Serious & Notifiable Infections — MCQs
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A 19-year-old previously healthy university student is admitted with suspected meningococcal meningitis and treated with IV ceftriaxone. Blood cultures grow Neisseria meningitidis serogroup W. He makes a full recovery. His flatmates (5 students) are concerned about their risk. What is the most appropriate chemoprophylaxis for the close contacts?
A 58-year-old man with diabetes mellitus presents with a 7-week history of cough, weight loss, and night sweats. Chest X-ray shows right upper lobe consolidation with cavitation. Sputum microscopy shows acid-fast bacilli. Sputum GeneXpert MTB/RIF detects Mycobacterium tuberculosis with rifampicin resistance. Culture and sensitivity are pending. What is the most appropriate initial management?
A 65-year-old woman with chronic lymphocytic leukaemia on ibrutinib presents with a 4-day history of fever, headache, and drowsiness. She is confused and has neck stiffness. Lumbar puncture shows: CSF white cells 120/mm³ (70% lymphocytes, 30% neutrophils), protein 0.9 g/L, glucose 2.8 mmol/L (plasma glucose 5.4 mmol/L). Gram stain is negative. Urgent CSF PCR is positive for Listeria monocytogenes. What is the most appropriate antibiotic therapy?
A 47-year-old man from Nepal presents with a 6-week history of fever, headache, and progressive confusion. MRI brain shows ring-enhancing lesions in the basal ganglia. Lumbar puncture shows: opening pressure 25 cmH2O, CSF clear with 180 white cells/mm³ (80% lymphocytes), protein 1.2 g/L, glucose 1.9 mmol/L (plasma glucose 5.5 mmol/L). Ziehl-Neelsen stain is negative. What is the most appropriate next investigation to confirm the diagnosis?
A 27-year-old man presents to the emergency department with a 14-hour history of headache, fever, photophobia, and vomiting. He is confused with a GCS of 13. Blood pressure is 110/70 mmHg. There is no rash. CT head is normal. Lumbar puncture shows: opening pressure 32 cmH2O, CSF cloudy with 2400 white cells/mm³ (90% neutrophils), protein 2.4 g/L, glucose 1.5 mmol/L (plasma glucose 6.0 mmol/L). He has already received IV ceftriaxone. What additional immediate treatment should be given?
A 32-year-old pregnant woman at 24 weeks gestation develops tuberculous meningitis. CT head shows basal meningeal enhancement and hydrocephalus. Which anti-tuberculosis drug regimen is most appropriate for initial management?
A 5-year-old girl is brought to the emergency department with fever, headache, and neck stiffness. She received her routine childhood vaccinations. Lumbar puncture shows: opening pressure 28 cmH2O, CSF white cells 850/mm³ (95% polymorphs), protein 1.8 g/L, glucose 1.8 mmol/L (plasma glucose 5.2 mmol/L). Gram stain shows Gram-positive diplococci. What is the most likely explanation for this infection occurring despite vaccination?
A 38-year-old woman with systemic lupus erythematosus on prednisolone 20 mg daily presents with a 5-week history of cough, night sweats, and weight loss. Chest X-ray shows bilateral upper lobe consolidation with cavitation. Three sputum samples are AFB-positive. Which additional investigation should be performed before starting anti-tuberculosis therapy?
A 15-year-old boy presents with a 12-hour history of fever, severe headache, and vomiting. He has a non-blanching purpuric rash on his trunk and lower limbs. His blood pressure is 85/50 mmHg and heart rate is 128 bpm. Which organism is the most likely causative agent?
A 42-year-old man with pulmonary tuberculosis is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. After 3 weeks of treatment, he develops painful, red eyes with photophobia and blurred vision. Examination reveals bilateral anterior uveitis. Which medication is most likely responsible for this adverse effect?
Serious & Notifiable Infections UK Medical PG Practice Questions and MCQs
Question 151: A 19-year-old previously healthy university student is admitted with suspected meningococcal meningitis and treated with IV ceftriaxone. Blood cultures grow Neisseria meningitidis serogroup W. He makes a full recovery. His flatmates (5 students) are concerned about their risk. What is the most appropriate chemoprophylaxis for the close contacts?
