Serious & Notifiable Infections — MCQs
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A 55-year-old man with end-stage renal failure on haemodialysis presents with fever, confusion, and neck stiffness. Blood cultures are taken and lumbar puncture is performed. CSF shows: WBC 1200/mm³ (80% neutrophils), protein 1.8 g/L, glucose 2.1 mmol/L (plasma glucose 6.2 mmol/L). Gram stain shows Gram-positive cocci in chains. Which antibiotic regimen provides the most appropriate empirical cover?
According to UK notification requirements, which one of the following clinical scenarios mandates urgent notification to the UK Health Security Agency (UKHSA) by the attending clinician?
A 35-year-old woman from the Philippines presents with a 12-week history of cough, weight loss, and night sweats. Chest X-ray shows bilateral upper zone cavitation. Three sputum samples are smear-positive for acid-fast bacilli. Molecular testing (Xpert MTB/RIF) detects Mycobacterium tuberculosis with rifampicin resistance. What is the most appropriate initial management?
A 22-year-old woman presents with a 10-hour history of severe headache, fever, and photophobia. She has a non-blanching purpuric rash on her legs. Blood cultures are taken and intravenous ceftriaxone is commenced. Lumbar puncture shows: opening pressure 28 cmH₂O, WBC 2400/mm³ (95% neutrophils), protein 2.8 g/L, glucose 1.2 mmol/L (plasma glucose 5.8 mmol/L). Gram stain shows Gram-negative diplococci. Which additional immediate treatment should be given?
A 40-year-old man with newly diagnosed pulmonary tuberculosis is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. After 2 weeks, he develops severe pruritus without rash. His liver function tests and full blood count are normal. What is the most appropriate management?
A 50-year-old man presents with a 6-week history of headache, low-grade fever, and gradually progressive confusion. He has type 2 diabetes mellitus treated with metformin. MRI brain shows basal meningeal enhancement and multiple small tuberculomas. Lumbar puncture shows: opening pressure 32 cmH2O, CSF protein 3.2 g/L, glucose 1.4 mmol/L (plasma 6.8 mmol/L), white cells 145/mm³ (85% lymphocytes). Ziehl-Neelsen stain is negative. CSF is sent for TB culture and GeneXpert. Which additional investigation would be most useful for rapid confirmation of tuberculous meningitis?
A 36-year-old man from Somalia with newly diagnosed HIV infection (CD4 count 110 cells/mm³, viral load 145,000 copies/mL) is diagnosed with disseminated tuberculosis affecting lungs and lymph nodes. Sputum culture confirms fully drug-sensitive Mycobacterium tuberculosis. He is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. When is the most appropriate time to initiate antiretroviral therapy?
A 58-year-old man with a history of splenectomy 10 years ago following trauma presents with a 24-hour history of fever, headache, and confusion. On examination, he has a GCS of 13, temperature 38.9°C, and neck stiffness. CT head shows no contraindications to lumbar puncture. Lumbar puncture reveals: protein 1.8 g/L, glucose 1.6 mmol/L (plasma 5.4 mmol/L), white cells 2400/mm³ (88% neutrophils). Gram stain shows Gram-positive diplococci. Which additional antimicrobial should be added to standard empirical bacterial meningitis therapy for this patient?
A 21-year-old university student presents with a 12-hour history of severe headache, fever, neck stiffness, and photophobia. Blood pressure is 118/75 mmHg, heart rate 102/min, temperature 38.7°C, GCS 15, no focal neurological signs, no rash. CT head is normal. Lumbar puncture shows: opening pressure 24 cmH2O, clear CSF, protein 0.65 g/L, glucose 3.2 mmol/L (plasma 5.8 mmol/L), white cells 380/mm³ (75% lymphocytes). Gram stain is negative. What is the most likely causative organism?
A 34-year-old woman with pulmonary tuberculosis is on treatment with rifampicin, isoniazid, pyrazinamide, and ethambutol. She develops jaundice 4 weeks into treatment. Blood tests show: bilirubin 85 μmol/L, ALT 420 U/L, ALP 180 U/L, INR 1.3. She is clinically well apart from jaundice. Viral hepatitis screen is negative. Which anti-tuberculous medication should be reintroduced first after liver function tests improve?
