Mock Infectious Diseases Module 2

A 45-year-old HIV-seropositive man presents with a two-week history of global headache, progressive confusion, and disorientation. His CD4 count three weeks ago was 50 cells/mm³. He declined antiretroviral therapy but takes co-trimoxazole as prophylaxis against Pneumocystis jirovecii pneumonia.

Examination reveals mild left-sided hemiparesis and a right homonymous hemianopia; fundoscopy is normal without papilloedema.

CT brain shows several areas of low attenuation in both cerebral hemispheres, without contrast enhancement or mass effect.

What is the most likely diagnosis?

Progressive multifocal leukoencephalopathy

Correct Incorrect Correct answer

Cerebral lymphoma

Correct Incorrect Correct answer

Cerebral toxoplasmosis

Correct Incorrect Correct answer

HIV encephalopathy

Correct Incorrect Correct answer

Neurosyphilis

Correct Incorrect Correct answer

A patient with suspected bacterial meningitis was started on IV ceftriaxone, benzylpenicillin, and dexamethasone. CSF cultures grow Listeria monocytogenes. Regarding the dexamethasone, what is the most appropriate next step?

Stop dexamethasone

Correct Incorrect Correct answer

Continue dexamethasone

Correct Incorrect Correct answer

Add vancomycin.

Correct Incorrect Correct answer

Add ciprofloxacin

Correct Incorrect Correct answer

Increase dose of dexamethasone

Correct Incorrect Correct answer

A patient with known HIV has the following CSF findings:

JC virus PCR positive.
Toxoplasma, EBV, CMV, TB, and Cryptococcus all negative.
Serum anti-Toxoplasma IgG negative.
CT brain shows multiple hypodense, non-enhancing cerebral white matter lesions involving the cerebellum and brainstem, without mass effect.

What is the most likely diagnosis?

Progressive multifocal leukoencephalopathy (PML)

Correct Incorrect Correct answer

Toxoplasma gondii encephalitis

Correct Incorrect Correct answer

CMV encephalitis

Correct Incorrect Correct answer

Primary CNS lymphoma

Correct Incorrect Correct answer

Tuberculous meningitis

Correct Incorrect Correct answer

A patient with suspected bacterial meningitis was started on IV ceftriaxone, benzylpenicillin, and dexamethasone. CSF cultures grow Streptococcus pneumoniae with a ceftriaxone MIC of 1.5 mg/L.

What is the antibiotic regimen of choice?

IV Vancomycin and ceftriaxone

Correct Incorrect Correct answer

IV ceftriaxone monotherapy

Correct Incorrect Correct answer

IV penicillin plus gentamicin

Correct Incorrect Correct answer

IV ampicillin

Correct Incorrect Correct answer

Continue with IV ceftriaxone and benzylpenicillin

Correct Incorrect Correct answer

CMV prophylaxis is routinely recommended in each of the following patient groups, except?

SLE patient on cyclophosphamide

Correct Incorrect Correct answer

Renal transplant patient on sirolimus

Correct Incorrect Correct answer

Heart transplant patient on tacrolimus

Correct Incorrect Correct answer

Liver transplant patient on cyclosporine.

Correct Incorrect Correct answer

Patient with allogeneic hematopoetic stem cell transplant

Correct Incorrect Correct answer

What is the most common cause of aseptic meningitis?

Enterovirus

Correct Incorrect Correct answer

Mycobacteria

Correct Incorrect Correct answer

Fungi

Correct Incorrect Correct answer

Spirochete

Correct Incorrect Correct answer

Legionella

Correct Incorrect Correct answer

Which of the following procedures is NOT an indication for antibiotic prophylaxis (to prevent procedure-related infection)?

