Infectious Diseases Practice Questions

Q: A 20-year-old male presents with fever, severe headache, vomiting, and photophobia. On examination, neck rigidity and Brudzinskis sign are positive. CT scan of the brain shows hydrocephalus. What is the most likely diagnosis?

Bacterial Meningitis. ***Bacterial Meningitis*** - The clinical triad of **fever**, **headache**, and **neck rigidity** (nuchal rigidity) is classic for acute meningitis [1]. - Positive meningeal signs like **Brudzinski's sign** confirm meningeal irritation, and hydrocephalus may occur due to impaired CSF flow or absorption (communicating or non-communicating) [1]. ***Normal Pressure Hydrocephalus*** - Characterized by the triad of gait disturbance, urinary incontinence, and **dementia** (Wacky, Wobbly, Wet). - Does not typically present with acute systemic symptoms like **fever** or acute signs of meningeal irritation (neck rigidity/Brudzinski's). ***Viral Encephalitis*** - While it presents with fever and headache, the hallmark is altered mental status (confusion, seizures) and focal neurological deficits, indicating **parenchymal involvement**. - Severe, rigid **neck stiffness** (a major sign of meningeal irritation) is usually less prominent compared to bacterial meningitis [1]. ***Subarachnoid Hemorrhage*** - Presents with a sudden worst headache of life (**thunderclap headache**) and meningeal signs (neck rigidity, photophobia) [1]. - **Fever** is usually low-grade (if present) and develops later, unlike the often high fever seen in bacterial meningitis.

Q: A 58-year-old male presents with burning micturition. Prostatic examination is normal. Urinalysis shows >50 pus cells per high power field, but urine culture shows no growth. What is the most likely diagnosis?

Sterile pyuria. ***Sterile pyuria*** - The combination of **pyuria** (>50 pus cells/HPF) and a **negative urine culture (no growth)** is known as sterile pyuria. This can be idiopathic or indicate conditions like **urethritis**, **tuberculosis**, or non-bacterial infections [1]. - The presence of symptoms (burning micturition) combined with pyuria and a normal prostate examination rules out typical bacterial prostatitis scenarios [1]. ***Chronic bacterial prostatitis*** - While chronic bacterial prostatitis involves recurrent symptomatic episodes and may sometimes show pyuria, it is characterized by **recurrent positive urine cultures** (often *E. coli*) and localization of bacteria to prostatic fluid. - The prostatic examination is often normal, but the hallmark is the presence of bacteria in the urine/prostatic fluid, which is absent here. ***Acute bacterial prostatitis*** - This presents with signs of systemic infection (fever, chills) and a very tender, boggy prostate, which is not mentioned, and the exam here is noted as **normal** [1]. - It always involves a **positive urine culture** due to the high bacterial load in the urine. ***Granulomatous prostatitis*** - This is a rare inflammatory condition, often related to fungal infections or **BCG therapy**, and typically manifests as a firm, nodular prostate that mimics prostate cancer. - While it can cause sterile pyuria, the presentation is usually dominated by prostatic enlargement or hardness, which is contradicted by the **normal prostatic examination** given in the prompt.

Q: A 56-year-old diabetic male presents with a complicated urinary tract infection and is found to be hypotensive. His blood pressure does not respond to intravenous fluids. Which of the following is the most appropriate antibiotic to manage his condition?

Meropenem. ***Meropenem*** - This patient has **septic shock** secondary to a complicated UTI (hypotension unresponsive to fluids), requiring prompt, broad-spectrum coverage against probable **Gram-negative bacilli** and potential extended-spectrum beta-lactamase (ESBL) producers, common in diabetic patients with complicated UTIs [1]. - **Meropenem**, a carbapenem, provides excellent empirical coverage for **multi-drug resistant (MDR) organisms** and is a first-line agent for critically ill patients with suspected septic shock of unknown or complicated origin [1]. ***Amoxicillin-Clavulanate*** - This combination (a moderate-spectrum penicillin-beta-lactamase inhibitor) lacks reliable coverage against common hospital-acquired or complicatd UTI pathogens, such as **_Pseudomonas aeruginosa_** or ESBL-producing Enterobacteriaceae [1]. - It is unsuitable for treating septic shock due to an inadequate spectrum and potential for **resistance** in this clinical setting [1]. ***Nitrofurantoin*** - This drug is concentrated in the urine and is only suitable for treating **uncomplicated cystitis** as it does not achieve adequate systemic levels for treating pyelonephritis, deep-seated infection, or **urosepsis**. - It has a narrow spectrum limited primarily to **Gram-positive cocci** and susceptible **_E. coli_** and is contraindicated in systemic infections or septic shock. ***Ceftriaxone*** - Ceftriaxone (a third-generation cephalosporin) is often used for complicated UTIs (pyelonephritis) but is generally not adequate as **monotherapy** for treating **septic shock** in a high-risk (diabetic) patient [2]. - There is a high risk of resistance, including from ESBL-producers, which necessitates broader coverage, like a **carbapenem**, in critically ill patients before susceptibility results are known.

