Microbiology EMQs Flashcards

1
Q
A Streptococcus pneumoniae
B Moraxella catarrhalis
C Haemophilus influenzae
D Legionella pneumophila
E Mycoplasma pneumonia
F Chlamydia pneumoniae
G Mycobacterium tuberculosis
H Pneumocystis jirovecii
I Staphylococcus aureus

A 25-year-old man with a history of recurrent chest infections presents to an infectious
disease specialist. A subsequent chest X-ray demonstrates widespread pulmonary
infiltrates. A sputum stain using Gomori’s methenamine silver reveals characteristic
cysts.

A

H Pneumocystis jirovecii

Pneumocystis jirovecii (H) is a yeast-like fungus that primarily affects
immunocompromised patients such as those with HIV. Pneumocystis
pneumonia may be the presenting feature of HIV and patients with a
CD4 count less than 200 cells/μL are particularly susceptible. Clinically,
Pneumocystis jirovecii infection presents with fever, non-productive
cough, weight loss and night sweats. Chest X-ray may show signs of
diffuse bilateral pulmonary infiltrates. Definitive diagnosis involves
histological examination of sputum or bronchio-alveolar lavage fluid.
Gomori’s methenamine silver stain reveals ‘flying saucer’ shaped cysts
on microscopy.

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2
Q
A Streptococcus pneumoniae
B Moraxella catarrhalis
C Haemophilus influenzae
D Legionella pneumophila
E Mycoplasma pneumonia
F Chlamydia pneumoniae
G Mycobacterium tuberculosis
H Pneumocystis jirovecii
I Staphylococcus aureus

A 54-year-old woman admitted to the respiratory ward is found to have right
sided consolidation on chest X-ray. Histological examination reveals Grampositive
cocci arranged in pairs.

A

A Streptococcus pneumoniae

Streptococcus pneumoniae (pneumococci; A) are α-haemolytic Grampositive
cocci arranged in pairs (diploccoci). As Streptococcus pneumoniae
are capsulated bacteria, the Quelling reaction in which pneumococci
are mixed with anti-serum and methylene blue causes the capsule
to swell can be visualized under the microscope. Optochin-sensitivity
also differentiates pneumococcus from Streptococcus viridans (also
α-haemolytic), which is optochin-insensitve. Clinically, lobar consolidation
is visible on X-ray, which represents a collection of pus, bacteria
and exudate in the alveoli.

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3
Q
A Streptococcus pneumoniae
B Moraxella catarrhalis
C Haemophilus influenzae
D Legionella pneumophila
E Mycoplasma pneumonia
F Chlamydia pneumoniae
G Mycobacterium tuberculosis
H Pneumocystis jirovecii
I Staphylococcus aureus

A 65-year-old woman is brought into accident and emergency with severe respiratory
distress. The patient’s history revealed that she had been seen by her
GP due to a viral infection 2 weeks previously. Histological examination reveals
Gram-positive cocci arranged in clusters.

A

I Staphylococcus aureus

Staphylococcus aureus (I) are β-haemolytic Gram-positive cocci
arranged in grape-like clusters. All staphylococci are also catalase positive,
whereas streptococci are catalase negative. Clinically, S. aureus can
cause consolidation, cavitations of the lungs and empyema (pus in the
pleural space). Staphylococcus aureus has a number of virulence factors
including anti-immune proteins (haemolysins, leukocidins and penicillinase)
as well as tissue break-down proteins (hyaluronidase, staphylokinase
and protease).

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4
Q
A Streptococcus pneumoniae
B Moraxella catarrhalis
C Haemophilus influenzae
D Legionella pneumophila
E Mycoplasma pneumonia
F Chlamydia pneumoniae
G Mycobacterium tuberculosis
H Pneumocystis jirovecii
I Staphylococcus aureus

A 40-year-old HIV positive man is seen by his GP. The patient admits a 4-week
history of cough. The GP requests acid-fast staining of the patient’s sputum.

A

G Mycobacterium tuberculosis

Mycobacterium tuberculosis (G) is an acid-fast bacillus which is transmitted
via aerosol droplets. Clinical manifestations include fever, cough
(with possible haemoptysis), weight loss and night sweats. Tuberculosis
is highly prevalent in HIV patients due to impaired cell-mediated immunity.
Chest X-ray reveals bihilar lymphadenopathy. Most commonly,
Ziehl–Neelson staining is performed on a sputum sample demonstrating
acid-fast bacilli, but auramine–rhodamine staining can also be used.
Mycobacterium tuberculosis, however, take approximately 6 weeks to
culture, and hence faster polymerase chain reaction diagnostic tests are
being developed.

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5
Q
A Streptococcus pneumoniae
B Moraxella catarrhalis
C Haemophilus influenzae
D Legionella pneumophila
E Mycoplasma pneumonia
F Chlamydia pneumoniae
G Mycobacterium tuberculosis
H Pneumocystis jirovecii
I Staphylococcus aureus

A 36-year-old engineer presents to his GP with a 1-week history of headache,
myalgia and cough. Blood tests reveal hyponatraemia. A urinary antigen test is
found to be positive.

A

D Legionella pneumophila

Legionella pneumophila (D) is an aerobic Gram-negative rod which
causes an atypical pneumonia. It primarily affects those who work with
air-conditioning units and can lead to milder Pontiac fever or more
severe Legionnaire’s disease. Clinical features of legionellosis are nonspecific
and may include headache, myalgia, confusion, rhabdomyolysis
and abdominal pain. Blood chemistry may reveal hyponatraemia,
hypophosphataemia and/or deranged liver enzymes. Diagnosis involves
culture of respiratory secretions on buffered charcoal yeast extract agar,
although a rapid urinary antigen test can also be used.

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6
Q
A Vibrio cholerae
B Staphylococcus aureus
C Enterobacteriaecae
D Listeria monocytogenes
E Salmonella enteritidis
F Shigellae
G Campylobacter jejuni
H Giardia lamblia
I Entamoeba histolytica

A 34-year-old HIV-positive woman is seen in the GP clinic due to 3 days of
diarrhoea, headaches and fever. History reveals the patient had recently drunk
unpasteurized milk. The causative organism is found to be β-haemolytic with
tumbling motility.

A

D Listeria monocytogenes

Listeria monocytogenes (D) is a β-haemolytic anaerobic Gram-positive
rod that may cause outbreaks of non-invasive gastroenteritis. Sources
include refrigerated food and unpasteurized dairy products. Clinical features
of listeria infection include watery diarrhoea, abdominal cramps,
headaches and fever, but minimal vomiting. Listeria demonstrates
‘tumbling motility’ as a result of flagellar-driven movements. Neonates
and immunocompromised patients are particularly susceptible. Invasive
infection can cause more serious problems in these groups including
septicaemia, meningitis and encephalitis.

