Infectious Diseases Practice Questions

Q: What is the appropriate management for a child who has been bitten by a cat?

All of the options are true. ***All of the options are true*** - Comprehensive management of a cat bite requires **multiple interventions** addressing infection prevention, rabies prophylaxis, and immediate wound care. - Cat bites have a high infection rate (30-50%) due to deep puncture wounds from sharp teeth that inoculate bacteria like *Pasteurella multocida*, *Streptococcus*, and *Staphylococcus* deep into tissues. *Administer prophylactic antibiotics to prevent infection* - **Prophylactic antibiotics** are recommended for cat bites due to the high risk of infection (particularly *Pasteurella multocida*). - First-line therapy is typically **amoxicillin-clavulanate** (Augmentin), which covers the most common pathogens. - Deep puncture wounds, bites to hands/feet, immunocompromised patients, and delayed presentation warrant antibiotic prophylaxis. *Rabies vaccination may be necessary* - **Rabies post-exposure prophylaxis (PEP)** is crucial if the cat is unvaccinated, a stray, or its vaccination status is unknown. - Rabies is nearly 100% fatal once symptoms appear, making prophylaxis essential in high-risk situations. - The decision depends on local rabies prevalence and assessment of the animal's behavior and health status. *Thoroughly clean the wound* - **Immediate and copious irrigation** with soap and water or saline is the most important initial step in management. - This reduces bacterial load significantly and decreases infection risk. - Most cat bite wounds should be left open (not sutured) due to high infection risk, unless on the face for cosmetic reasons.

Q: Which of the following statements about Koplik spots is true?

All of the options.. All of the options. - Koplik spots are pathognomonic of measles, meaning their presence is a definitive indicator of the disease [1]. - They typically appear as tiny, white spots on an erythematous base on the buccal mucosa, often opposite the molars [1]. Pathognomonic of measles. - While Koplik spots are a hallmark sign of measles, stating this is true alone doesn't encompass all true aspects for this question [1]. - Their presence, however, is a strong diagnostic indicator of rubeola. Present on buccal mucosa opposite the molars. - This is a correct description of their typical location, but not a complete answer to the question "Which of the following statements about Koplik spots is true?" if other options also hold true [1]. - These spots are found on the mucous membrane lining the inside of the cheeks [1]. Not always present. - Koplik spots are transient and may not be present throughout the entire course of measles, particularly if a patient is seen later in the disease [1]. - They also can be missed if not specifically looked for or if they are very few in number.

Q: Which of the following statements about rashes in children is incorrect?

Varicella - typically appears on day 1. ***Varicella - typically appears on day 1*** - This statement is incorrect because the typical rash of **varicella** (**chickenpox**) usually appears on **day 2 or 3** of the illness, following a prodrome of fever and malaise. - The rash begins as macules, quickly progressing to papules, vesicles, and then crusts, often in a **centrifugal distribution**. *Typhus - typically appears on day 5* - This statement is correct. The rash of **epidemic typhus** (caused by *Rickettsia prowazekii*) typically appears around **day 5 or 6** following the onset of fever. - It usually starts on the trunk and spreads peripherally, often sparing the face, palms, and soles. *Typhoid - typically appears on day 5* - This statement is correct. The classic "rose spots" rash of **typhoid fever** (caused by *Salmonella Typhi*) typically appears around **day 5 to 7** of the illness. - These are faint, salmon-colored, blanching maculopapular lesions, usually found on the trunk and chest. *Measles - typically appears on day 4* - This statement is correct. The characteristic **maculopapular rash of measles** (rubeola) typically appears around **day 3 or 4** after the onset of the prodromal symptoms (fever, cough, coryza, conjunctivitis). - The rash starts on the face and behind the ears, then spreads cephalocaudally over the body.

Q: Which of the following is the most characteristic feature of the rash distribution in chickenpox?

More concentrated on the trunk than limbs. ***More concentrated on the trunk than limbs*** - The rash of chickenpox (varicella) has a **pathognomonic centripetal distribution**, meaning it is most dense on the **trunk, face, and scalp**, with fewer lesions on the extremities. - This characteristic distribution pattern is the **most distinguishing feature** of chickenpox and helps differentiate it from other vesicular exanthems. - References: Nelson Textbook of Pediatrics, Ghai Essential Pediatrics *Superficial and not deep-seated* - While chickenpox lesions are indeed **superficial vesicles** affecting the epidermis, this characteristic is less specific. - Many other viral exanthems also produce superficial lesions, making this a less distinguishing feature. *Affects palms and soles* - **Incorrect.** Chickenpox lesions characteristically **spare the palms and soles**. - Involvement of palms and soles suggests hand, foot, and mouth disease, secondary syphilis, or other conditions. *Evolves rapidly with new spots appearing in waves over days* - While true that chickenpox lesions appear in **crops over 3-5 days** creating the "**dewdrops on a rose petal**" appearance with lesions in various stages, this describes the **temporal evolution** rather than the **spatial distribution pattern**. - The question specifically asks about the most characteristic feature, and centripetal distribution is more pathognomonic than the cropping pattern.

