| Opening pressure | 10 cmH20 |
| Lymphocyte count | 4 × 106/L (<5 × 106/L) |
| Glucose | 3.8 mmol/L (serum glucose 5.6 mmol/L) |
| Total protein | 0.33 g/L (0.10–0.65 g/L) |
| Gram stain | No organisms seen |
A. HIV-associated dementia
B. HIV-associated myelopathy
C. Cryptococcal meningoencephalitis
D. Cytomegalovirus polyradiculopathy
E. Zidovudine-related toxicity
14. A 64-year-old woman presents with fever and speech disturbance over the past week. Her temperature is 37.9° C. The patient is alert and oriented with respect to time but unable to name objects properly. Dysarthria and occasional word substitution are noted. The patient is able to follow simple but not three-step commands. Part of her magnetic resonance imaging of the brain is shown below. What is the most likely diagnosis?
A. Cerebral toxoplasmosis
B. Herpes simplex encephalitis
C. Meningococcal meningitis
D. Multiple sclerosis
E. Progressive multifocal leucoencephalopathy
15. A patient with human immunodeficiency virus (HIV) is concerned about changing facial appearance after receiving highly active anti-retroviral therapy (HAART). Which one of the following anti-retroviral drugs is most likely to cause lipoatrophy?
A. Delavirdine
B. Zidovudine
C. Nevirapine
D. Didanosine
E. Abacavir
16. Regarding Clostridium difficile infection, which one of the following is INCORRECT?
A. Judicious use of antibiotics, minimisation of cross-infection by observing careful hand hygiene and barrier precautions can prevent acquisition of C. difficile infection in hospitalised patients
B. There is significant antibiotic resistance in patients previously treated with oral metronidazole or oral vancomycin
C. Oral metronidazole is recommended as a first-line therapy for mild C. difficile infection because of its lower cost and concerns about the proliferation of vancomycin-resistant bacteria
D. Oral vancomycin is the recommended first-line agent for treating severe C. difficile infection due to the more prompt symptom resolution and a lower risk of treatment failure
E. Faecal transplantation remains unpopular for practical and aesthetic reasons despite proven efficacy in case series
17. In patients with human immunodeficiency virus (HIV) infection the definite indications for offering anti-retroviral therapy (ART) are:
A. CD4 cell count of 550 cells/μL in patients with previous history of Pneumocystis jiroveci pneumonia
B. CD8 cell counts of <400 cells/μL
C. Thrombocytopenia (platelet count <150 × 109 cells/L)
D. Age younger than 50 years
E. Diabetes in HIV-infected patient
18. Overwhelming post-splenectomy infection defines fulminating sepsis, meningitis or pneumonia in splenectomised and hyposplenic individuals. The most common causative organism is:
A. Neisseria meningitides
B. Escherichia coli
C. Pseudomonas aeruginosa
D. Enterococcus spp
E. Streptococcus pneumoniae
19. An 18-year-old girl was studying for examinations together with a friend who was hospitalised 2 days ago with meningitis. The blood cultures in her friend grew meningococcus group A. Which one of the following actions should be taken for the girl who was in contact with the patient with meningitis?
A. No treatment is required
B. Immunisation with meningococcus vaccine
C. Single-dose intramuscular ceftriaxone 250 mg
D. Single dose intramuscular ceftriaxone 250 mg and immunisation with meningococcus vaccine
E. Single-dose oral rifampicin and immunisation with meningococcus vaccine
20. A 29-year-old indigenous man was admitted with a 6-day history of abdominal pain, vomiting and diarrhoea. His medical history included chronic alcohol-related liver disease, co-infection with hepatitis B and human T-cell lymphotropic virus type 1 (HTLV-1). Blood cultures grew Escherichia coli. Rhabditiform larvae were seen on stool microscopy. He was given intravenous ceftriaxone. Forty-eight hours after admission, he became hypotensive and transferred to the intensive care unit. He was treated for septic shock. Apart from fluid resuscitation, intravenous ceftriaxone and inotropic support, which one of the following treatments is most appropriate?
A. Intravenous ganciclovir
B. Intravenous hydrocortisone
C. Intravenous metronidazole
D. Oral albendazole
E. Oral ivermectin
21. Which one of the following statements best describes the evaluation or management of patients with syphilis in Australia and New Zealand?
