**, and **anemia**. - It does not specifically cause the severe bone and joint pain associated with "break bone fever." *Japanese encephalitis* - **Japanese encephalitis** primarily causes **neurological symptoms** like fever, headache, altered mental status, seizures, and paralysis. - While fever is present, it does not typically manifest with the extreme musculoskeletal pain that would earn it the "break bone fever" moniker. *Malaria* - **Malaria** is characterized by cyclical fevers, chills, sweats, fatigue, and **anemia**. - Although it causes body aches, these are not typically as severe or specific to bone pain as in dengue, and it is not known as "break bone fever."

Q: Which of the following diseases is commonly referred to as 'breakbone fever'?

Dengue fever. ***Dengue fever*** - The colloquial term "**breakbone fever**" is commonly used to describe dengue due to the severe **myalgia** and **arthralgia** it causes, leading to a sensation of bones breaking [1]. - This **viral infection** is transmitted by mosquitoes and presents with high fever, headache, retro-orbital pain, and a rash, in addition to the characteristic muscle and joint pain [1]. *Typhoid fever* - This is a **bacterial infection** caused by *Salmonella Typhi*, characterized by a sustained fever, malaise, headache, and sometimes a rash (rose spots), but not the severe bone-breaking pain [2]. - It primarily affects the **gastrointestinal tract** and can lead to complications such as intestinal perforation [2]. *Malaria* - Malaria is a **parasitic disease** transmitted by mosquitoes, known for its cyclical fever patterns, chills, headache, and fatigue. - While it causes significant body aches and headaches, it is not typically referred to as "breakbone fever" because the pain is not as intensely localized to the joints and bones as in dengue. *Malignant fever* - "**Malignant fever**" is not a specific disease, but rather a descriptive term sometimes used for severe, high-grade fevers that are uncontrolled or associated with a grave prognosis. - It does not refer to a distinct condition with characteristic "breakbone" symptoms.

Q: One of your staff nurses sustained a deep needle stick injury from a needle used to inject an HIV positive individual. What is the treatment regime that should be started in her/him? Note that drug resistance was suspected in the HIV patient.

2 NIs + 1 protease inhibitor for 28 days. ***2 NIs + 1 protease inhibitor for 28 days*** - For **occupational post-exposure prophylaxis (PEP)** involving a significant exposure to HIV with suspected drug resistance in the source patient, a **three-drug regimen** is recommended [2]. - This typically includes **two nucleoside reverse transcriptase inhibitors (NRTIs)** and **one protease inhibitor (PI)**, administered for **28 days**. This combination provides potent antiviral activity and addresses potential resistance [2]. *2 NIs for 3 months* - A **two-drug regimen** of NRTIs alone is generally considered **insufficient** for PEP, especially when drug resistance in the source is suspected [2]. - While PEP is typically given for 28 days, a 3-month duration is longer than standard and not justified by a two-drug regimen [1]. *2 protease inhibitors + 2 NtIs for 3 months* - This regimen involves **too many drugs** (four) and an **excessively long duration** (3 months) for standard occupational PEP. - While it offers strong antiviral coverage, the increased risk of **side effects** and **patient non-adherence** outweighs the benefits unless specific, rare circumstances dictate such an aggressive approach [2]. *1 NI and 1 NtI for 28 days* - This regimen contains an **insufficient number of drugs** (only two, one NI and one NtI, which is essentially two NRTIs if 'NtI' refers to nucleotide analogue reverse transcriptase inhibitor) and may not be powerful enough to prevent HIV transmission, especially with suspected drug resistance [2]. - A **three-drug regimen** is the standard for high-risk exposures.

Q: All of the following statements about 'yaws' are true, except:

Late stages of yaws involve heart and nerves. ***Late stages of yaws involve heart and nerves*** - Unlike **syphilis**, which is caused by *Treponema pallidum subspecies pallidum*, late-stage yaws (caused by *Treponema pallidum subspecies pertenue*) primarily affects the **skin**, **bones**, and **cartilage**, leading to disfigurement, but generally spares the cardiovascular and nervous systems. - The absence of significant **cardiovascular** or **neurological involvement** is a key differentiating factor between yaws and tertiary syphilis. *Caused by Treponema pertenue* - This statement is true; **yaws** is indeed caused by the bacterium *Treponema pertenue*. - *Treponema pertenue* is a spiral-shaped bacterium closely related to the organism that causes syphilis, belonging to the **spirochete** family. *Transmitted non-venereally* - This statement is true; yaws is typically transmitted through **direct skin-to-skin contact** with an infected person's lesions, often among children in tropical and subtropical regions [1]. - Unlike syphilis, which is primarily a sexually transmitted infection, yaws is **non-venereal**, spreading through casual contact [1]. *Secondary yaws can involve bone* - This statement is true; **secondary yaws** can manifest with various lesions, including **periostitis** and **osteomyelitis**, affecting long bones and other skeletal structures [1]. - Bone involvement manifests as **painful bone swellings** and can lead to **saber shin deformity** or other bone deformities in later stages [1].

