Infectious disease Flashcards
Regarding secondary syphilis, which of the following statements is correct?
A Lesions are infectious because they contain spirochetes
B Lesions on genitals are painful
C Occurs 5 - 12 months post primary infection
D Lesions spare palms and soles
A
Explanation
Secondary syphilis occur on the palms and soles. The lesions on the genitalia, mucous membranes, palms and soles are painless. It occurs 2-10 weeks post primary infection
Regarding hepatitis B, which of the following statements is correct?
A Anti-HBe signifies an acute active infection
B Surface antigen occurs after symptoms
C IgG represents a recent infection
D HBeAG indicates an active replication
D
Explanation
HBsAG appears before the onset of symptoms.
Anti-HBe AG is detectable only after the disappearance of the HBeAg implying that acute infection has peaked and is on the wane.
Anti-HBe AG occurs as an adaptive response to infection.
IgG appears after acute infections (after IgM) and persists for life, representing life long immunity
Extra: The panel of tests suggested by the RACGP is actually: HBsAG, Anti HBs and Anti HBc
Extra: form a subscriber
Surface antigen (HBsAg) – active infection E antigen (HBeAg) – marker of viral replication and implies high infectivity Core antibodies (HBcAb) – implies past or current infection Surface antibody (HBsAb) – implies vaccination or past or current infection Hepatitis B virus DNA (HBV DNA) – this is a direct count of the viral load When screening for hepatitis B, test HBcAb (for previous infection) and HBsAg (for active infection). If these are positive do further testing for HBeAg and viral load (HBV DNA). HBsAb demonstrates an immune response to HBsAg. The HBsAg is given in the vaccine, so having a positive HBsAb may simply indicate they have been vaccinated and created an immune response to the vaccine. The HBsAb may also be present in response to an infection. The other viral markers are necessary to distinguish between previous vaccination and infection. HBcAb can help distinguish between acute, chronic and past infection. We can measure IgM and IgG versions of the HBcAb. IgM implies an active infection and will give a high titre with an acute infection and a low titre with a chronic infection. IgG indicates a past infection where the HBsAg is negative. HBeAg is important. Where the HBeAg is present it implies the patient is in an acute phase of the infection where the virus is actively replicating. The level of HBeAg correlates with their infectivity. If the HBeAg is higher, they are highly infectious to others. When they HBeAg is negative but the HBeAb is positive, this implies they have been through a phase where the virus was replicating but the virus has now stopped replicating and they are less infectious.
Which of the following is rarely transmitted by arthropods?
A Q fever
B Lyme disease
C Rocky mountain spotted fever
D Scrub typhus
A
Explanation
Q fever is disease caused by infection with Coxiella burnettii, a bacterium that affects humans and other animals . This organism is uncommon, but may be found in cattle, sheep and goats and other domestic mammals, including cats and dogs The infection results from inhilation of a spore-like small cell variant, and from contact with the milk, urine, feces, vaginal mucus, or semen of infected animals.
Rarely, the disease is tick borne. The other dieases are commonly spread by ticks.
Lymes disease is the most common tick borne disease in the northern hemisphere.
Aschoff bodies are classically seen in which of the following conditions?
A Acute myeloid leukemia (AML)
B Non-Hodgkins lymphoma
C Thalassemia major
D Rheumatic fever
D
Explanation
Aschoff bodies are nodules found in the hearts of individuals with acute rheumatic fever. They result from inflammation in the heart muscle. They are rarely seen in chronic rheumatic fever.
Regarding Hepatitis E, which of the following statements is correct?
A Occurs primarily in children
B Incubation of 5 days
C Causes chronic hepatitis
D Mortality of 20% in pregnant females
D
Explanation
Hepatitis E incubation period is 6 weeks. It is an enterically transmitted, water borne disease (faecal-oral). It is not associated with chronic liver disease. It occurs primarily in young to middel aged adults; sporadic infection and overt illness in children are rare. Symptoms resolve in 2-4 weeks during which the IgM is replaced with a persistent IgG anti-HEV titre. Mortality in pregnant women approaches 20%
Which of the following conditions can be caused by staphylococcus infection?
A Scarlet fever
B Dental infections
C Rheumatic fever
D Food poisoning
D
Explanation
Streptococcus causes tonsillitis, scarlet fever, impetigo and RF. Dental infections are caused by Strep Viridans. Remeber that staphylococcal infection can also cause impetigo, pneumonia, toxic shock syndrome, tonsillitis and sepsis, endocarditis and osteomyelitis. It seems that the jury is still out about stalococci dental infections. Some endodontists have reported case studies of staf dental infections bu tthe majority still hold that it is an unlikely source of dental infections
All of the following are DNA viruses, with the exception of?
A Varicella zoster virus (VZV)
B Human immunodeficiency virus (HIV)
C Epstein-Barr virus (EBV)
D Cytomegalovirus (CMV)
B
Explanation
DNA viruses include: adenovirus, Hepatitis B, herpes symplex virus (HSV), human papillomavirus (HPV), molluscum virus and the John Cunningham (JC) virus
HIV is a lentivirus, which is a subgroup of retroviridae, which are RNA viruses
What is the most common primary site for tuberculosis (TB)?
A In the upper part of the lower lobe
B Near the apical pleura
C In the lower part of the lower lobe
D Sub pleural
A
Explanation
Primary TB occurs in the lower part of the upper lobe or the upper part of the lower lobe usually close to the pleura.
Secondary TB occurs near the apical pleura.
Most common Extra-Pulmonary involvement = Lymph nodes: cervical, supraclavicular, axillary
Which of the following is an RNA virus?
A Varicella zoster virus (VZV)
B Herpes simplex virus (HSV)
C Epstein-Barr virus (EBV)
D Human immunodeficiency virus (HIV)
D
Explanation
RNA viruses include: echovirus, coxsackie, rhinovirus, influenza, RSV, mumps, hepatitis A D C E, human T-lymphotropic virus (HTLV) 1 and 2, dengue, yellow fever, rabies and Colorado tick
Common DNA Viruses include 1)Herpesviridae ( HSV, VZV, EBV, CMV and 2) HBV
Extra:
DNA viruses mnemonic: HHAPPPPy viruses (happy because they have DNA like us): Herpes- (CHEV: CMV, HHV-6/8, HSV-1/2, EBV, VZV) Hepadna- Adeno- Parvo- Papova- Papillo- Pox- All are icosahedral and have nuclear replication except pox- All are naked except pox-, hepadna-, herpes- All are double stranded except parvo- (because it’s really small) The rest are RNA viruses
Regarding Rickettsial infections, which of the following statements is correct?
