Infections
1. Neisseria
a. Colonise the oropharynx in around 10% of the population <= correct
b. Are gram negative rods - diplococci
c. Infection causing gonococcal arthritis is typically non purulent
d. Gonorrhoeae infection is usually symptomatic in women – asymptomatic -> PID, urethritis in men
e. Meningitides has three serotypes – at least 13
2. Staph aureus
a. Has enterotoxins which stimulate emetic receptors in the abdominal viscera
b. Has a lipase which degrades lipids on the skin surface
c. Has a capsule that allows it to attach to artificial materials
d. Has receptors on its surface which allow binding to host endothelial cells
e. All of the above <=
3. Staph aureus can cause all of the following EXCEPT:
a. Food poisoning
b. Osteomyelitis
c. Carbuncles
d. Scarlet fever – Strep pyogenes
e. Scalded skin syndrome
4. With hepatitis C infection
a. Associated with sexual transmission primarily
b. More than 50% become chronic <=
c. Transmission increases in pregnancy
d. ?
e. ?
5. With hepatitis E infection
a. It is transmitted primarily parenterally
b. It accounts for a greater than 20% mortality in pregnant mothers <=
c. ?
d. ?
e. ?
6. Clostridium species
a. Are all spore producing <=
b. C. tetani produces an endotoxin which causes muscle spasm – exotoxin (they are gram positive
anaerobic bacilli), blocks GABA
c. Vaccination against C. tetani has not significantly reduced the incidence of tetanus
d. C. botulinum blocks serotonin and dopamine receptors – Botox, blocks ACh -> flaccid paralysis
e. C. perfringens causes wound infections 10 days post operatively – 1 to 3 days
7. All of the following are associated with splenomegaly EXCEPT:
a. Leprosy <=
b. Toxoplasmosis
c. Tuberculosis
d. Typhoid fever
e. CMV
8. bacterial endotoxin
a. is exemplified by streptokinase - exo
b. is the cause of the severe form of diphtheria – G+ve rod, exotoxin (A-B), Nb B= binding, A = active
c. is the cause of gas gangrene – C.perfringens, G+ve anaerobe
d. induces the production of TNF <=
e. is the outer cell wall of gram positive bacteria – LPS cell wall component of G-ve
9. In pulmonary tuberculosis
a. The Ghon complex is a parenchymal perihilar lesion – distal airspaces, usually close to the pleura,
parenchymal granuloma and draining LN = the Ghon
b. Bacilli establish themselves in sites of low oxygen tension
c. Liquefactive necrosis precedes granuloma formation - caesous
d. Langhans cells occur in coaslescent granulomas <=
e. Primary TB causes more damage to lungs than secondary TB –secondary worse b/c heightened
immune response
10. The commonest site of primary TB lesion in lungs is
a. Apex
b. Base
c. Hilum
d. Lower zone of upper lobe <= The Ghon complex, or the upper part of the lower lobe.
e. Peripherally
11. Hepatitis C virus:
a. Carries a 50% risk of chronic progressive hepatitis – 80-85%, cirrhosis in 20-30%
b. Is a single stranded DNA virus - ssRNA
c. Produces elevated titres of antiHCV IgG following active infection which confers effective immunity
– seen in chronic state
d. Causes approximately 50% of transfusion associated hepatitis - rare
e. Has an incubation period of more than 6 months – 4-26 weeks
12. Hepatitis B virus:
a. Causes approximately 90% of transfusion associated hepatitis
b. Is a small defective RNA virus - DNA
c. Causes cirrhosis in 10% of cases
d. Has HbeAg which is required for concomitant hepatitis D infection -HbesAg
e. Produces immunologically mediated hepatocyte necrosis by sensitized cytotoxic T cells <=
13. Streptococci
a. Are aerobic gram positive cocci that grow in clusters – pairs or chains
b. Possess multiple virulence factors including clumping factor and beta toxin - Staph
c. Are known to commonly cause erythema nodosum, dental caries and impetigo <=
d. Infections are characterized microscopically by neutrophillic infiltrate and wide tissue destruction –
minimal tissue destrction (c.f staph)
e. Rarely cause infection in children under 15
14. Staph aureus enterotoxins:
a. Are not associated with food poisoning
b. Do not bind MHC on macrophages
c. Stimulate emetic receptors in abdominal viscera <=
d. Do not have an antigenic effect
e. Exhibit local effects only
15. Mycobacterium tuberculosis:
a. Infects about 5% of the world population – 1/3!
b. Stains blue with acid fast stains - red
c. May primarily infect the tonsils
d. Takes 1-2 weeks to culture <=
e. Resides in lysosomes
16. Which is the most common cause of infection to complicate burns?
a. Staphylococcus aureus
b. Pseudomonas aeruginosa <= G-ve bacillus, opportunistic
c. Candida species
d. Actinomyces
e. Clostridium perfringens
17. Concerning host barriers to infection:
a. Skin infections generally require organisms of high virulence
b. Shigella gastroenteritis can occur with only 100 ingested organisms <= ‘few hundred’?
c. Intact mucociliary apparatus is not required for host defence of the lung
d. Gastrointestinal infections occur with organisms of low virulence
e. Secretory products of mucosal surfaces are essential for host defence <= This is a better answer,
IgA def leads to infections..
