Labratory - The Infectious Agent Flashcards
How are infectious agents classified
Morphological features
Orientating the culture plate
The label is on the base where the agar is
Horse blood agar
Differential medium that supports the growth of more fastidious bacteria and is differential by haemolysis
Mannitol salt agar
Selective and differential medium promoting the growth of salt tolerant staphylococci
Gram positive cells
Purple crystal violet stains the outer layer
Gram-negative cells
Pink stain bc of the peptidoglycan layer which is too thick to retain the crystal violet
Nutrient agar and horse blood agar will facilitate
The growth of all non fastidious bacteria - therefore producing several distinct colonies morphologies for each species in the mix
Mannitol salt agar and macconkey agar
Have inhibitory effect on many species whilst promoting growth of others these medias allow for distinguishing differences in groups
Fungi require the same or different growth conditions too bacteria
Most require different
What is the primary culture medium for fungi
Sabouraud dextrose agar - low pH to support fungal growth whist inhibit bacterial
Also at a lower temperature
Filamentous fungi appearance
Furry appearance and colony morphology is described for the base and surface of the colony
Yeast culture
Larger diameter than bacteria and appear waxy
Non selective media type description and example
Nutrient agar - supports the growth of many different bacteria including the endogenous microbiota and bacterial pathogens
Differential media type description and example
Horse blood agar or mannitol salt agar
Distinguishes between bacteria by metabolic reactions
Selective culture media description and example
Mannitol salt agar (NaCl) - supports the growth of target pathogens but in bits growth of non target bacteria
