Infectious Diseases MCQ

8/13/2019 Infectious Diseases MCQ

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Infectious Diseases

Recognised features of infectious mononucleosis include:

A Palatal petechial haemorrhages (True)

B Aseptic meningitis (True)

C Vesicular rash on neck and trunk (False)

D Raised asparatate amino transferase (True)

E Splenomegaly (True)

Comments:Incubation period of infectious mononucleosis is 30-60 days. Results of infection:

1. Asymptomatic (most)2. Simple infection: fever, malaise, headache, myalgia, worsening sore throat

abdominal pain. Splenic enlargement in 50% to 2-3cm. 90% have

lymphadenopathy and 10% liver enlargement. Severe pharyngitis with exudate

and petechiae is often present, and maculopapular rash will occur in 80% given

Amoxycillin.3. Complications: Splenic rupture with trauma (


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Comments:a - BCG vaccine may given to newborns at high risk of exposure. b - The BCG vaccine

is an attenuated strain - it provides approximately 70% protection. c - It should NOT

be given to these children. A low reactivity Heaf test (grade 0 - 1) should be

documented before administration. d- BCG is given at Comprehensive school entry(age 11 - 13). e - It has also found a use in stimulating the immune system for the

treatment of some cancers.

Presenting features of HIV infection in childhood include:

A Persistent oral thrush beyond the neonatal period (True)

B Hepatosplenomegaly (True)

C Failure to thrive (True)D Bilateral perihilar infiltrates on chest x-ray (True)

E Recurrent otitis media (True)

Comments:

Post-neonatal thrush suggests cell-mediated immune deficiency if the child has not hadbroad-spectrum antibiotics. Hepatosplenomegaly and lymphadenopathy are

characteristic. Lymphoid interstitial pneumonitis (LIP) is a common finding,particularly in Africans. Recurrent common bacterial infections occur in early disease,

with pneumocystic pneumonia, pneumococcal septicaemia being disseminated CMVmaking further decline in their immunity.

Copyright 2002 Dr Colin Melville

Clinical features of toxoplasmosis include:

A microcephaly (True)

Bchoroidoretinitis (True)

C cervical lymphadenopathy (True)

D mouth ulcers (False)

E sacroiliitis (False)

Comments:


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Causes for Microcephaly include; * down's syndrome * congenital rubella * congenitaltoxoplamosis * congenital CMV * cri du chat syndrome * seckel'syndrome *

rubinstein-taybi syndrome * trisomy 13 * trisomy 18 * smith-lemli-opitz syndrome *

cornelia de Lange syndrome * uncontrolled maternal phenylketonura * methylmercury

poisoning

The following are features of congenital toxoplasmosis:

A Generalised lymphadenopathy (True)

B Microcephaly (True)

C Thrombocytopenia (True)

D Intracranial calcification (True)

E A good prognosis without treatment (False)

Comments:Congenital toxoplasmosis, fortunately rare, is associated with the usual manifestationsof congenital infection: IUGR, thrombocytopaenia, intracranial calcification,

chorioretinitis. Hydrocephalus is more common, but microcephaly well described.

Most cases are unaffected, but may present with chorioretinitis many years later. Theincidence used to be highest in France, because of their penchant for eating uncooked

meat, but public health measures have reduced the incidence there. Copyright 2002

Dr Colin Melville

IgA:

A Is involved in mucosal immunity. (True)

B Have 4 distinct sub-groups. (False)

C Activates complement via the classical pathway. (False)

D Is manufactured in lymph nodes. (True)

E Crosses the placenta. (False)

Comments:

IgA is the major antibody in serology: tears, sweat, lung, gut, urine. IgA avoidsdigestion by the presence of the secretory piece which is added as it is secreted onto

the mucosa. It is an important defence


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against surface binding of micro-organisms. There are 2 sub-types, IgA1 and IgA2.Only IgG is transferred across the placenta. Complement proteins circulate, therefore,

they rarely come into contact with IgA.


In ataxia telangiectasia:

A Inheritance is X-linked recessive. (False)

B The usual presentation is with lower respiratory infections. (False)

C Chromosome fragility is increased. (True)

D The immunodeficiency primarily affects phagocyte function. (False)

E Chronic thrombocytopenia is an important feature. (False)

Comments:

Ataxia telangiectasiais an autosomal recessive disorder, with a defect that has nowbeen localised to chromosome 11q 22-23. Ataxia occurs when a child first begins towalk, and subsequently, recurrent sino-pulmonary infections occur. Telangiectasiae

become evident at 3-6 years, because of the DNA repair defects (similar defects are

found in Fanconi's anaemia and Bloom's Syndrome). The immune deficiency isvariable, with the commonest being an IgA deficiency. Thrombocytopenia suggests

Wiskott-Aldrich Syndrome, particularly in a boy with immune deficiency and eczema.


The following conditions are thought to have an atopic basis:

A Seborrhoeic dermatitis (False)

B Dermatitis in response to nickel (False)

C Anaphylactic reaction to peanuts (True)

D Hereditary angio-neurotic oedema (False)

E Cow's milk protein intolerance (True)

Comments:

Seborrhoeic dermatitis is a condition of unknown aetiology, and is associated with


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greasy scales found on the scalp, forehead, cheeks. The patients are very well inthemselves, and have no particular itching.

In atopic dermatitis the skin lesions tend to be more on the cheeks, and later becomeflexural.

Nickel dermatitis is a contact dermatitis.

C1 inhibitor deficiency is hereditary angio-neurotic oedema. This is associated withabdominal pain in adolescence, but can occasionally involve life-threatening airway

obstruction.

Cow's milk intolerance is strongly associated with atopy.