- A. Single dose of intramuscular ceftriaxone 250 mg
- B. Oral ciprofloxacin 500 mg single dose (Correct Answer)
- C. Oral rifampicin 600 mg twice daily for 2 days
- D. No chemoprophylaxis required as the patient received ceftriaxone
- E. Oral azithromycin 500 mg single dose
Explanation: ***Oral ciprofloxacin 500 mg single dose***- A **single dose of oral ciprofloxacin** is the **first-line choice** for **meningococcal chemoprophylaxis** in close contacts due to its high efficacy in eradicating **nasopharyngeal carriage** of *Neisseria meningitidis*.- Its single-dose regimen improves **compliance** and convenience, making it ideal for managing close contacts like flatmates.*Single dose of intramuscular ceftriaxone 250 mg*- While **ceftriaxone** is effective for prophylaxis, the **intramuscular route** is generally reserved for specific populations, such as **pregnant women** or children, or when oral options are not feasible.- For healthy adult contacts, an oral agent is preferred due to its **less invasive** nature and ease of administration.*Oral rifampicin 600 mg twice daily for 2 days*- **Rifampicin** requires a **multi-dose regimen** (four doses over two days), which can lead to **reduced compliance** compared to single-dose options.- It also has a greater potential for **drug interactions** (due to CYP450 induction) and causes harmless but distinctive **orange discoloration** of body fluids.*No chemoprophylaxis required as the patient received ceftriaxone*- The **treatment of the index patient** with ceftriaxone successfully treats their infection but does not eliminate the risk for **close contacts** who may already be asymptomatically colonized.- **Chemoprophylaxis** aims to eradicate carriage in contacts to prevent secondary cases and stop further transmission within the close-contact group.*Oral azithromycin 500 mg single dose*- **Azithromycin** is an alternative agent for **meningococcal chemoprophylaxis**, particularly in situations where resistance to other first-line agents is a concern or when there are contraindications.- However, it is not consistently the **primary recommended agent** over ciprofloxacin in all national guidelines for routine prophylaxis of *Neisseria meningitidis* close contacts.
Question 152: A 58-year-old man with diabetes mellitus presents with a 7-week history of cough, weight loss, and night sweats. Chest X-ray shows right upper lobe consolidation with cavitation. Sputum microscopy shows acid-fast bacilli. Sputum GeneXpert MTB/RIF detects Mycobacterium tuberculosis with rifampicin resistance. Culture and sensitivity are pending. What is the most appropriate initial management?
- A. Start standard four-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol) and adjust when sensitivities available
- B. Start rifampicin, isoniazid, pyrazinamide, ethambutol, and add moxifloxacin as fifth drug
- C. Refer immediately to specialist TB service and start MDR-TB regimen (Correct Answer)
- D. Await full culture and sensitivity results before starting treatment
- E. Start isoniazid, pyrazinamide, ethambutol, and moxifloxacin (omit rifampicin only)
Explanation: ***Refer immediately to specialist TB service and start MDR-TB regimen*** - The detection of **rifampicin resistance** by **GeneXpert MTB/RIF** indicates a high likelihood of **multidrug-resistant tuberculosis (MDR-TB)**, requiring urgent specialist consultation and initiation of an appropriate regimen. - MDR-TB regimens are complex, involve **second-line anti-TB drugs**, and must be tailored by specialists to ensure efficacy and prevent further resistance. *Start standard four-drug therapy (rifampicin, isoniazid, pyrazinamide, ethambutol) and adjust when sensitivities available* - Starting a regimen that includes **rifampicin** when molecular testing has already confirmed resistance will lead to **treatment failure** and could worsen drug resistance. - Standard therapy is inappropriate for suspected **MDR-TB** and would not effectively