Pathogenic microbiology lab

i. Selective based on the ability to select for gram negative enteric bacteria

ii. Differential based on the ability of bacteria to ferment lactose.

indistinct zone of partial destruction of red blood cells around colony. Characteristic greenish-brown discoloration of blood agar.

characterized by a clear zone around the colonies complete with destruction of blood cells and decoloring of the medium from red to colorless.

also known as Butyrate esterase disks are paper disks containing bromo-chloro-indolyl butyrate. Most M. catarrhalis strains will make the enzyme butyrate esterase which hydrolyses the substrate and releases indoxyl.

is critical for the separation of Campylobacter jejuni (hydrolyzes Hippurate) and Campylobacter coli (negative). This test is used to detect the ability of bacteria to hydrolyse Hippurate into glycine and benzoic acid by action of hippuricase enzyme.

used to identify group B Streptococci (Streptococcus agalactiae). Group B Streptococci release an extracellular factor (called CAMP factor) to enhance hemolytic activity of the beta-­lysin produced by Staphylococcus aureus.