Recognised causes of polyarthritis in children include:

A Mumps (True)

B Rubella (True)

C Idiopathic thrombocytopenic purpura (False)

D Henoch Schonlein purpura (True)

E Acquired hypogammaglobulinaemia (False)

Comments:Recognised causes of polyarthritis in children include:

Juvenile chronic arthritis.

Septic arthritis: including Reiter's, gonococcus, MTB.

Post-infectious: including rubella, mumps, parvovirus, hepatitis B and HSP.

In immunocompromised patients: Aspergillus, mycoplasma, enteroviral,

arthritidies.

Polyarthritis is a common condition, and has both infectious and non-infectious

causes:

Viral: enterovirus infection, mumps, rubella, fifth disease, hepatitis B.

Bacterial: campylobacter, rat bite fever, and is also found in meningitis.

Inflammatory: Henoch Schonlein Purpura, inflammatory bowel disease,

Reiter's Syndrome, rheumatic fever, Sjogren's Syndrome, systemic lupuserythematosis, psoriasis.


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The following statements are true about immunological reactions:

A Serum sickness is caused by a type II reaction. (False)

B Grave's Disease is caused by a type IV reaction. (False)

C Angio-neurotic oedema is the most severe form of type I

reaction.(False)

D Urticaria usually responds to Cimetidine. (False)

E Deficiencies in the terminal components of complement increasethe risk of meningococcal disease.

(True)

Comments:

Serum sickness is due to circulating antibody-antigen complexes (Type III). Grave'sDisease is due to stimulating antibody (Type VI). The most severe variety of Type I

reaction is anaphylaxis, with angio-oedema an intermediate reaction associated with

wheeze and swelling of the lips and severe urticaria. These reactions are mediated byhistamine 1 receptor stimulation. Congenital C1 inhibitor deficiency is also causedhereditary angio-oedema. Deficiencies in C1r, s, and 2-4 result in vasculitidies; while

deficiencies in C2, 3 and 5-8 are associated with an increased risk of septicaemia.


The following forms of encephalitis are caused by a neuroimmunological

response:

A Herpes simplex (False)

B Measles (True)

C HIV infection (False)

D Enteral viruses (False)E Cytomegalovirus (False)

Comments:

Encephalitis may be caused by:


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Direct invasion by a neurotoxic virus (encephalitis).

Post-infectious encephalopathy: delayed brain swelling because of an

immunological response to the antigen.

Slow virus infection, e.g. HIV or SSPE.

Direct infection is most commonly caused by enteral viruses, HSV 1 and 2, varicella,CMV, and EBV. It is also occasionally caused by respiratory viruses, HHV6, rubellaor mumps. A post-infectious illness may also be caused by measlesor varicella zoster

(cerebellar ataxia).


Causes of confusion and seizures in patients with AIDS include:

A Toxoplasmosis (True)

B Progressive multifocal leuconencephalopathy (True)

C Cryptococcal meningitis (True)

D AIDS-dementia complex (True)

E CMV (True)

Comments:PML is a progressive infection of oligodendroglial cells by JC papovirus in immune

deficiency. Invariably fatal, but uncommon in children with HIV. Copyright 2002Dr Colin Melville

In herpes simplex encephalitis:

A brain MRI is characteristically normal (False)

B temporal lobe involvement is common (True)

C fits are uncommon (False)

D cold sores or genital herpes are usually present (False)

E viral identification by PCR on cerebrospinal fluid is non-specific (False)

Comments:MRI brain normally shows changes in the temporal lobes. Presenting features include

fever, headache, vomiting, reduced consciousness and seizures. There may be

dysphasia, hallucinations and peculiar behaviour. There are usually no skin

manifestations of herpes simplex infections. The virus is rarely isolated from CSF but


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E Presentation commonly before the age of 30 years (True)

Comments:

The rash is usually maculopapular. Jaundice is rare. In 10% the liver will be palpable

and 50% the spleen will be palpable, 90% have tonsillar lymphadenopathy. Pharyngitisand is common. WCC 10-20k (30% atypical lymph). Mild thrombocytopenia in 50%of cases. Rare in children less than 4 years of age, and rare in adults over 40 years of

age.


Falciparum malaria:

A acute infection is not associated with splenomegaly (False)

B is associated with periodic fever in a minority of cases (True)

C has an incubation period of 8-15 days (True)

D may present as a gastroenteritis (True)

E may be treated with primaquine (False)

Comments:Falciparum malariahas an incubation period of 8-15 days and is frequently

associated with splenomegaly and unlike the other malarias does not cause a typicalperiodic fever. Features include high fever, headaches, chills, arthralgia andgastroenteritis. It is treated with quinine as frequently it is chloroquine resistant and

primaquine is used for prophylaxis not treatment.

In a 6 month old child with meningitis, the following organisms should be covered

by first line antibiotic therapy:

A Group B Streptococcus (False)

B Listeria monocytogenes (False)

C E. Coli (False)

D Haemophilus Influenzae Type B (True)

E Pseudomonas. (False)

Comments:


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Antibiotics should be selected according to the common organisms prevalent at

various ages. Currently, in the UK these are:

6 years: Meningococcus, Pneumococcus.


Metronidazole:

A Inhibits dihydrofolate reductase. (False)

B Has 80% bioavailability if given rectally. (True)

C Has harmful effects with alcohol. (True)

D Causes coloured urine. (True)

E Causes peripheral neuropathy. (True)

Comments:Reduced to active derivative which binds to DNA and inhibits acid synthesis.