treat the patient, allowing disease progression and transmission. *Start rifampicin, isoniazid, pyrazinamide, ethambutol, and add moxifloxacin as fifth drug* - Including **rifampicin** in the regimen is ineffective given the confirmed resistance, and adding a single drug to a failing regimen is a common cause of **acquired drug resistance**. - Management of confirmed or suspected **MDR-TB** requires a comprehensive, specifically designed regimen involving multiple effective second-line agents, not merely augmenting a failing first-line regimen. *Await full culture and sensitivity results before starting treatment* - Delaying treatment in a patient with active, **sputum AFB-positive**, and **cavitary pulmonary TB** increases the risk of disease progression, poor outcomes, and transmission to others. - **GeneXpert** provides rapid and reliable detection of *M. tuberculosis* and **rifampicin resistance**, which is sufficient to initiate empirical **MDR-TB treatment** while awaiting phenotypic sensitivities. *Start isoniazid, pyrazinamide, ethambutol, and moxifloxacin (omit rifampicin only)* - While rifampicin is omitted, **rifampicin resistance** often correlates with **isoniazid resistance**, making this an inadequate regimen for probable **MDR-TB**. - This regimen lacks the necessary number and types of **effective second-line drugs** required for treating MDR-TB and should not be initiated without specialist guidance.
Question 153: A 65-year-old woman with chronic lymphocytic leukaemia on ibrutinib presents with a 4-day history of fever, headache, and drowsiness. She is confused and has neck stiffness. Lumbar puncture shows: CSF white cells 120/mm³ (70% lymphocytes, 30% neutrophils), protein 0.9 g/L, glucose 2.8 mmol/L (plasma glucose 5.4 mmol/L). Gram stain is negative. Urgent CSF PCR is positive for Listeria monocytogenes. What is the most appropriate antibiotic therapy?
- A. IV ceftriaxone
- B. IV amoxicillin and gentamicin (Correct Answer)
- C. IV vancomycin and ceftriaxone
- D. IV meropenem
- E. IV co-trimoxazole
Explanation: ***IV amoxicillin and gentamicin*** - High-dose **IV amoxicillin** (or ampicillin) is the treatment of choice for **Listeria monocytogenes** because the organism is naturally resistant to cephalosporins. - **Gentamicin** is added for its **synergistic effect**, enhancing bactericidal activity, which is crucial in treating **meningitis**, especially in immunocompromised patients like this one with CLL on ibrutinib. *IV ceftriaxone* - **Listeria** is inherently **resistant** to all generations of cephalosporins, including **ceftriaxone**, making it an ineffective monotherapy for *Listeria* meningitis. - While ceftriaxone covers common meningitis pathogens like *N. meningitidis* and *S. pneumoniae*, it must be combined with ampicillin or amoxicillin in at-risk groups (elderly, immunocompromised) to ensure *Listeria* coverage. *IV vancomycin and ceftriaxone* - This combination is standard **empiric therapy** for community-acquired bacterial meningitis to cover resistant *S. pneumoniae* and *N. meningitidis*, but it lacks appropriate activity against **Listeria**. - **Vancomycin** has poor central nervous system penetration and suboptimal clinical efficacy against *Listeria* compared to penicillins. *IV meropenem* - Although **meropenem** has some in vitro activity against *Listeria*, it is not considered the first-line gold standard for confirmed *Listeria* meningitis. - It is usually reserved for patients with severe allergies to penicillins or those with co-infections involving **extended-spectrum beta-lactamase (ESBL)**-producing organisms. *IV co-trimoxazole* - **Co-trimoxazole** (Trimethoprim-sulfamethoxazole) is an effective alternative for treating *Listeria* infections, particularly in patients with a severe **penicillin allergy**. - However, it remains a **second-line** option compared to the established efficacy and safety profile of high-dose amoxicillin/ampicillin for **Listeria meningitis**.
