Serious & Notifiable Infections — MCQs
On this page
A 42-year-old woman presents with a 4-week history of headache, low-grade fever, and personality changes. She is originally from India and moved to the UK 6 months ago. CT head shows basal meningeal enhancement and hydrocephalus. Lumbar puncture reveals: opening pressure 32 cmH2O, clear CSF, white cells 180/mm³ (80% lymphocytes), protein 2.5 g/L, glucose 1.9 mmol/L (plasma glucose 5.8 mmol/L). Ziehl-Neelsen stain is negative. What is the most appropriate initial management?
A 55-year-old man with type 2 diabetes is diagnosed with pulmonary tuberculosis. He has been on metformin 1g twice daily and gliclazide 80mg twice daily for glycaemic control. After starting standard four-drug anti-tuberculous therapy, his HbA1c increases from 58 mmol/mol to 76 mmol/mol over 4 weeks. What is the most likely explanation for this deterioration in glycaemic control?
A 19-year-old student presents with sudden onset headache, fever, vomiting, and drowsiness. On examination, she has neck stiffness and Kernig's sign is positive. Lumbar puncture shows: opening pressure 28 cmH2O, cloudy CSF, white cells 2400/mm³ (95% neutrophils), protein 3.2 g/L, glucose 1.8 mmol/L (plasma glucose 6.5 mmol/L). Gram stain shows Gram-negative diplococci. Which organism is most likely responsible?
A 28-year-old healthcare worker has a positive Mantoux test (15 mm induration) during routine occupational health screening. She is asymptomatic with a normal chest X-ray. She received BCG vaccination as a teenager. Her interferon-gamma release assay (IGRA) is positive. What is the most appropriate next management step?
A 32-year-old man with HIV (CD4 count 85 cells/mm³) presents with headache, fever, and confusion over 5 days. CT head shows multiple ring-enhancing lesions with surrounding oedema. Lumbar puncture reveals: opening pressure 24 cmH2O, CSF protein 0.8 g/L, glucose 2.1 mmol/L (plasma glucose 5.2 mmol/L), white cells 45/mm³ (90% lymphocytes). India ink stain is positive. What is the most likely causative organism?
A 45-year-old woman from Somalia, who moved to the UK 2 years ago, is diagnosed with active pulmonary tuberculosis. She lives in a house with her husband, two children aged 8 and 12 years, and her elderly mother. What is the most appropriate contact screening strategy for her household members?
A 24-year-old university student presents to the emergency department with a 6-hour history of severe headache, photophobia, neck stiffness, and fever of 39.2°C. On examination, she has a non-blanching purpuric rash on her lower limbs. Blood pressure is 95/60 mmHg and heart rate is 115 bpm. What is the most appropriate immediate management before lumbar puncture?
A 68-year-old man presents with a 3-week history of productive cough, night sweats, and unintentional weight loss of 5 kg. He is a former smoker with a 40 pack-year history. Chest X-ray shows upper lobe cavitation. Sputum smear microscopy reveals acid-fast bacilli. What is the most appropriate initial treatment regimen for this patient?
Serious & Notifiable Infections UK Medical PG Practice Questions and MCQs
Question 241: A 42-year-old woman presents with a 4-week history of headache, low-grade fever, and personality changes. She is originally from India and moved to the UK 6 months ago. CT head shows basal meningeal enhancement and hydrocephalus. Lumbar puncture reveals: opening pressure 32 cmH2O, clear CSF, white cells 180/mm³ (80% lymphocytes), protein 2.5 g/L, glucose 1.9 mmol/L (plasma glucose 5.8 mmol/L). Ziehl-Neelsen stain is negative. What is the most appropriate initial management?