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7
Q
A Vibrio cholerae
B Staphylococcus aureus
C Enterobacteriaecae
D Listeria monocytogenes
E Salmonella enteritidis
F Shigellae
G Campylobacter jejuni
H Giardia lamblia
I Entamoeba histolytica

A 10-year-old girl has just returned from a summer swimming camp at Lake
Windermere. She presents to accident and emergency with bloody diarrhoea
and abdominal pain. Blood tests reveal anaemia and thrombocytopenia.

A

C Enterobacteriaecae

Escherichia coli (C) is a Gram-negative rod-shaped bacterium that
is a common cause of traveller’s diarrhoea in those returning from
abroad. Transmission occurs via food and water that become contaminated
with human faeces, as can swimming in contaminated lakes.
Enterohaemorrhagic E. coli infection (serotype O157:H7) can lead to
haemolytic uraemic syndrome (HUS), characterized by haemolytic anaemia,
acute renal failure (uraemia) and a low platelet count (thrombocytopenia).
Other diarrhoea-causing strains of E. coli include enterotoxigenic,
enteropathogenic and enteroinvasive forms.

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8
Q
A Vibrio cholerae
B Staphylococcus aureus
C Enterobacteriaecae
D Listeria monocytogenes
E Salmonella enteritidis
F Shigellae
G Campylobacter jejuni
H Giardia lamblia
I Entamoeba histolytica

An 18-year-old on his gap year in India suddenly develops severe watery diarrhoea.
Microscopy of his stool reveals no leukocytes but rods with fast movements.

A

A Vibrio cholerae

Vibrio cholerae (A) are comma-shaped oxidase positive bacteria, causing
profuse watery diarrhoea containing no inflammatory cells on microscopy.
Transmission occurs via the faecal-oral route. Vibrio cholerae
colonizes the small intestinal section of the gut and secretes enterotoxin
containing subunits A (active) and B (binding). B subunit binds to GM1
ganglioside on the intestinal epithelial cells. Intracellularly, there is activation
of cAMP by A subunit, which causes active secretion of sodium
and chloride ions; as a consequence water is lost due to the osmotic
pull of NaCl.

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9
Q
A Vibrio cholerae
B Staphylococcus aureus
C Enterobacteriaecae
D Listeria monocytogenes
E Salmonella enteritidis
F Shigellae
G Campylobacter jejuni
H Giardia lamblia
I Entamoeba histolytica

A 25-year-old homosexual man presents to his GP with a 3-day history of foul
smelling, non-bloody diarrhoea, with abdominal cramps and flatulence. Stool
microscopy reveals pear-shaped organisms.

A

H Giardia lamblia

Giardia lamblia (H) is a pear-shaped trophozite containing two nuclei,
four flagellae and a suction disc. Transmission occurs via ingestion of
a cyst from faecally contaminated water and food. Trophozites attach
to the duodenum but do not invade. Instead, protein absorption is
inhibited, drawing water into the lumen of the gastrointestinal tract.
G. lamblia must be considered in travellers, hikers and homosexual
men. Clinically, foul smelling non-bloody steatorrhoea is produced,
with stool containing cysts visible on microscopy.

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10
Q
A Vibrio cholerae
B Staphylococcus aureus
C Enterobacteriaecae
D Listeria monocytogenes
E Salmonella enteritidis
F Shigellae
G Campylobacter jejuni
H Giardia lamblia
I Entamoeba histolytica

A 35-year-old woman presents to accident and emergency with fever, diarrhoea
and signs of shock. Her husband mentions that she had attended a work colleague’s
barbeque the previous day. The consultant believes superantigens are
responsible for the patient’s condition.

A

B Staphylococcus aureus

Staphylococcus aureus (B) are β-haemolytic Gram-positive cocci
arranged in grape-like clusters. In the gastrointestinal tract, S. aureus
produces the exotoxin TSST-1, which acts as a superantigen causing
non-specific activation of T cells and subsequent release of IL-1, IL-2
and TNF-α. A massive non-specific immune response follows causing
shock and multiple organ failure. Enterotoxin produced by bacteria
causes vomiting and diarrhoea 12–24 hours after the culprit food has
been consumed.

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11
Q
A Neisseria meningitides
B Herpes simplex virus-2
C Leptospira interrogans
D Listeria monocytogenes
E Cryptococcus neoformans
F Escherichia coli
G Streptococcus pneumoniae
H Borrelia burgdorferi
I Mycobacterium tuberculosis

A 45-year-old man presents to his GP with a 2-month history of headache.
After a CT scan demonstrates an opacity, a lumbar puncture is performed and
cerebrospinal fluid (CSF) analysis reveals a protein level of 4.5 g/L (0.15–0.4),
lymphocyte count 345 (1–5) and glucose 4.0 mmol/L (2.2–3.3).

A

I Mycobacterium tuberculosis

Mycobacterium tuberculosis (I) may lead to a subacute or chronic meningitis.
Symptoms are non-specific, including fever, headache and
confusion. Focal signs may be present as a result of a cerebral granuloma.
A tuberculous granuloma that occurs in the cortex of the brain,
subsequently rupturing into the subarachnoid space, is termed a Rich
focus. Diagnosis of tuberculous meningitis involves a lumbar puncture;
the CSF appears colourless and characteristically has high protein, low
glucose and raised lymphocyte levels. Nucleic acid amplification tests
as well as imaging studies (CT and MRI) can be useful in the diagnostic
work-up.

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12
Q
A Neisseria meningitides
B Herpes simplex virus-2
C Leptospira interrogans
D Listeria monocytogenes
E Cryptococcus neoformans
F Escherichia coli
G Streptococcus pneumoniae
H Borrelia burgdorferi
I Mycobacterium tuberculosis

A 26-year-old man has recently returned to the UK from a year of working in
Africa where he was taking part in a charity farming project. He presents to
accident and emergency with signs of meningism. A serological microscopic
agglutination test is positive.

A

C Leptospira interrogans

Leptospira interrogans (C) causes leptospirosis (also known as Weil’s
syndrome). Transmission occurs via contact with animals. Leptospira
are thin aerobic spirochaetes that are tightly coiled. The first stage of
infection is known as the leptospiramic phase, during which the patient
suffers non-specific symptoms such as fever, headache, malaise and
photophobia. In the second immune phase, IgM antibodies have formed
and meningitis, liver damage (causing jaundice) and renal failure may
develop. CSF examination will reveal a raised white cell count. The
microscopic agglutination test is considered the gold standard for diagnosing
leptospirosis.

