Other
infections
Cutaneous anthrax
This
condition is usually acquired through contact with infected livestock or animal
products such as wool
Previously rare in industrialized countries, its importance has
increased there since the recent wave of bio-terrorist attacks. The spores of Bacillusanthracis,
the causative organism, are highly resistantto physical and chemical agents.
Anthrax
has two main clinical variants: inhalational anthrax, which is outside the
scope of this book; and cutaneous anthrax. The incubation period of the latter
is usually between 2 and 5 days. A skin lesion then appears on an exposed part,
often in association with a variable degree of cutaneous oedema, which can
sometimes be massive, especially on the face. Within a day or two, the original
small painless papule shows vesicles that quickly coalesce into a larger single
blister. This ruptures to form an ulcer with a central dark eschar, which falls
off after 1–2 weeks leaving a scar. The skin lesions are often accompanied by
fever, headache, myalgia and regional lymphadenopathy. The mortality rate for
untreated cutaneous anthrax is up to 20%; with appropriate antibiotic
treatment, this falls to less than 1%.
Cultures
of material taken from the vesicle may be positive in 12– 48 h; a Gram stain
will show Gram-positive bacilli, occurring singly or in short chains. Quicker
results may be obtained by a direct fluorescent antibody test, or by an
enzyme-linked immuno-absorbant assay (ELISA)aboth of which are currently
available only at reference laboratories. Before the results are available, it
is wise to assume that the organism is penicillin- and tetracycline-resistant,
and to start treatment with ciprofloxacin at 400 mg intra-venously every 12 h
or, for milder cases, ciprofloxacin 50
mg orally every 12 h. The latter dose is suitable for prophylactic use
in those who are known to have been exposed to spores. A switch to an
alternative regimen can be made once the antibiotic sensitivity of the
organ-ism has been established. At present, anthrax vaccine is in short supply;
it requires six injections over 18 months, with subsequent boosters, to prevent
anthrax.
Skin
lesions are important clues to the diagnosis of this condition, in which the
symptoms and signs of classical gonorrhoea are usually absent. The patient,
usually a woman with recurring fever and joint pains, develops sparse crops of
skin lesions, usually around the hands and feet. The grey, often haemorrhagic,
vesicopustules are characteristic. Rather similar lesions are seen in chronic
meningococcal septicaemia.
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