- A. Start four-drug anti-tuberculous therapy immediately (Correct Answer)
- B. Wait for mycobacterial culture results before starting treatment
- C. Perform repeat lumbar puncture for larger CSF volume before starting treatment
- D. Start empirical aciclovir for possible viral meningoencephalitis
- E. Start empirical treatment for fungal meningitis with amphotericin B
Explanation: ***Start four-drug anti-tuberculous therapy immediately***- The patient's presentation with subacute headache, fever, and personality changes, combined with **basal meningeal enhancement** and **hydrocephalus** on CT, and classic CSF findings (**lymphocytic pleocytosis**, very **high protein**, very **low glucose**) in a patient from a **TB-endemic area**, is highly suggestive of **tuberculous meningitis**.- Given the high mortality and severe neurological sequelae if treatment is delayed, and the low sensitivity of **Ziehl-Neelsen stain** and slow growth of mycobacterial cultures, empirical **four-drug anti-tuberculous therapy** (RIPE) plus corticosteroids must be initiated immediately. *Wait for mycobacterial culture results before starting treatment*- **Mycobacterial cultures** can take several weeks to yield results, which is too long to delay treatment for a rapidly progressive and life-threatening condition like TB meningitis.- Delaying treatment significantly increases the risk of irreversible neurological damage, severe complications such as stroke and **hydrocephalus**, and death.*Perform repeat lumbar puncture for larger CSF volume before starting treatment*- While a larger CSF volume could potentially increase the yield for diagnostic tests, the current clinical and CSF findings are already strongly indicative of TB meningitis.- Delaying the initiation of life-saving therapy to obtain more CSF volume is not appropriate given the urgency of the situation and the clear diagnostic suspicion.*Start empirical aciclovir for possible viral meningoencephalitis*- **Viral meningoencephalitis**, particularly HSV, typically presents more acutely than the 4-week history seen here and usually has **normal CSF glucose** levels, unlike the severely low glucose in this case.- Furthermore, **basal meningeal enhancement** and **hydrocephalus** are far more characteristic of granulomatous infections like TB or fungal meningitis than typical viral etiologies.*Start empirical treatment for fungal meningitis with amphotericin B*- While fungal meningitis can present with similar CSF abnormalities (low glucose, high protein, lymphocytic pleocytosis) and imaging findings, it is less common than TB in this context and typically affects severely **immunocompromised individuals**.- The patient's background from a **TB-endemic area** and the characteristic overall picture make **tuberculous meningitis** a significantly more likely initial diagnosis, warranting immediate specific anti-TB therapy.
Question 242: A 55-year-old man with type 2 diabetes is diagnosed with pulmonary tuberculosis. He has been on metformin 1g twice daily and gliclazide 80mg twice daily for glycaemic control. After starting standard four-drug anti-tuberculous therapy, his HbA1c increases from 58 mmol/mol to 76 mmol/mol over 4 weeks. What is the most likely explanation for this deterioration in glycaemic control?
- A. Isoniazid-induced pancreatitis reducing insulin secretion
- B. Rifampicin-induced cytochrome P450 enzyme induction reducing gliclazide levels (Correct Answer)
- C. Pyrazinamide causing insulin resistance
- D. Ethambutol interfering with metformin absorption
- E. Poor adherence to diabetic medications due to pill burden
Explanation: ***Rifampicin-induced cytochrome P450 enzyme induction reducing gliclazide levels*** - **Rifampicin** is a potent inducer of hepatic **cytochrome P450 enzymes** (specifically CYP2C9 and CYP3A4), which speeds up the metabolism of many drugs. - **Gliclazide**, a sulfonylurea, is metabolized by these enzymes; increased metabolism reduces its plasma concentration, leading to a significant loss of **glycaemic control**. *Isoniazid-induced pancreatitis reducing insulin secretion* - While **isoniazid** can rarely cause **pancreatitis**, this would typically present with acute abdominal pain and elevated lipase, not just an isolated rise in HbA1c. - Isoniazid is more commonly associated with **peripheral neuropathy** and **hepatotoxicity** rather than pancreatic endocrine failure. *Pyrazinamide causing insulin resistance* - **Pyrazinamide** is well known for competing with **uric acid** excretion, leading to hyperuricaemia and potentially gout, but it does not cause **insulin resistance**. - It has no documented clinical mechanism for significantly altering **blood glucose** levels or causing secondary diabetes. *Ethambutol interfering with metformin absorption* - **Ethambutol** is primarily associated with **optic neuritis** and does not impact the gastrointestinal absorption of **metformin**. - Metformin is not metabolized by the **cytochrome P450 system**, making it less susceptible to the enzyme-inducing effects of TB therapy compared to sulfonylureas. *Poor adherence to diabetic medications due to pill burden* - While **pill burden** is a factor in TB treatment, the specific pharmacological interaction between **rifampicin** and **sulfonylureas** is a classic and more likely medical cause for such rapid deterioration. - In clinical scenarios involving **rifampicin**, the metabolic induction is the primary suspected mechanism for loss of control of other oral medications.