Q: A 25-year-old sewage worker presents with fever for 1 week and weakness for 1 day. Laboratory evaluation reveals elevated bilirubin and decreased urine output. Conjunctival redness? What is the most likely diagnosis?

Weil's disease. ***Weil's disease*** - The clinical triad of fever, **jaundice (elevated bilirubin)**, and **acute kidney injury (decreased urine output)**, particularly in an individual with exposure to contaminated water (**sewage worker**), is the classical presentation of the severe form of leptospirosis, also known as Weil's disease [1]. - **Conjunctival suffusion/redness** without inflammation or discharge is a pathognomonic physical sign highly suggestive of Weil's disease, caused by the spirochete **Leptospira interrogans** [1], [2]. *Brucellosis* - Usually presents with an undulating fever, night sweats, and localized infection in the bones (**spondylitis**) or reticuloendothelial system; it is often linked to consumption of **unpasteurized dairy**. - While mild hepatic involvement can occur, it rarely causes the severe combination of **acute renal failure** and deep jaundice seen in this patient. *Enteric fever* - Characterized by a gradually rising fever, **relative bradycardia**, and often features a dry cough, abdominal discomfort, and sometimes **rose spots**. [2] - Severe organ damage like acute kidney injury and profound jaundice simultaneously is unusual in typhoid fever, and **conjunctival suffusion** is not a feature. *Acute Viral Hepatitis* - Presents with fever, malaise, and eventually **jaundice (elevated bilirubin)**; the primary pathology is hepatocyte necrosis. [2] - It typically does not cause simultaneous severe **acute renal failure** and the specific finding of **conjunctival suffusion**, which are hallmarks of Weil's disease.

Q: A patient with HIV develops tuberculosis. When should ART be initiated?

Start ATT, then ART after 2 weeks. ***A. Start ATT, then ART after 2 weeks*** - This strategy is the standard recommendation, particularly for patients with CD4 counts >50 cells/mm³, to reduce the risk of **Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome (IRIS)** [1]. - Delaying ART by 2 weeks allows patients to establish tolerance to **Anti-Tubercular Treatment (ATT)** and simplifies the management of potential overlapping drug toxicities [2]. *B. Start ART and ATT simultaneously* - Simultaneous initiation significantly increases the risk and severity of developing **IRIS**, which can worsen the patient's clinical status due to paradoxical worsening of TB symptoms [1]. - This approach also makes it challenging to identify the source of **drug-related toxicities** (e.g., hepatotoxicity), as many ATT and ART drugs are metabolized by the liver [2]. *C. Start ART followed by ATT* - Delaying the initiation of **ATT** is dangerous as active tuberculosis is the immediate life-threatening condition that requires urgent treatment [2]. - Treatment priority in HIV-TB co-infection must first focus on effectively treating the active infection to prevent **disseminated disease** and death. *D. ART alone* - Administering **ART alone** will lead to the progression of active tuberculosis, resulting in significant morbidity and high mortality rates. - ART is necessary but must be combined with effective **ATT** as it is not a treatment for Mycobacterium tuberculosis itself.

Q: A patient with HIV is newly diagnosed with multidrug-resistant tuberculosis. Which of the following is the appropriate regimen, and what should the patient be monitored for?

