EMQs in Clinical Medicine.pdf - Peshawar Medical College

Infections – answers 243
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This is presentation of pulmonary tuberculosis. Treatment is started
empirically if acid-fast bacilli (AFBs) are seen on Ziehl–Neelsen staining.
Culture results (which take much longer) can be used to modify therapy
if any bacterial resistance to medication is detected.
A 45-year-old man rescued from a mountaineering accident presents
with an open fracture of the tibia. He is in severe pain and the lower
left limb is cold and pulseless. The muscles of the distal limb are
brownish-black in colour.
This is a presentation of gas gangrene. Clostridium perfringens, which
thrives in the relative anaerobic conditions of necrotic tissue, is the most
common infecting organism. Gas gangrene may be rapidly lethal as a result
of the fact that the toxins may have both local and systemic effects, e.g.
toxin has local lytic effects on erythrocytes, inflammatory and muscle cells,
but can also contribute to hypotension. Severe pain is always a prominent
feature. There are characteristic changes in the colour of the overlying skin
to a blue–black colour and the appearance of blebs that discharge watery
fluid and later blood. The classically described crepitus of gas gangrene is a
late feature and often masked by the coexistent oedema.
Gas gangrene is a medical and surgical emergency requiring surgical
débridement (amputation is sometimes indicated) and appropriate
antibiotic therapy to cover both aerobic and anaerobic organisms.
A 41-year-old sewer worker presents with fever, jaundice and
reddened conjunctivae.
This is a presentation of leptospirosis which is a zoonosis caused by
infection with the Gram-negative bacterium Leptospira interrogans.
Although commonly referred to as Weil’s disease, the latter term was
actually used to describe the clinical presentation of jaundice, renal
failure and haemorrhage (pulmonary haemorrhage in the original
description). This is a severe presentation carrying a 10 per cent mortality
rate. In reality there is a wide variation in severity and many cases are
probably not diagnosed.
There are two phases of infection: an initial acute phase and a secondary
immune phase.
The first phase of infection is characterized by symptoms associated with
proliferation and invasion of the leptospires (e.g. fever, headache,
reddened conjunctivae). The second phase is characterized by rising
antibody titres, with aseptic meningitis being a common finding. It is
during this immune phase that jaundice, hepatomegaly and renal failure
may develop, resulting in Weil’s disease.
Leptospires are sensitive to penicillin treatment.
A 12-year-old boy presents a few days after a sore throat with a
punctate, erythematous generalized rash that spares his face. He has a
‘strawberry tongue’.