Diagnostic gastroscopy

Correct Incorrect Correct answer

Endoscopic band ligation of oesophageal varices

Correct Incorrect Correct answer

ERCP with biliary obstruction

Correct Incorrect Correct answer

Endoscopic ultrasound with FNA of a cystic pancreatic lesion

Correct Incorrect Correct answer

PEG insertion

Correct Incorrect Correct answer

What is the recommended empirical antibiotic regimen for a brain abscess following penetrating head trauma, where the causative organism is still unknown?

Vancomycin and ceftriaxone

Correct Incorrect Correct answer

Ceftriaxone alone

Correct Incorrect Correct answer

Ceftriaxone and metronidazole

Correct Incorrect Correct answer

Ceftriaxone, metronidazole and vancomycin

Correct Incorrect Correct answer

Ceftriaxone and rifampicin

Correct Incorrect Correct answer

Which of the following antibiotics does NOT have a role in the treatment of a brain abscess?

Gentamicin

Correct Incorrect Correct answer

Benzylpenicillin

Correct Incorrect Correct answer

Ceftriaxone

Correct Incorrect Correct answer

Metronidazole

Correct Incorrect Correct answer

Vancomycin

Correct Incorrect Correct answer

A patient is suspected to have necrotising fasciitis secondary to Group A Streptococcal infection. In addition to early surgical debridement, what is the antibiotic regimen of choice?

Penicillin and clindamycin

Correct Incorrect Correct answer

Penicillin alone

Correct Incorrect Correct answer

Penicillin and gentamicin

Correct Incorrect Correct answer

Ampicillin and metronidazole

Correct Incorrect Correct answer

Flucloxacillin

Correct Incorrect Correct answer

A patient with an indwelling vascular catheter for total parenteral nutrition develops fever and a new murmur, raising suspicion of infective endocarditis.

What is the most likely causative organism?

Staphylococcus aureus

Correct Incorrect Correct answer

Streptococcus gallolyticus (bovis)

Correct Incorrect Correct answer

Streptococcus mutans

Correct Incorrect Correct answer

Streptococcus (viridans group)

Correct Incorrect Correct answer

Enterococcus faecalis

Correct Incorrect Correct answer

Each of the following is a recognised cause of culture-negative infective endocarditis, except?

Enterococcus faecalis

Correct Incorrect Correct answer

Coxiella burnetii

Correct Incorrect Correct answer

Bartonella

Correct Incorrect Correct answer

Chlamydia

Correct Incorrect Correct answer

Legionella

Correct Incorrect Correct answer

According to the modified Duke criteria (and 2023 Duke-ISCVID update), each of the following is a major criterion for infective endocarditis, except?

Septic pulmonary infarcts

Correct Incorrect Correct answer

Persistently positive blood cultures with a typical organism

Correct Incorrect Correct answer

Typical organism from two separate blood cultures in the absence of a primary focus

Correct Incorrect Correct answer

A positive serological test for Q fever (Coxiella burnetii phase I IgG >1:800)

Correct Incorrect Correct answer

Echocardiographic evidence of vegetation, abscess, or new prosthetic valve dehiscence

Correct Incorrect Correct answer

A patient with early syphilis is treated with a single intramuscular dose of benzathine penicillin G 2.4 million units. What is the pharmacological rationale for this treatment?

To maintain sustained, prolonged treponemicidal penicillin concentrations to eradicate slowly dividing treponemes

Correct Incorrect Correct answer

The organism is fully sensitive to penicillin-based agents

Correct Incorrect Correct answer

It is the only agent ever shown to work in syphilis

Correct Incorrect Correct answer

To prevent antibiotic resistance

Correct Incorrect Correct answer

To obtain synergy with gentamicin

Correct Incorrect Correct answer

Which test is best used to monitor disease activity and treatment response in syphilis?

VDRL and RPR

Correct Incorrect Correct answer

T. pallidum EIA

Correct Incorrect Correct answer

FTA-ABS

Correct Incorrect Correct answer

TPHA

Correct Incorrect Correct answer

TPPA

Correct Incorrect Correct answer

Which of the following antibiotic has no role in the treatment of Mycobacterium avium complex (MAC) infection?