BPaLM; monitor for immune reconstitution syndrome. ***BPaLM; monitor for immune reconstitution syndrome*** - The **BPaLM** regimen (Bedaquiline, Pretomanid, Linezolid, Moxifloxacin/Levofloxacin) is the recommended all-oral, shorter course (6-9 months) treatment for confirmed drug-resistant or **MDR/RR-TB** (Multidrug/Rifampicin-resistant TB). - HIV co-infected patients are at high risk for **Immune Reconstitution Inflammatory Syndrome (IRIS)**, a paradoxical immune reaction that occurs upon starting effective TB treatment, especially after initiating or optimizing **ART** (Antiretroviral Therapy) [2]. *INH + Levofloxacin + Pyrazinamide + Ethambutol, monitor for hepatotoxicity* - This regimen is inappropriate for **MDR-TB** because it contains **Isoniazid (INH)**, to which the patient's strain is resistant by definition. - While monitoring for **hepatotoxicity** (especially due to Pyrazinamide and INH) is crucial in general TB management, this combination lacks the necessary potent second-line agents. *INH + Levofloxacin + Streptomycin + Ethionamide, monitor for pyridoxine deficiency* - This regimen includes **INH** and older, more toxic second-line drugs like **Streptomycin** (an injectable agent now largely avoided) and **Ethionamide**. - Monitoring for **pyridoxine (Vitamin B6) deficiency** is necessary when using drugs like INH or Ethionamide, but the overall regimen is considered outdated and suboptimal for standard MDR-TB management [1]. *INH + Clarithromycin + Pyrazinamide + Ethambutol, monitor for optic neuritis* - This regimen is incorrect because it contains **INH** (ineffective in MDR-TB) and **Clarithromycin**, which is primarily used for **MAC** (Mycobacterium avium complex) and not a core drug for *M. tuberculosis*. - Although monitoring for **optic neuritis** is specific to **Ethambutol** toxicity, the inclusion of inappropriate drugs makes this an unsuitable MDR-TB treatment combination.

Q: According to WHO, which of the following is the recommended diagnostic test for spinal tuberculosis?

CB-NAAT. ***CB-NAAT*** - **WHO Consolidated Guidelines on TB (2021)** recommend **CB-NAAT/Xpert MTB/RIF** as the initial diagnostic test for all forms of TB, including **extrapulmonary and spinal tuberculosis**. - It provides **rapid diagnosis** within 2 hours and simultaneously detects **rifampicin resistance**, making it the preferred first-line diagnostic tool. *X-ray* - X-rays are useful for **initial screening** and assessing **bony destruction** like vertebral collapse (**Pott's spine**), but cannot confirm TB diagnosis. - They lack the ability to provide **bacteriological evidence** or detect **M. tuberculosis organisms** required for definitive diagnosis. *CT scan* - CT scans provide detailed imaging of **bony morphology**, **disc involvement**, and **soft tissue pathology** like paraspinal abscesses. - It remains an **imaging modality** and cannot replace the need for **microbiological confirmation** or **drug susceptibility testing**. *Culture and Sensitivity* - While considered the **gold standard** for TB confirmation and comprehensive **drug susceptibility testing**, it is not WHO's recommended **first-line diagnostic test**. - Culture takes **weeks to months** for results, whereas WHO emphasizes **rapid diagnosis** for timely treatment initiation.

Q: A 25 -year-male presents with high grade fever for 2 days. Vitals are pulse rate = 90 bpm and BP = 110/70 mm Hg. Labs were done and show positive NS-1 Antigen and platelet count = 40,000/cu.mm. The physical examination findings are shown below. What is the grade of severity of DHF?

Grade II. ***Correct Option: Grade II*** - The image displays features of **petechiae** and **epistaxis** (nosebleed), along with **thrombocytopenia** (platelet count 40,000/cu.mm) and a positive NS-1 antigen confirming dengue infection. - Grade II DHF is defined by **fever + thrombocytopenia + hemoconcentration + spontaneous bleeding** (skin hemorrhages such as petechiae, epistaxis, gum bleeds) **without any signs of circulatory failure**. - This patient's **stable vitals** (pulse 90 bpm, BP 110/70 mmHg) confirm the **absence of circulatory failure**, placing the patient firmly in Grade II. *Incorrect Option: Grade I* - Grade I DHF is characterized by **fever** and constitutional symptoms with a **positive tourniquet test** as the **only** hemorrhagic manifestation. - This patient has **spontaneous bleeding** (petechiae, epistaxis), which upgrades the classification beyond Grade I. *Incorrect Option: Grade III* - Grade III DHF requires signs of **circulatory failure**: rapid weak pulse, **narrow pulse pressure (≤20 mmHg)**, hypotension, cold clammy skin, and restlessness (early Dengue Shock Syndrome). - This patient's pulse pressure is 40 mmHg (110−70) and vitals are **entirely normal**, ruling out Grade III. *Incorrect Option: Grade IV* - Grade IV DHF is **profound shock** with **undetectable blood pressure and pulse** (Dengue Shock Syndrome). - The patient's stable BP (110/70 mmHg) and palpable pulse definitively exclude Grade IV.