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13
Q
A Neisseria meningitides
B Herpes simplex virus-2
C Leptospira interrogans
D Listeria monocytogenes
E Cryptococcus neoformans
F Escherichia coli
G Streptococcus pneumoniae
H Borrelia burgdorferi
I Mycobacterium tuberculosis

A 19-year-old woman who has recently started university is brought to accident
and emergency with a headache and a spreading non-blanching rash. Gramstain
of a blood sample reveals the presence of Gram-negative diplococci.

A

A Neisseria meningitides

Neisseria meningitides (meningococcus; A) is a Gram-negative diplococcus.
Infants aged 6 months to 2 years are most at risk as well as large
numbers of adults living in close quarters. Virulence factors include its
capsule (antiphagocytic), endotoxin (lipopolysaccharide causes haemorrhage
from blood vessels resulting in characteristic petechiae in meningococcaemia)
and IgA1 protease (destroys IgA). Neisseria meningitides
can lead to meningitis (headache, photophobia and neck stiffness)
and meningococcaemia (signs of sepsis with spreading petechial rash).
Neisseria meningitides is grown best on Thayer–Martin VCN media
(only allows Neisseria species to grow).

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14
Q
A Neisseria meningitides
B Herpes simplex virus-2
C Leptospira interrogans
D Listeria monocytogenes
E Cryptococcus neoformans
F Escherichia coli
G Streptococcus pneumoniae
H Borrelia burgdorferi
I Mycobacterium tuberculosis

A 46-year-old man with a history of HIV presents to accident and emergency
with neck stiffness, fever and severe photophobia. Examination of the CSF with
India ink reveals yeast cells surrounded by halos.

A

E Cryptococcus neoformans

Cryptococcus neoformans (E) is a polysaccharide encapsulated yeast
that causes a subacute or chronic meningoencephalitis. It is transmitted
by inhalation (the source of which is pigeon droppings). Cryptococcus
neoformans is usually asyptomatic, but can be pathogenic in immunocompromised
patients such as those with HIV. As well as meningitis,
C. neoformans can also cause pneumonia, skin ulcers and bone lesions.
Diagnosis is made by examination of CSF; India ink staining reveals
yeast cells with a surrounding halo. Cryptococcal antigen test is, however,
a more sensitive test.

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15
Q
A Neisseria meningitides
B Herpes simplex virus-2
C Leptospira interrogans
D Listeria monocytogenes
E Cryptococcus neoformans
F Escherichia coli
G Streptococcus pneumoniae
H Borrelia burgdorferi
I Mycobacterium tuberculosis

A 35-year-old woman presents to her infectious disease specialist due to recurrent
episodes of meningitis. During her last presentation CSF analysis reveals
a protein level of 0.8 g/L (0.15–0.4), lymphocyte count 290 (0–5) and glucose
2.2 mmol/L (2.2–3.3).

A

B Herpes simplex virus-2

Herpes simplex virus 2 (HSV-2; B) is the most common cause of viral
meningitis of all the herpes family. HSV-2 is transmitted via sexual
contact or via the mother during birth. The virus infects mucosal epithelial
cells or lymphocytes; retrograde transport occurs from peripheral
nerves to ganglion. Viral causes of meningitis can be diagnosed on
examination of CSF; it appears colourless, with a raised lymphocyte
level, moderately raised protein and normal glucose concentration.
Recurrent aseptic meningitis (Mollaret’s meningitis) can be caused by
both HSV-1 and HSV-2.

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16
Q
A Treponema pallidum
B Klebsiella granulomatis
C Neiserria gonorrhoeae
D Trichomonas vaginalis
E Candidia albicans
F Chlamydia trachomatis
G Bacterial vaginosis
H Haemophilus ducreyi
I Herpes simplex virus 2

A 28-year-old woman sees her GP complaining of fever, lower abdominal pain
and painful intercourse. Vaginal swabs are sent for a nucleic acid amplification
test which reveal sexually transmitted bacteria that can also cause lymphogranuloma
venereum.

A

F Chlamydia trachomatis

Chlamydia trachomatis (F) is a small Gram-negative obligate intracellular
bacterium, causing the sexually transmitted infection chlamydiosis. It
has an affinity towards columnar epithelia that line mucous membranes.
Serovars D–K cause genital chlamydiosis (as well as opthalmia neonatorum)
resulting in dyspareunia, dysuria and vaginal/penile discharge.
Serovars L1, L2 and L3 cause lymphogranuloma venereum, defined by a
painless papule or ulcer on the genitals which heals spontaneously; the
bacteria migrate along regional lymph nodes leading to lymphadenopathy.

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17
Q
A Treponema pallidum
B Klebsiella granulomatis
C Neiserria gonorrhoeae
D Trichomonas vaginalis
E Candidia albicans
F Chlamydia trachomatis
G Bacterial vaginosis
H Haemophilus ducreyi
I Herpes simplex virus 2

A 68-year-old man presents to his GP with a gumma on his nose. On examination,
the patient is found to have pupils that accommodate to light but do not
react. The man admits to unprotected sexual intercourse during his youth.

A

A Treponema pallidum

Treponema pallidum (A) causes syphilis. Syphilis has three clinical
stages: primary, secondary and tertiary. Primary syphilis is defined by a
firm painless chancre that appears approximately 1 month after sexual
contact and resolves within a few weeks. Secondary syphilis is a bacteri
aemic stage during which a widespread rash forms with lymphadenopathy.
Tertiary syphilis occurs decades after the primary infection
and involves multiple organs: gummatous lesions on skin and bone, aneurysm of the aortic arch, peripheral neuropathy, tabes dorsalis and
Argyll–Robertson pupils.

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18
Q
A Treponema pallidum
B Klebsiella granulomatis
C Neiserria gonorrhoeae
D Trichomonas vaginalis
E Candidia albicans
F Chlamydia trachomatis
G Bacterial vaginosis
H Haemophilus ducreyi
I Herpes simplex virus 2

A 35-year-old man presents to an infectious disease specialist with a painful
penile ulcer and associated unilateral lymphadenopathy of the inguinal nodes. A
swab of the ulcer is cultured on chocolate agar.

A

H Haemophilus ducreyi

Haemophilus ducreyi (H) is a Gram-negative coccobacillus that causes a
tropical ulcer disease (chancroid) and is contracted by sexual transmission.
Chancroid is characterized by a painful genital ulcer that leads to
unilateral painful swollen inguinal lymph nodes. Infected lymph nodes
may rupture releasing pus. The differential diagnosis for genital ulcers
includes syphilis (painless ulcer with bilateral painless lymphadenopathy),
herpes simplex virus 1 and 2 (vesicles that eventually break down)
and lymphogranuloma venereum (slowly developing painless inguinal
lymph nodes). Haemophilus ducreyi can be cultured on chocolate agar.