Disulfiram reaction with alcohol. Some types of Warfarin. Metallic taste, hypotension,peripheral neuropathy.Copyright 2002 Dr Colin Melville

AZT (Azidothymidine):

A Is a uridine analogue. (False)

B Inhibits reverse transcriptase. (True)

C Is contraindicated if neutrophil count


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nausea. Rapid resistance develops due to an error-prone replication of the HIV virusand rapid mutations. AZT is particularly useful for preventing vertical transmission

from mother to child. Copyright 2002 Dr Colin Melville

The following are characteristic of early tetanus:

A Rigid abdomen (True)

B Rigid jaw muscles (True)

C Dysphagia (True)

D Hyperpyrexia (True)

E Carpopedal spasm (False)

Comments:

Infantile generalised tetanus develops within 302 days of birth. The usual picture is of

poor feeding, hunger crying, paralysis and decreased movement. The child becomesstiff with muscular spasms and opythotomis. A contaminated umbilicus may be

obvious. The fever is usually secondary to muscular spasm (muscular energy).

Carpopedal spasms -/+ laryngospasm occurs in manifest tetany due to extreme vitaminD deficiency, hypomagnesiaemia or hypocalcaemia. The wrists are flexed withextended fingers and aducted thumbs with extended and aducted feet. Latent tetany

refers to carpopedal spasm occurring on ischaemia of the motor nerves caused by

blowing up of a blood pressure cuff.


Influenzae vaccine is recommended in the following patients:

A HIV infected child (True)

B Chronic purulent lung disease (True)

C Acute lymphoblastic leukaemia patient (True)

D Chronic heart disease (True)E Severe cerebral palsy/mentally retarded (True)

Comments:

Frequent genetic reassortments make vaccine production difficult. Currently, a

trivalent vaccine is used consisting of 2 types of 2 strains of type A and one strain of


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type B based on last year's circulating viruses. Usual protection is about 75%, althoughthis will reduce in pandemic years.

Recommendations are that the following receive influenza vaccine:

1. Diseases: a) Chronic respiratory disease including asthma. b) Chronic heart disease.c) Chronic renal failure. d) Diabetes mellitus. e) Immunosuppression due to disease ortreatment including asplenia or splenic dysfunction.

2. Those in residential homes.


Recognised complications of chickenpox infection include:

A Pneumonitis (True)

B Pancreatitis (True)

C Subacute encephalitis (True)

D Cerebellar encephalitis (True)

E Erythema marginatum (False)

Comments:Complications of chickenpox include:

Superinfection (Staph. and Strep.), which rarely results in varicella

gangrenousum, arthritis, osteomyelitis, and pneumonia.

Encephalitis/ cerebellar ataxia.

Reye's, hepatitis, or pancreatitis.

Thrombocytopenia.

Nephritis, nephrosis, or haemolytic uraemic syndrome.

Myocarditis or pericarditis.

Orchitis.

Pneumonitis (immunocompromised with lymphocyte count < 0.5x109/L,

newborn or pregnant).



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The following conditions may be significantly worsened by concurrent

corticosteroid or cytotoxic drug therapy:

A tuberculosis (True)

B amoebiasis (True)

C strongyloides (True)

D giardiasis (False)

E ascariasis (False)

Comments:a-easy, b!, c-may precipitate intestinal perforation

The following are recognised features of Lyme disease:

A Recurrent headache (True)

B Seventh nerve facial palsy (True)

C Behavioural change (True)

D CSF neutrophil leukocytosis (True)

E Neutrophil pleocytois on CSF examination (True)

Comments:Borrelia Burgdoferi(spirochete). Zoonosis (1xbdes deer tick) - Incubation 3-32 days.

Early - Localised: annular rash (erythema migrans), fever, malaise, headache.Disseminated: Haemotogenous spread, multiple small skin lesions, conjunctivitis,

nodes, aseptic meningitis, seventh nerve palsy. Late - Arthritis waxing and waningover weeks (knee in 90%) worsens over time. Complications - Dehydrating,

encephalitis, polyneuritis, impaired memory. Copyright 2002 Dr Colin Melville

An 8 month old girl presents with fever and lethargy. The following are true:

A The child can be safely discharged if only a maculopapular rashis found.

(False)

B The absence of a stiff neck, bulging fontanelle, and petechiae

excludes meningococcal infection.(False)


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C A capillary refill time of 3 seconds means that oral fluids shouldbe pushed.

(False)

D Petechiae in meningococcal septicaemia are characteristicallyfound on the trunk.

(False)

E Meningitis caused by H. Influenzae group B can be excluded ifthe child has received 2 or more immunisations.

(False)

Comments:

30% of meningococcal disease presents initially with a maculopapular rash. Neck

stiffness and bulging fontanelle are late signs. Petechiae are present in only 70% at

presentation and may be found anywhere. (Henoch Schnlein Purpura petechiae arefound on buttocks and extensor surfaces). A prolonged capillary refill time suggests

increased circulating volume, and the need for IV fluids. Protection from Hib vaccine

is around 99%, but invasive infections still occur.


The following mechanisms of microbial resistance are correctly ascribed:

A Pseudomonas aeruginosaby mutation of specific binding

proteins.(False)

B Staphylococcus epidermidisby slimeproduction. (True)

C Staphylococcus aureusby slime production. (False)

D Streptococcus faecalisbybeta lactamaseproduction. (True)

E Herpes simplex by mutations of viral thymidine kinase. (True)

Comments:

Pseudomonas produce induciblebetalactamases and slime. Staphylococcus aureusproduces betalactamases.


Causes of confusion and seizures in patients with AIDS include.

