What colour do Gram positive bacteria stain?
Purple
What colour do Gram negative bacteria stain?
Pink
What does the catalase test show?
It differentiates between Staph (catalase positive) and Strep (catalase negative)
What is gamma haemolysis?
No haemolysis
What is alpha haemolysis?
Partial haemolysis?
What is beta haemolysis?
Complete haemolysis
What test differentiates between beta haemolytic strep?
Lancefield grouping
What bacteria is group A strep?
Streptococcus pyogenes
What bacteria is optochin resistant?
Strep. viridans
What bacteria is optochin sensitive?
Strep. pneumoniae
What is the coagulase test for?
To differentiate between Staph
What colour colonies are Staph. aureus?
Golden on blood agar
What bacteria test coagulase positive?
S. aureus
What bacteria test coagulase negative?
S. epidermidis
What test narrows down which Gram negative bacteria is growing?
Lactose fermenting - MacConkey agar or CLED agar or XLD
Name some important lactose fermenters
E. coli
Name some important non-lactose fermenters
Salmonella, Yersinia, Shigella
Under the microscope after Gram staining, it is reported that the organism from the sample you sent is Gram negative. What organism are you worried about?
Neisseria meningitidis
What is infective endocarditis?
An infection of the endocardial lined structures e.g. heart valves
What organisms commonly cause infective endocarditis?
Strep. viridans, S. aureus, S. epidermidis
What are the clinical features of infective endocarditis?
Fever Splinter haemorrhages Janeway lesions Osler's nodes Roth spots New murmur Malaise Symptoms of septic emboli e.g. stroke, PE, pneumonia
What agar is used to grow H. influenzae?
Chocolate agar.
Factors X and V are released which H. influenzae to grow