Serious & Notifiable Infections UK Medical PG Practice Questions and MCQs
Question 101: A 55-year-old man with end-stage renal failure on haemodialysis presents with fever, confusion, and neck stiffness. Blood cultures are taken and lumbar puncture is performed. CSF shows: WBC 1200/mm³ (80% neutrophils), protein 1.8 g/L, glucose 2.1 mmol/L (plasma glucose 6.2 mmol/L). Gram stain shows Gram-positive cocci in chains. Which antibiotic regimen provides the most appropriate empirical cover?
- A. Intravenous ceftriaxone 2 g every 12 hours
- B. Intravenous cefotaxime 2 g every 6 hours and intravenous vancomycin 1 g every 12 hours (Correct Answer)
- C. Intravenous benzylpenicillin 2.4 g every 4 hours and intravenous gentamicin 5 mg/kg once daily
- D. Intravenous meropenem 2 g every 8 hours
- E. Intravenous ceftazidime 2 g every 8 hours and intravenous vancomycin 1 g once daily
Explanation: ***Intravenous cefotaxime 2 g every 6 hours and intravenous vancomycin 1 g every 12 hours***- Empirical treatment for suspected **bacterial meningitis** requires a third-generation cephalosporin and **vancomycin** to provide cover against **penicillin-resistant Streptococcus pneumoniae**.- Gram-positive cocci in chains specifically point toward **Streptococcus species**, and this combination ensures adequate CNS penetration and broad-spectrum coverage for common pathogens.*Intravenous ceftriaxone 2 g every 12 hours*- While ceftriaxone is a standard treatment for meningitis, monotherapy carries the risk of treatment failure if **penicillin-resistant pneumococcus** is the causative agent.- In the setting of **end-stage renal failure**, many clinicians prefer agents with more frequent dosing or specific metabolic profiles, though both cephalosporins require careful monitoring.*Intravenous benzylpenicillin 2.4 g every 4 hours and intravenous gentamicin 5 mg/kg once daily*- **Benzylpenicillin** is insufficient as empirical therapy due to the high global prevalence of **penicillin-resistant S. pneumoniae**.- **Gentamicin** has very poor **penetration into the cerebrospinal fluid (CSF)** and is not indicated for the primary treatment of bacterial meningitis.*Intravenous meropenem 2 g every 8 hours*- Meropenem is generally reserved for **multi-drug resistant** organisms or cases where there are contraindications to cephalosporins.- It does not provide superior coverage compared to the **cefotaxime/vancomycin** combination for community-acquired streptococcal meningitis.*Intravenous ceftazidime 2 g every 8 hours and intravenous vancomycin 1 g once daily*- **Ceftazidime** is primarily utilized for its activity against **Pseudomonas aeruginosa** and has significantly weaker activity against **Gram-positive cocci** like S. pneumoniae.- **Vancomycin** dosing once daily is appropriate for maintenance in **haemodialysis**, but the initial empirical regimen must prioritize the correct choice of cephalosporin for the identified Gram stain.
Question 102: According to UK notification requirements, which one of the following clinical scenarios mandates urgent notification to the UK Health Security Agency (UKHSA) by the attending clinician?
- A. A 45-year-old man with culture-confirmed pulmonary tuberculosis who is smear-negative and clinically improving on treatment
- B. A 28-year-old woman diagnosed with latent tuberculosis infection based on a positive interferon-gamma release assay and normal chest X-ray
- C. A 35-year-old man with suspected bacterial meningitis who has received the first dose of intravenous ceftriaxone in the emergency department (Correct Answer)
- D. A 50-year-old woman with tuberculous lymphadenitis confirmed by biopsy but with negative sputum samples
- E. A 60-year-old man with viral meningitis confirmed by PCR detection of enterovirus in cerebrospinal fluid
Explanation: ***A 35-year-old man with suspected bacterial meningitis who has received the first dose of intravenous ceftriaxone in the emergency department*** - **Suspected bacterial meningitis** is a medical emergency that requires **urgent notification** to the UKHSA based on clinical suspicion, even before laboratory confirmation. - Immediate notification is essential for public health interventions, such as **chemoprophylaxis** for close contacts and managing potential outbreaks. *A 45-year-old man with culture-confirmed pulmonary tuberculosis who is smear-negative and clinically improving on treatment* - While **active pulmonary tuberculosis** is a notifiable disease, it generally requires notification within **three days** rather than the urgent immediate notification required for meningitis. - Being **smear-negative** and clinically improving reduces the immediate public health risk compared to acute bacterial pathogens. *A 28-year-old woman diagnosed with latent tuberculosis infection based on a positive interferon-gamma release assay and normal chest X-ray* - **Latent tuberculosis infection (LTBI)** is not a notifiable condition under UK regulations as there is no active disease and no risk of transmission. - Notification is only required for **active tuberculosis** (pulmonary or extrapulmonary) where clinical symptoms or diagnostic evidence of disease are present. *A 50-year-old woman with tuberculous lymphadenitis confirmed by biopsy but with negative sputum samples* - Extrapulmonary tuberculosis, such as **tuberculous lymphadenitis**, is notifiable but does not carry the same **urgent** timeframe as acute bacterial meningitis. - Since it is non-infectious to others (negative sputum), the public health priority for **contact tracing** is less acute than for meningococcal disease. *A 60-year-old man with viral meningitis confirmed by PCR detection of enterovirus in cerebrospinal fluid* - **Viral meningitis** is generally not a notifiable disease unless it is caused by a specific notifiable pathogen like **measles**, **mumps**, or **poliovirus**. - Enteroviral meningitis, while clinically significant for the patient, does not trigger the same **statutory notification** requirements as bacterial meningitis.