A Toxoplasmosis. (True)


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B Progressive multifocal leuconencephalopathy. (True)

C Cryptococcal meningitis. (True)

D AIDS-dementia complex. (True)

E CMV (True)

Comments:PML is a progressive infection of oligodendroglial cells by JC papovirus in immune

deficiency. Invariably fatal, but uncommon in children with HIV.Copyright 2002 DrColin Melville

The following clinical features suggest that a febrile child of 9 months has a

severe infection:

A The presence of petechiae (False)

B Rousability to pain (True)

C Toe-core temperature difference of 4C (True)

D Wetting of the nappy once a day (True)

E Serum fibrinogen of 0.78g/L (True)

Comments:Only 7% of children with fever and petechiae have a serious infection, but petechiae

are characteristic of meningococcal disease, so 48 hours of antibiotics is reasonableuntil cultures are negative. Loss of consciousness is a late sign, suggesting septic shockis affecting brain function. A high toe-core temperature difference suggests poor

perfusion. Oliguria suggest renal dysfunction. Normal fibrinogen level is 2-4g/l (1.25-

3 in newborn). Low levels are found in disseminated intravascular coagulation.Copyright 2002 Dr Colin Melville

Epstein-Barr virus is associated with:

A Burkitt's lymphoma (True)

B Cervical neoplasia (False)

C nasopharyngeal carcinoma (True)

D pharyngitis (True)

E autoimminue haemolytic anaemia (True)


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Comments:a-Too easy. b-Seems a little vague. Is associated with lymphocytic lymphomas which

could present in the neck and cervical lymphadenpopathy in infectious mononucleosis.

c-Anaplastic nasopharyngeal carcinoma, common in SE China, virtually all cases have

evidence of EB in the tumour tissue. d-Infectious mononucleosis. Usually severepharyngitis. e-Usually resolves after 1-2 months.

The following should be avoided in suspected immunodeficiency:

A MMR (True)

B DPT (False)

C Oral polio vaccine (True)

D Pneumovax II vaccination (False)

E Transfusion of packed cells (True)

Comments:

Live vaccines: MMR, oral polio, BCG, measles.

Killed: pertussis.

Inactivated: IM polio.

Toxoids: DT.

Submit: Hib.

Packed cells contain a few lymphocytes which can give transfusional graft versus hostdisease (GVHD) in SCID, which is invariably fatal. Viruses can also be transmitted via

blood products.


The following micro-organisms are generally sensitive to

Benzylpenicillin:

A Streptococcus Pneumonaie (True)

B Cryptococcus neoformans (False)

C Bordetella pertussis (False)

D Streptococcus viridans (True)


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E Mycoplasma pneumoniae (False)

Comments:

Penicillin binds to specific penicillin-binding proteins (PBP's) in the cell wall, mainly

of gram positive organisms. Penicillin resistance is usually due to production of alteredPBPs or beta-lactamases which leave the penicillin molecule. Penicillin is mainlyuseful for Group A Strep., Group B Strep., meningococcal and pneumococcal

infections, though and anthrax are also sensitive. Pneumococci with modified PBPs are

an increasing problem.


In mumps

A The incubation period is usually 21 days. (False)

B Orchitis is typically bilateral. (False)

C Aseptic meningitis is a complication. (True)

D Amylase may be increased despite no evidence of pancreatitis

clinically.(True)

E Sublingual swelling may occur. (True)

Comments:Paramyxovirus infect the salivary glands, especially the parotids. It is spread by directcontact, saliva, droplets, and urine. 85% of patients are 10%clinically or ? up to 65%. Orchitis affects 25% of adolescents. Bilaterally in 30%, only

fertility, not sterility. It rarely causes oophoritis, pancreatitis, nephritis, thyroiditis,

myocarditis, mastitis, deafness (but important), ALSO, eye, joints and low platelets(3TP).Copyright 2002 Dr Colin Melville

The following statements are true:

A Brucellosis is characterised by neutrophil leucocytosis. (False)

B Brucellosis is a recognised cause of spondylitis. (True)

C Toxoplasmosis causes visceral larva migrans. (False)


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D Toxoplasmosis causes posterior uveitis. (True)

E Serological evidence of toxoplasmosis is rare in adults. (False)

Comments:

Brucellosis is a zoonosis, spreading from infected animals particularly cattle. There are4 species, melitensis, abortus, suis, and canis. Pasteurisation of milk has decreased the

incidence in the UK dramatically. Brucella are gram negative bacilli which are

fastidious. There is usually a history of exposure, and the symptoms are rather non-specific with fever, malaise, arthralgia and depression. 35% have hepatosplenomegaly.

Leukopaenia is common, and 75% have a positive blood culture (90% of bone marrow

cultures will be positive). Toxoplasma is most frequent in farming communities wherecontact occurs with cats, and patients eat raw meat. Clinical manifestations include:

focal choroidoretinitis or posterior uveitis, optic atrophy, retinal detachment, cataract

and glaucoma.


The following are true of tetanus:

A failure to culture Clostridium tetanifrom the wound would make

the diagnosis doubtful(False)

B infection confers lifelong immunity (False)

C there is a characteristic EEG (False)D Clostridium-specific intravenous immunoglobulin is of no benefit

once spasm has started(False)

E cephalic tetanus causes severe dysphagia (True)

Comments:A-absence of a wound does not exclude tetanus. B-patients need to be activelyimmunized after recovery. C-The toxin tetanospasmin doesn't cross the blood brain

barrier, it diffuses through the blood to bind to receptors containing gangliosides on the

neuronal membranes of presynaptic nerve terminals in muscles. The toxin does reach

the brain by axonal transport. D-it is ineffective once the toxin is attached to nervoustissue but may prevent progression. E-Cephalic meaning involving the cranial nerves

usually from a wound on the head and neck. May be confused with rabies buthydrophobia never occurs. (OTM, 3e, 7.11.20)


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Mediators of the febrile response include:

A Interleukins (True)

B Interferon (True)

C Prostaglandins (True)

D Endotoxins (True)

E Monocytes (True)

Comments:

The sequence of events is as follows: Exogenous pyrogen includes sources such asinfection, immunological reactions or toxins. Endogenous pyrogens consist ofcytokines such as IL1 and 6, TNFL,b and interferon-a. These are derived from

monocytes, endothelial cells, B cells, glial cells and epithelial cells. Exogenouspyrogens cause a release of endogenous pyrogens which act on the hypothalamuswhich released prostaglandin E2. The latter acts on the temperature regulatory centre

to reset it, resulting in heat conservation by the body and increased heat production.