Question 1

What is the role of Procalcitonin in pneumonia?

Accepted Answer

Early antibiotic discontinuation

Answer

Requirement of further investigation

Answer

Guiding initiation of antibiotic

Answer

No role

Question 2

A 20-year-old male presents with fever, severe headache, vomiting, and photophobia. On examination, neck rigidity and Brudzinskis sign are positive. CT scan of the brain shows hydrocephalus. What is the most likely diagnosis?

Accepted Answer

Bacterial Meningitis

Answer

Viral Encephalitis

Answer

Subarachnoid Hemorrhage

Answer

Normal Pressure Hydrocephalus

Question 3

A 58-year-old male presents with burning micturition. Prostatic examination is normal. Urinalysis shows >50 pus cells per high power field, but urine culture shows no growth. What is the most likely diagnosis?

Accepted Answer

Sterile pyuria

Answer

Granulomatous prostatitis

Answer

Chronic bacterial prostatitis

Answer

Acute bacterial prostatitis

Question 4

A 56-year-old diabetic male presents with a complicated urinary tract infection and is found to be hypotensive. His blood pressure does not respond to intravenous fluids. Which of the following is the most appropriate antibiotic to manage his condition?

Accepted Answer

Meropenem

Answer

Amoxicillin-Clavulanate

Answer

Nitrofurantoin

Answer

Ceftriaxone

Question 5

A patient underwent cardiac surgery and was admitted to the ICU. He later developed ventilator-associated pneumonia and was started on empirical antibiotics. A few hours later, the patient developed acute kidney injury. Serum procalcitonin was sent. Which of the following statements regarding procalcitonin is correct?

Accepted Answer

It helps in determining the duration of antibiotic therapy

Answer

It can be used to confirm source of infection

Answer

It is used to differentiate bacterial from fungal cause

Answer

It helps in identifying which empirical antibiotics to be started

Question 6

A 25-year-old sewage worker presents with fever for 1 week and weakness for 1 day. Laboratory evaluation reveals elevated bilirubin and decreased urine output. Conjunctival redness? What is the most likely diagnosis?

Accepted Answer

Weil's disease

Answer

Enteric fever

Answer

Acute Viral Hepatitis

Answer

Brucellosis

Question 7

A patient with HIV develops tuberculosis. When should ART be initiated?

Accepted Answer

Start ATT, then ART after 2 weeks

Answer

Start ART followed by ATT

Answer

ART alone

Answer

Start ART and ATT simultaneously

Question 8

A patient with HIV is newly diagnosed with multidrug-resistant tuberculosis. Which of the following is the appropriate regimen, and what should the patient be monitored for?

Accepted Answer

BPaLM; monitor for immune reconstitution syndrome

Answer

INH + Levofloxacin + Pyrazinamide + ethambutol, monitor for hepatotoxicity

Answer

INH + Levofloxacin + Streptomycin + Ethionamide, monitor for pyridoxine deficiency

Answer

INH + Clarithromycin + Pyrazinamide + Ethambutol, monitor for optic neuritis

Question 9

According to WHO, which of the following is the recommended diagnostic test for spinal tuberculosis?

Accepted Answer

CB-NAAT

Answer

CT scan

Answer

Culture and Sensitivity

Answer

X-ray

Question 10

A 25 -year-male presents with high grade fever for 2 days. Vitals are pulse rate = 90 bpm and BP = 110/70 mm Hg. Labs were done and show positive NS-1 Antigen and platelet count = 40,000/cu.mm. The physical examination findings are shown below. What is the grade of severity of DHF?

Accepted Answer

Grade II

Answer

Grade I

Answer

Grade III

Answer

Grade IV

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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