A. Screening for syphilis in Australia utilises enzyme immune assay (EIA) treponemal tests
B. Cerebrospinal fluid (CSF) analysis is not essential to confirm neurosyphilis
C. Azithromycin is the first-line treatment for all stages of syphilis in Australia
D. Different antibiotic regimens are indicated in HIV-positive patients with syphilis co-infection
E. Contacts presenting within 3 months of exposure to syphilis do not require treatment unless serologically positive
22. A 70-year-old man was admitted to the intensive care unit because of septic shock caused by Pseudomonas aeruginosa urinary tract infection. He received intravenous ceftazidime and amikacin via a central venous line. After 7 days of antibiotics he developed fever and blood culture was positive for Gram-positive cocci in chains, which were catalase negative. Vancomycin was started but the blood cultures remained positive for the same organism even after 3 days of therapy. The most likely organism causing this infection is:
A. Staphylococcus aureus
B. Pseudomonas aeruginosa
C. Enterococcus faecalis
D. Coagulase-negative staphylococcus
E. Streptococcus pyogenes
Theme: Opportunistic infections (for Questions 23–26)
A. Pneumocystis jirovecii
B. Candida albicans
C. Toxoplasmosis
D. Cryptosporidium
E. Cryptococcus
F. Varicella zoster
G. Cytomegalovirus
H. Mycobacterium avium intracellulare
For each of these patients, select the most likely organism.
23. A 43-year-old woman who is known to be human immunodeficiency virus (HIV) positive presents with nausea, dizziness, confusion and a stiff neck of 1 week’s duration. Her temperature is 38.5° C and mild neck stiffness is present; all other examination is normal. Complete blood count and routine chemistries are normal, except for mild leukopenia. Computed tomography of the head is unremarkable. Lumbar puncture is performed, with the following results: an opening pressure of 32 cmH2O; a low glucose level; an elevated protein level; and an elevated white cell count, with neutrophil predominance. What is the most likely infective organism responsible for this presentation?
24. A 46-year-old man who is HIV positive (CD4+ T-cell count of 42 cells/μL) presents after having a seizure. He reports that for the past 3 weeks he has been experiencing worsening tremor, visual disturbances and headaches. Computed tomography of the head with contrast showed a single thin-walled cavitating lesion with ring enhancement and oedema of the surrounding white matter. Which one of the infective organism can cause his clinical presentation?
25. A 45-year-old woman has been HIV positive for the past 10 years. Despite receiving highly active anti-retroviral therapy (HAART), her most recent CD4+ T-cell count was 180 cells/μL. Which opportunistic infection is this patient most at risk of developing?
26. A 39-year-old man who is HIV positive (CD4+ T-cell count 100 cells/μL) presents with a complaint of profuse, watery diarrhoea. He has had these symptoms for 2 weeks. Conservative treatment measures have been unsuccessful. Evaluation of the stool reveals oocysts. What is the most likely organism that can explain his presentation?
Answers
Basic Science
1. Answer C
The Epstein–Barr virus (EBV) is a γ-herpes virus that establishes a latent infection in B lymphocytes and epithelial cells. Under certain conditions such as immunosuppression, the virus may reactivate its full latent repertoire in the infected B cell to induce lymphoproliferative diseases which, under normal conditions, would lead to destruction of the cell by virtue of the expression of various latent proteins that unmask the infected cell to the immune system. Depending on the cell type and the immunological environment, EBV establishes different types of latent infection.
About 95% of all adults worldwide show serological markers of EBV infection. In most people, EBV infection is symptomless, but the virus occasionally induces infectious mononucleosis, a self-limiting lymphoproliferation with elevated lymphocytes and atypical monocytes. EBV is found in virtually all cases of undifferentiated nasopharyngeal carcinoma and nasal NK/T-cell lymphoma, in about 95% of cases of endemic Burkitt lymphoma (BL), in some subsets of Hodgkin lymphoma, in approximately 15% of diffuse large B-cell lymphoma and in about 10% of gastric carcinoma. In contrast to the endemic form, EBV is found only in 15–30% of sporadic BL. EBV is present in up to 90% of post-transplant lymphoma (PTLD) under immunosuppression (Lim et al., 2006).
The Epstein–Barr virus (EBV) is a γ-herpes virus that establishes a latent infection in B lymphocytes and epithelial cells. Under certain conditions such as immunosuppression, the virus may reactivate its full latent repertoire in the infected B cell to induce lymphoproliferative diseases which, under normal conditions, would lead to destruction of the cell by virtue of the expression of various latent proteins that unmask the infected cell to the immune system. Depending on the cell type and the immunological environment, EBV establishes different types of latent infection.
About 95% of all adults worldwide show serological markers of EBV infection. In most people, EBV infection is symptomless, but the virus occasionally induces infectious mononucleosis, a self-limiting lymphoproliferation with elevated lymphocytes and atypical monocytes. EBV is found in virtually all cases of undifferentiated nasopharyngeal carcinoma and nasal NK/T-cell lymphoma, in about 95% of cases of endemic Burkitt lymphoma (BL), in some subsets of Hodgkin lymphoma, in approximately 15% of diffuse large B-cell lymphoma and in about 10% of gastric carcinoma. In contrast to the endemic form, EBV is found only in 15–30% of sporadic BL. EBV is present in up to 90% of post-transplant lymphoma (PTLD) under immunosuppression (Lim et al., 2006).