Question 103: A 35-year-old woman from the Philippines presents with a 12-week history of cough, weight loss, and night sweats. Chest X-ray shows bilateral upper zone cavitation. Three sputum samples are smear-positive for acid-fast bacilli. Molecular testing (Xpert MTB/RIF) detects Mycobacterium tuberculosis with rifampicin resistance. What is the most appropriate initial management?
- A. Start standard four-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol) pending full culture sensitivities
- B. Start modified therapy with isoniazid, pyrazinamide, ethambutol, and moxifloxacin, and refer urgently to MDR-TB specialist service (Correct Answer)
- C. Start five-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol, streptomycin) at higher doses
- D. Wait for full culture and sensitivity results before starting any treatment
- E. Start standard four-drug therapy and add rifabutin to replace rifampicin
Explanation: ***Start modified therapy with isoniazid, pyrazinamide, ethambutol, and moxifloxacin, and refer urgently to MDR-TB specialist service*** - Detection of **rifampicin resistance** by **Xpert MTB/RIF** indicates likely **Multidrug-Resistant TB (MDR-TB)**, necessitating immediate consultation with a specialist.- A **fluoroquinolone (moxifloxacin)** is essential to replace rifampicin in the initial regimen for suspected MDR-TB, alongside other effective first-line drugs like isoniazid, pyrazinamide, and ethambutol (if susceptible).*Start standard four-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol) pending full culture sensitivities* - The **Xpert MTB/RIF** test has already identified **rifampicin resistance**, making the standard rifampicin-containing regimen ineffective and inappropriate.- Administering **rifampicin** when resistance is known could lead to treatment failure and potentially foster further drug resistance.*Start five-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol, streptomycin) at higher doses* - This option still includes **rifampicin**, which is ineffective due to confirmed resistance, and simply increasing its dose does not overcome this.- **Streptomycin** is not typically added as a primary countermeasure for rifampicin resistance and does not constitute appropriate initial MDR-TB therapy in this context.*Wait for full culture and sensitivity results before starting any treatment* - The patient has active, **smear-positive pulmonary TB** with cavitation and is highly infectious, demanding immediate therapeutic intervention to prevent disease progression and transmission.- **Xpert MTB/RIF** provides rapid, reliable results for **rifampicin resistance**, allowing for prompt initiation of an effective modified regimen without delay.*Start standard four-drug therapy and add rifabutin to replace rifampicin* - There is significant **cross-resistance** between **rifampicin** and **rifabutin**, meaning that if rifampicin is resistant, rifabutin is highly likely to be resistant as well.- Replacing rifampicin with rifabutin in the context of detected rifampicin resistance is an ineffective strategy and delays proper **MDR-TB** treatment.
Question 104: A 22-year-old woman presents with a 10-hour history of severe headache, fever, and photophobia. She has a non-blanching purpuric rash on her legs. Blood cultures are taken and intravenous ceftriaxone is commenced. Lumbar puncture shows: opening pressure 28 cmH₂O, WBC 2400/mm³ (95% neutrophils), protein 2.8 g/L, glucose 1.2 mmol/L (plasma glucose 5.8 mmol/L). Gram stain shows Gram-negative diplococci. Which additional immediate treatment should be given?