Q: All of the following are features of mumps, except:

Incubation period is less than 2 weeks. ***Incubation period is less than 2 weeks*** - Mumps typically has an **incubation period of 16-18 days**, with a range of 12-25 days. An incubation period of less than 2 weeks is uncharacteristic. - This statement is the "except" feature, as it incorrectly describes the typical timeframe for symptom onset after exposure. *Caused by paramyxovirus* - Mumps is indeed caused by the **mumps virus**, which is a single-stranded RNA virus belonging to the **Paramyxoviridae family**. - This is a correct characteristic of the causative agent of mumps. *Orchitis is a complication in adults* - **Orchitis**, the inflammation of one or both testicles, is a well-known and often painful complication of mumps, particularly in **postpubertal males**. - It can lead to testicular atrophy and, in some cases, infertility. *Aseptic meningitis is a complication in children* - **Aseptic meningitis** is a common neurological complication of mumps, occurring in approximately 10-20% of cases, especially in **young children** [1]. - It involves inflammation of the meninges and typically resolves without long-term sequelae.

Q: An elderly male admitted for pneumonia presents with diarrhea and gripping abdominal pain five days after discharge from the hospital. Which drug is likely to benefit him?

Metronidazole. **Metronidazole** - The symptoms of diarrhea and gripping abdominal pain five days post-discharge, especially after a hospital stay for pneumonia, strongly suggest **Clostridioides difficile infection (CDI)**, which is commonly associated with antibiotic use [1]. - **Metronidazole** is a first-line antibiotic used to treat mild to moderate CDI. *Levofloxacin* - **Levofloxacin** is a fluoroquinolone antibiotic and a common cause of **Clostridioides difficile infection** rather than a treatment for it [2]. - Using levofloxacin would likely worsen or perpetuate the underlying infection. *Imodium* - **Imodium (loperamide)** is an over-the-counter anti-diarrheal medication that works by slowing bowel movements. - It is generally **contraindicated** in infectious diarrhea, especially CDI, as it can delay the clearance of toxins and potentially lead to **toxic megacolon** [1]. *Diphenoxylate* - **Diphenoxylate** (often combined with atropine) is an opioid-receptor agonist used to slow intestinal motility and treat diarrhea. - Similar to loperamide, it can be harmful in cases of **infectious diarrhea** like CDI, as it may prolong exposure to toxins and worsen the condition.

Question 1

What is the most common site for extrapulmonary tuberculosis?

Accepted Answer

Lymph nodes

Answer

GIT

Answer

Pleura

Answer

Brain

Question 2

A 25 year old female, presents to the clinic with dysuria, urinary frequency and urgency. After a laboratory workup a diagnosis of cystitis is made. Which is the first line drug for the treatment for this patient?

Accepted Answer

Nitrofurantoin

Answer

Cephalexin

Answer

Norfloxacin

Answer

Amoxicillin

Question 3

Most common heart valve involved in IV drug users is

Accepted Answer

Tricuspid Valve

Answer

Mitral valve

Answer

Pulmonary valve

Answer

Aortic valve

Question 4

The most common etiology of native valve endocarditis is

Accepted Answer

Streptococcus viridans

Answer

Enterococcus faecalis

Answer

Gram negative bacilli

Answer

Staphylococcus aureus

Question 5

Break bone fever is ?

Accepted Answer

Dengue fever

Answer

Kala azar

Answer

Japanese encephalitis

Answer

Malaria

Question 6

Which of the following diseases is commonly referred to as 'breakbone fever'?

Accepted Answer

Dengue fever

Answer

Typhoid fever

Answer

Malaria

Answer

Malignant fever

Question 7

One of your staff nurses sustained a deep needle stick injury from a needle used to inject an HIV positive individual. What is the treatment regime that should be started in her/him? Note that drug resistance was suspected in the HIV patient.

Accepted Answer

2 NIs + 1 protease inhibitor for 28 days

Answer

2 NIs for 3 months

Answer

2 protease inhibitors + 2 NtIs for 3 months

Answer

1 NI and 1 NtI for 28 days

Question 8

All of the following statements about 'yaws' are true, except:

Accepted Answer

Late stages of yaws involve heart and nerves

Answer

Caused by Treponema pertenue

Answer

Transmitted non-venereally

Answer

Secondary yaws can involve bone

Question 9

All of the following are features of mumps, except:

Accepted Answer

Incubation period is less than 2 weeks

Answer

Caused by paramyxovirus

Answer

Orchitis is a complication in adults

Answer

Aseptic meningitis is a complication in children

Question 10

An elderly male admitted for pneumonia presents with diarrhea and gripping abdominal pain five days after discharge from the hospital. Which drug is likely to benefit him?

Accepted Answer

Metronidazole

Answer

Levofloxacin

Answer

Imodium

Answer

Diphenoxylate

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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