Lim, W.H., Russ, G.R., and Coates, P.T. (2006). Review of Epstein–Barr virus and post-transplant lymphoproliferative disorder post-solid organ transplantation. Nephrology (Carlton) 11, 355–366.
2. Answer A
Listeria monocytogenes is a small Gram-positive facultative intracellular bacillus. Listeria has the ability to spread from cell to cell without entering the extracellular environment. It does this by using an actin polymerisation propulsion system. Other pathogenic bacteria that can exist intracellularly include mycobacterium, brucella, rickettsia and chlamydia.
Endotoxins are part of the outer membrane of the cell wall of Gram-negative bacteria and are invariably associated with Gram-negative bacteria whether the organisms are pathogenic or not. Listeria monocytogenes is the only Gram-positive bacteria that produce endotoxins.
Listeria can cause meningoencephalitis, sepsis and gastroenteritis. Infection in pregnancy can lead to premature birth or fetal death. Immunosuppressed and elderly patients, pregnant women and newborns of infected mothers are typically affected by L. monocytogenes. Listeria is most commonly transmitted via unpasteurised dairy products, meat and vegetables. Also, it can spread transplacentally during delivery. Ampicillin is the treatment of choice. Listeria is always resistant to cephalosporins.
Listeria monocytogenes is a small Gram-positive facultative intracellular bacillus. Listeria has the ability to spread from cell to cell without entering the extracellular environment. It does this by using an actin polymerisation propulsion system. Other pathogenic bacteria that can exist intracellularly include mycobacterium, brucella, rickettsia and chlamydia.
Endotoxins are part of the outer membrane of the cell wall of Gram-negative bacteria and are invariably associated with Gram-negative bacteria whether the organisms are pathogenic or not. Listeria monocytogenes is the only Gram-positive bacteria that produce endotoxins.
Listeria can cause meningoencephalitis, sepsis and gastroenteritis. Infection in pregnancy can lead to premature birth or fetal death. Immunosuppressed and elderly patients, pregnant women and newborns of infected mothers are typically affected by L. monocytogenes. Listeria is most commonly transmitted via unpasteurised dairy products, meat and vegetables. Also, it can spread transplacentally during delivery. Ampicillin is the treatment of choice. Listeria is always resistant to cephalosporins.
3. Answer D
Progressive multifocal leucoencephalopathy (PML) is a potentially fatal demyelinating disease of the central nervous system that predominantly affects immunocompromised patients. The aetiological agent, JC virus (JCV), is a widespread polyomavirus with a very particular target, the myelin-producing oligodendroglia of the brain. During periods of immune suppression, the virus can be reactivated from lymphoid tissues and kidney, causing targeted myelin destruction and corresponding neurological deficits. The incidence of PML has increased in recent years, due to HIV infection and the growing number of patients receiving immunosuppressant treatment, including natalizumab treatment of multiple sclerosis. Serological studies have shown that more than 80% of the human population has antibodies to JCV.
Progressive multifocal leucoencephalopathy (PML) is a potentially fatal demyelinating disease of the central nervous system that predominantly affects immunocompromised patients. The aetiological agent, JC virus (JCV), is a widespread polyomavirus with a very particular target, the myelin-producing oligodendroglia of the brain. During periods of immune suppression, the virus can be reactivated from lymphoid tissues and kidney, causing targeted myelin destruction and corresponding neurological deficits. The incidence of PML has increased in recent years, due to HIV infection and the growing number of patients receiving immunosuppressant treatment, including natalizumab treatment of multiple sclerosis. Serological studies have shown that more than 80% of the human population has antibodies to JCV.
4. Answer A
Depletion of CD4 cells in human immunodeficiency virus (HIV) infection may occur as a result of direct infection and death of CD4 cells or by indirect mechanisms. HIV-1 infection has been associated with:
Depletion of CD4 cells in human immunodeficiency virus (HIV) infection may occur as a result of direct infection and death of CD4 cells or by indirect mechanisms. HIV-1 infection has been associated with:
- Impaired production of CD34 progenitor cells in the bone marrow
- Reduced proliferation of thymocytes and direct infection of CD4 thymocytes leading to reduced numbers of recent thymic emigrants and CD4 naïve cells
- Direct infection of circulating CD4 memory cells but at low frequency
- Depletion of mucosal CD4 cells by direct infection of both CCR5+ and CCR5– CD4 cells, dendritic cells and macrophages
- High levels of immune activation that increase the proliferation and death of both CD4 and CD8 cells, which are linked to lymph node fibrosis and retention of T cells in the lymph nodes (Cohen et al., 2011; Moir et al., 2011).
Cohen, M.S., Shaw, G.M., McMichael, A.J., and Haynes, B.F. (2011). Acute HIV-1 Infection. N Engl J Med 364, 1943–1954.
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