Question 154: A 47-year-old man from Nepal presents with a 6-week history of fever, headache, and progressive confusion. MRI brain shows ring-enhancing lesions in the basal ganglia. Lumbar puncture shows: opening pressure 25 cmH2O, CSF clear with 180 white cells/mm³ (80% lymphocytes), protein 1.2 g/L, glucose 1.9 mmol/L (plasma glucose 5.5 mmol/L). Ziehl-Neelsen stain is negative. What is the most appropriate next investigation to confirm the diagnosis?
- A. CSF auramine stain
- B. Repeat Ziehl-Neelsen stain on larger CSF volume
- C. CSF GeneXpert MTB/RIF (Correct Answer)
- D. CSF culture on Löwenstein-Jensen medium
- E. Serum tuberculosis interferon-gamma release assay
Explanation: ***CSF GeneXpert MTB/RIF*** - This is the most appropriate next step because it is a **rapid molecular diagnostic test** with significantly higher sensitivity than microscopy for **tuberculous meningitis (TBM)**, especially in endemic regions like Nepal. - It provides results within hours and can simultaneously detect **rifampicin resistance**, which is crucial for initiating appropriate treatment early in this subacute presentation with concerning CSF findings and ring-enhancing lesions. *CSF auramine stain* - While slightly more sensitive than **Ziehl-Neelsen stain**, it still relies on a high bacterial load and often yields **false negatives** in paucibacillary conditions like TBM. - It does not offer the same diagnostic yield or drug sensitivity information provided by **nucleic acid amplification tests** like GeneXpert. *Repeat Ziehl-Neelsen stain on larger CSF volume* - Although repeating the stain on a **large volume (at least 6ml)** can marginally increase yield, the sensitivity remains poor (often below 20%) compared to molecular methods for TBM. - This approach is time-consuming and labor-intensive, delaying more definitive diagnostic methods like the **GeneXpert** which offers both speed and improved sensitivity. *CSF culture on Löwenstein-Jensen medium* - This remains the **gold standard** for confirming Mycobacterium tuberculosis; however, results take **4 to 8 weeks** to grow, which is too slow for acute management. - Due to the high mortality and morbidity of TBM, waiting for culture results is not appropriate for immediate clinical decision-making and diagnostic confirmation. *Serum tuberculosis interferon-gamma release assay* - A positive **IGRA (e.g., QuantiFERON)** merely indicates prior exposure to M. tuberculosis and cannot distinguish between **latent infection** and active central nervous system disease like TBM. - While it has a high **negative predictive value** for active TB, it lacks the specificity and diagnostic power to confirm active TBM in a patient with acute neurological symptoms.
Question 155: A 27-year-old man presents to the emergency department with a 14-hour history of headache, fever, photophobia, and vomiting. He is confused with a GCS of 13. Blood pressure is 110/70 mmHg. There is no rash. CT head is normal. Lumbar puncture shows: opening pressure 32 cmH2O, CSF cloudy with 2400 white cells/mm³ (90% neutrophils), protein 2.4 g/L, glucose 1.5 mmol/L (plasma glucose 6.0 mmol/L). He has already received IV ceftriaxone. What additional immediate treatment should be given?
- A. Intrathecal gentamicin
- B. IV dexamethasone (Correct Answer)
- C. IV aciclovir
- D. IV vancomycin
- E. IV meropenem
Explanation: ***IV dexamethasone*** - Adjunctive **IV dexamethasone** is crucial in confirmed or highly suspected **bacterial meningitis** to reduce cerebral inflammation, prevent neurological complications like hearing loss, and improve survival. - It should be administered shortly before or concurrently with the first dose of antibiotics to be most effective, especially against *Streptococcus pneumoniae*. *Intrathecal gentamicin* - **Intrathecal antibiotics** are not a standard empirical treatment for bacterial meningitis and carry significant risks, including neurotoxicity and arachnoiditis. - Gentamicin has poor penetration into the CSF when given intravenously and is not typically used as first-line for meningitis, let alone intrathecally. *IV aciclovir* - **IV aciclovir** is the primary treatment for suspected **herpes simplex encephalitis**, which is a viral infection. - The patient's CSF profile (high **neutrophils**, low **glucose**) is highly indicative of bacterial, not viral, meningitis, which typically shows lymphocytic predominance and normal glucose. *IV vancomycin* - **IV vancomycin** is added to ceftriaxone only if there is a high prevalence of **penicillin-resistant *S. pneumoniae*** in the region, or in patients with specific risk factors like recent neurosurgery or severe penicillin allergy. - In a previously healthy young adult without such risk factors, ceftriaxone alone is generally considered sufficient initial empirical coverage for common bacterial pathogens. *IV meropenem* - **IV meropenem** is a broad-spectrum carbapenem reserved for cases with suspected **multidrug-resistant organisms**, severe penicillin allergy, or when first-line therapies like ceftriaxone fail. - There is no specific indication in this case for meropenem over ceftriaxone, which has already been administered and is appropriate for common community-acquired meningitis pathogens.
