Table 1. Supplemental tests which permit differentiation among common gram negative diplococcus (GND).
| GND | Oxidase test | Catalase reaction | DNAse test | Nitrate reduction | Acid from |
Colistin susceptibility | |||
|---|---|---|---|---|---|---|---|---|---|
| G | M | L | S | ||||||
| N. flavescens | + | Weak | – | – | – | – | – | – | S |
| N. gonorrhoeae | + | Srong | – | – | + | – | – | – | R |
| N. meningitides | + | Strong | – | – | + | + | – | – | R |
| M. catarrhalis | + | Variable | + | + | – | – | – | – | R |
Abbreviations: +, most strains positive; –, most strains negative; R, strains grow well on selective medium for N. gonorrhoeae and/or show no inhibition around a colistin disk (ten micrograms); acid from G (glucose), M (maltose), L (lactose), S (sucrose).