18. Abscesses:
a. Are focal localized collections of oedema fluid and reb blood cells
b. Are caused by suppuration consisting of red blood cells, necrotic cells and oedema fluid
c. Are produced by deep seeding of virus into a tissue
d. Have a peripheral region of necrotic white cells
e. May be walled off by connective tissue that limits further spread <=
19. Regarding viral killing of host cells:
a. Subacute sclerosing panencephalitis has a short latency period
b. HIV depletes CD4 and helper lymphocytes <=
c. Yellow fever virus lyses renal cells
d. Viral proteins inhibit cell fusion in HIV and measles
e. Viruses promote host cell DNA, RNA and protein synthesis
20. Which of the following links is FALSE?
a. Varicella Zoster virus – aerosol spread
b. Corynebacterium diphtheriae – toxin mediated myocardial damage
c. Polio virus – killed and live attenuated vaccine available
d. EBV – pancreatitis <=
e. Mumps – meningoencephalitis
21. Toxoplasmosis:
a. Has a chronic mucocutaneous manifestation
b. Is more severe in patients who lack an intact humoral immune system
c. Can cause severe consequences if contracted during the 3rd trimester of pregnancy
d. Can destroy part of the retina <=
e. Is commonly destroyed by neutrophils
22. Hepatitis A:
a. Has a mortality rate of 2%
b. Is caused by a double stranded DNA virus
c. Is spread primarily by sexual contact
d. Has an incubation period of 14-45 days <=
e. Causes hepatocellular carcinoma
23. CNS infections:
a. Caused by viral agents usually show elevated CSF sugar content
b. Do not result from axonal transport of agents
c. Most commonly occur by haematogenous spread <=
d. Are not a common feature of AIDS
e. In neonates are most commonly caused by H influenza
24. In aseptic meningitis
a. The glucose in the CSF is raised
b. The most commonly identified agent is an enterovirus <= (also by mycobacteria)
c. There is a more fulminant course than bacterial meningitis
d. Microscopically there is a large infiltration of lymphocytes - leukocytes
e. There is no brain swelling
25. In infectious diseases
a. Bacterial endotoxin is a mucoprotein on the inner cell wall - LPS
b. The molecular mechanisms of most exotoxins are unknown
c. Microbes that propagate in the lumen of the intestine are accessible to IgA antibodies
d. Macrophages in bronhi play a major role in protecting the lungs from bacterial infection
e. Bacterial adhesins that bind bacteria to host cells have a broad range of host cell specificity <=
26. In malaria
a. Plasmodium vivax causes severe anaemia – falciparum = severe
b. Inoculated sporozoites immediately invade the spleen
c. Parasites mature in red blood cells <=
d. Plasmodium infection initially causes hepatomegaly - eventually
e. Cerebral malaria is caused by parasites invading grey matter
.
27. Mumps virus is a
a. Adenovirus
b. Herpes virus
c. Paramyxovirus <=
d. Pox virus
e. Picornavirus
28. All of the following organisms cause a clinical effect via the production of an exotoxin EXCEPT:
a. Clostridium tetani
b. Staphylococcus aureus
c. E. coli
d. Pseudomonas aeruginosa <=
e. Vibrio cholerae
29. An infection complication of transfusion
a. Is most commonly hepatitis C
b. Is most commonly hepatitis B
c. Is rarely transmission of HIV since screening was instituted <=
d. Never includes gonorrhoea or malaria
e. Can be clinically apparent mononucleosis in about 7% of cases
30. In viral hepatitis
a. The majority of cases of acute hepatitis B infection result in a carrier state, without clinical evidence
of disease – 30%
b. Anti HbsAb appears in the first week of infection
c. Anti HCV IgG does not confer immunity to hepatitis C <= true
d. The major cause of death from hepatitis B is hepatocellular carcinoma - cirrhosis
e. Hepatitis A virus has an outer surface envelope of protein, lipid and carbohydrate
