Infectious Diseases Module 2

A 45-year-old HIV-seropositive man presents to the Emergency Department with a two-week history of global headache. His partner says that he has become increasingly confused and disorientated. The patient’s latest CD4 count, taken three weeks ago, was 50 cells/mm3.

He had chosen not to take antiretroviral therapy, but was taking co-trimoxazole as prophylaxis against Pneumocystis carinii pneumonia.

On examination he had mild weakness of his left arm and leg in all muscle groups and a right homonymous hemianopia. Fundoscopy was normal with no evidence of papilloedema.

A CT scan of his brain showed several areas of low attenuation in both cerebral hemispheres, but there was no enhancement with contrast and no mass effect.

What is the most likely diagnosis?

Progressive multifocal leukoencephalopathy

Cerebral lymphoma

Cerebral toxoplasmosis

HIV encephalopathy

Neurosyphilis

A patient suspected to have bacterial meningitis has been commenced on IV ceftriaxone and benzyl penicillin together with dexamethasone.Cultures have revealed Listeria monocytogenes.

What should be the next step?

Stop dexamethasone

Continue dexamethasone

Add vancomycin.

Add ciprofloxacin

Increase dose of dexamethasone

A patient with known HIV has the following CSF findings:

JC virus positive.
Toxoplasma negative
EBV negative
CMV negative
TB negative
Cryptococcus negative
serum anti-toxoplasma IgG negative
CT scan: Multiple hypodense non enhancing cerebral white matter lesions involving the cerebellum and brain stem.no mass effect.

What is the most likely diagnosis?

Progressive multifocal leukoencephalopathy(PML)

Toxoplasma gondii encephalitis

CMV encephalitis

Tuberculosis

A patient suspected to have bacterial meningitis has been commenced on IV ceftriaxone and benzyl penicillin together with dexamethasone.Cultures have revealed Strep pneumoniae with an MIC of 1.5 mg/L for ceftriaxone.

Which should be the antibiotic of choice?

IV Vancomycin and Ceftriaxone

IV Ceftriaxone only

IV Penicillin plus Gentamicin

IV Ampicillin

Continue with IV ceftriaxone and Benzylpenicillin

CMV prophylaxis is recommended in the following patient group except?

SLE patient on cyclophosphamide

Renal transplant patient on sirolimus

Heart transplant patient on tacrolimus

Liver transplant patient on cyclosporine.

Patient with allogeneic hematopoetic stem cell transplant

What is the most common cause of aseptic meningitis?

Enterovirus

Mycobacteria

Fungi

Spirochete

Legionella

Which of the following procedure is NOT an indication for antibiotic prophylaxis?

Gastroscopy

Treatment of esophageal varices

ERCP with obstruction

Endoscopic ultrasound with FNA

PEG insertion

What is the recommended empiric antibiotic regime for brain abscess following a penetrating trauma where the source of organism is still unknown?

Vancomycin and ceftriaxone

Ceftriaxone alone

Ceftriaxone and metronidazole

Ceftriaxone, metronidazole and vancomycin

Ceftriaxone and rifampicin

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

Gentamicin

Benzylpenicillin

Ceftriaxone

Metronidazole

Vancomycin

A patient is suspected to have necrotising fasciitis secondary to a Group A Streptococcal infection.

Besides, early surgical debribement, what would be the antibiotic of choice?

Penicillin and Clindamycin

Penicillin alone

Penicillin and Gentamicin

Ampicillin and metronidazole

Flucloxacillin

A patient who has an indwelling vascular catheter for TPN develops fever and a new murmur and therefore suspected to have infective endocarditis.

What is the most likely culprit organism?

Staphylococcus aureus

Streptococcus bovis/gallolyticus subspecies

Streptococcus mutans

Streptococcus viridans

Enterococci fecalis

The following are causes for culture negative endocarditis except?

Enterococcus fecalis

Coxiella burnetti

Bortenella

Chlamydia

Legionella

The following are major criterion for the diagnosis of infective endocarditis based on the modified Duke’s criteria, except?