- A. Intravenous dexamethasone 10 mg every 6 hours for 4 days (Correct Answer)
- B. Intravenous aciclovir 10 mg/kg every 8 hours
- C. Intramuscular benzylpenicillin 1.2 g stat dose
- D. Intravenous vancomycin 1 g every 12 hours
- E. Intravenous immunoglobulin 2 g/kg over 5 days
Explanation: ***Intravenous dexamethasone 10 mg every 6 hours for 4 days***- This patient's presentation with headache, fever, photophobia, a non-blanching purpuric rash, and CSF findings with Gram-negative diplococci is highly suggestive of **bacterial meningitis**, specifically **meningococcal meningitis**.- **Dexamethasone** is a crucial **adjunctive therapy** in bacterial meningitis, particularly when administered **before or concurrently with antibiotics**, to reduce inflammation and prevent complications such as **hearing loss** and other neurological sequelae.*Intravenous aciclovir 10 mg/kg every 8 hours*- **Aciclovir** is an **antiviral medication** primarily used for **herpes simplex encephalitis** or other severe viral infections of the CNS.- The **CSF analysis** (high white blood cells with neutrophil predominance, low glucose) and positive **Gram stain** for **Gram-negative diplococci** definitively indicate a **bacterial infection**, not a viral one.*Intramuscular benzylpenicillin 1.2 g stat dose*- **Intramuscular benzylpenicillin** is a common **pre-hospital** antibiotic given by emergency services or GPs for suspected **meningococcal disease** to initiate early treatment.- Since the patient is already receiving **intravenous ceftriaxone**, a powerful third-generation cephalosporin, an additional stat dose of penicillin is **superfluous** and not part of the standard in-hospital management.*Intravenous vancomycin 1 g every 12 hours*- **Vancomycin** is typically added to empiric meningitis regimens when there is a high suspicion of **penicillin-resistant *Streptococcus pneumoniae*** or other resistant Gram-positive organisms.- The **Gram stain result** showing **Gram-negative diplococci** (most likely *Neisseria meningitidis*) makes vancomycin unnecessary as ceftriaxone is highly effective against this pathogen.*Intravenous immunoglobulin 2 g/kg over 5 days*- **Intravenous immunoglobulin (IVIG)** is used for immune deficiencies, autoimmune conditions, or certain severe infections complicated by immune dysregulation, such as toxic shock syndrome.- There is **no established role** for **IVIG** in the immediate management of acute **bacterial meningitis** to alter its course or prevent neurological complications.
Question 105: A 40-year-old man with newly diagnosed pulmonary tuberculosis is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. After 2 weeks, he develops severe pruritus without rash. His liver function tests and full blood count are normal. What is the most appropriate management?
- A. Continue all medications and add oral antihistamines (Correct Answer)
- B. Stop all tuberculosis medications immediately and refer to specialist
- C. Replace pyrazinamide with levofloxacin
- D. Replace rifampicin with rifabutin
- E. Stop ethambutol and continue with three-drug therapy
Explanation: ***Continue all medications and add oral antihistamines*** - **Pruritus without rash** is a common minor side effect, particularly associated with **rifampicin**, and does not mandate treatment interruption if **liver function tests (LFTs)** are normal. - The most appropriate management is **symptomatic relief** using **antihistamines**, allowing the patient to continue the essential intensive-phase regimen. *Stop all tuberculosis medications immediately and refer to specialist* - This approach is reserved for severe reactions such as **drug-induced liver injury (DILI)**, **Stevens-Johnson Syndrome**, or a generalized **toxic rash**. - Since the patient has **normal LFTs** and no rash, stopping all four drugs unnecessarily risks **treatment failure** and the development of **drug resistance**. *Replace pyrazinamide with levofloxacin* - **Pyrazinamide** is often the culprit for arthralgia or hepatotoxicity, but it is not specifically indicated for replacement in isolated pruritis with normal LFTs. - Modifying the standard **first-line therapy** is not recommended for minor side effects that can be managed conservatively. *Replace rifampicin with rifabutin* - **Rifampicin** induces minor skin itching, but replacing it with **rifabutin** is typically reserved for patients with severe intolerance or specific **drug-drug interactions** (e.g., in HIV patients). - Both drugs are in the same class and may share side-effect profiles; switching is premature without evidence of a severe **hypersensitivity reaction**. *Stop ethambutol and continue with three-drug therapy* - **Ethambutol** is primarily associated with **optic neuritis** rather than dermatological side effects or itching. - Reducing the regimen to a **three-drug therapy** during the intensive phase without a clinical indication compromises the sterilization of the infection.