A Commonly infect the liver
B Infect the smooth muscle cells
C Produce significant toxins
D Involve the endothelial cells
D
Explanation
Rickettsial bacteria are vector borne obligate intracellular organisms. Rickettsial bacteria infect (replicate within membrane-bound vacuoles in vascular endothelial cells) the vascular endothelial cells, especially those of the brain and lungs. They have an endotoxin but lack secreted toxins. T lymphocyte mediated immunity is most important for clearing Rickettsial infections. Innate immunity with NK > IFN-gamma > reduce proliferation. Multiple organs are involved (SEVERE manifestations are due to vascular leakage secondary to endothelial cell damage), however, the liver and spleen, less common
NOTE: Chlamydia are similar but divide within epithelial cells
Epidemic typhus (Rickettsia prowazekii)
Scrub typhus (Orienta tsutsugamushi)
Rocky mountain spotted fevers (Rickettsia rickettsii) -dog tick vector
Gram NEGATIVE rod, though stain poorly
DIAGNOSIS
immunostaining of organisms, or serological detection of Abs
Which of the following statements is correct regarding the polio virus?
A It causes a viraemia before spreading to the spinal cord and brainstem
B It lives in the dorsal root ganglion
C It causes symptoms in 40% of people
D It is a RNA paramyxovirus
A
Explanation
Polio is a picornaviridae (RNA) virus. It infects humans only. It replicates in the anterior motor unit of the spinal cord or brain stem. It causes symptoms in 1% of infected people. Although it is clear that antiviral antibodies control the disease in most cases, it is not known why some individuals fail to control the virus. Viral spread to the nervous system may be secondary to viraemia or occurs by retrograde transport of the virus along axons of the motor neurons. Unfortunately, rare cases of polio after vaccination has been reported and is due to mutations of the attenuated viruses to wild form types.
Regarding staphylococcus aureus, which of the following staements is correct?
A Has a capsule that allows it to attach to artificial materials
B Has a lipase which degrades lipids on the skin surface
C All of the above
D Has enterotoxins which stimulate emetic receptors in the abdominal viscera
C
Explanation
Staphylococcus aureus is a pyogenic gram +ve coccus which form clusters like bunches of grapes. These bacteria cause a myriad of skin lesions as well as abscess, sepsis, osteomyelitis, pneumonia, endocarditis, food poisoning and toxic shock syndrome. S. aureus possess a multitude of virulence factors, which include surface proteins involved in adherence, secreted enzymes that degrade proteins and secreted toxins that damage host cells. The lipase of S. aureus degrades lipids on the skin surface, and thus has the ability to produce skin infections. S. aureus infecting prosthetic valves and catheters have a polysaccharide capsule that allows them to attach to the artificial material and to resist artificial host cell phagocytosis. Staphylococcal enterotoxins (SEs) are exotoxins produced by Staphylococcus aureus that cause staphylococcal food poisoning in humans. However, little is known about the mechanisms of the emetic activity of SEs.
Staphylococcus aureus can cause all of the following, with the exception of?
A Scarlet fever
B Carbuncles
C Scalded skin syndrome
D Osteomyelitis
A
Explanation
Streptococcus causes tonsillitis (more commonly), scarlet fever (group A B- haemolytic streptococcus-strep pyogenes), impetigo and rheumatic fever. Remember that staphylococcal infection can cause boils, carbuncles, impetigo, pneumonia, toxic shock syndrome and sepsis, endocarditis, scalded skin syndrome (production of exotoxin enzyme protease) and osteomyelitis. Less commonly, staf aureus can cause tonsillitis.
In regards to hepatitis B, which of the following statements is correct?
A The majority of cases of persistent infection result in cirrhosis
B HBsAg appears soon after overt disease
C Acute infection causes sub-clinical disease in 65% of cases
D Anti-HBs appears soon after HBsAg
C
Explanation
HBsAG appears before the onset of symptoms. Anti-HBe is detectable only after the disappearance of the HBeAg implying that acute infection has peaked and is on the wane. IgG appears after acute infections and persists for life and represents life long immunity.
In acute infection-
65% of cases result in subclinical disease, 100% of these will recover.
25% will develop acute hepatitis. 99% of these cases will recover, 1% will develop fulminant hepatitis
5-10% will develop chronic hepatitis.
Of those patients developing chronic hepatitis, 20-30% will develop cirrhosis and/0r 2-3% will develop hepatocellular carcinoma. 70% will recover
Note: There is a window period of couple of weeks, between disappearance of HbsAg and appearance of Anti-Hbs, conferring protective immunity.
Which of the following statements is correct in regards to hepatitis C?
A Exposure confers effective immunity to subsequent infection
B Has its highest prevelance in heamodialysis patients
C Causes chronic hepatitis at a higher rate than hepatitis B
D Is acquired by faecal-oral transmission
C
Explanation
The main routes of transmission are inoculations and blood transfusion. The groups considered at higher risk are homosexuals, haemodialysis patients, haemophiliacs and IV drug abusers. (The IV drug users have a risk of 50-90%). In contrast to hepatitis B (HBV), hepatitis C (HCV) has a higher rate of progression to chronic disease and cirrhosis, exceeding 50%. Elevated anti-HCV IgG occurring after an acute infection does not confer effective immunity. A characteristic infection of HCV is therefore repeated bouts of hepatic damage, the result of reactivation of a pre-existing infection or emergence of an endogenous newly mutated strain.
In relation to hepatitis C infection which of the following options is correct?
A Transmission increases in pregnancy
B More than 50% become chronic
C It is aquired by fecal-oral transmission
D It is primarily associated with sexual transmission
B
Explanation
The main routes of transmission are inoculations and blood transfusion. The groups considered higher risk are homosexuals, haemodialysis patients, haemophiliacs and IV drug abusers. (The IV drug users have a risk of 50-90%). In contrast to hepatitis B (HBV), hepatitis C (HCV) has a higher rate of progression to chronic disease and cirrhosis, exceeding 50%. Elevated anti-HCV IgG occurring after an acute infection does not confer effective immunity. A characteristic infection of HCV is therefore repeated bouts of hepatic damage, the result of reactivation of a pre-existing infection or emergence of an endogenous newly mutated strain
Regarding clostridium species, which of the following options is correct?
A Vaccination against C.tetani is not very effective
B C.tetani produces an endotoxin which causes muscle spasm
C C.botulinum toxin blocks serotonin and dopamine receptors
D They are all spore producing
D
Explanation
Clostridium are GRAM POSITIVE spore producing bacteria which grow in anaerobic conditions. C.tetani produces tetanospasmin which is a potent neurotoxin causing muscle spasm.
