Bacteria

Gram-positive

  • Purple stain, thick cell wall

Gram positive cocci

  • Staphylococcus. spp, Streptococcus spp., Enterococcus

Gram positive bacilli/rod

Acid fast bacilli

Branching

  • Actinomyces, Nocardia

No cell wall

  • Mycoplasma

Gram negative

Gram negative diplococci

Gram negative bacilli/rods

  • Enteric: Shigella, Salmonella, Yersinia

  • Respiratory: Haemophilus influenzae, bordatella, legionella

  • Opportunistic: pseudomonas

  • Anaerobic:

Spiral

  • Campylobacter, Helicobacter

Comma

  • Vibrio

Spirochaetes

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)