Question 243: A 19-year-old student presents with sudden onset headache, fever, vomiting, and drowsiness. On examination, she has neck stiffness and Kernig's sign is positive. Lumbar puncture shows: opening pressure 28 cmH2O, cloudy CSF, white cells 2400/mm³ (95% neutrophils), protein 3.2 g/L, glucose 1.8 mmol/L (plasma glucose 6.5 mmol/L). Gram stain shows Gram-negative diplococci. Which organism is most likely responsible?
- A. Escherichia coli
- B. Streptococcus pneumoniae
- C. Neisseria meningitidis (Correct Answer)
- D. Haemophilus influenzae type b
- E. Listeria monocytogenes
Explanation: ***Neisseria meningitidis***- The presence of **Gram-negative diplococci** on the CSF Gram stain is the classic and most definitive finding for *Neisseria meningitidis*.- The clinical presentation of sudden onset fever, headache, meningeal signs (neck stiffness, Kernig's) in a **young adult** (19-year-old student), coupled with the CSF profile (elevated opening pressure, cloudy, high protein, low glucose, and marked **neutrophilic pleocytosis**), is highly characteristic of bacterial meningitis caused by this organism.*Escherichia coli*- *Escherichia coli* are **Gram-negative bacilli (rods)**, which would appear as rod-shaped bacteria on Gram stain, not diplococci.- While a cause of bacterial meningitis, *E. coli* is predominantly seen in **neonates** or immunocompromised individuals, making it less likely in a healthy 19-year-old.*Streptococcus pneumoniae*- *Streptococcus pneumoniae* is a major cause of bacterial meningitis but is characterized by **Gram-positive diplococci**, staining purple, not Gram-negative.- This organism is more commonly associated with very young children, older adults, or individuals with specific risk factors like **splenic dysfunction**.*Haemophilus influenzae type b*- *Haemophilus influenzae type b* (Hib) appears as **Gram-negative coccobacilli**, which are smaller, more pleomorphic, and often less distinctly diplococcal than *Neisseria*.- The incidence of Hib meningitis has been significantly reduced in many populations due to widespread **childhood vaccination programs**.*Listeria monocytogenes*- *Listeria monocytogenes* are characterized as **Gram-positive rods**, directly contradicting the Gram-negative finding on the CSF Gram stain.- It typically affects specific vulnerable populations, including **neonates**, pregnant women, the **elderly**, and **immunocompromised** individuals.
Question 244: A 28-year-old healthcare worker has a positive Mantoux test (15 mm induration) during routine occupational health screening. She is asymptomatic with a normal chest X-ray. She received BCG vaccination as a teenager. Her interferon-gamma release assay (IGRA) is positive. What is the most appropriate next management step?
