A 34-year-old abattoir worker presents to the Emergency Department following the development of black skin lesions. On examination a black eschar is noted with extensive surrounding oedema. A diagnosis of cutaneous anthrax is suspected.
What is the most appropriate initial antibiotic therapy until sensitivities are known?
Correct Answer A: The current Health Protection Agency advice for the initial management of cutaneous anthrax is ciprofloxacin.
Anthrax:
Anthrax is caused by Bacillus anthracis, a Gram positive rod. It is spread by infected carcasses. It is also known as Woolsorters' disease. Bacillus anthracis produces a tripartite protein toxin:
Features:
Management:
A 23-year-old man has a Mantoux test prior to receiving the BCG vaccine. He develops a 12 mm indurated lesion on his forearm.
Which one of the following cytokines is most involved in this response?
Correct Answer B: Tuberculin skin tests are an example of type IV (delayed) hypersensitivity reactions. These are largely mediated by interferon-γ secreted by Th1 cells which in turn stimulates macrophage activity.
Tuberculosis: screening:
The Mantoux test is the main technique used to screen for latent tuberculosis. In recent years the interferon-gamma blood test has also been introduced. It is used in a number of specific situations such as:
Mantoux test:
False negative tests may be caused by:
Heaf test:
The Heaf test was previously used in the UK but has been since been discontinued. It involved injection of PPD equivalent to 100,000 units per ml to the skin over the flexor surface of the left forearm. It was then read 3-10 days later.
Which one of the following is a Gram positive coccus?
Correct Answer A:
Classification of bacteria:
Remember:
Therefore, only a small list of Gram positive rods (bacilli) need to be memorized to categorize all bacteria - mnemonic = ABCD L:
Remaining organisms are Gram negative rods.
A 25-year-old man with a history of epilepsy presents for advice regarding malarial prophylaxis. Next month he plans to travel to Vietnam. His trip will take him to some of the costal tourist destinations but he also plans to travel inland.
What is the most appropriate medication to prevent him developing malaria?
Correct Answer B: In certain parts of South-East Asia there is widespread chloroquine resistance. Chemoprophylaxis using atovaquone + proguanil (Malarone), mefloquine (Lariam) or doxycycline is therefore recommended. Mefloquine should be avoided in this patient due to his history of epilepsy.
Malaria: prophylaxis:
There are around 1,500-2,000 cases each year of malaria in patients returning from endemic countries. The majority of these cases (around 75%) are caused by the potentially fatal Plasmodium falciparum protozoa. The majority of patients who develop malaria did not take prophylaxis. It should also be remembered that UK citizens who originate from malaria endemic areas quickly lose their innate immunity.
Up-to-date charts with recommended regimes for malarial zones should be consulted prior to prescribing:
Pregnant women should be advised to avoid travelling to regions where malaria is endemic. Diagnosis can also be difficult as parasites may not be detectable in the blood film due to placental sequestration. However, if travel cannot be avoided:
It is again advisable to avoid travel to malaria endemic regions with children if avoidable. However, if travel is essential then children should take malarial prophylaxis as they are more at risk of serious complications:
Which one of the following statements regarding toxoplasmosis is true?
Correct Answer E:
Toxoplasmosis: Toxoplasma gondii is a protozoa which infects the body via the GI tract, lung or broken skin. It's oocysts release trophozoites which migrate widely around the body including to the eye, brain and muscle. The usual animal reservoir is the cat, although other animals such as rats carry the disease.
Most infections are asymptomatic. Symptomatic patients usually have a self-limiting infection, often having clinical features resembling infectious mononucleosis (fever, malaise, lymphadenopathy). Other less common manifestations include meningoencephalitis and myocarditis.
Investigation:
Treatment is usually reserved for those with severe infections or patients who are immunosuppressed:
Congenital toxoplasmosis is due to transplacental spread from the mother. It causes a variety of effects to the unborn child including microcephaly, hydrocephalus, cerebral calcification and choroidoretinitis.
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