C. Botulinum produces a neurotoxin which blocks synaptic release of Acetylcholine.
C. perfringens causes wound infections 1-3 days after injury.
Tetanus toxoid as part of the DPT (diptheria, pertussis, tetanus) immunisations given to children have greatly reduced the incidence of tetanus in developed and developing countries.
Extra: Tetanospasmin (and botulinum toxin) are exotoxins - that is, they are excreted by the bacterial cells. This is in contrast to endotoxins which are bacterial cell components (e.g. lipopolysaccharide).
Which of the following major infections are not associated with splenomegaly?
A Tuberculosis
B Toxoplasmosis
C Typhoid fever
D Leprosy
D
Explanation
Other infective causes of splenomegaly include: infective mononucleosis, TB, typhoid fever, toxoplasmosis, trypanosomiasis, brucellosis, cytomegalovirus (CMV), syphilis, malaria, histoplasmosis, schistosomiasis, leishmaniasis, echinococcosis and kala-azar
Note: the list comes from the current textbook. Leprosy is not mentioned but it infact can lead to splenomegaly. It does not appear to be a major cause.
With regards to bacterial endotoxin, which of the following options is correct?
A It is the outer cell wall of gram positive bacteria
B It is the cause of the severe form of diphtheria infection
C It induces the production of tumour necrosis factor (TNF)
D It is exemplified by streptokinase
C
Explanation
Bacterial endotoxin is a lipopolysaccharide (LPS) that is a structural component in the outer cell wall of a gram-negative bacterium. LPS are thought to play an important role in septic shock, ARDS and DIC mainly through the induction of excessive levels of cytokines such as tumour necrosis factor (TNF) and interleukin IL-1.
Streptokinase is a protein secreted by several species of streptococci (gram positive) that can bind and activate human plaminogen, it is an exotoxin. Diphtheria is a gram positive organism and therefore produces an exotoxin.
Regarding aseptic meningitis, which of the following statements is correct?
A There is a more fulminant course than bacterial meningitis
B The most commonly identified agent is an enterovirus
C Microscopically there is a large infiltration of neutrophils
D The glucose in the cerebrospinal fluid (CSF) is raised
B
Explanation
Aseptic meningitis is a term used clinically to designate an illness comprising of meningeal irritation, fever and alteration in consciousness of relatively acute onset, generally of viral -but rarely of bacterial or other- aetiology. The clinical course is less fulminant and the CSF finding is different from pyogenic meningitis. There is a lymphocyte pleocytosis, the protein is only moderately elevated and the sugar is nearly always normal. The infection is self-limiting. In 70% of cases the pathogen most commonly identified is an enterovirus.
Note: multiple searches reveal that Coxsackie or Echovirus groups of enteroviruses are the most common cause of viral meningitis. (Including Australia meningitis websites)
Chemical meningitis, CSF results may be similar to aseptic meningitis except that there is a neutrophil pleocytosis
Regarding mechanisms of bacterial injury, which of the following statements is correct?
A Innate host immune defenses include NK cells, phagocytic cells, plasma proteins
B Bacterial endotoxins are lipopolysaccharide secreted by the bacteria to cause disease
C Bacterial adhesions, which bind bacteria to host cells, have a narrow range of host cell specificity
D Bacterial exotoxins are components of the bacterial cell
A
Explanation
Infectious agents establish infections and damage tissues by three mechanisms:
They can contact or enter host cells and directly cause damage, they may release toxins, they can induce a host immune response directed against the agent but causing additional disease.
Bacterial endotoxin is a lipopolysaccharide that is a structural component in the outer cell wall of a gram-negative bacterium.
Bacterial exotoxins are secreted protiens that cause cellular injury and disease. They include: enzymes, toxins that alter intrasignaling pathways, neurotoxins and superantigens
Bacterial adhesions that bind bacteria to host cells are limited in type, but have broad range of host cell specificity. In contrast to viruses, which can infect a wide range of host cells, facultative intracellular bacteria infect mainly epithelial cells, macrophages or both
Innate host defenses include physical barriers, NK cells, phagocytic cells and plasma proteins.
Adaptive host defenses include T and B lymphocytes and their products
Which of the following options is correct in relation to malaria?
A Innoculated sporozoites immediately invade the spleen
B Parasites mature in red blood cells
C Plasmodium falciparum initially causes hepatomegaly
D Plasmodium vivax causes severe anaemia
B
Explanation
Plasmodium Falciparum causes severe anaemia. Inoculated sporozoites, released from the salivary glands of the female mosquito immediately invade the liver. Within the liver cells, the parasite multiplies, releasing as many as 30000merozites when each infected hepatocyte ruptures. P. Falcipirum causes splenomegaly. Cerebral malaria is caused by the blockage of vessels by the paratisized red cells
An intravenous drug user presents to the emergency department with suspected osteomyelitis of the ankle.
Which organism is frequently isolated in this type of patient?
A H.influenzae
B Salmonella
C Staphylococcus
D E.Coli
D
Explanation
Staph. aureus is responsible for 80-90% of cases of pyogenic osteomyelitis. IVDU and patients with genitourinary tract infections often have E.Coli, Pseudomonas and Klebsiella as the causative organisms. In the neonatal period, H.influenzae and group B streptococci are most commonly found and in sickle cell disease, salmonella in prevalent.
The above explanation is from the prescribed text book, but review from an ortho study 2010: Microbiology of bone and joint infections in injecting drug abusers:
RESULTS: Cultures yielded predominately Gram-positive bacteria: Staphylococcus aureus in 52% and coagulase-negative Staphylococcus in 20%. The proportion of oxacillin-resistant S aureus among S aureus infections increased from 21% in 1998 to 73% in 2005. Gram-negative organisms were present in 19% of infections and anaerobes in 13%. Patients with osteomyelitis had a higher prevalence of polymicrobial infections (46% versus 15%), infections due to Gram-negative organisms (24% versus 9%), and anaerobic infections (19% versus 6%) compared to patients with septic arthritis.
Note: “Staphylococcus aureus is responsible for 80% to 90% of the cases of culture-positive pyogenic osteomyelitis. These organisms express cell wall proteins that bind to bone matrix components such as collagen, which facilitates adherence of the bacteria to bone. Escherichia coli, Pseudomonas, and Klebsiella are more frequently isolated from individuals with genitourinary tract infections or who are intravenous drug abusers” direct from TB. The following is suggested: This could be interpreted differently; when E. coli is isolated, it is more likely to be from an IVDU or a person with a UTI. That doesn’t mean IVDU’s are more likely to have E. coli osteomyelitis. Good thought but hard to know the intensions of the MCQ writers. Again: users are saying that it is still Staph as this is the most common pathogen in up to 80-90% of cases,
A 6yr female presents to the ED with gingivostomatitis. Which of the following viruses is the likely cause?
