Urine Culture

Urine Gram Stain

Urine Culture Quantitation Clean catch or catheterized urine Plate = 1000 organisms/ml Clean catch: >105 orgs/ml Suprapubic urine Any colony is significiant

Urine Cultures 1. Plates initially read at 18-24 hr 2. All specimens plated after NOON of the previous day, hold another overnight 3. Gram positives take longer to grow

Most Common Pathogens of Human Urinary Tract Community acquired E. coli is most frequent pathogen isolated Klebsiella sp and other Enterobacteriaceae Staphylococcus saprophyticus Hospital acquired E. coli, Klebsiella, other Enterobacteriaceae Pseudomonas aeruginosa Enterococci and Staphylococci

Abbreviated Identification E. coli Non-swarming, spot indole pos, oxidase neg Lactose positive (MacConkey or eosin methylene blue), PYR (pyrrolidonyl arylamidase) test positive 2. API

Abbreviated Identification Proteus spp. Swarming growth Indole Negative: P. mirabilis/penneri P. mirabilis: maltose neg, ornithine pos P. penneri: maltose pos, ornithine neg Positive: P. vulgaris

Abbreviated Identification P. aeruginosa Oxidase-positive bacillus Typical smell (grapes) Colony morphology P. aeruginosa: metallic/pearlescent, rough, pigmented, mucoid Indole-negative

Abbreviated Identification CHROMagar Orientation Presumptive ID for some UTI pathogens E. coli (dark rose to pink) Enterococci (turquoise blue) S. saprophyticus (light pink to rose) S. agalactiae (light blue-green to light blue) Proteus-Morganella-Providencia group (brown) Klebsiella-Enterobacter-Serratia group (dark blue) Issues and challenges All except E. coli and enterococci require further ID Small E. coli colonies require spot indole Poor growth of some gram-positive bacteria Nonselective– other pathogens may or may not produce color change

Abbreviated Identification Enterococcus spp. Cocci or coccobacilli in pairs and chains >1 mm colonies Non-hemolytic on SBA Catalase-negative PYR-positive (pyrrolidonyl-a-naphthylamide hydrolysis)

Abbreviated Identification S. agalactiae (GBS) Cocci in pairs and chains Catalase-negative Narrow zone of beta-hemolysis on SBA Rapid hippurate hydrolysis test (beta strep only) OR Test for CAMP factor (spot or O/N) OR Typing by particle agglutination R/O beta hemolytic Enterococcus (PYR+) b-hem Enterococcus

Abbreviated Identification Yeast Candida albicans Microscopy required: oval, budding yeast Colonies <48 h old on blood-containing medium with “feet” or mycelial projections *CHROMagar

Abbreviated Identification Candida CHROMagar

Why females has higher incidence of UTI?? Short urethra Anus nearby urethra contraceptives

Now to the lab…