Q: In which of the following conditions can strawberry tongue be observed?

Both conditions mentioned above. ***Both conditions mentioned above*** - **Strawberry tongue** is a characteristic finding in both **streptococcal scarlet fever** and **Kawasaki disease** [2]. - In both conditions, the tongue initially appears white with prominent red papillae, resembling a white strawberry, and later becomes bright red, described as a red strawberry [2]. *Streptococcal scarlet fever* - **Strawberry tongue** is a classic symptom of **scarlet fever**, which is caused by Group A Streptococcus infection [2]. - Other symptoms often include a **diffuse red rash**, sore throat, and fever [2]. *Kawasaki disease* - **Strawberry tongue** is one of the mucocutaneous manifestations of **Kawasaki disease**, a multisystem vasculitis primarily affecting young children [1]. - Other key features include **fever lasting ≥5 days**, conjunctival injection, rash, cervical lymphadenopathy, and extremity changes [1]. *None of the options* - This option is incorrect because **strawberry tongue** is indeed observed in both scarlet fever and Kawasaki disease [1], [2]. - The presence of this specific tongue appearance is a well-documented clinical sign in these two distinct conditions.

Q: A 3-month-old baby presents with deafness, cataract, and patent ductus arteriosus. Which of the following is the most likely diagnosis?

Congenital rubella syndrome. ***Congenital rubella syndrome*** - The classic triad of **deafness**, **cataracts**, and **patent ductus arteriosus (PDA)** is highly characteristic of congenital rubella syndrome. - This syndrome results from **maternal rubella infection** during the first trimester of pregnancy. *Congenital herpes simplex virus infection* - Typically presents with **skin vesicles**, **keratoconjunctivitis**, and **encephalitis**. - **Deafness, cataracts, and PDA** are not common features of congenital HSV. *Congenital toxoplasmosis* - The classic triad involves **chorioretinitis**, **hydrocephalus**, and **intracranial calcifications**. - While it can cause microcephaly and seizures, **deafness, cataracts, and PDA** are not hallmark features. *Congenital cytomegalovirus infection* - Often causes **sensorineural hearing loss** and sometimes **chorioretinitis**, but the combination with **cataracts** and **PDA** is atypical. - Other common features include **periventricular calcifications**, **hepatosplenomegaly**, and **thrombocytopenia**.

Q: What is the most serious complication of measles?

Pneumonia. ***Pneumonia*** - **Pneumonia**, particularly **giant cell pneumonia**, is the most common cause of **measles-related deaths** in young children. - It results from the **direct viral infection** of the lungs or a **secondary bacterial superinfection**. *Croup* - **Croup (laryngotracheobronchitis)** can be a complication of measles, but it is typically **less severe** and **less life-threatening** than pneumonia. - It primarily affects the **upper airways**, causing a barking cough and stridor. *Meningo-encephalitis* - **Meningo-encephalitis** is a serious, albeit **less common**, complication of measles, occurring in approximately 1 in 1,000 cases. - While potentially fatal or leading to neurological sequelae, it is **outranked by pneumonia** in terms of overall mortality attributed to measles. *Otitis media* - **Otitis media** (middle ear infection) is a common complication of measles, but it is generally **not life-threatening**. - It usually responds well to **antibiotic treatment** and rarely leads to severe outcomes.

Q: Which of the following statements regarding Pertussis is INCORRECT?

Cerebellar ataxia is a known complication.. ***Cerebellar ataxia is a known complication.*** - **Cerebellar ataxia** is not a typical or known complication of pertussis. Complications usually involve the respiratory, neurological (e.g., seizures, encephalopathy due to hypoxia), and nutritional systems due to severe coughing. - While neurological complications can occur, **ataxia** specifically is not frequently sighted in the context of pertussis. *Some infections may be subclinical.* - Some individuals, especially those partially immunized or older, can experience **subclinical or atypical infections** with pertussis, often presenting as a mild cough. - This characteristic makes it difficult to control the spread of the disease as infected individuals may not be recognized. *The most infective stage is the catarrhal stage.* - The **catarrhal stage**, characterized by non-specific cold-like symptoms, is the most contagious phase because bacterial shedding is highest. - During this stage, symptoms are mild and often indistinguishable from a common cold, leading to widespread transmission before diagnosis. *The drug of choice is Erythromycin.* - **Erythromycin**, or other macrolides like azithromycin or clarithromycin, are the drugs of choice for treating pertussis. - These antibiotics are most effective when administered early in the **catarrhal stage** to reduce disease severity and prevent transmission.

Q: A baby from a second degree consanguineous marriage presents with diarrhoea and redness in the perianal diaper area. What is the most likely diagnosis?