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19
Q
A Treponema pallidum
B Klebsiella granulomatis
C Neiserria gonorrhoeae
D Trichomonas vaginalis
E Candidia albicans
F Chlamydia trachomatis
G Bacterial vaginosis
H Haemophilus ducreyi
I Herpes simplex virus 2

A 28-year-old woman sees her GP complaining of fever, lower abdominal pain
and painful intercourse. A vaginal swab is taken and subsequent Gram-staining
reveals Gram-negative diplococci.

A

C Neiserria gonorrhoeae

Neiserria gonorrhoeae (gonococcus; C) is an intracellular Gramnegative
diplococcus that causes gonorrhoea. Virulence factors allow
gonococci to evade phagocytosis and adhere to the non-ciliated epithelium
of the fallopian tubes. In both men and women N. gonorrhoeae
causes urethritis which presents with dysuria and purulent discharge
(with associated dyspareunia in women). Long-term complications
include pelvic inflammatory disease in women and epididymitis, prostititis
as well as urethral stricture in men. Systemic invasion of bacteria
causes pericarditis, endocarditis, meningitis and/or septic arthritis.
Diagnosis involves Gram stain and culture on Thayer–Martin VCN
medium, or PCR.

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20
Q
A Treponema pallidum
B Klebsiella granulomatis
C Neiserria gonorrhoeae
D Trichomonas vaginalis
E Candidia albicans
F Chlamydia trachomatis
G Bacterial vaginosis
H Haemophilus ducreyi
I Herpes simplex virus 2

A 35-year-old woman presents to her GP with a 2-week history of a fishy
odorous vaginal discharge, which occurs especially after sexual intercourse.
Microscopy of the discharge reveals clue cells.

A

G Bacterial vaginosis

Bacterial vaginosis (BV; G) is caused by an imbalance in the naturally
occurring bacterial flora of the vagina and is a condition associated
with sexual activity (not transmitted). A ‘fishy’ smelling white–cream
vaginal discharge is characteristically produced. Diagnosis involves
obtaining vaginal swabs. A litmus test will indicate loss of acidity with
a pH greater than 4.5 (normal vaginal pH = 3.8–4.2). If a sample of the
discharge is visualized under a microscope with sodium chloride, clue
cells will be seen.

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21
Q
A Amoxicillin
B Doxycycline
C Co-amoxiclav IV
D Meropenam
E Chloramphenicol
F Cefotaxime
G Vancomycin
H Trimethoprim
I Flucloxacillin

A 54-year-old man presents to his GP with a 1-week history of fever, cough and

fatigue. On examination his respiratory rate is 20 breaths per minute and he is
normotensive. Subsequent chest X-ray reveals right lower lobe consolidation.

A

A Amoxicillin

Amoxicillin (A) is a β-lactam antibiotic which inhibits enzymes responsible
for cell wall synthesis, leading to osmotic lysis of the bacteria. As
a result, β-lactams are ineffective against bacteria that lack cell walls
such as Mycoplasma spp. and Chlamydia spp. In this case, amoxicillin
is the best choice antibiotic to treat mild community acquired pneumonia.
It is also useful in the treatment of urinary tract infection (UTI),
Listeria meningitis, endocarditis prophylaxis and protection against
Streptococcus pneumoniae in asplenic patients. Major side effects can
be divided into allergic (anaphylaxis) and non-allergic (Steven–Johnson
syndrome) consequences.

22
Q
A Amoxicillin
B Doxycycline
C Co-amoxiclav IV
D Meropenam
E Chloramphenicol
F Cefotaxime
G Vancomycin
H Trimethoprim
I Flucloxacillin

A 38-year-old man presents to accident and emergency with an inflamed and
swollen right leg. He mentions that he had cut the same leg 2 days previously
playing football. A swab of the area isolates Staphylococcus aureus.

A

I Flucloxacillin

Flucloxacillin (I) is a β-lactam antibiotic that is especially effective
against Gram-positive bacteria that produce β-lactamase, for example
S. aureus. Just like amoxicillin, flucloxacillin inhibits cell wall synthesis.
Indications for its use include staphylococcal skin infections such
as cellulitis (in this case), folliculitis and mastitis as well as pneumonia
(adjunct), osteomyelitis, septic arthritis, endocarditis and prophylaxis in
surgery. A rare side effect of flucloxacillin is cholestatic jaundice which
may develop weeks after treatment is stopped.

23
Q
A Amoxicillin
B Doxycycline
C Co-amoxiclav IV
D Meropenam
E Chloramphenicol
F Cefotaxime
G Vancomycin
H Trimethoprim
I Flucloxacillin

A 34-year-old woman presents to her GP with lower abdominal pain and
dysuria. A dipstick of her urine reveals the presence of protein, white cells and
nitrites.

A

H Trimethoprim

Trimethoprim (H) is an inhibitor of folate metabolism; it impairs synthesis
of DNA by interfering with folic acid metabolism. It is used in the
treatment of uncomplicated UTIs. Trimethoprim should be used with caution
in patients with megaloblastic anaemia due to its interaction with
folate. Side effects of trimethoprim include thrombocytopenia, megaloblastic
anaemia and hyperkalaemia (via antagonism of sodium channels
in the distal convoluted tubule of nephrons). Trimethoprim combined
with another folate inhibitor, sulphamethoxazole, forms co-trimoxazole,
which is used in the treatment of Pneumocystis jirovecii infection.

24
Q
A Amoxicillin
B Doxycycline
C Co-amoxiclav IV
D Meropenam
E Chloramphenicol
F Cefotaxime
G Vancomycin
H Trimethoprim
I Flucloxacillin

A 56-year-old man is being cared for on the surgical ward after excision of
a segment of his bowel after being diagnosed with colorectal carcinoma. The
following day the surgical wound site is found to be inflamed. The patient has
a fever and his blood pressure is slowly declining. Blood cultures reveal Grampositive
cocci arranged in clusters that are resistant to β-lactam antibiotics.

A

G Vancomycin

Vancomycin (G) is the drug of choice in cases of methicillin-resistant
Staphylococcus aureus infections (MRSA). Vancomycin is a glycopeptide
antibiotic that inhibits cell wall synthesis. It is too large to traverse the
cell wall of Gram-negative bacteria and hence is primarily targeted to
Gram-positive bacteria. Side effects include renal failure, ototoxicity,
blood disorders, rash and anaphylaxis. Due to the potential side effects,
serum drug levels must be monitored. Vancomycin is also a second-line
antibiotic in the treatment of Clostridium difficile infection.