- A. No treatment required; likely due to previous BCG vaccination
- B. Offer treatment for latent tuberculosis infection with 3 months of rifampicin and isoniazid (Correct Answer)
- C. Offer treatment for latent tuberculosis infection with 6 months of isoniazid
- D. Repeat Mantoux test in 6 weeks to confirm result
- E. Commence full anti-tuberculous therapy with four drugs for 6 months
Explanation: ***Offer treatment for latent tuberculosis infection with 3 months of rifampicin and isoniazid*** - The patient has **Latent TB Infection (LTBI)**, confirmed by a **positive IGRA (interferon-gamma release assay)**, which is highly specific and not affected by previous **BCG vaccination**. - A 3-month course of **rifampicin and isoniazid (3HR)** is a preferred regimen due to higher **completion rates** and comparable efficacy to longer monotherapy courses for LTBI. *No treatment required; likely due to previous BCG vaccination* - While the **Mantoux test** can be falsely positive due to **BCG**, a **positive IGRA** specifically identifies infection with *Mycobacterium tuberculosis*, as it uses antigens not present in BCG. - Healthcare workers with confirmed **LTBI** require management to prevent **progression to active TB**, which has a 5-10% lifetime risk. *Offer treatment for latent tuberculosis infection with 6 months of isoniazid* - While **6 months of isoniazid (6H)** is a valid alternative for LTBI, current guidelines often prefer shorter, combined regimens due to better patient adherence. - This monotherapy is associated with potentially **lower compliance** compared to the 3-month rifampicin-isoniazid course because of its longer duration. *Repeat Mantoux test in 6 weeks to confirm result* - Repeating the **tuberculin skin test (Mantoux)** is unnecessary and not indicated when an **IGRA** has already provided a more specific and reliable confirmation of infection. - Delaying treatment with repeat testing increases the window of risk for **reactivation** of latent infection to active disease. *Commence full anti-tuberculous therapy with four drugs for 6 months* - Quadruple therapy (e.g., isoniazid, rifampicin, pyrazinamide, ethambutol) is reserved for **active tuberculosis disease**, whereas this patient is **asymptomatic** with a **normal chest X-ray**, indicating latent infection. - Using four drugs for **LTBI** unnecessarily increases the risk of **drug toxicity** (such as hepatitis) and is not clinically indicated for latent disease.
Question 245: A 32-year-old man with HIV (CD4 count 85 cells/mm³) presents with headache, fever, and confusion over 5 days. CT head shows multiple ring-enhancing lesions with surrounding oedema. Lumbar puncture reveals: opening pressure 24 cmH2O, CSF protein 0.8 g/L, glucose 2.1 mmol/L (plasma glucose 5.2 mmol/L), white cells 45/mm³ (90% lymphocytes). India ink stain is positive. What is the most likely causative organism?
- A. Toxoplasma gondii
- B. Cryptococcus neoformans (Correct Answer)
- C. Mycobacterium tuberculosis
- D. JC virus
- E. Listeria monocytogenes
Explanation: ***Cryptococcus neoformans*** - The positive **India ink stain** demonstrating encapsulated yeasts in the CSF is pathognomonic for **Cryptococcus neoformans** in this immunocompromised patient (CD4 count 85 cells/mm³). - The clinical picture of **meningitis** (headache, fever, confusion, elevated opening pressure, lymphocytic pleocytosis, low glucose) is characteristic, and **cryptococcomas** can explain the ring-enhancing lesions. *Toxoplasma gondii* - While **Toxoplasma gondii** is the most common cause of **multiple ring-enhancing lesions** in HIV, it would not yield a positive **India ink stain** on CSF examination. - CSF parameters in toxoplasmosis are typically non-specific, lacking the distinct **fungal meningitis** profile (low glucose, lymphocytic pleocytosis) seen here. *Mycobacterium tuberculosis* - **Tuberculous meningitis** usually presents with more profoundly **low CSF glucose** and significantly **higher CSF protein** levels than seen in this case. - Diagnosis of TB meningitis relies on **Acid-Fast Bacilli (AFB)** staining, PCR, or culture for *Mycobacterium tuberculosis*, not an India ink stain. *JC virus* - **JC virus** causes **Progressive Multifocal Leukoencephalopathy (PML)**, which is characterized by **non-enhancing white matter lesions** on CT or MRI, not ring-enhancing lesions. - PML does not typically cause the meningitic syndrome or the inflammatory CSF changes, such as elevated white cells and protein, seen in this patient. *Listeria monocytogenes* - **Listeria monocytogenes** causes bacterial meningitis, typically presenting with a **neutrophilic pleocytosis** in the CSF, unlike the lymphocytic predominance here. - Being a bacterium, it would not be detected by an **India ink stain**, and while it affects immunocompromised patients, the overall picture here points away from *Listeria*.
Question 246: A 45-year-old woman from Somalia, who moved to the UK 2 years ago, is diagnosed with active pulmonary tuberculosis. She lives in a house with her husband, two children aged 8 and 12 years, and her elderly mother. What is the most appropriate contact screening strategy for her household members?
