1. Urine Culture

2. Urine Gram Stain

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

4. 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

5. 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

6. 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

7. 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

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

9. 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

10. 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)

11. 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

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

13. Abbreviated Identification
Candida CHROMagar

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

15. Now to the lab…