Question 156: A 32-year-old pregnant woman at 24 weeks gestation develops tuberculous meningitis. CT head shows basal meningeal enhancement and hydrocephalus. Which anti-tuberculosis drug regimen is most appropriate for initial management?
- A. Rifampicin, isoniazid, pyrazinamide, and ethambutol (Correct Answer)
- B. Rifampicin, isoniazid, pyrazinamide, and streptomycin
- C. Rifampicin, isoniazid, and ethambutol only (avoid pyrazinamide)
- D. Rifampicin and isoniazid only with extended duration
- E. Standard four-drug therapy with addition of moxifloxacin
Explanation: ***Rifampicin, isoniazid, pyrazinamide, and ethambutol*** - This standard **four-drug regimen** is the recommended initial intensive phase treatment for **tuberculous meningitis** and is generally considered safe for use during **pregnancy**. - **Pyrazinamide** and **isoniazid** are crucial for their excellent **CSF penetration** and potent **bactericidal activity**, essential for effective treatment of CNS infections and preventing severe sequelae. *Rifampicin, isoniazid, pyrazinamide, and streptomycin* - **Streptomycin** is an **aminoglycoside** that is strictly **contraindicated** in pregnancy due to its established risk of **fetal ototoxicity**, which can cause permanent damage to the eighth cranial nerve. - Ethambutol is the preferred fourth agent over streptomycin in pregnant patients to avoid this severe adverse effect on the fetus. *Rifampicin, isoniazid, and ethambutol only (avoid pyrazinamide)* - While historical concerns existed, current **WHO and international guidelines** confirm that **pyrazinamide** is safe and an essential component of the intensive phase for severe forms of TB, including meningitis, in **pregnancy**. - Omitting pyrazinamide significantly weakens the regimen, increasing the risk of **treatment failure**, prolonged illness, and worse neurological outcomes in TB meningitis. *Rifampicin and isoniazid only with extended duration* - A two-drug regimen is insufficient for the **intensive phase** of **tuberculous meningitis** due to the high bacillary load and the critical need for rapid, potent bactericidal activity to prevent neurological damage. - This approach substantially increases the risk of **drug resistance** development and **treatment failure** in a severe, life-threatening condition like TB meningitis. *Standard four-drug therapy with addition of moxifloxacin* - **Moxifloxacin** (a fluoroquinolone) is generally avoided in **pregnancy** due to theoretical concerns regarding adverse effects on **fetal cartilage development**, although human data are limited. - The standard four-drug regimen (RIPE) is highly effective for drug-susceptible TB; adding moxifloxacin is typically reserved for **drug-resistant TB** or specific intolerances, which are not indicated here.
Question 157: A 5-year-old girl is brought to the emergency department with fever, headache, and neck stiffness. She received her routine childhood vaccinations. Lumbar puncture shows: opening pressure 28 cmH2O, CSF white cells 850/mm³ (95% polymorphs), protein 1.8 g/L, glucose 1.8 mmol/L (plasma glucose 5.2 mmol/L). Gram stain shows Gram-positive diplococci. What is the most likely explanation for this infection occurring despite vaccination?