- A. Mantoux test and chest X-ray for all contacts immediately
- B. Mantoux test for all contacts, with chest X-ray if positive; repeat Mantoux at 6 weeks if initially negative (Correct Answer)
- C. Interferon-gamma release assay (IGRA) for all contacts immediately with chest X-ray
- D. Chest X-ray for all contacts with Mantoux test only if symptomatic
- E. IGRA test for adults and Mantoux test for children, both with immediate chest X-ray
Explanation: ***Mantoux test for all contacts, with chest X-ray if positive; repeat Mantoux at 6 weeks if initially negative***- Initial screening for TB contacts involves the **Mantoux test** (tuberculin skin test) to identify **latent TB infection**. A **chest X-ray** is then performed only if the Mantoux test is positive or if the contact presents with symptoms of active disease.- A crucial step is to **repeat the Mantoux test at 6 weeks** if the initial result is negative, as there is a **window period** during which the immune response to TB infection may not yet be detectable. *Mantoux test and chest X-ray for all contacts immediately*- Performing a **chest X-ray on all contacts immediately** is an unnecessary exposure to **radiation** and not cost-effective, especially for individuals without a positive screening test or symptoms.- This strategy also fails to account for the **window period** of TB infection, potentially missing recent exposures that would only become detectable after several weeks. *Interferon-gamma release assay (IGRA) for all contacts immediately with chest X-ray*- While **IGRA** is a valid test for latent TB, **Mantoux test** is often preferred or used in conjunction, especially for initial broad household screening or in children, as per national guidelines like those in the UK (e.g., NICE).- An immediate **chest X-ray for all contacts** without initial screening results or symptoms is not the standard protocol and leads to **over-investigation**. *Chest X-ray for all contacts with Mantoux test only if symptomatic*- Relying solely on a **chest X-ray** and only performing a Mantoux test if symptomatic will miss many cases of **latent TB infection**, which are often asymptomatic but require treatment to prevent active disease.- A **chest X-ray** is primarily used to detect active pulmonary disease and cannot reliably diagnose **latent TB infection** in asymptomatic individuals. *IGRA test for adults and Mantoux test for children, both with immediate chest X-ray*- While differential testing based on age (IGRA for adults, Mantoux for children) can be appropriate, an **immediate chest X-ray for all** without a positive screening test or symptoms is excessive and not guideline-compliant.- This approach also neglects the vital requirement for a **follow-up test at 6 weeks** for those initially testing negative, which is critical for detecting recent seroconversion.
Question 247: A 24-year-old university student presents to the emergency department with a 6-hour history of severe headache, photophobia, neck stiffness, and fever of 39.2°C. On examination, she has a non-blanching purpuric rash on her lower limbs. Blood pressure is 95/60 mmHg and heart rate is 115 bpm. What is the most appropriate immediate management before lumbar puncture?
- A. Administer intravenous ceftriaxone immediately (Correct Answer)
- B. Perform CT head scan first
- C. Administer intravenous dexamethasone first
- D. Obtain blood cultures before any antibiotic administration
- E. Administer intravenous benzylpenicillin and await lumbar puncture results
Explanation: ***Administer intravenous ceftriaxone immediately***- In a patient with suspected **meningococcal meningitis** and **sepsis**, characterized by severe headache, neck stiffness, fever, and a **non-blanching purpuric rash**, immediate administration of empirical antibiotics is critical.- **Ceftriaxone** is a broad-spectrum third-generation cephalosporin and is the recommended first-line empirical antibiotic for suspected bacterial meningitis in adults, providing excellent coverage against *Neisseria meningitidis* and *Streptococcus pneumoniae*.*Perform CT head scan first*- A **CT head scan** before a lumbar puncture is indicated only if there are signs of raised intracranial pressure (e.g., focal neurological deficits, new-onset seizures, severe immunocompromise, papilledema, or significantly depressed level of consciousness), which are not explicitly mentioned as contraindications in this urgent scenario.- Delaying life-saving **antibiotic administration** for a CT scan in a rapidly deteriorating patient with suspected **meningococcal septicaemia** and signs of shock can lead to increased morbidity and mortality.*Administer intravenous dexamethasone first*- **Dexamethasone** is recommended to reduce neurological complications in bacterial meningitis, particularly if *Streptococcus pneumoniae* is suspected. However, it should be given **with or just before** the first dose of antibiotics.- Giving dexamethasone first, without concurrent antibiotics, would delay the most critical intervention for this life-threatening infection, especially in a patient showing signs of **septic shock**.*Obtain blood cultures before any antibiotic administration*- While obtaining **blood cultures** prior to antibiotic administration is generally good practice to identify the causative organism, in cases of suspected **meningococcal disease with sepsis** (evidenced by the purpuric rash and hemodynamic instability), antibiotics should not be delayed.- The priority is immediate treatment to prevent rapid progression and death. Cultures can be drawn quickly, but if there is any delay, antibiotics take precedence.*Administer intravenous benzylpenicillin and await lumbar puncture results*- **Benzylpenicillin** is a narrow-spectrum penicillin and is often used in the pre-hospital setting or by general practitioners if meningococcal disease is highly suspected and ceftriaxone is unavailable. However, in a hospital setting, **ceftriaxone** is preferred due to its broader spectrum of activity and superior penetration of the central nervous system.- Awaiting **lumbar puncture results** before administering antibiotics in a patient with clinical features highly suggestive of bacterial meningitis and sepsis is dangerous and can lead to rapid deterioration and death. The lumbar puncture may be delayed or contraindicated in unstable patients.
