Gram-positive

• Purple stain, thick cell wall

Gram positive cocci

• Staphylococcus. spp, Streptococcus spp., Enterococcus

Gram positive bacilli/rod

• Clostridium tetani (toxin)

• Corynyebacterium diphtheriae (toxin)

• Bacillus anthrax

• Listeria

Acid fast bacilli

• Mycobacterium tuberculosis

• Mycobacterium leprae

• Non-tuberculous mycobacteria

Branching

• Actinomyces, Nocardia

No cell wall

• Mycoplasma

Gram negative

Gram negative diplococci

• Neisseria meningitidis, Neisseria gonorrhoea, moraxella catarrhalis

Gram negative bacilli/rods

• Enteric: Shigella, Salmonella, Yersinia

• Respiratory: Haemophilus influenzae, bordatella, legionella

• Opportunistic: pseudomonas

• Anaerobic:

Spiral

• Campylobacter, Helicobacter

Comma

• Vibrio

Spirochaetes

• Borrelia

• Leptospira

• Treponema pallidum, 

Extended-spectrum beta-lactamases (ESBL)

• Gram-negative bacteria that produce an enzyme beta-lactamase that breaks down commonly used antibiotics (e.g. penicillin, cephalosporins), and requires carbapenems (e.g. meropenem)