- A. Vaccine failure due to inadequate immune response
- B. Infection with a non-vaccine serotype (Correct Answer)
- C. Waning immunity requiring a booster dose
- D. Underlying immunodeficiency
- E. The vaccine does not protect against this organism
Explanation: ***Infection with a non-vaccine serotype***- The lumbar puncture findings of **high CSF white cells (predominantly polymorphs)**, **low glucose**, and **high protein**, along with **Gram-positive diplococci** on stain, are highly indicative of **Streptococcus pneumoniae** meningitis.- The **pneumococcal conjugate vaccine (PCV)**, like PCV13, covers the most common and virulent serotypes, but *Streptococcus pneumoniae* has numerous other serotypes (over 90). Infection with a strain not included in the vaccine is a recognized phenomenon, especially due to **serotype replacement**.*Vaccine failure due to inadequate immune response*- **Primary vaccine failure** implies the child did not develop a sufficient immune response to the vaccine antigens, which is possible but less statistically probable in an otherwise healthy child who received routine vaccinations.- This typically means a lack of **antibody production** despite exposure to the vaccine, which is not suggested by the clinical context alone.*Waning immunity requiring a booster dose*- The **pneumococcal conjugate vaccine** provides robust and generally long-lasting protection against the included serotypes after the routine childhood schedule, which includes a booster dose around 12 months of age.- In a healthy 5-year-old, **antibody titers** for the vaccine-covered serotypes are usually still at protective levels, making waning immunity a less likely explanation for infection with a specific serotype at this age.*Underlying immunodeficiency*- While an **underlying immunodeficiency** (e.g., complement deficiency, asplenia, antibody deficiency) would increase susceptibility to encapsulated bacteria like *S. pneumoniae*, the clinical presentation does not suggest **recurrent infections** or other features typical of a primary immunodeficiency.- In an otherwise healthy child with no prior history of severe or unusual infections, this is a less likely explanation than exposure to an uncovered serotype.*The vaccine does not protect against this organism*- This statement is incorrect because the **pneumococcal conjugate vaccine (PCV)** is specifically designed to protect against **Streptococcus pneumoniae**, the organism strongly implicated by the Gram-positive diplococci and clinical picture.- The vaccine significantly reduces the incidence of **invasive pneumococcal disease**, including meningitis, caused by the serotypes it targets.
Question 158: A 38-year-old woman with systemic lupus erythematosus on prednisolone 20 mg daily presents with a 5-week history of cough, night sweats, and weight loss. Chest X-ray shows bilateral upper lobe consolidation with cavitation. Three sputum samples are AFB-positive. Which additional investigation should be performed before starting anti-tuberculosis therapy?
- A. Serum angiotensin-converting enzyme level
- B. CT chest with contrast
- C. Bronchoscopy with bronchoalveolar lavage
- D. HIV test (Correct Answer)
- E. Interferon-gamma release assay
Explanation: ***HIV test***- It is standard practice to offer **HIV testing** to all patients newly diagnosed with **tuberculosis** (TB), as TB is an **AIDS-defining illness**.- Knowing the HIV status is critical before initiating therapy because it influences the timing of **Antiretroviral Therapy (ART)**, the risk of **Immune Reconstitution Inflammatory Syndrome (IRIS)**, and the monitoring for drug interactions.*Serum angiotensin-converting enzyme level*- This test is used to support a diagnosis of **sarcoidosis**, which can mimic TB but would not typically show **AFB-positive** sputum.- ACE levels are neither sensitive nor specific for TB infections and do not guide TB management.*CT chest with contrast*- While CT can provide detailed anatomical views of **cavitation** or lymphadenopathy, it is not required when TB is already confirmed by **sputum AFB smear**.- It does not change the immediate management or the clinical decision to start **anti-tuberculosis therapy**.*Bronchoscopy with bronchoalveolar lavage*- This procedure is indicated if sputum samples are negative or cannot be produced but clinical suspicion for TB remains high.- Since the patient already has three **AFB-positive** sputum samples, the diagnosis is confirmed and invasive procedures are unnecessary.*Interferon-gamma release assay*- IGRA is primarily used for the detection of **latent TB infection** or in cases where diagnostic clarity is lacking.- It is not helpful in this scenario because the patient has **active TB disease** confirmed by microscopy, and the test cannot distinguish between latent and active infection.