31. The virus causing molluscum contagiosum belongs to the following viral family
a. Adeno
b. Herpes
c. Parvo
d. Pox <=
e. Picorna
32. The most common cause of Traveller’s diarrhoea is
a. Rotavirus
b. E. coli <=
c. Shigella
d. Salmonella
e. Giardia
33. Pneumocystis carinii
a. Produces pneumocystis pneumonia in normal persons
b. Causes a Ghon focus in the lung
c. Causes patchy atelectasis
d. Is a fungus <=
e. Attaches selectively to type II alveolar cells
34. Which is not a DNA virus?
a. Varicella zoster
b. CMV
c. Hepatitis B
d. Herpex simplex
e. HIV <=
35. Rickettsiae replicate in the cytoplasm of
a. endothelial cells <=
b. columnar epithelial cells
c. renal tubular cells
d. gastric mucosal cells
e. type I alveolar epithelial cells
36. In hepatitis B infection
a. Surface antigen occurs after symtpoms
b. HbeAg is associated with viral replication <=
c. IgG indicates recent infection
d. ?
e. ?
37. Regarding hepatitis C
a. Has a high association with sexual transmission
b. Transmission increases in pregnancy
c. ?
d. greater than 50% of infections become chronic <=
e. ?
38. Regarding streptococcal infection:
a. ?
b. ?
c. ?
d. ?
e. results in glomerulonephritis 3 weeks post infection <=
39. Which of the following is more common in people with diabetes mellitus
a. Mucomycoses
b. TB
c. Gas gangrene
d. Carbuncles
e. All of the above <=
40. Which is NOT more common in HIV
a. Mycoplasma pneumonia <=
b. Atypical pneumonia
c. HSV,
d. CMV
e. ?
41. Regarding hepatitis E
a. Mortality of 20% in pregnant females <=
b. Incubation of 5 days
c. Faecal-oral transmission <=
d. ?
e. ?
42. The pathogenesis of Mycobacterium tuberculosis is due to
a. Impaired antibody response/cell mediated
b. Hypersensitivity response to products of TB bacteria <=
c. Due to expanding granuloma -?
d. Due to caseous necrosis
e. Direct host cell killing by the bacillus
43. The Ghon focus is found in
a. The sub-pleural region
b. The lower part of the upper lobe <=
c. The hilum
d. The apex
e. ?
44. Which of the following is not transmitted by arthropods
a. Scrub typhus
b. Endemic typhus
c. Pediculosis
d. Q fever <= domestic animals
e. Rocky mountain spotted fever
45. Which of the following is true regarding polio virus?
a. It is a RNA paramyxovirus - enterovirus
b. It lives in the dorsal root ganglion
c. It causes a viraemia and then spreads to the spinal cord and brainstem <=
d. It causes symptoms in 40% of people – rarely
e. ?
46. Secondary syphilis
a. Lesions spare palms and soles - nope
b. Papular lesions on genitals – chancre is primary lesion
c. Infectious because they contain spirochaetes <=
d. Occurs 5-12 months post primary infection – 2-10 weeks
e. ?
47. The effects of exotoxin are the main cause of symptoms in
a. Viral hepatitis
b. Tuberculosis
c. Secondary syphilis
d. Tetanus <=
e. Subacute bacterial endocarditis
48. All of the following bacteria mediate their actions by exotoxins EXCEPT:
a. Corynebacterium diphtheriae
b. Vibrio cholerae
c. Escherischia coli
d. Clostridium perfringens
e. Salmonella typhi <= directly invades
49. Hepatitis C virus
a. Is a DNA virus
b. Has core antigens as serum markers
c. Is the “kissing disease”
d. Persistent infection and chronic hepatitis are the hallmarks <=
e. Has a low rate of cirrhosis
50. Which of the following indicates immunity to hepatitis B virus?
a. RNA polymerase
b. IgM anti HBc
c. Anti HBs <=
d. HbeAg
e. HBV-DNA
51. In tuberculosis
a. Mycobacteria are aerobic, spore forming bacilli – not spore forming
b. CD4+ T cells result in formation of granulomas by killing macrophages - activating
c. The major cause of tissue damage is granulomas <= not in secondary?
d. The granulomas in patients with AIDS are well formed – often miliary, no T cells
e. The CD8 T cells secrete cytokines inducing macrophage transformation – TH1 CD4+
52. Streptococcus
a. Viridans is beta-haemolytic – alpha or gamma
b. Produces an endotoxin which causes scarlet fever - exo
c. Causes erysipelas which involves significant tissue necrosis
d. Causes 50% of community acquired lobar pneumonias – more
e. Glomerulonephritis becomes chronic in less than 10% of children <= true
53. Clostridia
a. Perfringens produces toxin A – alpha toxin
b. Tetani neurotoxin produces both a heavy and a light chain <=?