Circulating immune complexes are seen in:

A Arthus reactions (True)

B Post-streptococcal glomerulonephritis (True)

C Late homograft rejection (False)

D Serum sickness (True)

E Rhesus incompatibility (False)

Comments:

An arthus reaction is a type 3 serum sickness type reaction, while graft rejection is type

4 and rhesus reaction is type 2.



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The following antimicrobial agents work in the way described:

A Penicillin by binding to specific receptors to increase bacterial

cell wall permeability.(True)

B Acyclovir by specific inhibition of viral thymidine kinase. (False)

C Erythromycin by inhibiting bacterial folate synthetase. (False)

D Vancomycin by inhibiting bacterial ribosomes. (False)

E Ciprofloxacin by inhibition of bacterial DNA gyrase. (True)

Comments:

Acycloviris phosphorylated by viral thymidine kinase, which is triphosphorylated by

cellular enzymes to inhibit the herpes simplex virus DNA polymerase, thereby actingas a DNA chain terminator.

Erythromycininhibits bacterial ribosomes.Vancomycininhibits cell wall synthesis by a mechanism that differs frombetalactamases (no cross-resistance).

Ciprofloxacinby inhibition of bacterial DNA gyrase

Penicillinby binding to specific receptors to increase bacterial cell wall permeability.

Regarding the epidemiology of infections, the following statements are true:

A Resistant vivax malaria is a major problem in Kenya. (False)

B Diphtheria has been eradicated in most parts of the world. (False)

C Polio has been eradicated in most parts of the world. (True)

D Tetanus has been eradicated in most parts of the world. (False)

E The AIDS epidemic seems to be declining worldwide. (False)

Comments:

Falciparumis the major resistance problem in sub-Saharan Africa (Kenya). Most

vivaxis Chloroquine sensitive, though resistant strains are appearing inNew Guinea

and Indonesia. Diphtheria is still prevalent in many parts of the world. An upsurge inpolio is now nearing eradication. Tetanus is still common. AIDS is increasinginexorably.



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The following are characteristic of acute hepatitis B:

A Most patients present with splenomegaly. (False)

B It confers immunity to hepatitis A. (False)

C It commonly presents with distal joint arthritis. (False)

D There is increased infectivity in the presence of the E antigen. (True)

E Pruritis is an important early symptom. (False)

Comments:

Clinical features of hepatitis B are as follows:

1. Most are asymptomatic.2. Symptoms: Lethargy, anorexia, arthralgia, rash (any type), papular

acrodermatitis (Gianotti Crosti), polyarthritis, glomerulonephritis, aplasticanaemia. 25 % have jaundice.

3. Complications: Acute fulminent hepatitis. Chronic hepatitis. Membranousglomerulonephritis. Hepatitis E antigen is present in the acute phase and

indicates a highly infectious state. Pruritis is characteristic of chronic hepatitis.


Herpes simplex:

A Is a common cause of erythema multiforme. (True)

B In the newborn is often fatal. (True)

C Infection of genitalia is always due to type II. (False)

D Primary infection is commonly followed by latent infection of

sensory ganglion cells.(True)

E May cause damage to the eyes. (True)

Comments:

Herpes simplex virus is a DNA enveloped virus which is extremely common. It causesinfections of skin, mucus membranes, eyes, CNS, genitalia or systemic systems. The

severity of disease is proportional to the degree of immuno-incompetence of the host.

HSV1 affects the skin and mucus membranes above the waist. HSV2 generally affectsthe genitalia and the neonate. Incubation period is 202 days (7mo.), and is through

close contact or skin breaks.


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Clinical features:

1. 85% are asymptomatic.2. Vesicular lesions causing a scab which heals over 700 days (2yr.), causing

local pain but rarely scarring.3. Primary mucus membrane involvement is manifest as gingivostomatitis, or

occasional eczema hepeticum or keratoconjunctivitis. Secondary involvement

usually results in cold sores or chronic keratoconjunctivitis. Systemic infection

usually occurs in the newborn or in immunocompromised patients such asthose with cancer or HIV. CNS infection results in fever, changes in conscious

level or personality with focal signs, and a pre?? For the temporal lobes.

4. Erythema multiforme is caused by hypersensitivity reaction to:o Drugs:such as Penicillin, Sulphanomide, Isoniazid, Tetracycline,

Aspirin or Carbamazepine.

o Infections: such as EBV, herpes simplex virus 1 and 2, mycoplasma,

TB, Group A Strep.o Other:Sunlight, leukaemia, lymphoma, HSP or Kawasaki Disease.

A 3 year old boy presents with fever and headache. He has received oral

Amoxycillin for 3 days. The following CSF findings exclude a partially treated

meningitis:

A Negative gram stain (False)

B A CSF glucose of 45% of blood glucose (False)

C A white cell count of 50 (True)

D A negative CSF culture (False)

E Negative Kernig's Sign (False)

Comments:

The assessment of children with suspected bacterial meningitis who have alreadyreceived antibiotic therapy is a diagnostic conundrum. This applies to about 25-50% of

children, so it is an important problem. Partial treatment may reduce the incidence ofpositive CSF gram stains to


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Concerning CNS involvement in AIDS:

A Toxoplasma may give rise to a focal lesion with neurological weakness. (True)

B The HIV virus can be isolated from the brain of an encephalopathic patient. (True)

C A diagnostic elevation in the CSF IgM occurs in toxoplasmic infection. (False)

D Cerebral toxoplasmosis can be treated by Pyrimethamine alone. (False)

E Occular involvement may cause blindness. (True)

Comments:

Cerebral toxoplasmosis presents very variably, from an acute encephalopathy to subtleneurological syndromes. It should be considered in all undiagnosed neurological

disease in the under ones, especially if there are retinal lesions.