Question 106: A 50-year-old man presents with a 6-week history of headache, low-grade fever, and gradually progressive confusion. He has type 2 diabetes mellitus treated with metformin. MRI brain shows basal meningeal enhancement and multiple small tuberculomas. Lumbar puncture shows: opening pressure 32 cmH2O, CSF protein 3.2 g/L, glucose 1.4 mmol/L (plasma 6.8 mmol/L), white cells 145/mm³ (85% lymphocytes). Ziehl-Neelsen stain is negative. CSF is sent for TB culture and GeneXpert. Which additional investigation would be most useful for rapid confirmation of tuberculous meningitis?
- A. CSF adenosine deaminase level (Correct Answer)
- B. Repeat lumbar puncture for larger volume CSF analysis
- C. Serum interferon-gamma release assay
- D. CSF lactate level
- E. Tuberculin skin test
Explanation: ***CSF adenosine deaminase level***- The clinical presentation, MRI findings of **basal meningeal enhancement** and **tuberculomas**, and CSF analysis (high protein, low glucose, lymphocytosis) are highly suggestive of **tuberculous meningitis (TBM)**. - **CSF Adenosine Deaminase (ADA)** is a rapid, highly sensitive, and specific biochemical marker for TBM, produced by activated T-lymphocytes, and can provide quick confirmation when conventional methods like **Ziehl-Neelsen stain** and **GeneXpert** may be negative or delayed.*Repeat lumbar puncture for larger volume CSF analysis*- While a larger volume of CSF can improve the yield for **acid-fast bacilli (AFB) smear** and culture, it is not a *rapid* diagnostic method as cultures take weeks to grow.- Given the **elevated intracranial pressure (32 cmH2O)** and the presence of **tuberculomas**, a repeat lumbar puncture carries inherent risks and would not provide immediate diagnostic confirmation.*Serum interferon-gamma release assay*- **Interferon-gamma release assays (IGRAs)**, such as QuantiFERON-TB Gold, detect a prior immune response to *Mycobacterium tuberculosis* but cannot distinguish between **latent TB infection** and **active disease**.- A positive IGRA indicates exposure to TB but does not confirm **tuberculous meningitis** as the cause of the patient's current neurological symptoms.*CSF lactate level*- **CSF lactate** is a non-specific marker of anaerobic metabolism that can be elevated in various forms of meningitis, including bacterial, fungal, and sometimes TBM.- It lacks the specificity to *rapidly confirm* **tuberculous meningitis** over other infectious or inflammatory causes of meningeal enhancement in this clinical context.*Tuberculin skin test*- The **tuberculin skin test (TST)** or **Mantoux test** has limited sensitivity in acute TBM, with false negatives occurring in up to 50% of active cases, particularly in patients with **anergy** or immunosuppression.- It is also a delayed test, requiring 48-72 hours for interpretation, thus not qualifying as a **rapid investigation** for urgent diagnosis.
Question 107: A 36-year-old man from Somalia with newly diagnosed HIV infection (CD4 count 110 cells/mm³, viral load 145,000 copies/mL) is diagnosed with disseminated tuberculosis affecting lungs and lymph nodes. Sputum culture confirms fully drug-sensitive Mycobacterium tuberculosis. He is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. When is the most appropriate time to initiate antiretroviral therapy?