c. Is a gram positive coccus that grows under both aerobic and anaerobic conditions
d. Botulinum releases a potent neurotoxin that causes convulsive contractions of skeletal muscles
e. Clostridial cellulites causes sever myonecrosis
54. Staphylococci
a. Are typical encapsulated diplococci
b. Produce multiple haemolytic toxins including alpha toxins <=
c. Rarely cause pyogenic infections in bone
d. Are the most common cause of hospital acquired infections
e. Lung infections are rarely opportunistic
55. Defence mechanisms against pulmonary infection include
a. Mucus clearance by ciliated epithelium at the front of the nasal cavity
b. Alveolar macrophage clearance of bacteria depositied in the alveoli <=
c. Mucociliary action of alveolar epithelium
d. The vomiting reflex
e. All of the above
56. Mycobacterium tuberculosis
a. Are aerobic, non spore-forming, non-motile cocci – acid fast bacilli
b. Induce type II hypersensitivity
c. Cause formation of epithelioid cell granulomae <=
d. Are killed by macrophages in primary infection
e. Induce formation of a Ghon complex after secondary infection
57. Viruses kill host cells by all of the following EXCEPT:
a. Inhibiting host cell DNA, RNA from protein synthesis
b. Damaging the plasma membrane
c. Lysing cells
d. Inducing host immune response to virus infected cells
e. By producing toxins <=
58. In hepatitis B infection
a. Anti Hbe appears before Anti HBc
b. Lack of anti HbeAb formation is a poor prognostic sign <=
c. The causative organism is a RNA virus
d. Chronic infection is distinguished from drug induced hepatitis by increased granuloma formation
e. Coinfection with hepatitis E leads to chronic hepatitis
59. Gram negative bacilli:
a. Have a single phospholipid bilayer – cell wall sandwiched between two
b. Include bacteroides species <=
c. Haemophilus influenzae species are 95% encapsulated – unencapsulated = 95%, but the
encapsulated form dominates by secreting haemocin
d. Stain dark purple using antibody probes
e. Are identified as the major causative organism in most pyogenic wound infections
60. Regarding clostridia
a. Clostridia degrade extracellular matrix proteins but their virulence is mainly due to the many toxins
they produce <=
b. C. botulinum proliferates in puncture wounds releasing a potent neurotoxin which causes
convulsive contractions of skeletal muscle
c. C. tetani causes an anaerobic cellulitis or myonecrosis and may cause severe sepsis
d. C. perfringens overgrows other flora in antibiotic-treated patients causing pseudomembranous
colitis
e. Clostridia are gram-negative bacilli that grow under anaerobic conditions – gram+ve anaerobes!
61. Regarding tuberculosis
a. Pathogenicity is related to its ability to escape killing by macrophages and induce delayed type
hypersensitivity <=
b. Commonly affects the thyroid and pancreas
c. Primary infection in the lungs most often occurs in the apices
d. Is associated with liquefactive necrosis
e. Infections and deaths are declining in Europe and Africa
62. Concerning pyogenic bacteria
a. Suppurative inflammation of the lungs caused by Strep pneumoniae destroys alveolar walls
b. Streptococci are obligatory anaerobic gram positive cocci
c. Staphylococci are able to auto induce expression of virulence factors <=
d. Alpha toxin is a haemolytic toxin produced by streptococci
e. Skin exfoliation is a common complication of group A streptococci
63. The following regarding mycoplasma infections are true EXCEPT:
a. Formation of hyaline membranes reflecting alveolar damage
b. Are frequently superimposed by viral infections <=
c. Bind to epithelial cells and causes non gonococcal urethritis
d. Causes atypical pneumonia
e. Mycoplasma lacks a cell wall
64. Regarding N. meningitides, which of the following is TRUE?
a. There are at least two serotypes of N. meningitides - 13
b. Approximately 10% of the population is colonized at any time <=
c. The death rate of N. meningitidis infection, despite antibiotics is about 10%
d. It is a major cause of bacterial meningitis in the elderly - young
e. There is a low rate of efficiency of complement against N. meningitidis infections
65. Clostridium tetani:
a. Is a gram negative bacillus
b. Produces neurotoxins which promote release of neurotransmitters
c. Produces spores that are present in soil <=
d. Causes gas gangrene
e. Is used in cosmetic surgery – Botox from botulinum
66. The primary cells infected by mycobacterium tuberculosis are:
a. Macrophages <=
b. TH1 cells
c. TH2 cells
d. Type I alveolar cells
e. B cells