Question 248: A 68-year-old man presents with a 3-week history of productive cough, night sweats, and unintentional weight loss of 5 kg. He is a former smoker with a 40 pack-year history. Chest X-ray shows upper lobe cavitation. Sputum smear microscopy reveals acid-fast bacilli. What is the most appropriate initial treatment regimen for this patient?
- A. Rifampicin, isoniazid, pyrazinamide, and ethambutol for 2 months, then rifampicin and isoniazid for 4 months (Correct Answer)
- B. Rifampicin and isoniazid for 6 months
- C. Rifampicin, isoniazid, and pyrazinamide for 6 months
- D. Rifampicin, isoniazid, pyrazinamide, and ethambutol for 6 months
- E. Rifampicin, isoniazid, pyrazinamide, ethambutol, and streptomycin for 2 months, then rifampicin and isoniazid for 10 months
Explanation: ***Rifampicin, isoniazid, pyrazinamide, and ethambutol for 2 months, then rifampicin and isoniazid for 4 months***- This regimen is the **standard initial treatment** for **drug-sensitive active pulmonary tuberculosis**, consisting of a 2-month **intensive phase** (RIPE) followed by a 4-month **continuation phase**.- The four-drug combination is crucial for rapidly reducing the **bacterial load**, preventing **drug resistance**, and effectively treating the cavitary disease observed in the patient. *Rifampicin and isoniazid for 6 months*- This regimen lacks the essential **intensive phase** with pyrazinamide and ethambutol, which is critical for sterilizing lesions and preventing **drug resistance** in active TB.- It is insufficient for treating active **smear-positive pulmonary TB** and would likely lead to treatment failure and increased risk of resistance. *Rifampicin, isoniazid, and pyrazinamide for 6 months*- This regimen omits **ethambutol** from the initial phase, which is important for covering potential **isoniazid resistance** until drug susceptibility results are known.- Continuing **pyrazinamide** for the full 6 months is not standard practice; it is typically used only during the initial 2-month intensive phase due to its potential for **hepatotoxicity**. *Rifampicin, isoniazid, pyrazinamide, and ethambutol for 6 months*- Administering all four drugs (RIPE) for the entire 6 months is not the standard protocol for **drug-sensitive TB** and significantly increases the risk of **adverse drug reactions** like **optic neuritis** (ethambutol) and **hyperuricemia** (pyrazinamide).- Standard protocols transition to a two-drug **continuation phase** after 2 months to minimize toxicity while maintaining efficacy. *Rifampicin, isoniazid, pyrazinamide, ethambutol, and streptomycin for 2 months, then rifampicin and isoniazid for 10 months*- This regimen includes **streptomycin**, an injectable aminoglycoside, which is generally reserved for **multidrug-resistant TB (MDR-TB)** or specific forms of **extrapulmonary TB** due to its **ototoxicity** and **nephrotoxicity**.- A 12-month treatment duration is typically indicated for more complex or resistant cases, such as **TB meningitis**, and is excessively long for standard drug-sensitive pulmonary TB.
Practice by Chapter
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free