25
Q
A Amoxicillin
B Doxycycline
C Co-amoxiclav IV
D Meropenam
E Chloramphenicol
F Cefotaxime
G Vancomycin
H Trimethoprim
I Flucloxacillin

An 18-year-old woman student presents to accident and emergency with headache,
neck stiffness and photophobia. CT scan reveals no raised intracranial pressure.
Gram-negative diploccoci are visualized on Gram-staining of the patient’s CSF.

A

F Cefotaxime

Cefotaxime (F) is a third generation cephalosporin and is the drug of
choice in treating Neisseria meningitidis, which is the most common
cause of meningitis in the UK. Cefotaxime is a β-lactam antibiotic and
therefore inhibits cell wall synthesis. If meningitis is suspected in the
community, the patient should be started on benzyl-penicillin until they are transferred to a secondary care unit. Cefotaxime is also useful in the
treatment of pyelonephritis, sepsis secondary to hospital acquired pneumonia
and soft tissue infections.

26
Q
A Human immunodeficiency virus
(HIV)
B Epstein–Barr virus (EBV)
C Hepatitis B virus
D Cytomegalovirus (CMV)
E Hepatitis D virus
F Varicella zoster virus
G Hepatitis C virus
H Human herpes virus 8
I Influenza virus

A 38-year-old man presents to his GP with vomiting, mild fever and loss of
appetite. He admits to travelling to sub-Saharan Africa 2 months previously. On
examination the patient is evidently jaundiced.

A

C Hepatitis B virus

Hepatitis B virus (HBV; C) is a double-stranded DNA virus that is prevalent
in sub-Saharan Africa. It is transmitted via sexual contact, contaminated
blood products, intravenous drug use as well as vertical transfer
from mother to child during child birth. The virus has an incubation
period of 2–6 months with 80 per cent of infections remaining acute
and 20 per cent becoming chronic with risk of cirrhosis and hepatocellular
carcinoma. HBV antigens include HBsAg (surface antigen), HBcAg
(core antigen) and HBeAg (soluble antigen).

27
Q
A Human immunodeficiency virus
(HIV)
B Epstein–Barr virus (EBV)
C Hepatitis B virus
D Cytomegalovirus (CMV)
E Hepatitis D virus
F Varicella zoster virus
G Hepatitis C virus
H Human herpes virus 8
I Influenza virus

A 39-year-old homosexual man is referred to the gastroenterology department
for an oesophogastroduodenoscopy (OGD) due to recent onset odynophagia.
The OGD reveals multiple raised white plaques that can be removed by endoscopic
scraping.

A

A Human immunodeficiency virus
(HIV)

Human immunodeficiency virus (HIV; A) possesses single-stranded RNA
as well as enzymes (reverse transcriptase, integrase and protease) in its
core. HIV is transmitted via sexual intercourse, blood products, intravenous
drug use and vertically from mother to child. HIV infects CD4+
T cells; within the cell the RNA undergoes reverse transcription to make
DNA which is integrated into the host DNA; the virus then becomes
latent or buds to infect further. AIDS (CD4+ count

28
Q
A Human immunodeficiency virus
(HIV)
B Epstein–Barr virus (EBV)
C Hepatitis B virus
D Cytomegalovirus (CMV)
E Hepatitis D virus
F Varicella zoster virus
G Hepatitis C virus
H Human herpes virus 8
I Influenza virus

A 15-year-old girl presents to her GP complaining of a sore throat, fever,
fatigue and loss of appetite. A blood film demonstrates atypical lymphocytes
and monospot test is positive.

A

B Epstein–Barr virus (EBV)

Epstein–Barr virus (EBV; B) primarily infects B lymphocytes, binding via
a complement receptor. Transmission involves person-to-person transfer
through close contact. EBV is associated with glandular fever (infectious mononucleosis) which causes pharyngitis, lymphadenopathy, fever, splenomegaly
and hepatomegaly. Rare sequelae include thrombocytopenia
and erythema multiforme. EBV can also cause Hodgkin’s lymphoma
(latent reactivation of EBV), Burkitt’s lymphoma and nasopharyngeal
cancers. It is diagnosed on blood film (atypical lymphocytes), monospot
test (positive heterophil antibody test) and/or EBV antibodies in the
blood.

29
Q
A Human immunodeficiency virus
(HIV)
B Epstein–Barr virus (EBV)
C Hepatitis B virus
D Cytomegalovirus (CMV)
E Hepatitis D virus
F Varicella zoster virus
G Hepatitis C virus
H Human herpes virus 8
I Influenza virus

A 68-year-old woman presents to her GP after a 3-day history of fever, cough,
headache and nasal congestion. The doctor believes her symptoms are due to a
virus that binds to sialic acid receptors.

A

I Influenza virus

Influenza virus (I) is part of the orthomyxoviridae group of viruses and
causes epidemics of influenza annually. The influenza virus causes primary
pneumonia as well as delayed secondary bacterial pneumonia and
otitis media in immunocompromised patients. It is a spherical virion
with haemagglutinin (HA) and neuraminidase (NA) glycoproteins on the
surface. HA binds to sialic acid receptors present in the upper respiratory
tract; viral RNA is subsequently inserted into the host cell and HA is
cleaved by clara cell tryptase. NA cleaves neuraminic acid, a component
of protective mucin; as a result the protective barrier is disrupted exposing
sialic acid receptor sites beneath. NA also has a role facilitating the
release of newly formed influenza virions.

30
Q
A Human immunodeficiency virus
(HIV)
B Epstein–Barr virus (EBV)
C Hepatitis B virus
D Cytomegalovirus (CMV)
E Hepatitis D virus
F Varicella zoster virus
G Hepatitis C virus
H Human herpes virus 8
I Influenza virus

A 55-year-old man who is being treated for lung cancer with chemotherapeutic
agents sees his oncologist for a routine check-up. There is a rash in a dermatomal
pattern on the patient’s forehead; the patient complains that there is a
burning sensation in the distribution of the rash.

A

F Varicella zoster virus

Varicella zoster virus (VZV; F) is a droplet-spread herpes virus that
causes chickenpox in children and shingles in adults. Chickenpox is
characterized by fever, malaise and a rash (erythematous base with
fluid top) that spreads over the body. Complications include secondary
bacterial infection and encephalitis. VZV remains dormant in
the dorsal root ganglia and may reactivate in states of immunosuppression.
The most common symptom is neuralgia which occurs in a
dermatomal distribution; other manifestations include encephalitis,
Guillain–Barré syndrome, facial palsy and progressive outer retinal
necrosis.

31
Q
A Acyclovir
B Oseltamivir
C Interferon-α
D Zidovudine
E Gancylcovir
F Lamivudine
G Efivarenz
H Ritonavir
I Adamantadine

A 40-year-old man presents to an infectious disease specialist with a 4-month
history of weight loss, fever and malaise. On examination the patient has
lymphadenopathy. His CD4 count is found to be 289 copies/μL. The patient is
started on lamivudine, ritonavir and one other drug.

