WEEK 1 - CLASSICAL DIAGNOSTIC MICROBIOLOGY
class 07


Bacitracin sensitive, Group A streptococcus isolate, showing (beta) haemolysis around colonies on a Horse Blood Agar (HBA) plate.

Backlighting to show the haemolysis more clearly.
Throat swab culture on HBA plate (24hr, 37C, aerobic). Left picture is taken from above. Right picture is taken from the back of the plate. Note the haemolytic colonies compared to those that cause greening.

Left:'Streptex' Lancefield grouping test, gp A isolate.

Right: Catalase test. Staphylococcus +ve control at left. GAS isolate at right.


 
Gram strain
Antibiotic sensitivity plate assay, before incubation
Antibiotic sensitivity plate. GAS isolate on sensitest blood agar plate. After incubation 24 hr, 37C. The bacterial lawn is easily seen in the left picture, while the non-haemolysed zones of growth inhibition are seen clearly in the right picture.
ab. sens. test
Reflected light
ab. sens. test. trans.
Light from behind

 





Web page by MDS, 2007