in 1984 the Gram stain was developed by Hans Christian Gram as told by my brother , and the bacteria are generally classified into Gram +ve and gram -ve and additional group wich no comes under those two categories .
The proteobacteria are a major group of Gram-negative bacteria, including Escherichia coli,
and other Enterobacteriaceae,
acetic acid bacteria,
alpha-proteobacteria as Wolbachia and many others. Other notable groups of Gram-negative bacteria include the
green sulfur and green non-sulfur bacteria.
Medically relevant Gram-negative cocci include three organisms, which cause a sexually transmitted disease (Neisseria gonorrhoeae), a meningitis (Neisseria meningitidis), and respiratory symptoms (Moraxella catarrhalis).
Medically relevant Gram-negative bacilli include a multitude of species. Some of them primarily cause respiratory problems (Hemophilus influenzae, Klebsiella pneumoniae, Legionella pneumophila, Pseudomonas aeruginosa), primarily urinary problems (Escherichia coli, Proteus mirabilis, Enterobacter cloacae, Serratia marcescens), and primarily gastrointestinal problems (Helicobacter pylori, Salmonella enteritidis, Salmonella typhi).
Gram negative bacteria associated with nosocomial infections include Acinetobacter baumannii, which cause bacteremia, secondary meningitis, and ventilator-associated pneumonia in intensive care units of hospital establishments.
Gram Positive bacteria
the Gram-positive organisms made up the phylum Firmicutes, a name now used for the largest group.
It includes many well-known such as:
Corynebacterium diptheriae ,
Sarcina and many others..
It has also been expanded to include the Mollicutes, bacteria like Mycoplasma that lack cell walls and cannot be Gram stained, but are derived from such forms.
Actinobacteria are the other major group of Gram-positive bacteria, which have a high guanosine and cytosine content in their genomes (high G+C group). This contrasts with the Firmicutes, which have a low G+C content.
Other major groups: which includes Acid-fast rods ,Spiral organisms,Small pleomorphicand small intracellular parasites .
I hope i tried my best and i can feel i left more and more on the classification of bacteria ... but that is what i tried to collect,....