A Epstein-Barr virus
B Cytomegalovirus
C Varicella-Zoster virus
D Herpes simplex virus
D
Explanation
Most orofacial herpetic infections are caused by herpes simplex virus type 1 (HSV-1), with the remainder being caused by HSV-2 (genital herpes). With changing sexual practices, oral HSV-2 is increasingly common. Primary infections typically occur in children between 2 and 4 years of age and are often asymptomatic. However, in 10% to 20% of cases the primary infection manifests as acute herpetic gingivostomatitis, with abrupt onset of vesicles and ulcerations throughout the oral cavity. Most adults harbor latent HSV-1, and the virus can be reactivated, resulting in a so-called “cold sore” or recurrent herpetic stomatitis.
What is the route of transmission of Hepatitis E?
A Sexual intercourse
B Faecal-oral
C Injection-blood borne
D Respiratory droplet
B
Explanation
Hepatitis E is an enterically transmitted water-borne infection that occurs primarily in young to middle aged adults. HEV is a zoonotic disease with animal reservoirs: monkeys, cats, pigs and dogs.
Extra: a nice way to remember
“Vowels” (hAv and hEV) hit the bowels
Which if the following group of people should get a Hepatitis B vaccination?
A All persons receiving a blood transfusion
B Day care workers r
C All persons who are high risk of attracting hepatitis A
D A child at the age of 4 months, receiving their first vaccination as per the Australia schedule
B
Explanation
Hepatitis vaccination program should occur at ages: 0, 2, 4 , 6 months
Hepatitis A is faecal oral spread (water-food). There is an increase of attracting hepatitis E
Blood products are heavily screened in Australia and the risk in negligible
Horizontal spread of hepatitis B can occur through minor breaks in the skin and mucous membranes. Therefore, healthcare workers, day care workers, sexual workers are all at increased risk and should be immunized.
I have left the answer as day care workers. The recommendation to get vaccinated following blood transfusions or risk of hepatitis A exposure does not apply to every one
Extra: form QLD health
People who work with children All people working with children, including: staff and students working in early childhood education and care correctional staff working where infants/children cohabitate with mothers school teachers (including student teachers) outside school hours carers child counselling services workers youth services workers Influenza Measles Mumps Rubella (German measles) Whooping cough (pertussis) Chickenpox (varicella) Staff working in early childhood education and care As above plus hepatitis A
Extra: form immunise.health.gov.au
This further reduces the residual risk of hepatitis B transmission through transfusion in Australia, to approximately 1 in 982 000 per unit transfused. However, persons with clotting disorders who receive blood product concentrates, persons with recurrent transfusion requirements, and persons with underlying immunocompromise have an elevated risk of hepatitis B virus infection, and should therefore be vaccinated.
Combination hepatitis A/hepatitis B vaccines should be considered for susceptible persons in whom both hepatitis A and hepatitis B vaccines are recommended, including:
travelers to, and expatriates living in, moderately to highly endemic areas for hepatitis A and B
persons whose lifestyle puts them at increased risk of hepatitis A and hepatitis B (sexually active men who have sex with men, sex industry workers, persons who inject drugs and inmates of correctional facilities)
persons who attend or work at residential or non-residential facilities for people with developmental disabilities
persons with occupational risks of exposure to both hepatitis A and hepatitis B
persons with chronic liver disease and/or hepatitis C
solid organ transplant liver recipients or solid organ transplant recipients who have chronic liver disease
The incubation period of Hepatitis B is
A 18-160 days
B 10-140 days
C 6-175 days
D 14-182 days
D
Explanation
Incubation periods
Hepatitis A: 2-6 weeks
Hepatitis B: 2-26 weeks (mean 8w)
Hepatitis C: 4-26 weeks (mean 9w)
Hepatitis D: 2-26 weeks (mean 8w)
Hepatitis E: 4-5 weeks
Note: Hep B and C incubation periods have changed AGAIN in the latets editions of Robbin’s
Extra: from a user-who has tried to make sense of all of the changes
From a bit of digging on reputable websites it seems that the consensus is HepB incubation min is 4 weeks and HepC is 2 weeks. It looks as though the textbook diagrams are correct and the text is back to front. In the 10th ed they fixed the typo for HepB but not HepC. Robbins & Cotran Pathologic Basis of Disease 9th Ed HepB Text: HBV has a prolonged incubation period (2 to 26 weeks). HepB Diag: 4–26 weeks (average 8) HepC Text: The incubation period for HCV hepatitis ranges from 4 to 26 weeks, with a mean of 9 weeks. HepC Diag: 2–26 weeks (mean 6–12) Robbins & Cotran Pathologic Basis of Disease 10th Ed HepB Text: HBV has a prolonged incubation period (4 to 26 weeks). HepB Diag: 4–26 weeks (average 8) HepC Text: The incubation period for HCV hepatitis ranges from 4 to 26 weeks, with a mean of 9 weeks. HepC Diag: 2–26 weeks (mean 6–12)
Which of the following regarding Chlamydial infections is FALSE?
A Lymphogranuloma venereum is a genital infection caused by the L serotype of C. trachomatis
B Chlamydia is a gram positive bacterium that is an obligate intracellular parasite
C Amplified nucleic acid tests have surpassed cultures in testing for the disease
D Chlamydia is the most common sexually transmitted bacterial disease in the world
B
Explanation
Chlamydia is the most common sexually transmitted bacterial disease in the world. Chlamydia is the most frequent infectious cause of female infertility and blindness (chronic conjunctival scarring). It is a gram-negative bacterium that is an obligate intracellular parasite. Lymphogranuloma venereum is a genital infection caused by the L serotype of C. trachomatis. It is a chronic ulcerative disease of the genitalia. It is sporadic in the USA but endemic in parts of Africa, Asia, Caribbean and South America. PCR tests are more sensitive than cultures. Different serotypes cause different diseases: L types-lymphogranuloma venereum. D to K types- urogenital and conjunctival infections. A, B and C- ocular infections of children (trachoma)
Regarding bacterial septic arthritis
A The different causative organisms affects men and women equally
B The joint most affected in non-gonococcal septic arthritis is the knee
C Joints are affected more commonly by direct inoculation
D The main causative organism in adults is gonococcus
B
Explanation
In bacterial septic arthritis the bacteria usually seed the joint during an episode of bacteraemia. Joints can become infected by direct inoculation or from contiguous spread from a soft tissue abscess or focus of osteomyelitis. H. influenza arthritis predominates in children <2yrs. Staf is the main causative agent in older children and adults. Gonococcus is prevalent during late adolescence and young adulthood. Those with sickle cell anaemia are prone to infection with SALMONELLA at any age. These joint infections affect the sexes equally except for gonococcus which is seen mainly in sexually active women. In 90% of non-gonococcal cases, the infection involves only a single joint, usually the knee followed in frequency by the hip, shoulder, elbow, wrist and sternoclavicular joints.