Characteristic are hydrocephalus, seizures with focal defects, spinal or bulbar palsies,

microcephaly, and decreased IQ. Investigations such as skull x-ray or CT scan show

calcification of the periventricular area, tachyzoites in the CSF and positive blood titres.Pyrimethamine and Sulphadiazine have a synergistic effect in treating it, and folinic

acid may be necessary to prevent seizures.


Giardia lamblia:

A Is widespread in Europe. (True)

B Is waterborne. (True)

C Is a recognised cause of steatorrhoea. (True)

D Is often asymptomatic. (True)

E Is eradicated by Mebendazole. (False)

Comments:

Giardia is a worldwide protozoa. It causes variable villus flattening on jejunal biopsy.The majority of cases are asymptomatic, though they may cause acute or chronic

diarrhoea and a malabsorption syndrome. Symptoms are considerably worse in the

immunosuppressed or immunodeficient. Metronidazole should be given if the patients

are symptomatic


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Regarding diphtheria:

A It is predominantly spread from cutaneous lesions. (False)

B It is characterised by an inflammatory exudate forming a greyish membrane

on the buccal mucosa.(False)

C It produces a toxin which affects the myocardium, nervous and adrenal

tissues.(True)

D 3 doses of toxoid provides 75% protection. (False)

E About 50 cases per year are seen in the UK. (False)

Comments:

Diphtheria is spread by droplets, through contact with soiled articles (fomites), and, inareas of poor hygiene, from cutaneous spread. The inflammatory exudate forms a

greyish membrane on the tonsils and respiratory tract which may cause respiratory

obstruction. Incubation is between 2 and 5 days, and patients may be infectious for 4weeks. The toxin affects the myocardium, nervous and adrenal tissues. The

immunisation has been tremendously successful, and most cases seen in the UK are

imported from the Indian subcontinent or Africa. Recently, there has been a worrying

epidemic of diphtheria in Russia and the newly independent states of the former SovietUnion. In 1995, 52,000 cases and 1,700 deaths were reported.

In HIV infected children:

A Extrapulmonary pneumocytosis is recognised. (True)

B CNS toxoplasmosis is recognised. (True)

C Congenital CMV is common. (False)

D Cytosporidial disease may be prolonged. (True)

E Infectious mononucleosis may be fatal. (False)

Comments:HIV infected children go through stages as their immunity declines.

Stage 1: Increased frequency of common infections such as otitis media, sinusitis,

chest infections, oral candida and pneumococcal and salmonella septicaemia.


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Stage 2: Opportunistic infections including cryptosporidia (causing prolongeddiarrhoea which can be very difficult to treat), pneumocysitis pneumonia, CMV

(pneumonitis, hepatitis, retinopathy, and septicaemia), and CNS toxoplasmosis, in

addition to candida oesophagitis and mycobacterium aviumintracellularae infection

(chronic weight loss). Congenital CMV occurs in about 1%, as in the normal

population, though it may be more prevalent in patients from the developing world. Itis certainly more symptomatic. Pneumocystis is very rarely seen outside the lung, but

is recognised.

In meningococcal septicaemia:

A Clinical features of meningitis are usually present (False)

B Ciprofloxacin is a suitable choice for prophylaxis (True)

C Prophylaxis does not reduce nasal carriage (False)D Treatment should await bacteriological confirmation (False)

E A petechial rash is associated with DIC (True)

Comments:Many patients with meningococcal septicaemia have no meningeal involvement. Themortality of meningococcal septicaemia is even higher than for meningitis. Prompt

treatment is essential and all suspected cases must be given antibiotics without

awaiting bacteriological confirmation. Ciprofloxacinand Rifampicinare the drugsmost frequently used in chemoprophylaxis, the purpose of which is to eradicate

nasopharyngeal carriage. The characteristic petechial rash is due to release ofcytokines, prostaglandins and free radicals, which cause vasculitis and can lead to DIC

and multi-organ failure.

Infection with Neisseria gonorrhoea may present with:

A Arthritis (True)

B Phylyctenular conjunctivitis

6

(False)

C Keratoderma blenorrhagica (False)

D Proctitis (True)

E Endocarditis (True)

Comments:


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Incubation is 1-4 days. In most cases it is asymptomatic.

Uncomplicated: Urethritis with purulent discharge and local inflammation.

Ophthalmitis (child).

Disseminated: (1-3%) after 7-30 days. Arthritis, dermatitis, carditis, meningitis,

osteomyelitis.

Complications: Pelvic inflammatory disease, hepatitis, septic abortion, concurrent

STD. Keratoderma is associated with various congenital abnormalities. It consists of

psoriasis-like plaques especially on the soles of the feet. Phlyctenular conjunctivitiscan occur in TB and coccidioidomycosis and consists of small yellow lesions at the

corneal ...

Chicken Pox:

A has an incubation period of 5 - 7 days (False)

B rash occurs in the mouth (True)

C may develop in non-immune children who have been in contact with an

adult with Herpes zoster infection(True)

D maternal infection during the last 2 weeks of pregnancy is not harmful to

the fetus(False)

E the rash is preceeded by 4 - 5 days of prodromal illness (True)

Comments:a - 10 - 21 days. b - And also at other mucosal sites such as the genitals. e - Theprodrome is usually very short 1 - 2 days but can be up to 5 days in older

children/adults - take your pick!