Penicillin

Correct Incorrect Correct answer

Clarithromycin

Correct Incorrect Correct answer

Azithromycin

Correct Incorrect Correct answer

Rifabutin

Correct Incorrect Correct answer

Ethambutol

Correct Incorrect Correct answer

What is the most commonly reported adverse reaction to the seasonal influenza vaccine in New Zealand?

Injection site inflammation

Correct Incorrect Correct answer

Arm pain

Correct Incorrect Correct answer

Headache

Correct Incorrect Correct answer

Fever

Correct Incorrect Correct answer

Vasovagal reaction

Correct Incorrect Correct answer

Which factor is a major risk determinant for perinatal (vertical) transmission of hepatitis C virus?

Maternal HCV viral load (and concurrent HIV co-infection)

Correct Incorrect Correct answer

Breastfeeding

Correct Incorrect Correct answer

Concomitant hepatitis B infection

Correct Incorrect Correct answer

Concomitant human immunodeficiency virus (HIV) infection.

Correct Incorrect Correct answer

Mode of delivery

Correct Incorrect Correct answer

The annual influenza epidemics are best explained by which of the following mechanisms?

Antigenic drift in the H and N proteins of influenza A

Correct Incorrect Correct answer

Antigenic shift in the H and N proteins of influenza A

Correct Incorrect Correct answer

Point mutations in the M protein of influenza A

Correct Incorrect Correct answer

Development of neuraminidase resistance.

Correct Incorrect Correct answer

Recombination of influenza A and B haemagglutinins.

Correct Incorrect Correct answer

The effect of neuraminidase inhibitors (e.g., zanamivir, oseltamivir) when started early (within 48 hours of symptom onset) in otherwise healthy adults with influenza is best described as?

Reduction in the severity of symptoms and shortening of symptom duration by approximately one day

Correct Incorrect Correct answer

Complete suppression of influenza symptoms within a day of treatment

Correct Incorrect Correct answer

Reduction in symptom severity with no effect on duration of illness

Correct Incorrect Correct answer

Reduction in illness duration by three to five days, with no effect on symptom severity

Correct Incorrect Correct answer

No effect on the illness, but a marked reduction in the individual's infectivity

Correct Incorrect Correct answer

Which of the following best describes the antiviral mechanism of oseltamivir against the influenza virus?

Inhibition of viral neuraminidase

Correct Incorrect Correct answer

Inhibition of M2 ion channel activity

Correct Incorrect Correct answer

Competitive blocking of surface haemagglutinin

Correct Incorrect Correct answer

Inhibition of reverse transcriptase

Correct Incorrect Correct answer

Inhibition of DNA polymerase

Correct Incorrect Correct answer

What is the most sensitive and specific test for the diagnosis of pertussis in the early phase of illness?

Culture from nasopharyngeal secretions

Correct Incorrect Correct answer

PCR (nucleic acid amplification testing) for Bordetella pertussis

Correct Incorrect Correct answer

Serology

Correct Incorrect Correct answer

Direct fluorescent antibody (DFA) testing

Correct Incorrect Correct answer

Pulsed-field gel electrophoresis

Correct Incorrect Correct answer

Which of the following vaccines is the most inappropriate for a significantly immunosuppressed patient?

Yellow fever

Correct Incorrect Correct answer

Hepatitis A

Correct Incorrect Correct answer

Hepatitis B

Correct Incorrect Correct answer

Influenzae

Correct Incorrect Correct answer

Tetanus toxoid

Correct Incorrect Correct answer

A 57-year-old patient is suspected of having bacterial meningitis. CSF Gram stain reveals gram-positive bacilli.

What is the most likely causative organism?

Listeria monocytogenes

Correct Incorrect Correct answer

Cryptococcus neoformans

Correct Incorrect Correct answer

Haemophilus influenzae

Correct Incorrect Correct answer

Streptococcus pneumoniae

Correct Incorrect Correct answer

Escherichia coli

Correct Incorrect Correct answer

Which of the following is the most likely mechanism of vancomycin resistance in enterococci?

