Copy of Infectious Diseases Module 4

An 83-year-old man with advanced chronic obstructive pulmonary disease (COPD) and poorly controlled diabetes mellitus presents to the emergency department with severe pneumonia. He is febrile and tachypnoeic and has a productive cough with purulent sputum.

His chest X-ray shows bilateral infiltrates. He was hospitalised two months ago for a COPD exacerbation and treated with intravenous antibiotics, during which Pseudomonas aeruginosa was isolated from sputum culture.

Considering his clinical history, what is the strongest single risk factor for his current respiratory infection with Pseudomonas aeruginosa?

What is the most common organism causing hospital-acquired urinary tract infection?

Which of the following is the most common life-threatening healthcare-associated infection?

Which sexual exposure carries the highest probability of HIV transmission?

Which of the following is the most common cause of recurrent bacterial meningitis?

Which of the following characteristics is not considered a risk factor for the development of human papillomavirus (HPV)–related cancer?

An 18-year-old woman became sexually active two years ago. Over the past six months she has had two sexual partners who intermittently used condoms. She has not received HPV vaccination but has previously received Hepatitis B vaccine.

She is asymptomatic and examination is unremarkable. Based on routine screening recommendations, which infections should this patient be tested for?

Fidaxomicin is capable of eradicating which type of bacteria?

All of the following statements are true regarding HIV-2 except?

Which of the following antibiotics is least useful in the treatment of methicillin-resistant Staphylococcus aureus (MRSA)?

A 28-year-old man presents with a two-week history of fever, sore throat, myalgia, and a maculopapular rash following a high-risk sexual exposure.

Which of the following clinical features, if present, is most specific for acute HIV-1 infection (acute retroviral syndrome) as opposed to a common viral exanthem?

A 25-year-old renal transplant recipient on mycophenolate and sirolimus attends for pre-travel advice.

Which of the following vaccines is contraindicated?

A 16-year-old presents shortly after unprotected sex with a man known to be HIV positive.

Which single test would most reliably establish very early HIV-1 infection during the window period?

Which of the following dental procedures does NOT require infective endocarditis prophylaxis (in an at-risk patient)?

Which of the following Aedes mosquitoes is the principal vector for Zika virus?

Which of the following is the strongest single predictive marker of disease progression at all stages of HIV?

Regarding the rash of Mpox (monkeypox), all of the following statements are true except:

Which of the following statements regarding Candida auris is incorrect?

Which of the following statements about rezafungin is false?

A 38-year-old man presents with six months of progressive dyspnoea, non-productive cough, low-grade fevers, and weight loss. He denies travel, sick contacts, or TB exposure, has no family history of immunodeficiency, does not smoke, and has no injecting drug use. He is cachectic with a low-grade fever, mild tachypnoea, and bilateral crackles.

Full blood count is normal. Flow cytometry shows a CD4+ count of 180 cells/µL. HIV antigen/antibody assay and HIV RNA are negative. Work-up for HTLV, SLE, and sarcoidosis is negative.

High-resolution CT suggests Pneumocystis jirovecii pneumonia.

Which statement regarding the underlying condition is incorrect?

Statins are recommended for primary cardiovascular prevention in many people with HIV and because all statins are metabolised to some degree by CYP3A4, which statin must be avoided in a person taking a protease-inhibitor– or cobicistat-boosted regimen?

A 25-year-old woman with HIV, who has a 6-year-old son also living with HIV, is pregnant and asks about her baby’s risk of acquiring HIV if she takes antiretroviral therapy throughout pregnancy.

What is the approximate risk of mother-to-child transmission?

All of the following are associated with an increased risk of HIV transmission except:

What is the effect of being heterozygous for the CCR5 delta-32 allele on HIV acquisition and progression?

A patient with HIV who has taken antiretroviral therapy for 10 years has a stable CD4 count and an undetectable viral load. He asks whether he can stop treatment.

What is the most appropriate advice?

A patient with HIV treated with Ritonavir (protease inhibitor) develops lipodystrophy. He is treated with oral lovastatin as part of management of his lipodystrophy.