Fungal infection. ***Fungal infection (Candida diaper dermatitis)*** - **Diarrhea with perianal diaper rash** is the classic presentation of **Candida (fungal) diaper dermatitis**, the most common cause of diaper rash in infants with diarrhea. - **Diarrhea increases skin moisture and alters pH**, creating optimal conditions for **Candida albicans overgrowth**. - **Perianal involvement with bright erythema** is characteristic of Candida, often with **satellite lesions** and involvement of skin folds. - This is a **clinical diagnosis** based on distribution pattern and association with diarrhea; consanguinity is not directly relevant to this common condition. *Lactose intolerance* - **Congenital lactase deficiency** is extremely rare (< 50 cases worldwide) and unlikely to be the primary diagnosis. - While **secondary lactose intolerance** can occur with gastroenteritis causing diarrhea, it doesn't explain the **specific perianal rash pattern** described. - The perianal redness in lactose malabsorption would be **irritant contact dermatitis** from acidic stools, which would secondarily get infected with **Candida** - making fungal infection the more complete diagnosis. *Shigella infection* - Typically presents with **bloody diarrhea (dysentery)**, high fever, abdominal cramps, and tenesmus. - Would not specifically cause the **perianal diaper rash pattern** characteristic of Candida. - Consanguinity doesn't predispose to this bacterial infection. *Salmonella infection* - Usually presents with **fever, vomiting, and systemic symptoms** along with diarrhea. - May cause bloody or non-bloody diarrhea but doesn't explain the **characteristic perianal redness pattern**. - Not associated with consanguinity as it's an acquired infectious disease.

Q: What is the most common symptom of AIDS in infants?

Failure to thrive. ***Failure to thrive*** - **Growth retardation** and **weight loss** in infants with AIDS are directly related to the chronic stress of the infection, recurrent infections, and malabsorption. - This symptom reflects the body's inability to maintain normal growth and development due to the underlying severe **immunosuppression**. *GI infection* - While **gastrointestinal infections** are common in infants with AIDS due to immune compromise, they are a consequence rather than the initial, most common presenting symptom. - They often contribute to, but are not synonymous with, the broader syndrome of **failure to thrive**. *Persistent cough* - A **persistent cough** can be a symptom of various opportunistic infections, such as *Pneumocystis jirovecii* pneumonia (PJP), which is common in infants with AIDS. - However, it is not the single most common *initial* symptom across all presentations of pediatric AIDS. *Lymphadenopathy* - **Lymphadenopathy** (swollen lymph nodes) is a very common sign of HIV infection in children due to chronic immune stimulation. - While prevalent, it is often a *physical finding* on examination rather than the primary symptom that parents typically notice leading to presentation, which is often related to the child's overall well-being and growth.

Question 1

What is the appropriate management for a child who has been bitten by a cat?

Accepted Answer

All of the options are true

Answer

Administer prophylactic antibiotics to prevent infection

Answer

Rabies vaccination may be necessary

Answer

Thoroughly clean the wound

Question 2

Which of the following statements about Koplik spots is true?

Accepted Answer

All of the options.

Answer

Pathognomonic of measles.

Answer

Present on buccal mucosa opposite the molars.

Answer

Not always present.

Question 3

Which of the following statements about rashes in children is incorrect?

Accepted Answer

Varicella - typically appears on day 1

Answer

Typhoid - typically appears on day 5

Answer

Typhus - typically appears on day 5

Answer

Measles - typically appears on day 4

Question 4

Which of the following is the most characteristic feature of the rash distribution in chickenpox?

Accepted Answer

More concentrated on the trunk than limbs

Answer

Superficial and not deep-seated

Answer

Affects palms and soles

Answer

Evolves rapidly with new spots appearing in waves over days.

Question 5

In which of the following conditions can strawberry tongue be observed?

Accepted Answer

Both conditions mentioned above

Answer

Streptococcal scarlet fever

Answer

Kawasaki disease

Answer

None of the options

Question 6

A 3-month-old baby presents with deafness, cataract, and patent ductus arteriosus. Which of the following is the most likely diagnosis?

Accepted Answer

Congenital rubella syndrome

Answer

Congenital herpes simplex virus infection

Answer

Congenital toxoplasmosis

Answer

Congenital cytomegalovirus infection

Question 7

What is the most serious complication of measles?

Accepted Answer

Pneumonia

Answer

Croup

Answer

Otitis media

Answer

Meningo-encephalitis

Question 8

Which of the following statements regarding Pertussis is INCORRECT?

Accepted Answer

Cerebellar ataxia is a known complication.

Answer

The drug of choice is Erythromycin.

Answer

Some infections may be subclinical.

Answer

The most infective stage is the catarrhal stage.

Question 9

A baby from a second degree consanguineous marriage presents with diarrhoea and redness in the perianal diaper area. What is the most likely diagnosis?

Accepted Answer

Fungal infection

Answer

Shigella infection

Answer

Salmonella infection

Answer

Lactose intolerance

Question 10

What is the most common symptom of AIDS in infants?

Accepted Answer

Failure to thrive

Answer

Persistent cough

Answer

Lymphadenopathy

Answer

GI infection

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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