E coli: Leading cause of UTI. Colonies show green metallic sheen on EMB agar

Staphylococcus saphrolyticus: 2nd leading cause of UTI in sexually active women

Klebsiella pneumoniae: 3rd leading cause of UTI. Large mucoid capsule.

Proteus mirabillis: Motility causes "swarming" on agar; produces urease; associated with struvite stones

Diagnostic markers:- Leukocyte esterase = evidence of WBC activity- Nitrate test = reduction of urinary nitrates by bacterial species (E. coli)- Urease test = urease-producing bugs (S saphrolyticus, Proteus, Klebsiella)