Which complication could potentially arise from this treatment?

What is the primary indication for the use of lefamulin?

A 68-year-old man is admitted with fever and dysuria three weeks after returning from an elective surgical procedure in India. Urine culture grows Escherichia coli with the following susceptibility profile:

Molecular testing detects an NDM-1 gene.

What is the biochemical mechanism by which this enzyme confers resistance to the affected agents?

A 24-year-old man who injects drugs presents with a fluctuant abscess over the right forearm and fever. Blood cultures are collected. Gram stain of the drained pus shows Gram-positive cocci in clusters. Culture grows Staphylococcus aureus with the following results:

Which genetic element is most likely responsible for this resistance phenotype?

A 55-year-old woman on haemodialysis via a tunnelled catheter develops rigors during dialysis. Blood cultures from two sites grow MRSA.

A transthoracic echocardiogram is normal. She is started on vancomycin. The catheter is removed.

On day 4, repeat blood cultures remain positive. Vancomycin trough is therapeutic and the isolate’s vancomycin minimum inhibitory concentration is 1.5 mg/L. She has no rash or renal impairment.

Which is the most appropriate next step in management?

A 62-year-old man with acute myeloid leukaemia is neutropenic following induction chemotherapy. He develops fever.

A midstream urine specimen collected while asymptomatic (no dysuria, frequency or suprapubic pain) grows Enterococcus faecium that is vancomycin resistant (vanB). Blood cultures are pending.

He has a peripherally inserted central catheter in situ. Chest imaging is clear. He is commenced on piperacillin-tazobactam per the febrile neutropenia protocol.

Regarding the vancomycin-resistant enterococcus in the urine, what is the most appropriate initial action?

A 70-year-old woman with a biliary stent develops cholangitis. Blood cultures grow Enterobacter cloacae with the following initial susceptibilities:

She is commenced on ceftriaxone. After 4 days of clinical improvement she deteriorates, and repeat blood cultures grow Enterobacter cloacae now resistant to ceftriaxone and ceftazidime.

What is the mechanism responsible for this change in susceptibility?

A 58-year-old man presents with fever and flank pain. He is haemodynamically stable. Urine and blood cultures both grow Escherichia coli with the following results:

The isolate is confirmed as an ESBL producer. He is diagnosed with an ESBL E. coli bacteraemia secondary to pyelonephritis.

Which is the most appropriate definitive therapy?

A 45-year-old woman presents with dysuria, urinary frequency and suprapubic discomfort, without fever or systemic features. She has no flank pain.

Urine culture grows Escherichia coli confirmed as an ESBL producer with the following results:

She is diagnosed with ESBL E. coli cystitis and is otherwise well with normal renal function (eGFR >60 mL/min/1.73m²).

Which is the most appropriate treatment?

A 72-year-old man is transferred from an overseas hospital and develops a hospital-acquired pneumonia with bacteraemia.

Blood cultures grow Klebsiella pneumoniae resistant to all penicillins, cephalosporins and carbapenems.

The reference laboratory confirms a KPC-2 carbapenemase.

Ceftazidime-avibactam susceptibility is pending.

Which is the most appropriate targeted therapy?

An 80-year-old woman is transferred to your intensive care unit directly from a hospital in a European country where a Candida auris outbreak has been reported.

She is intubated with a central venous catheter and urinary catheter in situ. She currently has no signs of infection. Screening swabs are pending.

What is the most appropriate immediate infection prevention measure?

A 66-year-old man is admitted from a residential aged care facility with septic shock (lactate 4.8 mmol/L; reference <2.0 mmol/L), hypotension requiring noradrenaline, and a presumed urinary source.

He was hospitalised in Southeast Asia two months ago. He has been colonised with an ESBL-producing E. coli on a prior urine culture.

Local rates of ESBL in urinary E. coli exceed 10%. Blood cultures are collected and empirical therapy must be commenced immediately.

Which is the most appropriate empirical antimicrobial choice?