- A. Immediately, concurrently with anti-tuberculous therapy
- B. After 2 weeks of anti-tuberculous therapy (Correct Answer)
- C. After 2 months of anti-tuberculous therapy
- D. After completion of the initial intensive phase and continuation phase of TB treatment
- E. Wait until TB treatment is completed before starting antiretroviral therapy
Explanation: ***After 2 weeks of anti-tuberculous therapy*** - In patients with **CD4 counts <50 cells/mm³**, ART should be started within 2 weeks; for those with **CD4 <200 cells/mm³**, evidence supports early initiation (within 2-8 weeks) to reduce **mortality**. - Given the patient's low CD4 count (110 cells/mm³), early initiation balances the prevention of further **opportunistic infections** against the risk of **Immune Reconstitution Inflammatory Syndrome (IRIS)**. *Immediately, concurrently with anti-tuberculous therapy* - Starting both regimens on the same day is avoided to establish tolerance to **anti-tuberculous drugs** and clarify the cause of any potential **adverse drug reactions**. - Immediate start significantly increases the **pill burden** and the risk of severe **overlap toxicities** before the patient is stable. *After 2 months of anti-tuberculous therapy* - Delaying ART until the end of the **intensive phase** (2 months) is only considered in patients with higher CD4 counts (>500 cells/mm³) to avoid **drug-drug interactions**. - In advanced HIV (CD4 110), waiting 8 weeks significantly increases the risk of **AIDS-defining illnesses** and death compared to earlier initiation. *After completion of the initial intensive phase and continuation phase of TB treatment* - This approach is incorrect as it leaves the patient **severely immunosuppressed** for the entire 6-month duration of TB therapy. - Waiting this long for a patient with a **viral load of 145,000** and low CD4 count would lead to unacceptably high **mortality rates**. *Wait until TB treatment is completed before starting antiretroviral therapy* - Delaying ART until TB is fully cured is contraindicated in almost all **HIV/TB co-infection** cases regardless of CD4 count. - Long-term outcomes are significantly worse when **HIV replication** is left unchecked for the duration of a 6-9 month TB treatment course.
Question 108: A 58-year-old man with a history of splenectomy 10 years ago following trauma presents with a 24-hour history of fever, headache, and confusion. On examination, he has a GCS of 13, temperature 38.9°C, and neck stiffness. CT head shows no contraindications to lumbar puncture. Lumbar puncture reveals: protein 1.8 g/L, glucose 1.6 mmol/L (plasma 5.4 mmol/L), white cells 2400/mm³ (88% neutrophils). Gram stain shows Gram-positive diplococci. Which additional antimicrobial should be added to standard empirical bacterial meningitis therapy for this patient?
- A. Vancomycin (Correct Answer)
- B. Ampicillin
- C. Gentamicin
- D. Metronidazole
- E. Azithromycin
Explanation: ***Vancomycin***- The patient's history of **splenectomy** places him at high risk for overwhelming post-splenectomy infection (OPSI), particularly from **encapsulated bacteria** like **Streptococcus pneumoniae**. The **Gram-positive diplococci** on Gram stain strongly suggest this pathogen.- **Vancomycin** is crucial to add to standard empirical meningitis therapy (typically a third-generation cephalosporin like ceftriaxone) because of the high prevalence of **penicillin-resistant Streptococcus pneumoniae**, especially in high-risk patients such as those who are asplenic.*Ampicillin*- This antibiotic is primarily added to empirical meningitis regimens to cover **Listeria monocytogenes**, which is a concern in specific populations like those over 50 years old, pregnant, or immunocompromised.- However, **Listeria** typically appears as **Gram-positive rods** or coccobacilli, which does not match the **Gram-positive diplococci** found in this patient's CSF, making it a less likely pathogen here.*Gentamicin*- **Gentamicin** is an **aminoglycoside antibiotic** primarily used for Gram-negative bacterial infections or for synergistic treatment in some Gram-positive infections like endocarditis.- It has **poor penetration into the central nervous system (CNS)** and is therefore not indicated as an additional agent for empirical treatment of bacterial meningitis, especially for suspected **Streptococcus pneumoniae**.*Metronidazole*- **Metronidazole** is highly effective against **anaerobic bacteria** and some parasites, and it is commonly used for conditions like brain abscesses, not for acute bacterial meningitis from typical pathogens.- It has **no significant activity** against the common bacterial causes of community-acquired meningitis, such as **Streptococcus pneumoniae**.*Azithromycin*- **Azithromycin** is a **macrolide antibiotic** typically used for atypical respiratory infections, certain sexually transmitted diseases, or other specific bacterial infections.- It does not achieve sufficient **cerebrospinal fluid (CSF) concentrations** and lacks reliable activity against **Streptococcus pneumoniae**, particularly against resistant strains, making it unsuitable for treating acute bacterial meningitis.
Question 109: A 21-year-old university student presents with a 12-hour history of severe headache, fever, neck stiffness, and photophobia. Blood pressure is 118/75 mmHg, heart rate 102/min, temperature 38.7°C, GCS 15, no focal neurological signs, no rash. CT head is normal. Lumbar puncture shows: opening pressure 24 cmH2O, clear CSF, protein 0.65 g/L, glucose 3.2 mmol/L (plasma 5.8 mmol/L), white cells 380/mm³ (75% lymphocytes). Gram stain is negative. What is the most likely causative organism?