Note: the wording of the textbook is confusing: late adolescence and young adulthood- a web search gives this age 18-24yrs. Older children and adults- overlaps the 18-24 age bracket as well. The wording however, comes directly from the textbook.
I think that the stem which says “The main causative organism in adults is gonococcus” is incorrect because it should say YOUNG adults
In which part of the CNS does polio not affect?
A Posterior horn of the spinal cord
B Anterior horn of the spinal cord
C Cranial motor nuclei
D Dorsal root ganglion
D
Explanation
Polio invades the CNS and replicates in the motor neurons of the spinal cord and brainstem. Commonly the anterior horn motor neurons of the spinal cord are involved. The posterior horns of the spinal cord and the cranial motor nuclei are sometimes involved.
It does not involve the dorsal root ganglion = Trunk ganglion which is located adjacent to the spine on a dorsal root and contains the cell bodies of afferent sensory nerves.
Which of the following is characteristic of the rash of measles?
A “Slapped cheek” appearance and lacy reticular pattern.
B Painful vesicles in a dermatomal distribution.
C Pustules on an erythematous base.
D Begins as a maculopapular rash, then becomes vesicular.
E Maculopapular eruption starting on upper trunk and spreading downward.
E
Explanation
The characteristic measles rash is classically described as a generalised maculopapular erythematous rash. It starts on the head and trunk before spreading to cover most of the body. Morphology: The blotch reddish brown rash of measles is produced by dilated skin vessels, oedema, and a moderate nonspecific mononuclear perivascular infiltrate. In the mouth-Koplik spots- are ulcerated mucosal lesions near the duct of Stensen are marked by necrosis, neutrophilic exudate and neovascularization.
Extra: measles is a single stranded RNA virus of the paramyxovirus family. There is only one serotype. It is spread by respiratory droplets. Antibody-mediated immunity to the virus prevents reinfection. Measles can also produce severe immunosupression in patients resulting in secondary bacterial and viral infections responsible for much of the measles related morbidity and mortality.
Note: Measles - Maculopapular eruption starting on upper trunk and spreading downward. Erythema toxicum neonatorum-pustules on an erythematous base. Chickenpox begins as a maculopapular rash, then becomes vesicular. Shingles appear as painful vesicles in a dermatomal distribution. Human parvovirus B19 (fifth disease or erytherma infectiosum) has a “slapped cheek” appearance and lacy reticular pattern.
The disease of anthrax, which is correct?
A It produces an exo-toxin containing 2 subunits: A and B
B There are only two clinical manifestations of the disease: cutaneous and inhalational
C Bacteraemia and death is common following the cutaneous anthrax infection
D It is a large, spore forming gram negative rod bacterium
A
Explanation
Bacillus anthracis is a large, spore forming gram + rod bacterium. Common in farm and wild animals that come into soil contaminated with the bacteria spores. B. anthracis is typically acquired through exposure to animal or animal products like wool or hide. 3 major anthrax syndromes occur: cutaneous anthrax, inhalational anthrax and gastrointestinal anthrax.
Cutaneous anthrax- makes up 95% of infections. Begins as a vesicle which ruptures and is then covered by a black eschar. It dires and falls off. Bacteraemia is rare.
Inhalational anthrax- fever cough and hypoxia, bacteraemia develops which leads to shock and frequently death. Menigitis can develop form the bacteraemia.
Extra:
Bacillus anthracis is a large, spore forming gram positive rod bacterium. It is commonly found in farm and wild animals that have contact with soil contaminated with the bacteria spores. B. anthracis is typically acquired through exposure to animal or animal products like wool or hide. o It produces potent exotoxin which has A and B subunits. 3 major anthrax syndromes occur: cutaneous anthrax, inhalational anthrax and gastrointestinal anthrax.
Cutaneous anthrax account for 95% of infections and begin as vesicles which ruptures and is then covered by a black eschar. It dries and falls off. Bacteraemia is rare.
Inhalational anthrax begins with a prodoromal illness lasting 1-6 days with features consistent of fever, cough and chest or abdominal discomfort followed by an abrupt onset of worsening fever, hypoxia and sweating. Haemorrhagic mediastinitis and meningitis can develop from the bacteraemia. Inhalational anthrax rapidly leads to shock and frequently death within 1 to 2 days.
GIT anthrax is uncommon. It is usually contracted from ingestion of undercooked meat contaminated with B. anthracis. Initially causes nausea, abdominal pain and vomiting followed by severe bloody diarrhoea. Mortality >50%
GIT anthrax: uncommon. After exposure to uncooked meat. Severe bloody diarrhoea develops which leads to death in 50% of cases.
The exo-toxin is potent and has an A and B subunit.
Which is the most most common infection to complicate burns?
A Clostridium perfringens
B Pseudomonas aeruginosa
C Staf Aureus
D Candida
B
Explanation
A burn site is ideal for growth of microorganisms. The serum and debris provide nutrients and the burn injury compromises blood flow, blocking effective inflammatory responses. As a result, almost all burn become colonised. Infections of the burn site is defined by the presence of greater than 105 bacteria per gram of tissue. The most common offender is Pseudomonas aeruginosa, but antibiotic resistant strains of other common hospital acquired bacteria eg S. aureus and fungi particularly Candida may also be involved.
The diagnosis of Epstein-Barr Virus depends on all EXCEPT?
A Heterophilic antibodiy reaction
B Specific antibodies for EBV antigens
C Abnormal liver function tests
D Lymphocytosis
C
Explanation
The diagnosis of Epstein-Barr virus depends on the following findings (in increasing order of specificity)
1 - Lymphocytosis with the characteristic atypical lymphocytes in the peripheral blood
2 - Monospot test +=heterophile antibody reaction
3 - Specific antibodies for EBV antigens (viral capsid antigens, early antigens, nuclear antigens).
In most patients EBV resolves in 4-6weeks, but in some, fatigue lasts longer.
Which of the following illnesses are NOT associated with EBV infection?