Alteration of cell-wall peptidoglycan precursors preventing vancomycin binding

Correct Incorrect Correct answer

Increased production of a beta-lactamase.

Correct Incorrect Correct answer

Alteration of ribosomal targets preventing vancomycin binding

Correct Incorrect Correct answer

Increased enzymatic breakdown of vancomycin

Correct Incorrect Correct answer

Diminished affinity of penicillin-binding proteins (PBPs).

Correct Incorrect Correct answer

Which of the following best describes the most common mechanism of ampicillin resistance in Haemophilus influenzae?

Production of beta-lactamase

Correct Incorrect Correct answer

Altered penicillin-binding proteins

Correct Incorrect Correct answer

Decreased cell-wall permeability

Correct Incorrect Correct answer

Efflux pump activity

Correct Incorrect Correct answer

Pus formation

Correct Incorrect Correct answer

Which of the following best describes the mode of action of aminoglycoside antibiotics?

Inhibition of protein synthesis

Correct Incorrect Correct answer

Disruption of cytoplasmic membrane function.

Correct Incorrect Correct answer

Inhibition of bacterial DNA gyrase

Correct Incorrect Correct answer

Inhibition of cell-wall synthesis

Correct Incorrect Correct answer

Interference with bacterial folic acid metabolism.

Correct Incorrect Correct answer

Which of the following is most predictive of multidrug-resistant tuberculosis (MDR-TB) in a patient with tuberculosis infection?

Prior treatment for TB

Correct Incorrect Correct answer

Acquisition of TB infection overseas

Correct Incorrect Correct answer

Cavitating lesion on chest X-ray

Correct Incorrect Correct answer

Extrapulmonary TB

Correct Incorrect Correct answer

Smear-positive sputum

Correct Incorrect Correct answer

In adults older than 65, which vaccine is most likely to improve survival?

Influenza

Correct Incorrect Correct answer

Diphteria and tetanus

Correct Incorrect Correct answer

Pertussis

Correct Incorrect Correct answer

Pneumococcal

Correct Incorrect Correct answer

Varicella

Correct Incorrect Correct answer

A 22-year-old man is admitted with dengue fever confirmed by positive NS1 antigen, on day 5 of illness. He had been improving but now develops increasing abdominal pain and lethargy as his fever settles.

On examination he is restless, with cool peripheries, a narrow pulse pressure (blood pressure 96/84 mmHg), heart rate 122/min and a tender abdomen with shifting dullness.

Investigations (compared with admission):

Test	Day 3	Day 5	Reference range
Haematocrit	0.42	0.56	0.40–0.54
Platelets	88 x10⁹/L	24 x10⁹/L	150–400
Albumin	38 g/L	26 g/L	35–50

Chest x-ray shows bilateral small pleural effusions.

Which pathophysiological mechanism is most directly responsible for this deterioration?

Increased vascular permeability with plasma leakage

Correct Incorrect Correct answer

Disseminated intravascular coagulation causing haemorrhage

Correct Incorrect Correct answer

Direct viral myocarditis causing cardiogenic shock

Correct Incorrect Correct answer

Bone marrow suppression causing pancytopenia

Correct Incorrect Correct answer

Immune complex–mediated glomerulonephritis

Correct Incorrect Correct answer

Mock Infectious Diseases Module 2

Quiz Summary

Information

Results

Results

Categories

1. Question

2. Question

3. Question

4. Question

5. Question

6. Question

7. Question

8. Question

9. Question

10. Question

11. Question

12. Question

13. Question

14. Question

15. Question

16. Question

17. Question

18. Question

19. Question

20. Question

21. Question

22. Question

23. Question

24. Question

25. Question

26. Question

27. Question

28. Question

29. Question

30. Question

Average score
Your score