Question 159: A 15-year-old boy presents with a 12-hour history of fever, severe headache, and vomiting. He has a non-blanching purpuric rash on his trunk and lower limbs. His blood pressure is 85/50 mmHg and heart rate is 128 bpm. Which organism is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Neisseria meningitidis (Correct Answer)
- C. Haemophilus influenzae type b
- D. Listeria monocytogenes
- E. Group B Streptococcus
Explanation: ***Neisseria meningitidis*** - This organism is the classic cause of **meningococcemia**, characterized by a **non-blanching purpuric rash** and rapid progression to **septic shock** (low blood pressure and tachycardia). - It is a leading cause of bacterial meningitis in **adolescents** and young adults, often involving **meningitis** symptoms like fever, headache, and vomiting. *Streptococcus pneumoniae* - While it is the most common cause of bacterial meningitis in all ages, it typically presents with **pneumonia** or ear infections rather than a **purpuric rash**. - It generally does not cause the severe **vascular damage** and vasculitis seen with meningococcal infections. *Haemophilus influenzae type b* - This was historically a major cause of meningitis, but its incidence has significantly decreased due1 to widespread **Hib vaccination** protocols. - It usually presents with symptoms of meningitis or **epiglottitis** but lacks the characteristic widespread **haemorrhagic rash**. *Listeria monocytogenes* - This pathogen primarily affects **neonates**, the **elderly**, and **immunocompromised** individuals, often transmitted through contaminated food. - It is not associated with the classic **purpuric rash** seen in healthy adolescents presenting with acute sepsis. *Group B Streptococcus* - This is the most common cause of meningitis in **neonates** (acquired during birth) but is an unlikely cause in a 15-year-old. - It typically presents as **early-onset sepsis** or late-onset meningitis in infants rather than purpuric shock in teenagers.
Question 160: A 42-year-old man with pulmonary tuberculosis is started on rifampicin, isoniazid, pyrazinamide, and ethambutol. After 3 weeks of treatment, he develops painful, red eyes with photophobia and blurred vision. Examination reveals bilateral anterior uveitis. Which medication is most likely responsible for this adverse effect?
- A. Rifampicin
- B. Isoniazid
- C. Pyrazinamide
- D. Ethambutol (Correct Answer)
- E. None of these medications cause this adverse effect
Explanation: ***Ethambutol*** - **Ethambutol** is a primary anti-tubercular drug well-known for causing **ocular toxicity**, including **optic neuritis** and, less commonly, **anterior uveitis**. - The patient's symptoms of **painful, red eyes**, **photophobia**, and **blurred vision**, along with bilateral **anterior uveitis**, are classic presentations of ocular adverse effects attributed to Ethambutol. *Rifampicin* - **Rifampicin** is commonly associated with **hepatotoxicity** and a harmless **orange-red discoloration** of urine, sweat, and tears. - It does not typically cause **ocular inflammation** or conditions like **uveitis**. *Isoniazid* - **Isoniazid** is primarily linked to **peripheral neuropathy** (prevented by co-administration of **pyridoxine/Vitamin B6**) and **hepatotoxicity**. - It does not commonly cause **anterior uveitis** or the specific ocular symptoms described. *Pyrazinamide* - **Pyrazinamide** is known for causing **hepatotoxicity** and **hyperuricemia**, which can precipitate **gouty arthritis**. - It is not associated with **ocular inflammation**, **uveitis**, or **visual disturbances**. *None of these medications cause this adverse effect* - This statement is incorrect because **Ethambutol** is a well-established cause of **ocular toxicity**, including **optic neuritis** and **uveitis**. - The patient's symptoms are directly attributable to a known adverse effect of one of the prescribed medications.
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