DMF MSE 3 2007

1

Which one of the following statements is correct regarding viral replication?


  Most RNA viruses replicate in the nucleus

  Viral proteins are made from mRNA by viral encoded enzymes

  To replicate, viruses must either comprise mRNA or produce mRNA from their genome

  Mutations leading to the generation of numerous viral variants are rare in RNA viruses

  Most antivirals are broad spectrum, blocking the replication cycle of many virus types

2

Which one of the following statements is correct concerning the phenomenon of continual antigenic drift seen in influenza viruses?


  It results from antibody binding to and causing a mutation in the viral hemagglutinin

  It is possible because of the lack of proof reading function when RNA viruses replicate

  It is not associated with influenza B viruses

  It results from reassortment of genomes when two influenza viruses co-infect the same cell

  It explains why current influenza vaccines will not protect against infection with the Asian bird influenza strain H5N1

3

Human papilloma virus (HPV) infection is a persistent infection because features of its replication cycle result in an impaired immune response. Which one of the following statements is incorrect regarding the replication cycle and the host immune response?


  Dendritic cells have reduced access to HPV antigens

  HPV replicates as an episome for much of its replication cycle

  Outer capsid proteins are not produced until very late in the replication cycle

  HPV replication does not include a viremic phase

  Antibodies to the capsid proteins can efficiently target HPV-induced carcinoma cells

4

It is correct to say that in the first weeks following viral infection, primary HIV-1:


  Is life-threatening with a mortality rate of ~25%

  Frequently triggers the reactivation of latent infections with the herpesviruses

  Causes a serious depletion of CD8+ T-cells

  Rarely produces detectable levels of HIV-1 viraemia

  Results in seroconversion heralded by the development of anti-HIV antibody

5

Which one of the statements about the following antiviral agents is correct?


  Acyclovir is a guanosine analogue that acts on a broad range of DNA and RNA viruses

  Acyclovir is a prodrug that requires phosphorylation in host cells to affect viral nucleic acid synthesis

  Acyclovir is specific for HIV because the drug can act as a substrate for the viral reverse transcriptase which adds a phosphate group

  Neuraminidase inhibitors act by removing host sialic acid receptors during viral release

  Amantadine can inhibit influenza virus replication because it blocks virus binding to sialic acid on host cells

6

Which one of the following statements is correct regarding viral hepatitis?


  Replication of hepatitis B virus involves the reverse transcriptase enzyme (RNA dependent DNA polymerase)

  An effective vaccine is available to prevent infection by both hepatitis B and hepatitis C viruses

  Liver damage following infection with hepatitis B virus is due to the virus causing cell lysis after replication

  In Australia infection with hepatitis B virus is usually a result of transmission from mother to child

  Chronic infections with hepatitis B virus respond well to treatment with immune globulin

7

Which one of the following statements concerning the Herpesviruses is correct? They:


  Exhibit chronic infection with continued low level viral shedding

  Commonly exhibit lifelong persistent infections

  Are found only in humans

  Undergo latency where the viral genome integrates into host DNA

  Are effectively treated by viral protease inhibitors

8

To be effective, an antenatal screening program needs to fulfil several criteria. Which one of the following is not a consideration for including a particular test in the program? That:


  The diagnostic test is both sensitive and specific

  The diagnostic test is used when maternal infection is symptomatic

  The prevalence of the infection being tested for is known

  The predictive value of the test can be determined

  The outcome of screening has a cost benefit

9

A 21 yr old male presents to the Communicable diseases clinic with a urethral discharge for the past three days. He tells you that for the last two days he has been taking penicillin tablets which were left over from a previous visit to his G.P. A urethral swab was collected, and a Gram stain was prepared. The Gram stain showed many neutrophils but no significant bacteria. Which one of the following organisms is the most likely cause of his urethritis?


  Candida albicans

  Treponema pallidum

  Chlamydia trachomatis

  Neisseria gonorrhoeae

  Cytomegalovirus

10

Which one of the following statements about the treatment of diarrhoea is correct?


  In children, infective diarrhoea caused by viruses is typically mild, causes no serious problems and seldom requires treatment

  The use of anti-motility agents in the treatment of diarrhoea is recommended for young children

  Most cases of diarrhoea can be treated with oral rehydration therapy only

  Diarrhoea of protozoal origin seldom requires treatment with antiprotozoal agents

  Therapeutic agents which act to remove toxins from the gut by adsorbing them should be successful in treating most cases of diarrhoea

11

Which one of the following statements regarding malaria infection is incorrect?


  Pathology is related to the number of parasites entering the host

  Plasmodium vivax infection has a dormant liver stage

  The vector for the malaria parasite is the female Anopheles mosquito

  The spike in fever is due to the release of merozoites from ruptured schizonts

  A high parasitemia is rapidly achieved in infection with Plasmodium falciparum

12

Which one of the following statements regarding helminths is incorrect?