A

D Zidovudine

Zidovudine (D) is a nucleoside reverse transcriptase inhibitor (NRTI)
used in the treatment of HIV/AIDS (as well as prevention of vertical
transmission from infected mothers). Treatment is commenced once the
CD4 count falls below 350 copies/μL. Zidovudine works by inhibiting
the action of the enzyme reverse transcriptase, preventing the conversion
of HIV RNA to DNA, which consequently cannot be incorporated
into the host DNA. Side effects include anaemia, neutropenia, hepatic
and cardiac dysfunction as well as myopathy. The standard treatment
regimen involves the use of two nucleoside reverse transcriptase
inhibitors (NRTIs) and a non-nucleoside reverse transcriptase inhibitor
(NNRTI; Efivarenz) or a protease inhibitor (PI; Ritonavir).

32
Q
A Acyclovir
B Oseltamivir
C Interferon-α
D Zidovudine
E Gancylcovir
F Lamivudine
G Efivarenz
H Ritonavir
I Adamantadine

A 38-year-old intravenous drug user presents to an infectious disease specialist
with a 1-week history of fever and malaise; on examination hepatomegaly
is noted. The patient is found to be HBeAg positive and is subsequently commenced
on lamivudine and one other drug.

A

C Interferon-α

Interferon-α (IFN-α; C) is a protein that is used in the treatment of
hepatitis B; it potentiates the immune system to fight active viral infection.
IFN-α acts on the JAK-STAT pathway; IFN-α binds to the IFN-α
receptor, causing phosphorylation of STAT1 and STAT2, which subsequently
form a complex with IRF9 (a transcription factor), leading to
the synthesis of anti-viral proteins. A NRTI and IFN-α is the standard
treatment for hepatitis B infection. Pegylated-IFN-α is used in the treatment
of hepatitis C; similar to IFN-α, the addition of polyethylene glycol
increases the half life of the drug.

33
Q
A Acyclovir
B Oseltamivir
C Interferon-α
D Zidovudine
E Gancylcovir
F Lamivudine
G Efivarenz
H Ritonavir
I Adamantadine

A 25-year-old man presents to his GP with a 3-day history of fever, cough,
body aches and severe headaches. The patient is told to rest and drink plenty of
fluids. However, he returns the following week stating his symptoms have not
improved and is started on a drug that acts on viral neuraminidase.

A

B Oseltamivir

Oseltamivir (B) is a viral neuraminidase inhibitor used in the treatment
of influenza. Osteltamivir is in fact a pro-drug; once metabolized in the
liver the active form GS4071 is produced. Once a newly formed influenza
virion is produced, the surface viral protein haemagglutinin is bound
to sialic acid receptors along the upper respiratory tract. Neuraminidase
is normally responsible for cleaving the haemagglutinin–sialic acid
receptor bond, hence facilitating the release of newly formed virions.
Therefore, inhibiting neuraminidase activity prevents further viral
replication.

34
Q
A Acyclovir
B Oseltamivir
C Interferon-α
D Zidovudine
E Gancylcovir
F Lamivudine
G Efivarenz
H Ritonavir
I Adamantadine

A 3-year-old girl diagnosed with severe combined immunodeficiency is due to
undergo a bone marrow transplant. She is given a drug as prophylaxis against
cytomegalovirus infection.

A

E Gancylcovir

Gancyclovir (E) is a 2´-deoxyguanosine analogue used in the treatment
of cytomegalovirus (CMV) infection. It is the first line drug for
the prophylaxis of CMV in bone marrow transplant patients. 2´-deoxyguanosine
is phosphorylated to the triphosphate form, which prevents
viral DNA polymerase from elongating viral DNA and therefore inhibits
CMV replication. Gancyclovir can cause bone marrow toxicity; it may
therefore be prescribed together with granulocyte-colony stimulating
factor (G-CSF). Gancyclovir is also used in the treatment of human herpes
virus 6 (HHV-6) and Epstein–Barr virus infection.

35
Q
A Acyclovir
B Oseltamivir
C Interferon-α
D Zidovudine
E Gancylcovir
F Lamivudine
G Efivarenz
H Ritonavir
I Adamantadine

A 28-year-old woman presents to her GP with cold sores dotted across her
lower lip. She is started on a medication that inhibits DNA polymerase function
to speed the healing processes.

A

A Acyclovir

Acyclovir (A) is a guanosine analogue anti-viral drug used primarily in
the treatment of herpes simplex virus infections (HSV-1 and HSV-2). It is converted to acyclo-guanosine monophosphate (acyclo-GMP) by viral
thymidine kinase. Acyclo-GMP is further phosphorylated to acycloguanosine
triphosphate (acyclo-GTP). Acyclo-GTP is incorporated into
the viral DNA strand, terminating the chain and stopping DNA polymerase
from functioning. Aciclovir is also indicated for the treatment of
varicella zoster, Epstein–Barr virus and cytomegalovirus infections (with
decreasing efficacy).

36
Q
A Cryptoccus neoformans
B Pityriasis versicolour
C Aspergillus flavus
D Histoplasma capsulatum
E Phialophora verrucosa
F Tinea capitis
G Sporothrix schenckii
H Tinea corporis
I Candida albicans

A 38-year-old man with known HIV presents to his GP with a 1-week history of
white coloured creamy deposits inside his mouth. The patient is prescribed an
oral nystatin wash.

A

I Candida albicans

Candida albicans (I) can affect both immunocompetent and immunocompromised
hosts. In the immunocompetent host, clinical features
range from oral thrush (creamy-white patches with red base over
mucous membranes of mouth; treated with nystatin) to vaginitis (vaginal
inflammation, pruritis and discharge; speculum examination reveals
patches of cottage cheese-like clumps fixed to vaginal wall). In immunocompromised
patients, C. albicans infection leads to oesophagitis,
characterized by odynophagia. Candidaemia can lead to severe flu-like
symptoms and can be diagnosed by testing for blood β-D-glucan (a
component of fungal cell walls).

37
Q
A Cryptoccus neoformans
B Pityriasis versicolour
C Aspergillus flavus
D Histoplasma capsulatum
E Phialophora verrucosa
F Tinea capitis
G Sporothrix schenckii
H Tinea corporis
I Candida albicans

A 45-year-old man with known HIV presents to accident and emergency with
headache, nausea, confusion and fever. Investigation of the patient’s CSF with
India ink stain reveals yeast cells surrounded by a halo.