Regarding Group B Streptococcal infection in the newborn:

A The risk of infection in the fetus increased following membranerupture for greater than 18 hours.

(True)

B 95% of late infections are caused by type III. (True)

C Symptomatic infection is usually mild. (False)

D Purulent conjunctivitis is a common presentation of late disease. (False)


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E Clinical appearances may be indistinguishable from hyalinemembrane disease.

(True)

Comments:

Symptomatic infection carries a 10-20% mortality, and complications include:meningitis and neurological sequelae; pneumothorax, persistent fetal circulation, andARDS; arthritis and osteomyelitis. Conjunctivitis is rare. A 'ground glass' appearance

is seen in 50% of Group B Strep. pneumonias, patchy pneumonia in 30%.

The following clinical signs may be associated with an underlying specific

immunodeficiency:

A Eczema and petechiae (True)

B Short limbs and abnormal hair (True)

C Ataxia (True)

D Truncus arteriosus (True)

E Situs inversus (False)

Comments:

The combination of eczema and petechiae suggestsS

Wiskott Aldrich Syndromein aboy (X-linked recessive). Abnormal hair plus short limbs is found inS cartilage hairhypoplasia, and this is associated with combined T and B cell defects, sometimes

severe. Situs inversus is associated withS Kartagener's Syndrome, a defect of ciliary

function, which is therefore a defect of non-specific immunity. Ataxia is associatedwith ataxia telangiectasia, a DNA repair defect associated with variable immune

defects, particularly IgA deficiency.

A 2 month old boy presents with possible meningitis. If the CSF findings are as

follows, the given interpretations are reasonable:

A 20 white cells/mm3 - normal (True)

B Glucose of 0.2mmol/L - TB meningitis (True)

C 250 lymphocytes - bacterial meningits (False)

D Protein of 2gm/L - viral meningitis (False)

E CSF glucose of 67% of blood glucose - viral meningitis (True)


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Comments:

In the premature neonate, up to 25 mononuclear cells or 10 polymorphs may be seen inthe CSF. In term newborns, up to 20 mononuclear cells or 10 polymorphs may be

seen. In the neonatal period, up to 5 mononuclear cells or 10 polymorphs may be seen.Thereafter, more than 5 mononuclear cells should be considered abnormal. CSFprotein levels are considerably higher in the premature or newborn infant, with levels

upto 3g/L in the former and 1.2g/L in the latter. In older children, levels above 0.4g/L

should be considered abnormal. CSF glucose levels are normally >50% of those in theblood. They are normal in viral meningitis, reduced in bacterial meningitis, and may be

extremely low in TB meningitis.


Which of the following are true of osteomyelitis?

A Is most commonly due to a staphylococcus aureus infection (True)

B Can be due to salmonella infection in patients with sickle cell

anaemia(True)

C Infection usually involves the metaphysis of long bones (True)

D Dead bone within the medullary canal is known as theinvolucrum

(False)

E New bone forming beneath the periosteum is known a thesequestrum

(False)

Comments:Osteomyelitis is usually due to staphylococcus aureus infection. Streptococcuspyogenes, Haemophilis influenza and gram-negative organisms can also infect bone.

In children the infection is usually aquired by haematogenous spread to the metaphysis

of long bones. The dead bone within the medullary canal is the sequestrum. Newsubperiosteal bone formation is the involucrum.

The following are specific conditions with increased susceptibility

to infection:

A Noonan's Syndrome (False)

B Right atrial isomerism (True)

C Down's Syndrome (True)


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D Zinc deficiency (True)

E Copper deficiency (False)

Comments:

Right atrial isomerism is associated with asplenia. There is a high risk of infection withencapsulated bacteria. Howell Jolly bodies may be seen on blood film. Down's

Syndrome has a variety of immune defects and a high incidence of otitis media due to

eustachian tube structure. With zinc deficiency there is a low lymphocyte function.


Renal damage is a recognised complication of infection with:

A Plasmodium falciparum (True)

B Schistosoma haematobium (True)

C Plasmodium malariae (True)

D Leptospira icterohaemorrhagica (True)

E Mycobacterium leprae (True)

Comments:c-Immune complex injury during chronic or repeated infections.

Pneumocystis pneumoniae

A Is an obligate intracellular organism. (False)

B May be usefully diagnosed by serology. (False)

C Can cause disease outside the respiratory system. (True)

D Can have normal chest X-ray with prominent clinical signs. (False)

E Is adequately treated with Erythromycin alone. (False)

Comments:

Pneumocystis is an obligate extracellular parasite with attributes of both fungi and

protozoa. Most humans are seropositive by 4 years of age, though the transmissionmode is unknown. 40% of children with HIV and 10% with leukaemia get PCP if no

prophylaxis is given. Infection is almost always of the lungs, and rarely outside. The


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onset is subtle, at a peak incidence of 3-6 months of age in HIV infected individuals,with a raised respiratory rate but no fever. There is a gradual increase in respiratory

distress and cyanosis with few clinical signs. Chest x-ray reveals marked changes of

alveolitis, on some occasions looking like "post-neonatal hyaline membrane disease".

Diagnosis is most effectively by bronchi-alveolar lavage or brushings are even better

by lung biopsy. Treatment is high dose septrin and high dose steroids.


The following statements are true regarding microbiological

specimens:

A Blood cultures should be collected after the sterilisation of the

skin with 2 alcohol wipes.(False)

B A bag urine with 100 white cells and >105E. Coli/ml confirmsurinary tract infection in an infant.

(False)

C Bordetella pertussiscan usually be grown from pernasal swabsof children with a classical whoop.