  There are three major groups of helminths – the roundworms, the flatworms and the tapeworms

  Enterobius vermicularis is a common helminth, infecting the developed and developing world

  The roundworms are tubelike prokaryotes, covered with a cuticle

  Taenia solium infections may be contracted by eating raw pork

  Pinworm infections can be diagnosed by placing adhesive tape over the anus and examining for eggs

13

Mr. B.S, a 55 year old teacher, presented to his G.P. with a productive cough which he had had for 3 weeks. He had lost more than 10% of his weight over the past 2 months and had fever and night sweats. The results of sputum microscopy suggested that Mr. B.S. had tuberculosis. He had worked as an aid worker in Africa from 1969 – 1980, and had received BCG vaccine prior to leaving Australia in 1969. He had been well until now.

Which one of the following statements is correct?


  Mr. B.S. was most likely to be infected by Mycobacterium tuberculosis within the last 2 months

  Mr. B.S. should have been protected against tuberculosis if he had been vaccinated with BCG vaccine.

  Protection against tuberculosis is principally due to the production of antibodies which coat the organism and allow effective phagocytosis

  A Mantoux test performed on Mr. B.S. is likely to be positive if Mr. B.S. had been vaccinated with BCG vaccine before he went to Africa.

  The results of sputum microscopy are sufficient for the diagnosis and management of Mr. B.S.’s disease

14

An outbreak of a febrile disease occurred at a boys' boarding school and by the time the epidemic was over about 25% of the boys had been ill. Some of the boys had sore throats, malaise and fever; two had severe headache and neck stiffness and one was found to have aseptic meningitis. The school doctor's suspicions were confirmed by the laboratory which reported significant isolations of:


  Neisseria meningitidis

  Legionella pneumophila

  Haemophilus influenzae

  Coxiella burnetii

  Coxsackievirus

15

A 63 year old woman was admitted to hospital with a diagnosis of a perforated appendix. She was treated with a combination of flucloxacillin, cefotaxime and metronidazole, and a laparotomy was performed. Which one of the statements below best describes the main reason for choosing these three antibiotics?


  They will reduce the likelihood of resistance in organisms which might cause postoperative infections

  They will act synergistically on organisms which may contaminate the operating site

  Lower doses of each antibiotic can be given in combination than if a single antibiotic alone was administered

  They are not associated with side-effects

  They cover the range of organisms with differing susceptibilities that are likely to be responsible for this patient's infection

16

Which of the options below is LEAST likely to be part of a sensitive breast examination?


  Informing the patient that if there is discomfort during the examination that the examination can be stopped

  Eliciting consent to undertake the examination

  To examine the axillary and supraclavicular lymph nodes

  To ask about the patient's past history of breast problems whilst performing the examination

  To perform the examination using a stripe pattern fashion to ensure all areas of the breast tissues are palpated

17

Which of the following statements about a persons living with HIV/ AIDS is LEAST likely to be true?


  Life expectancy with HIV infection has increased in industrialised nations over the past 10 years.

  Patients are often uncertain about their life expectancy

  Out of pocket expenses for treatment contribute to reduced standard of living in some patients with HIV

  Leaving work usually results in an improved sense of wellbeing for patients with HIV

  Leaving work leads to improved social activity

18

Which of the following statements is correct regarding the obligations that a medical practitioner has when treating a patient who is a practicing doctor?


  The treating doctor should report the patient to the medical board if he/she has an infectious disease

  The doctor must report the patient to the medical board if he/she acquired a communicable infection in the work place

  The doctor should inform the board if the patient is impaired in their ability to function as a doctor

  The doctor must report the patient if he/she has not informed their workplace

  The doctor should inform the health department in the case of a notifiable disease

19

Which of the following statements about doctor’s health is LEAST likely to be correct?


  Doctors have a lower mortality rate than the general population in Australia

  Doctors often fail to follow current preventative health guidelines for their physical health

  About half the doctors in Australia do not have an established relationship with a general practitioner

  Doctors are permitted to write prescriptions for themselves as long as it is not for analgesics

  The medical board recommends that doctors not write prescriptions for family members

20

Which of the following groups is LEAST represented in new cases of HIV in Australia


  Male homosexuals

  Heterosexual contact with a HIV positive partner

  Needle stick injury

  Intravenous drug use

  Blood transfusion

21

Which of the following causes the LEAST deaths globally in children?


  Acute bacterial respiratory infections

  Diarrhoeal diseases

  Polio

  Malaria

  Measles

22

Which of the following statements about tuberculosis is LEAST likely to be correct?


  Tuberculosis is one of the most common causes of death of young adults in the world

  The prevalence of tuberculosis disease is approximately one third of the global human population

  If fewer than 5 new infections are transmitted by each infectious case of tuberculosis, rates of the disease will eventually fall

  A wild animal reservoir of M. tuberculosis infection hinders control of human tuberculosis

  Treatment of latent tuberculosis infection reduces the chance of developing tuberculosis disease