A Lymphoma
B Pneumonitis
C Leukaemia
D Nasopharyngeal Ca
C
Explanation
The outcome of EBV infection in a normal immune-competent patient is either asymptomatic or mononucleosis-pneumonitis, hepatitis, splenitis, meningitis and encephalitis. In the setting of immunodeficiency, EBV is implicated in the development of EBV positive tumours (which are usually but not always derived form B cells) B cell lymphoma, nasopharyngeal Ca, Hodgkin and non-Hodgkin lymphomas and Burkitt lymphoma.
Extra:
The current text book reports the following regarding EBV and leukaemia “EBV in young children classically presents with fever, sore throat, lymphadenitis, and the other features mentioned earlier. However, malaise, fatigue, and lymphadenopathy are the common presentation in young adults with infectious mononucleosis and can raise the spectre of leukemia or lymphoma”
Web search:
Pubmed
Infection with Epstein-Barr virus (EBV) may be correlated to the onset of acute leukemia (AL).
https://pubmed.ncbi.nlm.nih.gov/28225168
Cancer.org
EBV infection increases a person’s risk of getting nasopharyngeal cancer(cancer of the area in the back of the nose) and certain types of fast-growing lymphomas such as Burkitt lymphoma. It may also be linked to Hodgkin lymphoma and some cases of stomach cancer . EBV-related cancers are more common in Africa and parts of Southeast Asia. Overall, very few people who have been infected with EBV will ever develop these cancers.
Not entirely clear if EBV actually causes ALL.
A 70yr male presents to the emergency department with trismus and sustained spasm of the facial muscles. What is the most likely causative agent?
A Clostridium tetani
B Clostridium perfringens
C Clostridium botulinum
D Clostridium difficile
A
Explanation
Clostridial infections, including clostridium botulinum and clostridium tetani, produce muscle paralysis.
Clostridium botulinum, botulism toxin, eaten in contaminated foods or absorbed from foods, binds gangliosides on motor neurons and is transported into the cell. The toxin cleaves a protein, synaptobrevin, which prevents the release of Ach at the neuromuscular junction. This results in FLACCID PARALYSIS.
Clostridium tetani, tetanus toxin, is similar to that of the botulism toxin, but tetanus toxin causes a violent SPASTIC PARALYSIS by blocking the release of γ-aminobutyric acid, a neurotransmitter that inhibits motor neurons.
Which is true concerning enterocolitis?
A Salmonella cannot survive in gastric contents
B Shigella has 3 major recognised strains
C Campylobactor is the most common bacterial enteric pathogen in developed countries
D Salmonella cause fevers which lasts for 5 days, but diarrhoea can persist for 2
C
Explanation
Campylobactor is the most common bacterial enteric pathogen is developed countries and is an important cause of traveller’s diarrhoea. Most infections are associated with improperly cooked chicken but can occur due to unpasteurised milk and contaminated water.
Shigella has 4 major recognised strains. Shigella are unencapsulated non motile facultative anaerobes.
Salmonella cause fevers which lasts for 2 days, but diarrhoea can persist for 2 weeks.
S.Typhi causes typhoid fever endemically, but S. Paratyphi is more common amongst travellers, probably due to the vaccine against S.Typhi. Salmonella can survive in gastric contents
Which is incorrect regarding Campylobacter Jejuni?
A Dysentery develops in 15% of patients
B Patients do not shed bacteria following clinical resolution
C Extra intestinal manifestations includes Guillain Barre Syndrome
D Campylobacter Jejuni is the most common bacterial enteric pathogen is developed countries
B
Explanation
Campylobacter Jejuni is the most common bacterial enteric pathogen is developed countries and is an important cause of traveller’s diarrhoea. Most infections are associated with improperly cooked chicken but can occur due to unpasteurised milk and contaminated water.
Campylobacter has 4 major virulence properties: motility, adherence, toxin production and invasion.
It contains flagella that allow it to be motile. This facilitates adherence and colonisation, which is necessary for mucosal invasion
Extra intestinal manifestations include: arthritis, Guillain Barre Syndrome.
Clinical: ingestion of as little as 500 C. Jejuni can cause disease. Incubation period up to 8 days. Watery diarrhoea with or following acute prodrome flu like illness is the primary symptom and dysentery develops in 15% of patients. Patients may shed bacteria up to one month following clinical resolution. Antibiotics are generally not required
An unimmunised patient presents to the ED with a measles rash. Which of the following statements is true?
A The rash starts on the head and trunk before spreading to cover most of the body
B Ulcerated mucosal lesions near the ducts of Stenson are not pathognomonic of measles
C Rash is classically described as a generalised vesicular erythematous rash
D Conjunctivitis is an uncommon feature associate with the measles rash
A
Explanation
The characteristic measles rash is classically described as a generalised maculopapular erythematous rash. It starts on the head and trunk before spreading to cover most of the body.
Morphology: The blotch reddish brown rash of measles is produced by dilated skin vessels, oedema, and a moderate nonspecific mononuclear perivascular infiltrate. In the mouth-Koplik spots- are ulcerated mucosal lesions near the duct of Stensen are marked by necrosis, neutrophilic exudate and neovascularization.-pathognomonic of measles.
Classic signs and symptoms of measles include four-day fevers and the three Cs- cough, coryza and conjuctivitis along with fever and rashes
Extra: measles is a single stranded RNA virus of the paramyxovirus family. There is only one serotype. It is spread by respiratory droplets. Antibody-mediated immunity to the virus prevents reinfection. Measles can also produce severe immunosuppression in patients resulting in secondary bacterial and viral infections responsible for much of the measles related morbidity and mortality.
Which of the following dieases cause fatigue and loss of vision in one eye?
A Thromboangitis obliterans
B Polyarteritis nodosa
C Infectious vasculitis
D Giant cell arteritis
D
Explanation
This question can be in an EMQ format
Giant cell (temporal) arteritis is rare before age 50.
Symptoms:
Vague, constitutional- fever, fatigue and weight loss.
Facial or head pain along the course of the superficial temporal artery, painful to palpation
Ocular symptoms: (involvement of the ophthalmic artery) appear abruptly in 50% of people. The symptoms range from diplopia to acute vison loss. Diagnose depends on biopsy and histologic confirmation
Treatment: corticosteroids or anti-TNF therapies are usually effective
Other stem options include:
Takayasu arteritis, Wegeners granulomatisis, Churg-strass syndrome and microscopic polyangitis
Which of the following diseases cause high fevers, swollen gums and lymph node enlargement in children?
A Infective vasculitis
B Kawasaki Disease
C Thromboangitis obliterans
D Takayasu arteritis
B
Explanation
This question can be in an EMQ format
Kawasaki disease
Self-limiting childhood acute febrile illness. (80% occur in <4yrs old)
Associated with arteritis affecting large to medium sized and even small vessels.