A

A Cryptoccus neoformans

Cryptococcus neoformans (A) is an encapsulated yeast that is transmitted
via inhaled spores from pigeon droppings. It is usually asymptomatic
in most cases. Seventy-five per cent of cases occur in immunocompromised
patients, characterized by the development of sub-acute or chronic
meningitis. Cryptococcal meningitis is fatal without treatment due to
the associated cerebral oedema and brainstem compression. Diagnosis is
made by CSF analysis with India ink stain which reveals yeast cells surrounded
by a halo (polysaccharide capsule). A cryptococcal antigen test
can also be used which offers higher sensitivity.

38
Q
A Cryptoccus neoformans
B Pityriasis versicolour
C Aspergillus flavus
D Histoplasma capsulatum
E Phialophora verrucosa
F Tinea capitis
G Sporothrix schenckii
H Tinea corporis
I Candida albicans

A 35-year-old woman presents to her GP with hyperpigmented spots on her
back. Scrapings of the affected areas reveal a ‘spaghetti with meatballs’ appearance
under the microscope.

A

B Pityriasis versicolour

Pityriasis versicolor (B) is a chronic fungal infection caused by
Malassezia furfur, characterized by hypopigmentation (in patients with
dark skin tones) and hyperpigmentation (in patients with pale skin tones). Spots affect the back, underarm, arms, legs, chest, neck and rarely
the face. Microscopic investigation of the M. furfur with potassium
hydroxide reveals a ‘spaghetti with meatballs’ appearance. Wood’s light
may also reveal an orange fluorescence in some cases.

39
Q
A Cryptoccus neoformans
B Pityriasis versicolour
C Aspergillus flavus
D Histoplasma capsulatum
E Phialophora verrucosa
F Tinea capitis
G Sporothrix schenckii
H Tinea corporis
I Candida albicans

A 48-year-old HIV positive man who has recently migrated from sub-Saharan
Africa presents to accident and emergency with chest pain, shortness of breath,
fever and cough. A chest X-ray demonstrates a spherical opacity in the upper
left lung field.

A

C Aspergillus flavus

Aspergillus flavus (C) is a fungus that commonly grows on stored grains
and can cause a spectrum of disease. Allergic reaction in the airways
may cause allergic broncho-pulmonary aspergillosis (ABPA) which
occurs due to an IgE mediated type I hypersensitivity reaction leading
to bronchospasm and eosinophilia. Infection in pre-formed lung cavities
(for example in TB patients) may lead to a fungal ball visible on
chest X-ray (aspergilloma). Invasive aspergillosis is a chronic necrotizing
infection that may occur in neutropenic patients (chemotherapy) or
patients with end stage AIDS (CD4 count

40
Q
A Cryptoccus neoformans
B Pityriasis versicolour
C Aspergillus flavus
D Histoplasma capsulatum
E Phialophora verrucosa
F Tinea capitis
G Sporothrix schenckii
H Tinea corporis
I Candida albicans

A 32-year-old gardener presents to his GP with small raised lesions on his left
arm. He remembers working in a garden a few days previously which had been
swamped with rose-thorns.

A

G Sporothrix schenckii

Sporothrix schenckii (Rose garderner’s disease; G) is a fungus found in
soil and plants that causes sporotrichosis. A prick by thorns causes nodular
lesions to appear on the surface of the skin. Initially the lesions will
be small and painless; left untreated they become ulcerated. Infection
may also spread to joints, bone and muscle by this route. Inhalation of
spores may lead to pulmonary disease and systemic infection may lead
to central nervous system involvement. Treatment options include itraconazole,
fluconazole and oral potassium iodide.

41
Q
A Psittacosis
B Rabies
C Brucellosis
D Q fever
E Leptospirosis
F Mycobacterium marinium
G Lyme disease
H Cat scratch disease
I Rocky mountain spotted fever

A 45-year-old man has returned to the UK from a holiday to France. A week
later he presents with flu-like symptoms, drenching sweats, a recurring fever
and is beginning to complain of a lower back pain. He admits to have brought
back some local cheeses on visits to regional farms.

A

C Brucellosis

Brucellosis (C) is a Gram-negative rod-shaped bacterium that is harboured
by cattle (Brucella abortus), goats (B. melitensis), pigs (B. suis) and dogs
(B. canis). Brucella spp. are transmitted by inhalation, unpasteurized dairy produce and direct contact with animals. Symptoms include fever,
myalgia, arthralgia, tiredness and in chronic cases may be associated with
depression. Diagnosis is made by blood culture on Castaneda medium.
Complications include granulomatous hepatitis (histology of liver
biopsy demonstrates granulomata), endocarditis, oseteomyelitis and
thrombocytopenia.

42
Q
A Psittacosis
B Rabies
C Brucellosis
D Q fever
E Leptospirosis
F Mycobacterium marinium
G Lyme disease
H Cat scratch disease
I Rocky mountain spotted fever

A 36-year-old man presents to his GP with a painful right knee. He states that
he visited the Prairie regions of Canada a month previous to this episode and
states that his wife had mentioned there was a red rash on his back; on examination
a target shaped rash is observed.

A

G Lyme disease

Lyme disease (G) is caused by the spirochaete Borrelia burgdorferi
which is transmitted by the Ixodes ticks harboured by certain species of
mice and deer. Initial symptoms include erythema migrans (a spreading
annular skin lesion with a characteristic target-shaped appearance),
malaise, fever and musculoskeletal pain. Several weeks after the primary
infection, the patient may experience neurological (headache, meningitis
and Bell’s palsy) and cardiac (arrhythmias, myocarditis and pericarditis)
effects. Late features include arthralgia and arthritis.

43
Q
A Psittacosis
B Rabies
C Brucellosis
D Q fever
E Leptospirosis
F Mycobacterium marinium
G Lyme disease
H Cat scratch disease
I Rocky mountain spotted fever

A 38-year-old sewage worker presents to his GP with 1-week history of flulike
symptoms with diarrhoea. A microscopic agglutination test reveals the
diagnosis.

A

E Leptospirosis

Leptospirosis (Weil’s disease; E) is a zoonotic disease caused by
Leptospira interrogans which is harboured by both wild and domestic
animals. It is transmitted via drinking water that has become contaminated
with the urine of infected animals; as a result those involved in
water-sports and sewage workers are at particular risk. Lyme disease is
characterized by an influenza-like disease with/without gastrointestinal
symptoms. Diagnosis can be made by ELISA, PCR or microscopic agglutination
test (MAT). Long-term complications include hepatitis and renal
failure.

44
Q
A Psittacosis
B Rabies
C Brucellosis
D Q fever
E Leptospirosis
F Mycobacterium marinium
G Lyme disease
H Cat scratch disease
I Rocky mountain spotted fever

A 48-year-old man presents to his GP with flu-like symptoms. On examination
the patient has a maculopapular rash on his trunk. The patient also shows an
area where a vague bite mark is visible.

