ABSTRACT
The microbiology station is a relatively recent addition to the Membership of the Royal College of Surgeons (MRCS) Part B objective structured clinical examination (OSCE). This chapter covers the common topics that candidates are expected to be familiar with for the exam. They are gram staining, mycobacteria, Human immunodeficiency virus (HIV), necrotising fasciitis, clostridia group of organisms, staphylococci, streptococci, Methicillin-Resistant Staphylococcus Aureus (MRSA), pseudomonas, infective endocarditis and taking blood cultures. The principal molecules in the outer membrane of Gram-negative bacteria are lipopolysaccharides. These structural differences form the basis of the Gram stain. Mycobacteria are obligate aerobic, rod-shaped, non-spore forming, non-motile bacilli with a waxy coat that causes them to retain certain stains after being treated with acid and alcohol; they are therefore known as acid–alcohol-fast bacilli. Necrotising fasciitis is a rapidly progressive inflammatory infection of the fascia, with secondary necrosis of the subcutaneous tissues.