Clinical picture: conjunctival and oral erythema with blistering. Oedema of the hand and feet. Erythema of palms and soles. Cervical lymph enlargement. 20% of untreated patient developed cardiac sequel ranging form asymptomatic coronary arteritis, to coronary ectasia, to giant coronary aneurysms leading to rupture , thrombosis, myocardial infarction and death.
If disease is identified early, treatment with aspirin and immunoglobulin sharply reduces the risk of coronary artery disease.
Note: there is no mention of gum disease in the current prescribed textbook. The stem should have possibly said swollen tongue. I have left it as is.
Other stem options include:
Takayasu arteritis, Wegeners granulomatisis, Churg-strass syndrome and microscopic polyangitis
Which of the following bacterial infections are related to dairy products, cause abortions in pregnancy?
A Bordetella pertussis
B Anthrax
C Mycobacterium Leprae
D Listeria monocytogenes
D
Explanation
This question can present as an EMQ
Listeria monocytogenes is a gram positive bacillus that causes severe food borne infections. Outbreaks have been linked to dairy products, chicken and hotdogs. Pregnant women, neonates, older adults and immunosuppressed patients are susceptible to listeria infections.
In pregnant women, infection causes amnionitis resulting in abortion, stillbirth or neonatal sepsis. In neonates and immunosuppressed the infections results in exudative meningitis and can result in disseminated disease (granulomatosis infantiseptica of the newborn)
Other stem options: Staph Aureus, Staph pyogenes, TB
Which of the following bacterial infections causes a sunburn like rash that evolves into bullae?
A Enterococci
B Steptococcal pyogenes
C Listeria monocytogenes
D Staph Aureus
D
Explanation
This question can present as an EMQ
Staphylococcal scalded skin syndrome, also called Ritter’s disease, occurs most frequently in children with S. aureus infection of the nasopharynx or skin. There is a sunburn liker ash that spread over the entire body and evolves into fragile bullae that leads to partial or total skin loss. The desquamation occurs at the level granulosa layer of the epidermis. This is different to toxic epidermal necrolysis, which is secondary to drug hypersensitivity and causes desquamation at the level of the epidermal junction
The pathogenesis underlying diarrhea in cholera infection involves production/stimulation of which of the following
A Guanylyl cyclase
B Na/K ATPase
C Adenylate cyclase
D cAMP
D
Explanation
V. cholerae causes diarrhea by production of a cholera toxin that is internalized after binding enterocyte surface GM1 gangliosides. The toxin A subunit is processed to a fragment which interacts with ADP ribosylation factors to activate G protein G-S,alpha, which stimulates adenylate cyclase. The resulting surge in cAMP opens the cystic fibrosis conductance regulatory, CFTR, and releases chloride ions into the lumen.
Note:
Not a great question: the words production and stimualtion cannot both be in the question. According to the current textbook-the toxin STIMULATES adenylate cyclase which results in (PRODUCES) cAMP. I have left the question as is.
Cholera infection has the greatest impact on?
A Rectum
B Colon
C Small bowel
D Stomach
C
Explanation
Cholera is caused by V. cholerae, gram-negative bacteria typically transmitted by drinking contaminated water. Humans, plankton and shellfish are the only reservoirs. It affects primarily the small intestine. Other infectious entercolitides affecting primarily the small intestine include enteric (typhoid) fever, ETEC and EPEC strains of E. Coli, Whipple disease, and mycobacterial infection.
A 50-year-old man with unimmunized grandchildren suffers from recurrent violent coughing episodes resulting in syncope. Which type of organism is the most likely cause?
A Gram positive coccus
B Gram negative coccobacillus
C Gram positive bacillus
D Gram negative bacillus
B
Explanation
Pertussis is caused by Bordatella pertussis, a gram-negative cocco-bacillus, and causes paroxysms of violent coughing (whooping cough). Infection causes laryngotracheobronchitis with mucosal erosion, and mucopurulent exudates associated with striking peripheral lymphocytosis.
What is the main feature of infection with Norovirus?
A Gastroenteritis
B Encephalitis
C Pericarditis
D Pneumonia
A
Explanation
Many notorious gastrointestinal pathogens are intrinsically resistant to local defenses, particularly those that enter the host by ingestion. Norovirus (the scourge of the cruise ship industry) is a non-enveloped virus that is resistant to inactivation by acid, bile, and pancreatic enzymes and hence easily spread in places where people are crowded together.
Source: Robbins, basic pathology
A 22-year-old woman returns from South-East Asia and is diagnosed with Hepatitis. She is told this particular type of the virus does not progress to chronic disease and does not cause fatal hepatotoxicity. Which virus does she have?
A Hepatitis D
B Hepatitis B
C Hepatitis E
D Hepatitis A
D
Explanation
Frequency of chronic liver disease in hepatitis infections Hep A: 0% Hep B: 5-10% Hep C: > 80% Hep D: 10% (coinfection), 90-100% for superinfection Hep E: immunocompromised only (20% rate of fatal hepatitis in pregnant women)
A 7-year-old boy suffers a diarrhoeal illness for one week and then develops hypertension, edema and oliguria. What is the likely cause?
A Henoch–Schönlein purpura
B Rapidly progressive glomerulonephritis
C Post-streptococcal glomerulonephritis
D Minimal change disease
A
Explanation
Henoch-Schonlein Purpura typically presents in children aged 3-8. Findings include purpuric skin lesions (due to a vasculitis), abdominal symptoms (pain, vomiting, bleeding), arthralgia, and GN with some combination of haematuria, nephritic syndrome and/or nephrotic syndrome.
Note: The more appropriate answer may be minimal change disease because the stem describes a nephrotic syndrome, not GN. Minimal change disease is most common type of nephrotic syndrome in children.
Extra
If you are laeading to GN, but strep does not classically cause gastroenteritis. If the stem said sore throat, this answer would make more sense.