A

I Rocky mountain spotted fever

Rocky Mountain spotted fever (I) is caused by Rickettsia spp. infection,
a Gram-negative genus of bacteria, most prevalent in North and South
America. It is harboured in small wild rodents and domestic animals
(transmitted to humans by ticks). Rickettsia bacteria invade the endothelial
lining of capillaries causing a vasculitis. Clinical features include
headache, fever, myalgia, vomiting and confusion. Late signs include
a rash that is maculopapular and/or petechial on the distal parts of the
limbs which then spreads to the trunk and face. Rocky Mountain spotted
fever may lead to thrombocytopenia, hyponatraemia and/or elevated
liver enzymes.

45
Q
A Psittacosis
B Rabies
C Brucellosis
D Q fever
E Leptospirosis
F Mycobacterium marinium
G Lyme disease
H Cat scratch disease
I Rocky mountain spotted fever

A 34-year-old bird handler presents to his GP with a few days’ history of fever,
mild cough and myalgia. The patient states that his shop had recently taken a
new shipment of parrots from Central America. Giemsa staining of the patient’s
sputum reveals cytoplasmic inclusions.

A

A Psittacosis

Psittacosis (A) is a zoonotic infectious disease caused by Chlamydia psittaci
which is contracted from a wide variety of birds (parrots, pigeons
and cockatiels to name a few). Human symptoms mainly involve a
severe pneumonia (with or without hepatitis). Although the patient may
report mild symptoms, the X-ray will generally appear to show severe
pathology. Diagnosis is made by visualizing cytoplasmic inclusions on
Giemsa or fluorescent antibody stained sputum or biopsy sample.

46
Q
A Rubella
B Syphilis
C Measles
D Hepatitis B
E Mumps
F Listeria monocytogenes
G Cytomegalovirus
H Haemophilus influenzae
I HIV

A 10-year-old boy is brought to see the GP by his mother as he has recently
developed parotid swelling associated with a fever. Blood tests reveal a raised
amylase level. The boy’s mother reveals that his immunization schedule is not
complete as they were living in Tunisia at the time.

A

E Mumps

Mumps (E) is spread by droplets in the air which travel via the lungs
to parotid tissue and subsequently to distant sites. Clinical features of
infection consist of fever, malaise and transient hearing loss. Parotitis
is characteristic of mumps infection with unilateral or bilateral swelling
and pain on chewing. Plasma amylase levels may be elevated as a result
of inflammation of the salivary glands. Complications such as viral
meningitis, orchitis/oophoritis, mastitis and arthritis may result from
long-standing infection. The MMR vaccine given at 12–18 months has
drastically reduced the incidence of mumps.

47
Q
A Rubella
B Syphilis
C Measles
D Hepatitis B
E Mumps
F Listeria monocytogenes
G Cytomegalovirus
H Haemophilus influenzae
I HIV

A 3-week-old baby develops vomiting and is feeding poorly. On examination he
has a reduced level of consciousness and an arched back. Analysis of the CSF
reveals the presence of Gram-positive rods.

A

F Listeria monocytogenes

Listeria monocytogenes (F) is a β-haemolytic anaerobic Gram-positive
rod that can cause meningitis in the neonate to 3 months age group.
Listeria monocytogenes may be transmitted vertically from mother to
baby in utero (due to the ingestion of infected food by the mother) or
during birth (transvaginal transfer). Early signs of meningitis are nonspecific
in the age group affected (fever, poor feeding, vomiting, seizures
and reduced consciousness) whereas late signs include a bulging
fontanelle, neck stiffness, opisthotonos (arched back), Brudzinski and
Kernig signs positive as well as meningococcaemia.

48
Q
A Rubella
B Syphilis
C Measles
D Hepatitis B
E Mumps
F Listeria monocytogenes
G Cytomegalovirus
H Haemophilus influenzae
I HIV

A 3-year-old girl presents to the GP with a cough, fever and runny nose. On
examination, the child has white spots scattered on the buccal mucosa. Her
mother admits that she denied her child a certain vaccine due to scares presented
by the media.

A

C Measles

Measles (C) is a viral respiratory system infection caused by the genus
Morbillivirus. Infection presents with cough, coryza, conjunctivitis and/
or a discrete maculopapular rash. White spots on the buccal mucosa
(Koplik spots) are pathognomonic for measles. Complications of measles
infection may involve the respiratory (pneumonia and tracheitis) and
neurological (febrile convulsions and encephalitis) systems. Subacute
sclerosing panencephalitis (SSPE) may occur several years after the primary
infection; infection persists in the central nervous system leading
to loss of neurological function, dementia and eventually death.

49
Q
A Rubella
B Syphilis
C Measles
D Hepatitis B
E Mumps
F Listeria monocytogenes
G Cytomegalovirus
H Haemophilus influenzae
I HIV

A 4-year-old boy presents to accident and emergency with a reduced level of
consciousness, headache and neck stiffness. Analysis of the CSF reveals the presence
of Gram-negative rods. The child’s mother reveals that his immunization
record is not complete as they have only migrated from Ethiopia recently.

A

H Haemophilus influenzae

Haemophilus influenzae (H) is a Gram-negative rod shaped bacterium
that causes meningitis in children older than 3 months who have not
been vaccinated. Other organisms that cause meningitis in older children
include Streptococcus pneumoniae and Neisseria meningitidis.
Diagnosis involves culture of the bacteria using chocolate agar, with
subsequent Gram-stain and microscopy. Latex particle agglutination and
PCR are more sensitive and specific investigative tests. The Haemophilus
influenzae type B (Hib) vaccine has dramatically reduced Hib-related
meningitis; the first dose is given when the child is 8 weeks old.

50
Q
A Rubella
B Syphilis
C Measles
D Hepatitis B
E Mumps
F Listeria monocytogenes
G Cytomegalovirus
H Haemophilus influenzae
I HIV

An 8-month old girl is seen by a paediatrician due to concerns about
developmental delay. On examination cataracts are noted in both eyes.
Echocardiography reveals a patent ductus arteriosus.

A

A Rubella

Rubella (German measles; A) is a viral infection which can be congenital
or acquired. Congenital rubella syndrome (CRS) occurs in a developing
fetus if the mother has contracted rubella in her first trimester. CRS
is characterized by sensorineural deafness, eye abnormalities (cataracts,
glaucoma, retinopathy) and congenital heart disease (patent ductus
arteriosus). Other associations include microcephaly and developmental
delay. Acquired rubella is transmitted via the respiratory route.
Characteristically, a rash appears on the face which spreads to the trunk
and disappears after a few days.