(False)

D The diagnosis of pulmonary tuberculosis in infants is best made

with 3 successive early-morning gastric washings.(True)

E Conjunctival scrapings may be helpful in diagnosing chlamydial

eye infection in infants.(True)

Comments:

For good quality blood cultures, iodine or Chlorhexidine should be used. At least 2

urine samples should be obtained (preferably including a catheter specimen or

suprapubic aspirate) prior to commencing antibiotics. Bordetella culture is notoriouslydifficult, with true cultures 30-40%. Infants cough up and swallow their sputum.

Conjunctival scrapings can be used for culture or immunoflouresence and are the

diagnosis method of choice. Remember to treat the accompanying (present in >50%)with oral Erythromycin.


Chronic granulomatous disease:

A Is always inherited as an X-linked recessive condition. (False)

B Is characterised by defective oxidative killing. (True)


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C Infections are characteristically caused by catalase-positiveorganisms.

(True)

D Abscesses in this condition contain no pus. (False)

E The prognosis is excellent. (False)

Comments:

There are multiple defects described of defects in neutrophil oxidation but most are x-linked, but AR described. Catalase positive organisms (Staphylococcus aureus,

Klebsiella, Candida, Aspergillus) cause recurrent pyogenic infections, abscesses and

pneumonias. The LFA0CD11b)) is found on neutrophils and is necessary for them to

leave the circulation. Thus, in LFA1-deficiency, no pus can be formed. Pus productionis characteristic of chronic granulomatous disease (CGD). The morbidity in this

condition is so high that bone marrow transplant may be considered.


Pyogenic meningitis

A is commonly a result of meningococcal infection in the UK (True)

B due to meningococcal infection is very rare in those aged lessthan 1 year old

(False)

C is associated with raised levels of IgM in the cerebrospinal fluid (True)

D due to haemophilus influenzae is prone to run a subacute course

in children, with the development of subdural effusion(True)

E is complicated by cranial nerve lesions (True)

Comments:Pyogenic meningitis is most commonly due to meningococcal infection. The diseaseoccurs mostly in those aged 2 months to 20 with a peak incidence in the winter. IgM to

Meningococcus is found in the CSF. Haemophilus influenzae on the other hand may

run a more insidious course but is associated with more post-infective co-morbidity,

deafness etc in particular VIII nerve deficits - deafness.

Concerning falciparum malaria:

A The temperature pattern is quartan. (False)


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B Hypoglycaemia is a recognised consequence. (True)

C Is likely to recur 5 years after leaving an endemic area. (False)

D Corticosteroids are of no benefit in treating cerebral malaria. (True)

E Primaquine is the treatment of choice in chloroquine-resistantareas. (False)

Comments:

Falciparum produce a variable pattern of fever (subtertian or malignant tertian); Vivax

and ovale produce benign tertian and quartan. Hypoglycaemia occurs, especially in

infants. Recurrences of Vivax or ovale may recur weeks after apparently successfultreatment (napatic cycle), but rarely after more than a year. In comatose stage of

cerebral malaria, Dextran 70 may prevent intravascular coagulation . Convulsions need

anti-convulsants. Quinine may be used in Chloroquine-resistance.


With regard to malaria:

A Proguanil is recommended as prophylaxis for areas of

Chloroquine resistance.(True)

B Congenital malaria can resemble neonatal sepsis. (True)

C Primaquine should not be given to glucose-6-phosphatedehydrogenase deficient patients.

(True)

D Self treatment with Pyrimethamine-Sulfadoxine (Fansidar) is

appropriate.(False)

E Negative blood films exclude the diagnosis. (False)

Comments:

Malaria results when red cells are invaded by any of the few species of plasmodiacarried by the female Anopheles mosquito. Incubation is around 2 weeks, and the

species of plasmodia are vivax, ovale, malariae and falciparum. Vivax and ovale cause48 hourly fevers (benign tertian), and can recrudesce if treatment is inadequate.Malariae causes a quartan fever every 72 hours. Falciparum causes malignant tertian

fever every 48 hours or so, but this less predictable. Congenital malaria is rare because

of relative placental protection. Blackwater Fever is caused by falciparum malaria andsevere haemolysis occurring in non-immune (usually Caucasian subjects). Non-

immune subjects have more serious illness and higher fevers. High tolerance occurs,


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particularly in Africans due to repeated infections. Blood film is not 100% indiagnosis.

Treatment:a) Prophylaxis - Proganuil, Pyrimethamine (sometimes as Fansidar), or Chloroquine.

b) Treatment - 1. Chloroquine or Quinine. 2. Supportive therapy.c) Primaquine for vivax or ovale to prevent relapse, but remember G6PD deficiency isa contraindication to its use (Asians and Mediterraneans in particular).

d) Primaquine to kill gametocytes in falciparum.


The following statements are true about malaria:

A Vivax is resistant to Chloroquine. (False)

B If P. Falciparum is resistant to Quinine, Chloroquine may begiven.

(False)

C If a person visited an endemic area, but had not developedmalaria falciparum a few months later, there is no chance it may

develop.

(False)

D Blackwater fever is commoner in Caucasians. (True)

E Cerebral malaria from Plasmodium falciparum can be treated

with Quinine.(True)

Comments:Occasional Chloroquine resistance vivax strains occur in Indonesia but not in Africa atpresent. Falciparum is a big problem there, and quinine is useful in treatment.

Falciparum can occur up to a year after return from abroad in those who have not

received prophylaxis. Cerebral malaria occurs with falciparum and paraenteral anti-

malarials, PICU care, seizure control and supportive, and Dextran 75 are indicated.Blackwater fever is commonest in non-immune Caucasians. Copyright 2002 Dr

Colin Melville

Infectious Diseases MCQ

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