Thoughts from the a user (thank you)-the question has created some issues:
I think the description in the answer is incorrect. The stem does not describe Nephrotic because of the inclusion of hypertension and oliguria are only in Nephritic. You tend to have low BP and reduced urine output (not oliguria) with nephrotic syndrome because of the hypoalbuminaemia reduces vascular oncotic pressure resulting in fluid shift, oedema and reduced urine. From the TB: The nephritic patient usually presents with hematuria, red cell casts in the urine, azotemia, oliguria, and mild to moderate hypertension. Proteinuria and edema are common, but these are not as severe as those encountered in the nephrotic syndrome. Nephrotic syndrome is caused by a derangement in glomerular capillary walls resulting in increased permeability to plasma proteins. The manifestations of the syndrome include: * Massive proteinuria, with the daily loss of 3.5gm or more of protein (less in children) * Hypoalbuminemia, with plasma albumin levels less than 3 gm/dL * Generalised oedema * Hyperlipidemia and lipiduria Therefore; A) Rapidly progressive glomerulonephritis - Absolutely could be a cause but it is rare in the paediatric population with peak occurrence at age 60-85y. B) Minimal change disease - is wrong because it is a nephrotic syndrome C) Henoch-Schonlein Purpura - a strange choice since they fail to mention the rash which occurs in 100% of cases. The question clearly implies a post infective origin given the symptoms developed one week after a diarrhoeal illness. According to RCH “Recent upper respiratory tract infection is present in 50% of HSP cases, commonly viral or Group A streptococcus infections” https://www.rch.org.au/clinicalguide/guideline_index/HenochSchonlein_purpura/ So it seems they are arguing a post viral gastro as the infective cause for HSP making C correct. D) Post-streptococcal glomerulonephritis - Would be preceded by a sore throat not diarrhoea. Nonstreptococcal Acute Glomerulonephritis (Postinfectious Glomerulonephritis) would be correct if it was an option. I hope you appreciate this answer since I wasted over an hour on it.
A 65-year-old lady presents with a painful, vesicular rash localized to her right forehead region. What is the likely causative organism?
A HSV-1
B Varicella Zoster
C HSV-2
D Herpes Zoster
B
Explanation
This condition, called Herpes Zoster, is caused by reactivation of the varicella zoster virus which remains latent in sensory ganglia following initial infection some years earlier.
Carcinoma of which organ is an AIDS-defining illness?
A Liver
B Gastric
C Tongue
D Cervix
D
Explanation
AIDS-defining illnesses include infections and tumours. Tumours include Kaposi sarcoma, lymphomas, and SCC of cervix and anus.
Extra:
AIDS related cancers
People living with HIV are much more likely to get certain types of cancer than people without HIV. Certain kinds of cancer are called AIDS-defining cancers or AIDS-defining malignancies. This means when people with HIV develop one of them, their HIV infection has progressed to AIDS. AIDS-defining cancers are:
Kaposi sarcoma
Aggressive B-cell non-Hodgkin lymphoma (NHL)
Cervical cancer
What causes AIDS related cancers?
The cause of cancer in people living with HIV isn’t clearly understood. But when a person becomes infected with HIV, we know that their immune system doesn’t work as well as it should. This puts them at higher risk for infections. It makes their body less able to control viral growth, and some viruses are linked to cancer. For instance, HPV (human papillomavirus) infection has been linked to certain head and neck cancers, anal, and cervical cancer, as well as many other kinds of cancer. Lymphoma has been linked to viral infections, too.
Source:https://www.cedars-sinai.org/health
An AIDS patient with a CD4+ count of 50 presents with cough, fever and diffuse infiltrates. Which is the most likely causative organism?
A Candida
B S. aureus
C CMV
D Aspergillus
C
Explanation
We have changed the answer. Although we thought the previous answer was candida-being the most common pathogen, the question specifically refers to a CD4 count of 50. Therefore…
From the TB
CD4 T cell count is often useful in narrowing the differential diagnosis.
As a rule of thumb, bacterial and tubercular infections occur with mildly suppressed CD4 counts (>200).
Pneumocystis pneumonia usually occurs when CD4<200.
CMV and M. Avium complexes are uncommon until the very late stages of the disease (CD4 <50).
Original thought
Candida is the most common fungal pathogen. CMV may be systemic but more commonly involves the eye and GIT.
Extra:
Pneumocystis jiroveci used to be a very common opportunistic infection in HIV (also fungal), but incidence is much less common in patients responding to antivirals (note the low CD4 count in stem suggesting pt is still quite affected by HIV).
Robbins: Approximately 15% to 30% of untreated HIV-infected people develop pneumonia at some time during the course of the disease, caused by the fungus Pneumocystis jiroveci (reactivation of a prior latent infection). Before the advent of HAART, this infection was the presenting feature in about 20% of cases, but the incidence is much less in patients who respond to HAART. * Many patients present with an opportunistic infection other than P. jiroveci pneumonia. Among the most common pathogens are CANDIDA, cytomegalovirus, atypical and typical mycobacteria, Cryptococcus neoformans, Toxoplasma gondii, Cryptosporidium, herpes simplex virus, papovaviruses, and Histoplasma capsulatum.
Candidiasis is the most common fungal infection in patients with AIDS, and infection of the oral cavity, vagina, and oesophagus are its most common clinical manifestations. In asymptomatic HIV-infected individuals’ oral candidiasis is a sign of immunologic decompensation, and it often heralds the transition to AIDS. Invasive candidiasis is infrequent in patients with AIDS, and it usually occurs when there is drug-induced neutropenia or use of indwelling catheters. *
Cytomegalovirus may cause disseminated disease, although, more commonly, it affects the eye and gastro-intestinal tract. Chorioretinitis was seen in approximately 25% of patients before the advent of HAART, but this has decreased dramatically after the initiation of HAART. Cytomegalovirus retinitis occurs almost exclusively in patients with CD4+ T cell counts less than 50 per microliter. Gastrointestinal disease, seen in 5% to 10% of cases, manifests as esophagitis and colitis, the latter associated with multiple mucosal ulcerations.
HPV (Human papilloma virus) vaccination helps prevent which cancer?
A Ovarian cancer
B Uterine cancer
C Cervical cancer
D Vaginal cancer
C
Explanation
Human papilloma virus is an important cause of benign warts, cervical cancer and oropharyngeal cancer. It is an agent that is spread through sexual contact, is responsible for a large majority of cases of cervical carcinoma and an increasing fraction of head and neck cancers.
HPV (Human papilloma virus) infection can lead to which cancer?
A Uterine cancer
B Ovarian cancer
C Vaginal cancer
D Cervical cancer
D
Explanation
Cervial cancer
Note: very similar questions about HPV.
An elderly man presents with subacute infective endocarditis, what is the likely cause?
A Staph epidermidis
B Staph aureus
C Strep pyogenes
D Strep viridans
D
Explanation
Subacute IE is characterized by organisms with lower virulence (e.g., viridans streptococci) that cause insidious infections of deformed valves with overall less destruction.
Acute infective endocarditis is typically caused by infection of a previously normal heart valve by a highly virulent organism (e.g., Staphylococcus aureus) that rapidly produces necrotizing and destructive lesions.
