Different species of Neisseria can utilize different carbohydrates. The ability to utilize a specific carbohydrate can help to determine the species.
Isolate selection: Neisseria species
The isolate is inoculated into separate tubes of media, each with a different carbohydrate. The carbohydrate is the only energy source in each tube. The tubes are incubated for 4 hours, then read.
Positive reaction: color indicator for acid production (yellow for phenol red)
Negative reaction: color indicator unchanged (red for phenol red)
Carbohydrate
Neisseria species
glucose
N. gonorrhoeae
maltose
N. meningitidis
lactose
N. lactamica
sucrose and fructose
N. mucosa
Causes of a false positive reaction:
(1) mixed isolate
(2) use of non-reagent grade carbohydrate source contaminated with another carbohydrate (for example glucose within maltose
Cause of a false negative reaction:
(1) failure to add the carbohydrate to the tube
To read more or access our algorithms and calculators, please log in or register.