Septic pulmonary infarcts

A positive blood culture for IE. Typical organism growing in 2 cultures in absence of a primary focus.

A persistently positive blood culture

A positive serological test for Q fever

ECHO evidence of mass, abscess, dehiscence

A patient with early syphilis is treated with intramuscular procaine penicillin (long acting) 1g daily for 10 days.

What is the rationale for the use of this antibiotic?

To obtain continuous levels of penicillin to eliminate the treponemes.

To prevent antibiotic resistance

To obtain synergy with gentamicin

Is the only efficacious agent proven to work in syphilis.

The organism if fully sensitive to penicillin based agents.

Which of the following test is best used to monitor disease activity in syphilis?

VDRL and RPR

T. pallidum EIA

FTA- Abs

TPHA

TPPA

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

Penicillin

Clarithromycin

Azithromycin

Rifabutin

Ethambutol

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

Injection site inflammation

Arm pain

Headache

Fever

Vasovagal reaction

Which of the following factor is a major risk determinant for perinatal transmission of hepatitis C virus?

Maternal viral load.

Breastfeeding

Concomitant hepatitis B infection

Concomitant human immunodeficiency virus (HIV) infection.

Mode of delivery

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

Antigenic drift in H and N proteins of influenza A.

Antigenic shift in H and N proteins of influenza A.

Point mutations in the M proteins of influenza A.

Development of neuraminidase resistance.

Recombination of influenza A and B haemagglutinins.

The effect of neuraminidase inhibitors (such as zanamivir) when given within 24 hours of onset of symptoms on the course of influenza infection is best described as:

reduction in the severity of influenza symptoms and shortening of the duration of symptoms by one to two days

complete suppression of influenza symptoms within a day of commencing treatment

reduction in the severity of influenza symptoms with no effect on duration of illness

reduction in the duration of illness by three to five days, with no effect on the severity of symptoms

no effect on the course of the illness itself, but a marked reduction in the infectivity of the individual.

Which of the following best describes the antiviral effect of Oseltamivir on the influenza virus?

Inhibition of viral neuraminidase

Inhibition of M2 ion channel activity.

Competitive blocking of surface haemagglutinins.

Inhibition of reverse transcriptase

Inhibition of DNA polymerase

What is the most sensitive and specific test for the diagnosis of pertussis?

Culture from nasopharyngeal secretion

PCR testing for Pertussis.

Serology

Direct fluorescent antibody (DFA) testing

Pulsed field gel electrophoresis

Which one of the following vaccines would be the most inappropriate for an immunosuppressed patient?

Yellow fever

Hepatitis A

Hepatitis B

Influenzae

Tetanus toxoid

A 57 year old patient is suspected to have bacterial meningitis. A lumbar puncture is performed and the CSF reported a growth of gram positive bacilli on gram stain.

What is the most likely organism?

Listeria monocytogenes

Cryptococcus

Haemophilus influenzae

Streptococcus pneumoniae

E.coli

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

Changes in the enterococcal cell wall to prevent vancomycin binding.

Increased production of a beta-lactamase.

Alterations to enterococcal ribosomes to prevent vancomycin binding.

Increased breakdown of vancomycin

Diminished affinity of penicillin-binding proteins (PBPs).

Which of the following best describes the mechanism of resistance of Haemophilus influenzae to ampicillin?

Production of beta lactamase

Altered binding proteins.

Decreased permeability of cell wall.

Efflux pump.

Pus formation

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

Inhibition of protein synthesis

Disruption of cytoplasmic membrane function.

Inhibition of bacterial DNA gyrase

Inhibition of cell wall synthesis.

Interference with bacterial folic acid metabolism.

Which of the following is most predictive of the presence of multi-drug resistance in a patient with tuberculosis infection?

Prior treatment for TB

Acquisition of TB infection overseas

Cavitating lesion on CXR

Extra-pulmonary TB

Smear positive sputum

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

Influenza

Diphteria and tetanus

Pertussis

Pneumococcal

Varicella

Infectious Diseases Module 2

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