- A. Enterovirus (Correct Answer)
- B. Streptococcus pneumoniae
- C. Neisseria meningitidis
- D. Listeria monocytogenes
- E. Herpes simplex virus
Explanation: ***Enterovirus*** - The CSF profile showing **lymphocytic pleocytosis** (75% lymphocytes), **normal CSF glucose** (ratio 0.55, typically > 0.5), and mildly elevated protein is highly characteristic of **viral (aseptic) meningitis**. - **Enteroviruses** are the most common cause of viral meningitis in young adults and typically present with acute meningeal symptoms without focal neurological deficits or rash, matching this patient's presentation. *Streptococcus pneumoniae* - **Bacterial meningitis**, including that caused by *S. pneumoniae*, typically presents with **neutrophilic pleocytosis** (> 80% neutrophils), significantly **low CSF glucose** (often < 40% of plasma glucose), and markedly elevated protein. - The presence of predominant lymphocytes and normal glucose in the CSF strongly argues against *S. pneumoniae* as the causative agent here. *Neisseria meningitidis* - While common in university students, *N. meningitidis* usually causes **bacterial meningitis** with a more fulminant course and frequently presents with a **petechial rash**, which is absent in this patient. - CSF findings would typically include a high white cell count with a significant **neutrophil predominance** and **low CSF glucose**, unlike the lymphocytic picture and normal glucose seen. *Listeria monocytogenes* - *Listeria monocytogenes* meningitis is primarily seen in specific vulnerable populations: **neonates**, **elderly** (> 60 years), pregnant women, and **immunocompromised** individuals. This 21-year-old healthy student does not fit these risk factors. - Although Listeria can sometimes cause a mixed or even lymphocytic CSF pleocytosis, the patient's demographic and clear presentation for typical viral meningitis make it less likely. *Herpes simplex virus* - While **HSV-2** can cause recurrent lymphocytic meningitis, **HSV-1** typically causes **encephalitis**, which is characterized by altered mental status, focal neurological deficits, or seizures, none of which are present in this patient (GCS 15, no focal signs). - The clinical picture of classic meningeal irritation without encephalopathy, coupled with a benign GCS and clear CSF, makes an enterovirus more probable than HSV.
Question 110: A 34-year-old woman with pulmonary tuberculosis is on treatment with rifampicin, isoniazid, pyrazinamide, and ethambutol. She develops jaundice 4 weeks into treatment. Blood tests show: bilirubin 85 μmol/L, ALT 420 U/L, ALP 180 U/L, INR 1.3. She is clinically well apart from jaundice. Viral hepatitis screen is negative. Which anti-tuberculous medication should be reintroduced first after liver function tests improve?
- A. Ethambutol (Correct Answer)
- B. Rifampicin
- C. Isoniazid
- D. Pyrazinamide
- E. All four drugs should be reintroduced simultaneously at reduced doses
Explanation: ***Ethambutol*** - **Ethambutol** is not considered hepatotoxic and is often continued or the first to be reintroduced because it does not contribute to **drug-induced liver injury (DILI)**. - According to standard guidelines, once **transaminases** fall below 2 times the upper limit of normal, drugs are reintroduced sequentially starting with the agent least likely to cause further liver damage. *Rifampicin* - **Rifampicin** is typically reintroduced second (after ethambutol) because it is the most critical bactericidal component of the regimen despite being potentially **hepatotoxic**. - It is less likely to cause a significant rise in **ALT** compared to isoniazid or pyrazinamide, although it may cause **transient cholestasis**. *Isoniazid* - **Isoniazid** is usually reintroduced third, as it is a common cause of **idiosyncratic hepatotoxicity** and requires careful monitoring of liver enzymes upon restart. - If a reaction occurs during its reintroduction, it identifies isoniazid as the **culprit drug**, requiring a modification of the long-term treatment plan. *Pyrazinamide* - **Pyrazinamide** is the most **hepatotoxic** of the first-line drugs and is therefore reintroduced last or omitted entirely if the previous drugs were tolerated. - Due to its high risk of causing severe **liver injury**, many clinicians avoid reintroducing it if the initial hepatitis was clinically significant (jaundice or high ALT). *All four drugs should be reintroduced simultaneously at reduced doses* - Simultaneous reintroduction is contraindicated because it prevents the identification of the specific **offending agent** that caused the hepatitis. - A **sequential reintroduction** strategy with a 3–7 day gap between drugs is the standard of care to ensure patient safety and **regimen tolerability**.
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